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Sample records for cavity quantum cascade

  1. Analysis of Trace Gas Mixtures Using an External Cavity Quantum Cascade Laser Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Mark C.; Taubman, Matthew S.; Brumfield, Brian E.; Kriesel, Jason M.

    2015-07-01

    We measure and analyze mixtures of trace gases at ppb-ppm levels using an external cavity quantum cascade laser sensor with a 1-second response time. Accurate spectral fits are obtained in the presence of overlapping spectra.

  2. Rapid Swept-Wavelength External Cavity Quantum Cascade Laser for Open Path Sensing

    Energy Technology Data Exchange (ETDEWEB)

    Brumfield, Brian E.; Phillips, Mark C.

    2015-07-01

    A rapidly tunable external cavity quantum cascade laser system is used for open path sensing. The system permits acquisition of transient absorption spectra over a 125 cm-1 tuning range in less than 0.01 s.

  3. Electrically tunable terahertz quantum cascade lasers based on a two-sections interdigitated distributed feedback cavity

    Energy Technology Data Exchange (ETDEWEB)

    Turčinková, Dana; Scalari, Giacomo; Beck, Mattias; Faist, Jérôme [ETH Zurich, Institute for Quantum Electronics, Auguste-Piccard-Hof 1, 8093 Zurich (Switzerland); Amanti, Maria Ines [ETH Zurich, Institute for Quantum Electronics, Auguste-Piccard-Hof 1, 8093 Zurich (Switzerland); Univ. Paris Diderot, Lab. Matererk iaux et Phenomenes Quantiques, F-75205 Paris (France)

    2015-03-30

    The continuous electrical tuning of a single-mode terahertz quantum cascade laser operating at a frequency of 3 THz is demonstrated. The devices are based on a two-section interdigitated third-order distributed feedback cavity. The lasers can be tuned of about 4 GHz at a constant optical output power of 0.7 mW with a good far-field pattern.

  4. Active mode locking of quantum cascade lasers operating in external ring cavity

    CERN Document Server

    Revin, D G; Wang, Y; Cockburn, J W; Belyanin, A

    2015-01-01

    Stable ultrashort light pulses and frequency combs generated by mode-locked lasers have many important applications including high-resolution spectroscopy, fast chemical detection and identification, studies of ultrafast processes, and laser metrology. While compact mode-locked lasers emitting in the visible and near infrared range have revolutionized photonic technologies, the systems operating in the mid-infrared range where most gases have their strong absorption lines, are bulky and expensive and rely on nonlinear frequency down-conversion. Quantum cascade lasers are the most powerful and versatile compact light sources in the mid-infrared range, yet achieving their mode locked operation remains a challenge despite dedicated effort. Here we report the first demonstration of active mode locking of an external-cavity quantum cascade laser. The laser operates in the mode-locked regime at room temperature and over the full dynamic range of injection currents of a standard commercial laser chip.

  5. Standoff Hyperspectral Imaging of Explosives Residues Using Broadly Tunable External Cavity Quantum Cascade Laser Illumination

    Energy Technology Data Exchange (ETDEWEB)

    Bernacki, Bruce E.; Phillips, Mark C.

    2010-05-01

    We describe experimental results on the detection of explosives residues using active hyperspectral imaging by illumination of the target surface using an external cavity quantum cascade laser (ECQCL) and imaging using a room temperature microbolometer camera. The active hyperspectral imaging technique forms an image hypercube by recording one image for each tuning step of the ECQCL. The resulting hyperspectral image contains the full absorption spectrum produced by the illumination laser at each pixel in the image which can then be used to identify the explosive type and relative quantity using spectral identification approaches developed initially in the remote sensing community.

  6. Diffraction coupled phase-locked arrays of quantum cascade lasers with monolithically integrated Talbot cavities

    CERN Document Server

    Wang, Lei; Jia, Zhi-Wei; Zhao, Yue; Liu, Chuan-Wei; Liu, Ying-Hui; Zhai, Shen-Qiang; Zhuo, Ning; Liu, Feng-Qi; Xu, Xian-Gang

    2016-01-01

    Diffraction coupled arrays of quantum cascade laser are presented. The phase-locked behavior is achieved through monolithic integration of a Talbot cavity at one side of the laser array. The principle is based on fractional Talbot effect. By controlling length of Talbot cavity to be a quarter of Talbot distance (Zt/4), in-phase mode operation is selected. Measured far-field radiation patterns reflect stable in-phase mode operation under different injection currents, from threshold current to full power current. Diffraction-limited performance is shown from the lateral far-field, where three peaks can be obtained and main peak and side peak interval is 10.5{\\deg}. The phase-locked arrays with in-phase mode operation may be a feasible solution to get higher output power and maintain well beam quality meanwhile.

  7. Trace-gas sensing using the compliance voltage of an external cavity quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Mark C.; Taubman, Matthew S.

    2013-06-04

    Quantum cascade lasers (QCLs) are increasingly being used to detect, identify, and measure levels of trace gases in the air. External cavity QCLs (ECQCLs) provide a broadly-tunable infrared source to measure absorption spectra of chemicals and provide high detection sensitivity and identification confidence. Applications include detecting chemical warfare agents and toxic industrial chemicals, monitoring building air quality, measuring greenhouse gases for atmospheric research, monitoring and controlling industrial processes, analyzing chemicals in exhaled breath for medical diagnostics, and many more. Compact, portable trace gas sensors enable in-field operation in a wide range of platforms, including handheld units for use by first responders, fixed installations for monitoring air quality, and lightweight sensors for deployment in unmanned aerial vehicles (UAVs). We present experimental demonstration of a new chemical sensing technique based on intracavity absorption in an external cavity quantum cascade laser (ECQCL). This new technique eliminates the need for an infrared photodetector and gas cell by detecting the intracavity absorption spectrum in the compliance voltage of the laser device itself. To demonstrate and characterize the technique, we measure infrared absorption spectra of chemicals including water vapor and Freon-134a. Sub-ppm detection limits in one second are achieved, with the potential for increased sensitivity after further optimization. The technique enables development of handheld, high-sensitivity, and high-accuracy trace gas sensors for in-field use.

  8. External cavity-quantum cascade laser (EC-QCL) spectroscopy for protein analysis in bovine milk.

    Science.gov (United States)

    Kuligowski, Julia; Schwaighofer, Andreas; Alcaráz, Mirta Raquel; Quintás, Guillermo; Mayer, Helmut; Vento, Máximo; Lendl, Bernhard

    2017-04-22

    The analytical determination of bovine milk proteins is important in food and non-food industrial applications and yet, rather labour-intensive wet-chemical, low-throughput methods have been employed since decades. This work proposes the use of external cavity-quantum cascade laser (EC-QCL) spectroscopy for the simultaneous quantification of the most abundant bovine milk proteins and the total protein content based on the chemical information contained in mid-infrared (IR) spectral features of the amide I band. Mid-IR spectra of protein standard mixtures were used for building partial least squares (PLS) regression models. Protein concentrations in commercial bovine milk samples were calculated after chemometric compensation of the matrix contribution employing science-based calibration (SBC) without sample pre-processing. The use of EC-QCL spectroscopy together with advanced multivariate data analysis allowed the determination of casein, α-lactalbumin, β-lactoglobulin and total protein content within several minutes.

  9. Mid-infrared gas absorption sensor based on a broadband external cavity quantum cascade laser

    Science.gov (United States)

    Sun, Juan; Deng, Hao; Liu, Ningwu; Wang, Hongliang; Yu, Benli; Li, Jingsong

    2016-12-01

    We developed a laser absorption sensor based on a pulsed, broadband tunable external cavity quantum cascade laser (ECQCL) centered at 1285 cm-1. Unlike traditional infrared spectroscopy system, a quartz crystal tuning fork (QCTF) as a light detector was used for laser signal detection. Fast Fourier transform was applied to extract vibration intensity information of QCTF. The sensor system is successfully tested on nitrous oxide (N2O) spectroscopy measurements and compared with a standard infrared detector. The wide wavelength tunability of ECQCL will allow us to access the fundamental vibrational bands of many chemical agents, which are well-suited for trace explosive, chemical warfare agent, and toxic industrial chemical detection and spectroscopic analysis.

  10. Use of external cavity quantum cascade laser compliance voltage in real-time trace gas sensing of multiple chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Mark C.; Taubman, Matthew S.; Kriesel, Jason M.

    2015-02-08

    We describe a prototype trace gas sensor designed for real-time detection of multiple chemicals. The sensor uses an external cavity quantum cascade laser (ECQCL) swept over its tuning range of 940-1075 cm-1 (9.30-10.7 µm) at a 10 Hz repetition rate.

  11. Radiocarbon Dioxide detection based on Cavity Ring-Down Spectroscopy and a Quantum Cascade Laser

    CERN Document Server

    Genoud, Guillaume; Phillips, Hilary; Dean, Julian; Merimaa, Mikko

    2015-01-01

    Monitoring of radiocarbon ($^{14}$C) in carbon dioxide is demonstrated using mid-infrared spectroscopy and a quantum cascade laser. The measurement is based on cavity ring-down spectroscopy, and a high sensitivity is achieved with a simple setup. The instrument was tested using a standardised sample containing elevated levels of radiocarbon. Radiocarbon dioxide could be detected from samples with an isotopic ratio $^{14}$C/C as low as 50 parts-per-trillion, corresponding to an activity of 5 kBq/m$^3$ in pure CO$_2$, or 2 Bq/m$^3$ in air after extraction of the CO$_2$ from an air sample. The instrument is simple, compact and robust, making it the ideal tool for on-site measurements. It is aimed for monitoring of radioactive gaseous emissions in nuclear power environment, during the operation and decommissioning of nuclear power plants. Its high sensitivity also makes it the ideal tool for the detection of leaks in radioactive waste repositories.

  12. Demonstration of a rapidly-swept external cavity quantum cascade laser for atmospheric sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.; Suter, Jonathan D.

    2016-07-01

    The application of quantum cascade lasers (QCLs) in atmospheric science for trace detection of gases has been demonstrated using sensors in point or remote sensing configurations. Many of these systems utilize single narrowly-tunable (~10 cm-1) distributed feedback (DFB-) QCLs that limit simultaneous detection to a restricted number of small chemical species like H2O or N2O. The narrow wavelength range of DFB-QCLs precludes accurate quantification of large chemical species with broad rotationally-unresolved vibrational spectra, such as volatile organic compounds, that play an important role in the chemistry of the atmosphere. External-cavity (EC-) QCL systems are available that offer tuning ranges >100 cm-1, making them excellent IR sources for measuring multiple small and large chemical species in the atmosphere. While the broad wavelength coverage afforded by an EC system enables measurements of large chemical species, most commercial systems can only be swept over their entire wavelength range at less than 10 Hz. This prohibits broadband simultaneous measurements of multiple chemicals in plumes from natural or industrial sources where turbulence and/or chemical reactivity are resulting in rapid changes in chemical composition on sub-1s timescales. At Pacific Northwest National Laboratory we have developed rapidly-swept EC-QCL technology that acquires broadband absorption spectra (~100 cm-1) on ms timescales. The spectral resolution of this system has enabled simultaneous measurement of narrow rotationally-resolved atmospherically-broadened lines from small chemical species, while offering the broad tuning range needed to measure broadband spectral features from multiple large chemical species. In this talk the application of this technology for open-path atmospheric measurements will be discussed based on results from laboratory measurements with simulated plumes of chemicals. The performance offered by the system for simultaneous detection of multiple chemical

  13. Broadband spectroscopy with external cavity quantum cascade lasers beyond conventional absorption measurements.

    Science.gov (United States)

    Lambrecht, Armin; Pfeifer, Marcel; Konz, Werner; Herbst, Johannes; Axtmann, Felix

    2014-05-07

    Laser spectroscopy is a powerful tool for analyzing small molecules, i.e. in the gas phase. In the mid-infrared spectral region quantum cascade lasers (QCLs) have been established as the most frequently used laser radiation source. Spectroscopy of larger molecules in the gas phase, of complex mixtures, and analysis in the liquid phase requires a broader tuning range and is thus still the domain of Fourier transform infrared (FTIR) spectroscopy. However, the development of tunable external cavity (EC) QCLs is starting to change this situation. The main advantage of QCLs is their high spectral emission power that is enhanced by a factor of 10(4) compared with thermal light sources. Obviously, transmission measurements with EC-QCLs in strongly absorbing samples are feasible, which can hardly be measured by FTIR due to detector noise limitations. We show that the high power of EC-QCLs facilitates spectroscopy beyond simple absorption measurements. Starting from QCL experiments with liquid samples, we show results of fiber evanescent field analysis (FEFA) to detect pesticides in drinking water. FEFA is a special case of attenuated total reflection spectroscopy. Furthermore, powerful CW EC-QCLs enable fast vibrational circular dichroism (VCD) spectroscopy of chiral molecules in the liquid phase - a technique which is very time consuming with standard FTIR equipment. We present results obtained for the chiral compound 1,1'-bi-2-naphthol (BINOL). Finally, powerful CW EC-QCLs enable the application of laser photothermal emission spectroscopy (LPTES). We demonstrate this for a narrowband and broadband absorber in the gas phase. All three techniques have great potential for MIR process analytical applications.

  14. Cascade quantum teleportation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Nan-run; GONG Li-hua; LIU Ye

    2006-01-01

    In this letter a cascade quantum teleportation scheme is proposed. The proposed scheme needs less local quantum operations than those of quantum multi-teleportation. A quantum teleportation scheme based on entanglement swapping is presented and compared with the cascade quantum teleportation scheme. Those two schemes can effectively teleport quantum information and extend the distance of quantum communication.

  15. Tunable External Cavity Quantum Cascade Lasers (EC-QCL): an application field for MOEMS based scanning gratings

    Science.gov (United States)

    Grahmann, Jan; Merten, André; Ostendorf, Ralf; Fontenot, Michael; Bleh, Daniela; Schenk, Harald; Wagner, Hans-Joachim

    2014-03-01

    In situ process information in the chemical, pharmaceutical or food industry as well as emission monitoring, sensitive trace detection and biological sensing applications would increasingly rely on MIR-spectroscopic anal­ysis in the 3 μm - 12 μm wavelength range. However, cost effective, portable, low power consuming and fast spectrometers with a wide tuning range are not available so far. To provide these MIR-spectrometer properties, the combination of quantum cascade lasers with a MOEMS scanning grating as wavelength selective element in the external cavity is addressed to provide a very compact and fast tunable laser source for spectroscopic analysis.

  16. Demonstration of a rapidly-swept external cavity quantum cascade laser for rapid and sensitive quantification of chemical mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.

    2016-02-13

    A rapidly-swept external cavity quantum cascade laser (ECQCL) system for fast open-path quantification of multiple chemicals and mixtures is presented. The ECQCL system is swept over its entire tuning range (>100 cm-1) at frequencies up to 200 Hz. At 200 Hz the wavelength tuning rate and spectral resolution are 2x104 cm-1/sec and < 0.2 cm-1, respectively. The capability of the current system to quantify changes in chemical concentrations on millesecond timescales is demonstrated at atmospheric pressure using an open-path multi-pass cell. The detection limits for chemicals ranged from ppb to ppm levels depending on the absorption cross-section.

  17. An off Axis Cavity Enhanced Absorption Spectrometer and a Rapid Scan Spectrometer with a Room-Temperature External Cavity Quantum Cascade Laser

    Science.gov (United States)

    Liu, Xunchen; Kang, Cheolhwa; Xu, Yunjie

    2009-06-01

    Quantum cascade laser (QCL) is a new type of mid-infrared tunable diode lasers with superior output power and mode quality. Recent developments, such as room temperature operation, wide frequency tunability, and narrow line width, make QCLs an ideal light source for high resolution spectroscopy. Two slit jet infrared spectrometers, namely an off-axis cavity enhanced absorption (CEA) spectrometer and a rapid scan spectrometer with an astigmatic multi-pass cell assembly, have been coupled with a newly purchased room temperature tunable mod-hop-free QCL with a frequency coverage from 1592 cm^{-1} to 1698 cm^{-1} and a scan rate of 0.1 cm^{-1}/ms. Our aim is to utilize these two sensitive spectrometers, that are equipped with a molecular jet expansion, to investigate the chiral molecules-(water)_n clusters. To demonstrate the resolution and sensitivity achieved, the rovibrational transitions of the static N_2O gas and the bending rovibrational transitions of the Ar-water complex, a test system, at 1634 cm^{-1} have been measured. D. Hofstetter and J. Faist in High performance quantum cascade lasers and their applications, Vol.89 Springer-Verlag Berlin & Heidelberg, 2003, pp. 61-98. Y. Xu, X. Liu, Z. Su, R. M. Kulkarni, W. S. Tam, C. Kang, I. Leonov and L. D'Agostino, Proc. Spie, 2009, 722208 (1-11). M. J. Weida and D. J. Nesbitt, J. Chem. Phys. 1997, 106, 3078-3089.

  18. Fully reflective external-cavity setup for quantum-cascade lasers as a local oscillator in mid-infrared wavelength heterodyne spectroscopy.

    Science.gov (United States)

    Stupar, Dusan; Krieg, Jürgen; Krötz, Peter; Sonnabend, Guido; Sornig, Manuela; Giesen, Thomas F; Schieder, Rudolf

    2008-06-01

    To our knowledge we present the first experiments with a fully reflective external-cavity quantum-cascade laser system at mid-infrared wavelengths for use as a local oscillator in a heterodyne receiver. The performance of the presented setup was investigated using absorption spectroscopy as well as heterodyne techniques. Tunability over approximately 30 cm(-1) at 1130 cm(-1) was demonstrated using a grating spectrometer. A continuous tuning range of 0.28 cm(-1) was verified by observing the spectra of an internally coupled confocal Fabry-Pérot interferometer and the absorption lines of gas phase SO(2). In a second step the output from the system was used as a local oscillator signal for a heterodyne setup. We show that spectral stability and side mode suppression are excellent and that a compact external-cavity quantum-cascade laser system is well suited to be used as a local oscillator in infrared heterodyne spectrometers.

  19. Rapid and Sensitive Quantification of Isotopic Mixtures Using a Rapidly-Swept External Cavity Quantum Cascade Laser

    Energy Technology Data Exchange (ETDEWEB)

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.

    2016-05-23

    A rapidly-swept external-cavity quantum cascade laser with an open-path Herriott cell is used to quantify gas-phase chemical mixtures of D2O and HDO at an update rate of 40 Hz (25 ms measurement time). The chemical mixtures were generated by evaporating D2O liquid near the open-path Herriott cell, allowing the H/D exchange reaction with ambient H2O to produce HDO. Fluctuations in the ratio of D2O and HDO on timescales of < 1 s due to the combined effects of plume transport and the H/D exchange chemical reaction are observed. Noise equivalent concentrations (1σ) (NEC) of 147.0 ppbv and 151.6 ppbv in a 25 ms measurement time are estimated for D2O and HDO respectively with a 127 m optical path. These NECs are reduced to 23.0 and 24.0 ppbv with a 1 s averaging time for D2O and HDO respectively. NECs < 200 ppbv are also estimated for N2O, F134A, CH4, Acetone, and SO2 for a 25 ms measurement time. Based on the NECs obtained for D2O and HDO, the isotopic precision for measurement of the [D2O]/[HDO] concentration ratio was studied. An isotopic precision of 33‰ and 5‰ was calculated for the current experimental conditions for measurement times of 25 ms and 1 s, respectively.

  20. Unconditional preparation of entanglement between atoms in cascaded optical cavities.

    Science.gov (United States)

    Clark, Stephen; Peng, Amy; Gu, Mile; Parkins, Scott

    2003-10-24

    We propose a scheme to unconditionally entangle the internal states of atoms trapped in separate high-finesse optical cavities. The scheme uses the technique of quantum reservoir engineering in a cascaded cavity-QED setting, and for ideal (lossless) coupling between the cavities generates an entangled pure state. Highly entangled states are also shown to be possible for realizable cavity-QED parameters and with nonideal coupling.

  1. Unconditional preparation of entanglement between atoms in cascaded optical cavities

    CERN Document Server

    Clark, S; Gu, M; Parkins, S; Clark, Stephen; Peng, Amy; Gu, Mile; Parkins, Scott

    2003-01-01

    We propose a scheme to unconditionally entangle the internal states of atoms trapped in separate high finesse optical cavities. The scheme uses the technique of quantum reservoir engineering in a cascaded cavity QED setting, and for ideal (lossless) coupling between the cavities generates an entangled pure state. Highly entangled states are also shown to be possible for realizable cavity QED parameters and with nonideal coupling.

  2. Integrated Broadband Quantum Cascade Laser

    Science.gov (United States)

    Mansour, Kamjou (Inventor); Soibel, Alexander (Inventor)

    2016-01-01

    A broadband, integrated quantum cascade laser is disclosed, comprising ridge waveguide quantum cascade lasers formed by applying standard semiconductor process techniques to a monolithic structure of alternating layers of claddings and active region layers. The resulting ridge waveguide quantum cascade lasers may be individually controlled by independent voltage potentials, resulting in control of the overall spectrum of the integrated quantum cascade laser source. Other embodiments are described and claimed.

  3. Enhancing the sensitivity of mid-IR quantum cascade laser-based cavity-enhanced absorption spectroscopy using RF current perturbation.

    Science.gov (United States)

    Manfred, Katherine M; Kirkbride, James M R; Ciaffoni, Luca; Peverall, Robert; Ritchie, Grant A D

    2014-12-15

    The sensitivity of mid-IR quantum cascade laser (QCL) off-axis cavity-enhanced absorption spectroscopy (CEAS), often limited by cavity mode structure and diffraction losses, was enhanced by applying a broadband RF noise to the laser current. A pump-probe measurement demonstrated that the addition of bandwidth-limited white noise effectively increased the laser linewidth, thereby reducing mode structure associated with CEAS. The broadband noise source offers a more sensitive, more robust alternative to applying single-frequency noise to the laser. Analysis of CEAS measurements of a CO(2) absorption feature at 1890  cm(-1) averaged over 100 ms yielded a minimum detectable absorption of 5.5×10(-3)  Hz(-1/2) in the presence of broadband RF perturbation, nearly a tenfold improvement over the unperturbed regime. The short acquisition time makes this technique suitable for breath applications requiring breath-by-breath gas concentration information.

  4. Atmospheric ammonia measurements in Houston, TX using an external cavity-quantum cascade laser-based sensor

    Science.gov (United States)

    Gong, L.; Lewicki, R.; Griffin, R. J.; Flynn, J. H.; Lefer, B. L.; Tittel, F. K.

    2010-12-01

    Ammonia (NH3) plays a significant role in atmospheric chemistry. It has many anthropogenic (e.g., agricultural crops and mineral fertilizers) and natural sources (e.g., animals, oceans, and vegetation) in the environment. In certain areas, industrial and motor vehicle activities also can contribute to increases in atmospheric NH3 levels. From a perspective of environmental concern, NH3 is a precursor of particulate matter (PM) because it can lead to production of ammonium salts (e.g., (NH4)2SO4 and NH4NO3) through chemical reactions with sulfuric and nitric acid. As a result, the abundance of NH3 in the atmosphere has a great impact on aerosol nucleation and composition. Despite this, NH3 is not regulated. It is crucial, however, to improve our understanding of the dynamics of NH3 in an industrial and urban area such as Greater Houston where atmospheric NH3 data are limited. In this study, a 10.4 µm external cavity quantum cascade laser (EC-QCL)-based sensor was developed and utilized. To monitor atmospheric NH3 at trace gas concentration levels, an amplitude modulated photo-acoustic spectroscopy (AM-PAS) technique was employed. The minimum detection limit obtained from the sensor is ~1.5 ppb for a 5-second data acquisition time. After averaging data over 300 seconds a sub-ppb NH3 concentration level can be achieved. The NH3 sensor has been deployed on the roof of a ~60-meter-high building (North Moody Tower) located on the University of Houston campus since November 2009. Several episodes of high NH3 concentrations were observed. For example, the sensor recorded a significant and lasting increase in NH3 concentrations (~21 ppb) on August 14, 2010, when a major accident occurred during the same time period on the Gulf Freeway (I-45) in Houston only 2 miles from the sampling site. The elevated concentration levels are assumed to be associated with NH3 generation from a chemical fire resulting from the collision involving two 18-wheelers, one carrying fertilizer

  5. Time-resolved spectral characterization of ring cavity surface emitting and ridge-type distributed feedback quantum cascade lasers by step-scan FT-IR spectroscopy.

    Science.gov (United States)

    Brandstetter, Markus; Genner, Andreas; Schwarzer, Clemens; Mujagic, Elvis; Strasser, Gottfried; Lendl, Bernhard

    2014-02-10

    We present the time-resolved comparison of pulsed 2nd order ring cavity surface emitting (RCSE) quantum cascade lasers (QCLs) and pulsed 1st order ridge-type distributed feedback (DFB) QCLs using a step-scan Fourier transform infrared (FT-IR) spectrometer. Laser devices were part of QCL arrays and fabricated from the same laser material. Required grating periods were adjusted to account for the grating order. The step-scan technique provided a spectral resolution of 0.1 cm(-1) and a time resolution of 2 ns. As a result, it was possible to gain information about the tuning behavior and potential mode-hops of the investigated lasers. Different cavity-lengths were compared, including 0.9 mm and 3.2 mm long ridge-type and 0.97 mm (circumference) ring-type cavities. RCSE QCLs were found to have improved emission properties in terms of line-stability, tuning rate and maximum emission time compared to ridge-type lasers.

  6. External cavity-quantum cascade laser infrared spectroscopy for secondary structure analysis of proteins at low concentrations

    Science.gov (United States)

    Schwaighofer, Andreas; Alcaráz, Mirta R.; Araman, Can; Goicoechea, Héctor; Lendl, Bernhard

    2016-09-01

    Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopy are analytical techniques employed for the analysis of protein secondary structure. The use of CD spectroscopy is limited to low protein concentrations (5 mg ml-1). Here we introduce a quantum cascade laser (QCL)-based IR transmission setup for analysis of protein and polypeptide secondary structure at concentrations as low as 0.25 mg ml-1 in deuterated buffer solution. We present dynamic QCL-IR spectra of the temperature-induced α-helix to β-sheet transition of poly-L-lysine. The concentration dependence of the α-β transition temperature between 0.25 and 10 mg ml-1 was investigated by QCL-IR, FTIR and CD spectroscopy. By using QCL-IR spectroscopy it is possible to perform IR spectroscopic analysis in the same concentration range as CD spectroscopy, thus enabling a combined analysis of biomolecules secondary structure by CD and IR spectroscopy.

  7. Three qubit quantum phase gate based on cavity QED

    Science.gov (United States)

    Chang, Juntao; Zubairy, M. Suhail

    2004-10-01

    We describe a three qubit quantum phase gate in which the three qubits are represented by the photons in a three-modes optical cavity. This gate is implemented by passing a four-level atom in a cascade configuration through the cavity. We shall discuss the application of such a quantum phase gate to quantum searching.

  8. Cascaded optical transparency in multimode-cavity optomechanical systems.

    Science.gov (United States)

    Fan, Linran; Fong, King Y; Poot, Menno; Tang, Hong X

    2015-01-14

    Electromagnetically induced transparency has great theoretical and experimental importance in many areas of physics, such as atomic physics, quantum optics and, more recent, cavity optomechanics. Optical delay is the most prominent feature of electromagnetically induced transparency, and in cavity optomechanics, the optical delay is limited by the mechanical dissipation rate of sideband-resolved mechanical modes. Here we demonstrate a cascaded optical transparency scheme by leveraging the parametric phonon-phonon coupling in a multimode optomechanical system, where a low damping mechanical mode in the unresolved-sideband regime is made to couple to an intermediate, high-frequency mechanical mode in the resolved-sideband regime of an optical cavity. Extended optical delay and higher transmission as well as optical advancing are demonstrated. These results provide a route to realize ultra-long optical delay, indicating a significant step towards integrated classical and quantum information storage devices.

  9. Quantum entanglement purification in cavities

    CERN Document Server

    Romero, J L; Saavedra, C; Retamal, J C

    2002-01-01

    A physical implementation of an entanglement purification protocol is studied using a cavity quantum electrodynamic based proposal, where, the quantum information is stored in quantum field sates inside cavities. Also a procedure is given for quantifying the degree of entanglement between quantum fields. (Author)

  10. Photonic crystal slab quantum cascade detector

    Energy Technology Data Exchange (ETDEWEB)

    Reininger, Peter, E-mail: peter.reininger@tuwien.ac.at; Schwarz, Benedikt; Harrer, Andreas; Zederbauer, Tobias; Detz, Hermann; Maxwell Andrews, Aaron; Gansch, Roman; Schrenk, Werner; Strasser, Gottfried [Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Floragasse 7, Vienna 1040 (Austria)

    2013-12-09

    In this Letter, we demonstrate the design, fabrication, and characterization of a photonic crystal slab quantum cascade detector (PCS-QCD). By employing a specifically designed resonant cavity, the performance of the photodetector is improved in three distinct ways. The PCS makes the QCD sensitive to surface normal incident light. It resonantly enhances the photon lifetime inside the active zone, thus increasing the photocurrent significantly. And, the construction form of the device inherently decreases the noise. Finally, we compare the characteristics of the PCS-QCD to a PCS - quantum well infrared photodetector and outline the advantages for certain fields of applications.

  11. Short-lived species detection of nitrous acid by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Hongming [Laboratoire de Physicochimie de l' Atmosphère, Université du Littoral Côte d' Opale, 189A, Av. Maurice Schumann, 59140 Dunkerque (France); Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 1125, 350 Shushanhu Road, Hefei, Anhui 230031 (China); Maamary, Rabih; Fertein, Eric; Chen, Weidong, E-mail: chen@univ-littoral.fr [Laboratoire de Physicochimie de l' Atmosphère, Université du Littoral Côte d' Opale, 189A, Av. Maurice Schumann, 59140 Dunkerque (France); Gao, Xiaoming [Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 1125, 350 Shushanhu Road, Hefei, Anhui 230031 (China); Sigrist, Markus W. [ETH Zurich, Institute for Quantum Electronics, HPT H4.1, Auguste-Piccard-Hof 1, CH-8093 Zürich (Switzerland)

    2015-03-09

    Spectroscopic detection of short-lived gaseous nitrous acid (HONO) at 1254.85 cm{sup −1} was realized by off-beam coupled quartz-enhanced photoacoustic spectroscopy (QEPAS) in conjunction with an external cavity quantum cascade lasers (EC-QCL). High sensitivity monitoring of HONO was performed within a very small gas-sample volume (of ∼40 mm{sup 3}) allowing a significant reduction (of about 4 orders of magnitude) of air sampling residence time which is highly desired for accurate quantification of chemically reactive short-lived species. Calibration of the developed QEPAS-based HONO sensor was carried out by means of lab-generated HONO samples whose concentrations were determined by direct absorption spectroscopy involving a ∼109.5 m multipass cell and a distributed feedback QCL. A minimum detection limit (MDL) of 66 ppbv (1 σ) HONO was achieved at 70 mbar using a laser output power of 50 mW and 1 s integration time, which corresponded to a normalized noise equivalent absorption coefficient of 3.6 × 10{sup −8 }cm{sup −1} W/Hz{sup 1/2}. This MDL was down to 7 ppbv at the optimal integration time of 150 s. The corresponding 1σ minimum detected absorption coefficient is ∼1.1 × 10{sup −7 }cm{sup −1} (MDL ∼ 3 ppbv) in 1 s and ∼1.1 × 10{sup −8 }cm{sup −1} (MDL ∼ 330 pptv) in 150 s, respectively, with 1 W laser power.

  12. Lens Coupled Quantum Cascade Laser

    Science.gov (United States)

    Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor)

    2013-01-01

    Terahertz quantum cascade (QC) devices are disclosed that can operate, e.g., in a range of about 1 THz to about 10 THz. In some embodiments, QC lasers are disclosed in which an optical element (e.g., a lens) is coupled to an output facet of the laser's active region to enhance coupling of the lasing radiation from the active region to an external environment. In other embodiments, terahertz amplifier and tunable terahertz QC lasers are disclosed.

  13. Multicomponent gas analysis using broadband quantum cascade laser spectroscopy

    NARCIS (Netherlands)

    Reyes Reyes, A.; Hou, Z.; Van Mastrigt, E.; Horsten, R.C.; De Jongste, J.C.; Pijnenburg, M.W.; Urbach, H.P.; Bhattacharya, N.

    2014-01-01

    We present a broadband quantum cascade laser-based spectroscopic system covering the region between 850 and 1250 cm−1. Its robust multipass cavity ensures a constant interaction length over the entire spectral region. The device enables the detection and identification of numerous molecules present

  14. Dynamics of quantum cascade lasers: numerics

    Science.gov (United States)

    Van der Sande, Guy; Verschaffelt, Guy

    2016-04-01

    Since the original demonstration of terahertz quantum-cascade lasers (QCLs), the performance of these devices has shown rapid improvement. QCLs can now deliver milliwatts or more of continuous-wave radiation throughout the terahertz frequency range (300 GHz to 10 THz). Therefore, QCLs have become widely used in various applications such as spectroscopy, metrology or free-space telecommunications. For many of these applications there is a need for compact tuneable quantum cascade lasers. Nowadays most tuneable QCLs are based on a bulky external cavity configuration. We explore the possibility of tuning the operating wavelength through a fully integrated on-chip wavelength selective feedback applied to a dual wavelength QCL. Our numerical and analytical analyses are based on rate equation models describing the dynamics of QCLs extended to include delayed filtered optical feedback. We demonstrate the possibility to tune the operating wavelength by altering the absorption and/or amplification of the signal in the delayed feedback path. The tuning range of a laser is limited by the spectral width of its gain. For inter-band semiconductor lasers this spectral width is typically several tens of nm. Hence, the laser cavity supports the existence of multiple modes and on chip wavelength selective feedback has been demonstrated to be a promising tuning mechanism. We have selected a specific QCL gain structure with four energy levels and with two lasing transitions in the same cascade. In this scheme, the two lasing modes use a common upper level. Hence, the two modes compete in part for the same carriers to account for their optical gain. We have added delayed wavelength specific filtered optical feedback to the rate equation model describing these transitions. We have calculated the steady states and their stability in the absence of delay for the feedback field and studied numerically the case with non-zero delay. We have proven that wavelength tuning of a dual wavelength

  15. Time-resolved in situ detection of CO in a shock tube using cavity-enhanced absorption spectroscopy with a quantum-cascade laser near 4.6 µm.

    Science.gov (United States)

    Sun, Kai; Wang, Shengkai; Sur, Ritobrata; Chao, Xing; Jeffries, Jay B; Hanson, Ronald K

    2014-10-06

    Cavity-enhanced absorption spectroscopy (CEAS) using a mid-infrared DFB quantum-cascade laser is reported for sensitive time-resolved (10 μs) in situ CO measurements in a shock tube. Off-axis alignment and fast scanning of the laser wavelength were used to minimize coupling noise in a low-finesse cavity. An absorption gain factor of 91 was demonstrated, which enabled sub-ppm detection sensitivity for gas temperatures of 1000-2100K in a 15 cm diameter shock tube. This substantial improvement in detection sensitivity compared to conventional single-pass absorption measurements, shows great potential for the study of reaction pathways of high-temperature combustion kinetics mechanisms in shock tubes.

  16. Lateral Modes in Quantum Cascade Lasers

    Directory of Open Access Journals (Sweden)

    Gregory C. Dente

    2016-03-01

    Full Text Available We will examine the waveguide mode losses in ridge-guided quantum cascade lasers. Our analysis illustrates how the low-loss mode for broad-ridge quantum cascade lasers (QCLs can be a higher-order lateral waveguide mode that maximizes the feedback from the sloped ridge-wall regions. The results are in excellent agreement with the near- and far-field data taken on broad-ridge-guided quantum cascade lasers processed with sloped ridge walls.

  17. Nanofriction in Cavity Quantum Electrodynamics.

    Science.gov (United States)

    Fogarty, T; Cormick, C; Landa, H; Stojanović, Vladimir M; Demler, E; Morigi, Giovanna

    2015-12-01

    The dynamics of cold trapped ions in a high-finesse resonator results from the interplay between the long-range Coulomb repulsion and the cavity-induced interactions. The latter are due to multiple scatterings of laser photons inside the cavity and become relevant when the laser pump is sufficiently strong to overcome photon decay. We study the stationary states of ions coupled with a mode of a standing-wave cavity as a function of the cavity and laser parameters, when the typical length scales of the two self-organizing processes, Coulomb crystallization and photon-mediated interactions, are incommensurate. The dynamics are frustrated and in specific limiting cases can be cast in terms of the Frenkel-Kontorova model, which reproduces features of friction in one dimension. We numerically recover the sliding and pinned phases. For strong cavity nonlinearities, they are in general separated by bistable regions where superlubric and stick-slip dynamics coexist. The cavity, moreover, acts as a thermal reservoir and can cool the chain vibrations to temperatures controlled by the cavity parameters and by the ions' phase. These features are imprinted in the radiation emitted by the cavity, which is readily measurable in state-of-the-art setups of cavity quantum electrodynamics.

  18. Cavity QED: applications to quantum computation

    Science.gov (United States)

    Xiong, Han; Zubairy, M. Suhail

    2004-10-01

    Possible schemes to implement the basic quantum gates for quantum computation have been presented based on cavity quantum electrodynamics (QED) systems. We then discuss schemes to implement several important quantum algorithms such as the discrete quantum fourier transform (QFT) algorithm and Grover's quantum search algorithm based on these quantum gates. Some other applications of cavity QED based systems including the implementations of a quantum disentanglement eraser and an entanglement amplifier are also discussed.

  19. Quantum Cascade Photonic Crystal lasers

    Science.gov (United States)

    Capasso, Federico

    2004-03-01

    QC lasers have emerged in recent years as the dominant laser technology for the mid-to far infrared spectrum in light of their room temperature operation, their tunability, ultrahigh speed operation and broad range of applications to chemical sensing, spectroscopy etc. (Ref. 1-3). After briefly reviewing the latter, I will describe a new class of mid-infrared QC lasers, Quantum Cascade Photonic Crystal Surface Emitting Lasers (QCPCSELS), that combine electronic and photonic band structure engineering to achieve vertical emission from the surface (Ref. 4). Devices operating on bandedge mode and on defect modes will be discussed. Exciting potential uses of these new devices exist in nonlinear optics, microfluidics as well as novel sensors. Finally a bird's eye view of other exciting areas of QC laser research will be given including broadband QCLs and new nonlinear optical sources based on multiwavelength QCLs. 1. F. Capasso, C. Gmachl, D. L. Sivco, and A. Y. Cho, Physics Today 55, 34 (May 2002) 2. F. Capasso, C. Gmachl, R. Paiella, A. Tredicucci, A. L. Hutchinson, D. L. Sivco, J. N. Baillargeon, A. Y. Cho and H. C. Liu, IEEE Journal of Selected Topics in Quantum Electronics, 6, 931 (2000). 3. F. Capasso, R. Paiella, R. Martini, R. Colombelli, C. Gmachl, T. L. Myers, M. S. Taubman, R. M. Williams, C. G. Bethea, K. Unterrainer, H. Y. Hwang, D. L. Sivco, A. Y. Cho, A. M. Sergent, H. C. Liu, E. A. Whittaker, IEEE J. Quantum Electron. 38, 511 (2002) 4. R. Colombelli, K. Srivasan, M. Troccoli, O. Painter, C. Gmachl, D. M. Tennant, A. M. Sergent, D. L. Sivco, A. Y. Cho and F. Capasso, Science 302, 1374 (2003)

  20. A quantum cascade phonon-polariton laser

    CERN Document Server

    Ohtani, Keita; Bosco, Lorenzo; Beck, Mattias; Faist, Jérôme

    2016-01-01

    We report a laser that coherently emits phonon-polaritons, quasi-particles arising from the coupling between photons and transverse optical phonons. The gain is provided by an intersubband transition in a quantum cascade structure. The polaritons at h$\

  1. Quantum Cascade Laser Frequency Combs

    CERN Document Server

    Faist, Jérôme; Scalari, Giacomo; Rösch, Markus; Bonzon, Christopher; Hugi, Andreas; Beck, Mattias

    2015-01-01

    It was recently demonstrated that broadband quantum cascade lasers can operate as frequency combs. As such, they operate under direct electrical pumping at both mid-infrared and THz frequencies, making them very attractive for dual-comb spectroscopy. Performance levels are continuously improving, with average powers over 100 mW and frequency coverage of 100 cm$^{-1}$ in the mid-infrared. In the THz range, 10 mW of average power and 600 GHz of frequency coverage are reported. As a result of the very short upper state lifetime of the gain medium, the mode proliferation in these sources arises from four wave mixing rather than saturable absorption. As a result, their optical output is characterized by the tendency of small intensity modulation of the output power, and the relative phases of the modes to be similar to the ones of a frequency modulated laser. Recent results include the proof of comb operation down to a metrological level, the observation of a Schawlow-Townes broadened linewidth, as well as the fir...

  2. Mesoscopic Cavity Quantum Electrodynamics with Quantum Dots

    CERN Document Server

    Childress, L I; Lukin, M D

    2003-01-01

    We describe an electrodynamic mechanism for coherent, quantum mechanical coupling between spacially separated quantum dots on a microchip. The technique is based on capacitive interactions between the electron charge and a superconducting transmission line resonator, and is closely related to atomic cavity quantum electrodynamics. We investigate several potential applications of this technique which have varying degrees of complexity. In particular, we demonstrate that this mechanism allows design and investigation of an on-chip double-dot microscopic maser. Moreover, the interaction may be extended to couple spatially separated electron spin states while only virtually populating fast-decaying superpositions of charge states. This represents an effective, controllable long-range interaction, which may facilitate implementation of quantum information processing with electron spin qubits and potentially allow coupling to other quantum systems such as atomic or superconducting qubits.

  3. Delay time calculation for dual-wavelength quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Hamadou, A., E-mail: abd-hamado@yahoo.fr [Département des Sciences et Techniques, Faculté des Sciences et de la Technologie, Université de Bordj Bou Arreridj 34000 (Algeria); Laboratoire d’étude des surfaces et interfaces des matériaux solides (LESIMS), Sétif 19000 (Algeria); Lamari, S. [Laboratoire d’étude des surfaces et interfaces des matériaux solides (LESIMS), Sétif 19000 (Algeria); Département de Physique, Faculté des Sciences, Université Sétif 1, 19000 (Algeria); Thobel, J.-L. [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR 8520, Université Lille1, Avenue Poincaré, BP 60069, 59652 Villeneuve d' Ascq Cédex (France)

    2013-11-28

    In this paper, we calculate the turn-on delay (t{sub th}) and buildup (Δt) times of a midinfrared quantum cascade laser operating simultaneously on two laser lines having a common upper level. The approach is based on the four-level rate equations model describing the variation of the electron number in the states and the photon number present within the cavity. We obtain simple analytical formulae for the turn-on delay and buildup times that determine the delay times and numerically apply our results to both the single and bimode states of a quantum cascade laser, in addition the effects of current injection on t{sub th} and Δt are explored.

  4. Position and mode dependent coupling of terahertz quantum cascade laser fields to an integrated diode

    Science.gov (United States)

    Dyer, Gregory C.; Nordquist, Christopher D.; Cich, Michael J.; Ribaudo, Troy; Grine, Albert D.; Fuller, Charles T.; Reno, John L.; Wanke, Michael C.

    2013-10-01

    A Schottky diode integrated into a terahertz quantum cascade laser waveguide couples directly to the internal laser fields. In a multimode laser, the diode response is correlated with both the instantaneous power and the coupling strength to the diode of each lasing mode. Measurements of the rectified response of diodes integrated in two quantum cascade laser cavities at different locations indicate that the relative diode position strongly influences the laser-diode coupling.

  5. Position and mode dependent coupling of terahertz quantum cascade laser fields to an integrated diode

    CERN Document Server

    Dyer, Gregory C; Cich, Michael J; Ribaudo, Troy; Grine, Albert D; Fuller, Charles T; Reno, John L; Wanke, Michael C

    2016-01-01

    A Schottky diode integrated into a terahertz quantum cascade laser waveguide couples directly to the internal laser fields. In a multimode laser, the diode response is correlated with both the instantaneous power and the coupling strength to the diode of each lasing mode. Measurements of the rectified response of diodes integrated in two quantum cascade laser cavities at different locations indicate that the relative diode position strongly influences the laser-diode coupling.

  6. Cavity quantum electrodynamics: coherence in context.

    Science.gov (United States)

    Mabuchi, H; Doherty, A C

    2002-11-15

    Modern cavity quantum electrodynamics (cavity QED) illuminates the most fundamental aspects of coherence and decoherence in quantum mechanics. Experiments on atoms in cavities can be described by elementary models but reveal intriguing subtleties of the interplay of coherent dynamics with external couplings. Recent activity in this area has pioneered powerful new approaches to the study of quantum coherence and has fueled the growth of quantum information science. In years to come, the purview of cavity QED will continue to grow as researchers build on a rich infrastructure to attack some of the most pressing open questions in micro- and mesoscopic physics.

  7. Quantum networks based on cavity QED

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, Stephan; Bochmann, Joerg; Figueroa, Eden; Hahn, Carolin; Kalb, Norbert; Muecke, Martin; Neuzner, Andreas; Noelleke, Christian; Reiserer, Andreas; Uphoff, Manuel; Rempe, Gerhard [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching (Germany)

    2014-07-01

    Quantum repeaters require an efficient interface between stationary quantum memories and flying photons. Single atoms in optical cavities are ideally suited as universal quantum network nodes that are capable of sending, storing, retrieving, and even processing quantum information. We demonstrate this by presenting an elementary version of a quantum network based on two identical nodes in remote, independent laboratories. The reversible exchange of quantum information and the creation of remote entanglement are achieved by exchange of a single photon. Quantum teleportation is implemented using a time-resolved photonic Bell-state measurement. Quantum control over all degrees of freedom of the single atom also allows for the nondestructive detection of flying photons and the implementation of a quantum gate between the spin state of the atom and the polarization of a photon upon its reflection from the cavity. Our approach to quantum networking offers a clear perspective for scalability and provides the essential components for the realization of a quantum repeater.

  8. Cavity QED-based quantum walk

    Science.gov (United States)

    di, Tiegang; Hillery, Mark; Zubairy, M. Suhail

    2004-09-01

    We discuss a possible experimental scheme for the implementation of a quantum walk. The scheme is based on the passage of an atom inside a high- Q cavity. The chirality is characterized by the atomic states and the displacement is characterized by the photon number inside the cavity. The quantum steps are described by appropriate interactions with a sequence of classical and quantized cavity fields.

  9. Quantum Dynamics of Nonlinear Cavity Systems

    OpenAIRE

    Nation, Paul D.

    2010-01-01

    We investigate the quantum dynamics of three different configurations of nonlinear cavity systems. To begin, we carry out a quantum analysis of a dc superconducting quantum interference device (SQUID) mechanical displacement detector comprised of a SQUID with a mechanically compliant loop segment. The SQUID is approximated by a nonlinear current-dependent inductor, inducing a flux tunable nonlinear Duffing term in the cavity equation of motion. Expressions are derived for the detector signal ...

  10. Spectrally resolved far-fields of terahertz quantum cascade lasers

    CERN Document Server

    Brandstetter, Martin; Krall, Michael; Kainz, Martin A; Detz, Hermann; Zederbauer, Tobias; Andrews, Aaron M; Strasser, Gottfried; Unterrainer, Karl

    2016-01-01

    We demonstrate a convenient and fast method to measure the spectrally resolved far-fields of multimode terahertz quantum cascade lasers by combining a microbolometer focal plane array with an FTIR spectrometer. Far-fields of fundamental TM0 and higher lateral order TM1 modes of multimode Fabry-P\\'erot type lasers have been distinguished, which very well fit to the results obtained by a 3D finite-element simulation. Furthermore, multimode random laser cavities have been investigated, analyzing the contribution of each single laser mode to the total far-field. The presented method is thus an important tool to gain in-depth knowledge of the emission properties of multimode laser cavities at terahertz frequencies, which become increasingly important for future sensing applications.

  11. Analytical expression for the second threshold in quantum cascade lasers

    CERN Document Server

    Vukovic, Nikola; Milanovic, Vitomir; Boiko, Dmitri L

    2016-01-01

    We have obtained a closed-form expression for the threshold of Risken-Nummedal-Graham-Haken (RNGH) multimode instability in a Fabry-P\\'erot (FP) cavity quantum cascade laser (QCL). This simple analytical expression is a versatile tool that can easily be applied in practical situations which require analysis of QCL dynamic behavior and estimation of its second threshold. Our model for a FP cavity laser accounts for the carrier coherence grating and carrier population grating as well as their relaxation due to carrier diffusion. In the model, the RNGH instability threshold is analyzed using a second-order bi-orthogonal perturbation theory and we confirm our analytical solution by a comparison with the numerical simulations. In particular, the model predicts a low second threshold in QCLs. This agrees very well with experimental data available in the literature.

  12. Normal Incident Long Wave Infrared Quantum Dash Quantum Cascade Photodetector

    Science.gov (United States)

    Wang, Feng-Jiao; Ren, Fei; Liu, Shu-Man; Zhuo, Ning; Zhai, Shen-Qiang; Liu, Jun-Qi; Liu, Feng-Qi; Wang, Zhan-Guo

    2016-09-01

    We demonstrate a quantum dash quantum cascade photodetector (QDash-QCD) by incorporating self-assembled InAs quantum dashes into the active region of a long wave infrared QCD. Sensitive photoresponse to normal incident light at 10 μm was observed, which is attributed to the intersubband (ISB) transitions in the quantum well/quantum dash (QW/QDash) hybrid absorption region and the following transfer of excited electrons on the extraction stair-like quantum levels separated by LO-phonon energy. The high density InAs quantum dashes were formed in the Stranski-Krastanow mode and stair-like levels were formed by a lattice matched InGaAs/InAlAs superlattice. A stable responsivity from 5 mA/W at 77 K to 3 mA/W at as high as 190 K was observed, which makes the QDash-QCD promising in high temperature operation.

  13. Nanobeam photonic crystal cavity quantum dot laser

    CERN Document Server

    Gong, Yiyang; Shambat, Gary; Sarmiento, Tomas; Harris, James S; Vuckovic, Jelena

    2010-01-01

    The lasing behavior of one dimensional GaAs nanobeam cavities with embedded InAs quantum dots is studied at room temperature. Lasing is observed throughout the quantum dot PL spectrum, and the wavelength dependence of the threshold is calculated. We study the cavity lasers under both 780 nm and 980 nm pump, finding thresholds as low as 0.3 uW and 19 uW for the two pump wavelengths, respectively. Finally, the nanobeam cavity laser wavelengths are tuned by up to 7 nm by employing a fiber taper in near proximity to the cavities. The fiber taper is used both to efficiently pump the cavity and collect the cavity emission.

  14. Quantum-engineered interband cascade photovoltaic devices

    Science.gov (United States)

    Yang, Rui Q.; Lotfi, Hossein; Li, Lu; Hinkey, Robert T.; Ye, Hao; Klem, John F.; Lei, L.; Mishima, T. D.; Keay, J. C.; Santos, M. B.; Johnson, M. B.

    2013-12-01

    Quantum-engineered multiple stage photovoltaic (PV) devices are explored based on InAs/GaSb/AlSb interband cascade (IC) structures. These ICPV devices employ multiple discrete absorbers that are connected in series by widebandgap unipolar barriers using type-II heterostructure interfaces for facilitating carrier transport between cascade stages similar to IC lasers. The discrete architecture is beneficial for improving the collection efficiency and for spectral splitting by utilizing absorbers with different bandgaps. As such, the photo-voltages from each individual cascade stage in an ICPV device add together, creating a high overall open-circuit voltage, similar to conventional multi-junction tandem solar cells. Furthermore, photo-generated carriers can be collected with nearly 100% efficiency in each stage. This is because the carriers travel over only a single cascade stage, designed to be shorter than a typical diffusion length. The approach is of significant importance for operation at high temperatures where the diffusion length is reduced. Here, we will present our recent progress in the study of ICPV devices, which includes the demonstration of ICPV devices at room temperature and above with narrow bandgaps (e.g. 0.23 eV) and high open-circuit voltages.

  15. Single-mode GaAs/AlGaAs quantum cascade microlasers

    Institute of Scientific and Technical Information of China (English)

    Gao Yu; Liu Junqi; Liu Fengqi; Zhang Wei; Zhang Quande; Liu Wanfeng; Li Lu; Wang Lijun; Wang Zhanguo

    2009-01-01

    Single-mode edge emitting GaAs/A1GaAs quantum cascade microlasers at a wavelength of about 11.4 μm were realized by shortening the Fabry-P6rot cavity length. The spacing of the longitudinal resonator modes is inversely proportional to the cavity length. Stable single-mode emission with a side mode suppression ratio of about 19 dB at 85 K for a 150-μm-long device was demonstrated.

  16. High efficiency quantum cascade laser frequency comb

    Science.gov (United States)

    Lu, Quanyong; Wu, Donghai; Slivken, Steven; Razeghi, Manijeh

    2017-01-01

    An efficient mid-infrared frequency comb source is of great interest to high speed, high resolution spectroscopy and metrology. Here we demonstrate a mid-IR quantum cascade laser frequency comb with a high power output and narrow beatnote linewidth at room temperature. The active region was designed with a strong-coupling between the injector and the upper lasing level for high internal quantum efficiency and a broadband gain. The group velocity dispersion was engineered for efficient, broadband mode-locking via four wave mixing. The comb device exhibits a narrow intermode beatnote linewidth of 50.5 Hz and a maximum wall-plug efficiency of 6.5% covering a spectral coverage of 110 cm−1 at λ ~ 8 μm. The efficiency is improved by a factor of 6 compared with previous demonstrations. The high power efficiency and narrow beatnote linewidth will greatly expand the applications of quantum cascade laser frequency combs including high-precision remote sensing and spectroscopy. PMID:28262834

  17. High efficiency quantum cascade laser frequency comb

    Science.gov (United States)

    Lu, Quanyong; Wu, Donghai; Slivken, Steven; Razeghi, Manijeh

    2017-03-01

    An efficient mid-infrared frequency comb source is of great interest to high speed, high resolution spectroscopy and metrology. Here we demonstrate a mid-IR quantum cascade laser frequency comb with a high power output and narrow beatnote linewidth at room temperature. The active region was designed with a strong-coupling between the injector and the upper lasing level for high internal quantum efficiency and a broadband gain. The group velocity dispersion was engineered for efficient, broadband mode-locking via four wave mixing. The comb device exhibits a narrow intermode beatnote linewidth of 50.5 Hz and a maximum wall-plug efficiency of 6.5% covering a spectral coverage of 110 cm‑1 at λ ~ 8 μm. The efficiency is improved by a factor of 6 compared with previous demonstrations. The high power efficiency and narrow beatnote linewidth will greatly expand the applications of quantum cascade laser frequency combs including high-precision remote sensing and spectroscopy.

  18. Proposal for a telecom quantum repeater with single atoms in optical cavities

    Science.gov (United States)

    Uphoff, Manuel; Brekenfeld, Manuel; Niemietz, Dominik; Ritter, Stephan; Rempe, Gerhard

    2016-05-01

    Quantum repeaters hold the promise to enable long-distance quantum communication via entanglement generation over arbitrary distances. Single atoms in optical cavities have been shown to be ideally suited for the experimental realization of many tasks in quantum communication. To utilize these systems for a quantum repeater, it would be desirable to operate them at telecom wavelengths. We propose to use a cascaded scheme employing transitions at telecom wavelengths between excited states of alkali atoms for entanglement generation between a single photon at telecom wavelength and a single atom at the crossing point of two cavity modes. A cavity-assisted quantum gate can be used for entanglement swapping. We estimate the performance of these systems using numerical simulations based on experimental parameters obtained for CO2 laser-machined fiber cavities in our laboratory. Finally, we show that a quantum repeater employing the aforementioned scheme and current technology could outperform corresponding schemes based on direct transmission.

  19. Beam combining of quantum cascade laser arrays.

    Science.gov (United States)

    Lee, Benjamin G; Kansky, Jan; Goyal, Anish K; Pflügl, Christian; Diehl, Laurent; Belkin, Mikhail A; Sanchez, Antonio; Capasso, Federico A

    2009-08-31

    Wavelength beam combining was used to co-propagate beams from 28 elements in an array of distributed-feedback quantum cascade lasers (DFB-QCLs). The beam-quality product of the array, defined as the product of near-field spot size and far-field divergence for the entire array, was improved by a factor of 21 by using wavelength beam combining. To demonstrate the applicability of wavelength beam combined DFB-QCL arrays for remote sensing, we obtained the absorption spectrum of isopropanol at a distance of 6 m from the laser array.

  20. Quantum-to-classical transition in cavity quantum electrodynamics.

    Science.gov (United States)

    Fink, J M; Steffen, L; Studer, P; Bishop, Lev S; Baur, M; Bianchetti, R; Bozyigit, D; Lang, C; Filipp, S; Leek, P J; Wallraff, A

    2010-10-15

    The quantum properties of electromagnetic, mechanical or other harmonic oscillators can be revealed by investigating their strong coherent coupling to a single quantum two level system in an approach known as cavity quantum electrodynamics (QED). At temperatures much lower than the characteristic energy level spacing the observation of vacuum Rabi oscillations or mode splittings with one or a few quanta asserts the quantum nature of the oscillator. Here, we study how the classical response of a cavity QED system emerges from the quantum one when its thermal occupation-or effective temperature-is raised gradually over 5 orders of magnitude. In this way we explore in detail the continuous quantum-to-classical crossover and demonstrate how to extract effective cavity field temperatures from both spectroscopic and time-resolved vacuum Rabi measurements.

  1. Scheme for Implementation of Quantum Game in Cavity QED

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-Chun; CAO Shu-Ai; WU Yue-Qin; FANG Mao-Fa; LI Huai-Fan; ZHENG Xiao-Juan; ZHAO Ren; WANG Xin-Wen; LI Ze-Hua

    2008-01-01

    We propose an experimentally feasible scheme to implement two-player quantum game in cavity quantum electrodynamics (QED). During the process, the cavity is only virtually excited, thus our scheme is insensitive to the cavity field states and cavity decay. The scheme can be realized in the range of current cavity QED techniques.

  2. A scheme for implementing quantum game in cavity QED

    Institute of Scientific and Technical Information of China (English)

    CaoShuai; Fang Mao-Fa; Liu Jian-Bin; Wang Xin-Wen; Zheng Xiao-juan

    2009-01-01

    In this paper, we propose a scheme fot implementing quantum game (QG) in cavity quantum electrodynam-ics(QED). In the scheme, the cavity is only virtually excited and thus the proposal is insensitive to the cavity fields states and cavity decay. So our proposal can be experimentally realized in the range of current cavity QED techniques.

  3. Large payload quantum steganography based on cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Ye Tian-Yu; Jiang Li-Zhen

    2013-01-01

    A large payload quantum steganography protocol based on cavity quantum electrodynamics (QED) is presented in this paper,which effectively uses the evolutionary law of atoms in cavity QED.The protocol builds up a hidden channel to transmit secret messages using entanglement swapping between one GHZ state and one Bell state in cavity QED together with the Hadamard operation.The quantum steganography protocol is insensitive to cavity decay and the thermal field.The capacity,imperceptibility and security against eavesdropping are analyzed in detail in the protocol.It turns out that the protocol not only has good imperceptibility but also possesses good security against eavesdropping.In addition,its capacity for a hidden channel achieves five bits,larger than most of the previous quantum steganography protocols.

  4. Quantum search via superconducting quantum interference devices in a cavity

    Institute of Scientific and Technical Information of China (English)

    Lu Yan; Dong Ping; Xue Zheng-Yuan; Cao Zhuo-Liang

    2007-01-01

    We propose a scheme for implementing the Grover search algorithm with two superconducing quantum interference devices (SQUIDs) in a cavity. Our scheme only requires single resonant interaction of the SQUID-cavity system and the required interaction time is very short. The simplicity of the process and the reduction of the interaction time are important for restraining decoherence.

  5. Contributed Review: Quantum cascade laser based photoacoustic detection of explosives

    Energy Technology Data Exchange (ETDEWEB)

    Li, J. S., E-mail: jingsong-li@ahu.edu.cn; Yu, B. [Key Laboratory of Opto-Electronic Information Acquisition and Manipulation of Ministry of Education, Anhui University, Hefei (China); Fischer, H. [Department of Atmospheric Chemistry, Max Planck Institute for Chemistry, Mainz (Germany); Chen, W. [Laboratoire de Physicochimie de l’Atmosphére, Université du Littoral Côte d’Opale, Dunkerque (France); Yalin, A. P. [Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523-1374 (United States)

    2015-03-15

    Detecting trace explosives and explosive-related compounds has recently become a topic of utmost importance for increasing public security around the world. A wide variety of detection methods and an even wider range of physical chemistry issues are involved in this very challenging area. Optical sensing methods, in particular mid-infrared spectrometry techniques, have a great potential to become a more desirable tools for the detection of explosives. The small size, simplicity, high output power, long-term reliability make external cavity quantum cascade lasers (EC-QCLs) the promising spectroscopic sources for developing analytical instrumentation. This work reviews the current technical progress in EC-QCL-based photoacoustic spectroscopy for explosives detection. The potential for both close-contact and standoff configurations using this technique is completely presented over the course of approximately the last one decade.

  6. Quantum measurements of atoms using cavity QED

    CERN Document Server

    Dada, Adetunmise C; Jones, Martin L; Kendon, Vivien M; Everitt, Mark S

    2010-01-01

    Generalized quantum measurements are an important extension of projective or von Neumann measurements, in that they can be used to describe any measurement that can be implemented on a quantum system. We describe how to realize two non-standard quantum measurements using cavity quantum electrodynamics (QED). The first measurement optimally and unabmiguously distinguishes between two non-orthogonal quantum states. The second example is a measurement that demonstrates superadditive quantum coding gain. The experimental tools used are single-atom unitary operations effected by Ramsey pulses and two-atom Tavis-Cummings interactions. We show how the superadditive quantum coding gain is affected by errors in the field-ionisation detection of atoms, and that even with rather high levels of experimental imperfections, a reasonable amount of superadditivity can still be seen. To date, these types of measurement have only been realized on photons. It would be of great interest to have realizations using other physical ...

  7. Impedance-matched cavity quantum memory

    CERN Document Server

    Afzelius, Mikael

    2010-01-01

    We consider an atomic frequency comb based quantum memory inside an asymmetric optical cavity. In this configuration it is possible to absorb the input light completely in a system with an effective optical depth of one, provided that the absorption per cavity round trip exactly matches the transmission of the coupling mirror ("impedance matching"). We show that the impedance matching results in a readout efficiency only limited by irreversible atomic dephasing, whose effect can be made very small in systems with large inhomogeneous broadening. Our proposal opens up an attractive route towards quantum memories with close to unit efficiency.

  8. Normal Incident Long Wave Infrared Quantum Dash Quantum Cascade Photodetector.

    Science.gov (United States)

    Wang, Feng-Jiao; Ren, Fei; Liu, Shu-Man; Zhuo, Ning; Zhai, Shen-Qiang; Liu, Jun-Qi; Liu, Feng-Qi; Wang, Zhan-Guo

    2016-12-01

    We demonstrate a quantum dash quantum cascade photodetector (QDash-QCD) by incorporating self-assembled InAs quantum dashes into the active region of a long wave infrared QCD. Sensitive photoresponse to normal incident light at 10 μm was observed, which is attributed to the intersubband (ISB) transitions in the quantum well/quantum dash (QW/QDash) hybrid absorption region and the following transfer of excited electrons on the extraction stair-like quantum levels separated by LO-phonon energy. The high density InAs quantum dashes were formed in the Stranski-Krastanow mode and stair-like levels were formed by a lattice matched InGaAs/InAlAs superlattice. A stable responsivity from 5 mA/W at 77 K to 3 mA/W at as high as 190 K was observed, which makes the QDash-QCD promising in high temperature operation.

  9. Electrical derivative measurement of quantum cascade lasers

    Science.gov (United States)

    Guo, Dingkai; Cheng, Liwei; Chen, Xing; Choa, Fow-Sen; Fan, Jenyu; Worchesky, Terry

    2011-02-01

    The electrical derivative characteristics of quantum cascade lasers (QCLs) are investigated to test the QCL threshold, leakage current, and possibly explore carrier transport. QCL thresholds can be identified by searching for the slope peak of the first derivative of the I-V curves and can be further confirmed with its alignment to the peak of the second derivative of the I-V curves. Leakage current in QCLs with oxide-blocked ridge waveguides and buried heterostructure (BH) waveguides are studied and compared. The oxide-blocking structures provide the lowest leakage current although the capped-mesa-BH (CMBH) QCLs provide the toughest durability under highly stressful operations. The leakage current of CMBH QCLs are also compared at different temperatures.

  10. Cavity quantum electrodynamics: Beyond strong

    Science.gov (United States)

    Murch, Kater

    2017-01-01

    When light and matter are strongly coupled, they lose their distinct character and merge into a hybrid state. Three experiments explore this exotic regime using artificial atoms, with promise for quantum technologies.

  11. Fundamental tests in Cavity Quantum Electrodynamics

    CERN Document Server

    CERN. Geneva

    2010-01-01

    At the dawn of quantum physics, Einstein and Bohr had the dream to confine a photon in a box and to use this contraption in order to illustrate the strange laws of the quantum world. Cavity Quantum Electrodynamics has now made this dream real, allowing us to actually achieve in the laboratory variants of the thought experiments of the founding fathers of quantum theory. In our work at Ecole Normale Supérieure, we use a beam of Rydberg atoms to manipulate and probe non-destructively microwave photons trapped in a very high Q superconducting cavity. We realize ideal quantum non-demolition (QND) measurements of photon numbers, observe the radiation quantum jumps due to cavity relaxation and prepare non-classical fields such as Fock and Schrödinger cat states. Combining QND photon counting with a homodyne mixing method, we reconstruct the Wigner functions of these non-classical states and, by taking snapshots of these functions at increasing times, obtain movies of the decoherence process. These experiments ope...

  12. Nonlocal quantum cloning via quantum dots trapped in distant cavities

    Institute of Scientific and Technical Information of China (English)

    Yu Tao; Zhu Ai-Dong; Zhang Shou

    2012-01-01

    A scheme for implementing nonlocal quantum cloning via quantum dots trapped in cavities is proposed.By modulating the parameters of the system,the optimal 1 → 2 universal quantum cloning machine,1 → 2 phase-covariant cloning machine,and 1 → 3 economical phase-covariant cloning machine are constructed.The present scheme,which is attainable with current technology,saves two qubits compared with previous cloning machines.

  13. Scheme for implementing quantum secret sharing via cavity QED

    Institute of Scientific and Technical Information of China (English)

    Chen Zhi-Hua; Lin Xiu-Min

    2005-01-01

    An experimentally feasible scheme for implementing quantum secret sharing via cavity quantum electrodynamics (QED) is proposed. The scheme requires the large detuning of the cavity field from the atomic transition, the cavity is only virtually excited, thus the requirement on the quality factor of the cavity is greatly loosened.

  14. Beam shaping in high-power broad-area quantum cascade lasers using optical feedback

    Science.gov (United States)

    Ferré, Simon; Jumpertz, Louise; Carras, Mathieu; Ferreira, Robson; Grillot, Frédéric

    2017-01-01

    Broad-area quantum cascade lasers with high output powers are highly desirable sources for various applications including infrared countermeasures. However, such structures suffer from strongly deteriorated beam quality due to multimode behavior, diffraction of light and self-focusing. Quantum cascade lasers presenting high performances in terms of power and heat-load dissipation are reported and their response to a nonlinear control based on optical feedback is studied. Applying optical feedback enables to efficiently tailor its near-field beam profile. The different cavity modes are sequentially excited by shifting the feedback mirror angle. Further control of the near-field profile is demonstrated using spatial filtering. The impact of an inhomogeneous gain as well as the influence of the cavity width are investigated. Compared to existing technologies, that are complex and costly, beam shaping with optical feedback is a more flexible solution to obtain high-quality mid-infrared sources. PMID:28287175

  15. Beam shaping in high-power broad-area quantum cascade lasers using optical feedback

    Science.gov (United States)

    Ferré, Simon; Jumpertz, Louise; Carras, Mathieu; Ferreira, Robson; Grillot, Frédéric

    2017-03-01

    Broad-area quantum cascade lasers with high output powers are highly desirable sources for various applications including infrared countermeasures. However, such structures suffer from strongly deteriorated beam quality due to multimode behavior, diffraction of light and self-focusing. Quantum cascade lasers presenting high performances in terms of power and heat-load dissipation are reported and their response to a nonlinear control based on optical feedback is studied. Applying optical feedback enables to efficiently tailor its near-field beam profile. The different cavity modes are sequentially excited by shifting the feedback mirror angle. Further control of the near-field profile is demonstrated using spatial filtering. The impact of an inhomogeneous gain as well as the influence of the cavity width are investigated. Compared to existing technologies, that are complex and costly, beam shaping with optical feedback is a more flexible solution to obtain high-quality mid-infrared sources.

  16. Terahertz Quantum Cascade Laser Based 3D Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — LongWave Photonics proposes a terahertz quantum-cascade laser based swept-source optical coherence tomography (THz SS-OCT) system for single-sided, 3D,...

  17. Linewidth and tuning characteristics of terahertz quantum cascade lasers.

    Science.gov (United States)

    Barkan, A; Tittel, F K; Mittleman, D M; Dengler, R; Siegel, P H; Scalari, G; Ajili, L; Faist, J; Beere, H E; Linfield, E H; Davies, A G; Ritchie, D A

    2004-03-15

    We have measured the spectral linewidths of three continuous-wave quantum cascade lasers operating at terahertz frequencies by heterodyning the free-running quantum cascade laser with two far-infrared gas lasers. Beat notes are detected with a GaAs diode mixer and a microwave spectrum analyzer, permitting very precise frequency measurements and giving instantaneous linewidths of less than -30 kHz. Characteristics are also reported for frequency tuning as the injection current is varied.

  18. Quantum cascade laser Kerr frequency comb

    CERN Document Server

    Lecaplain, Caroline; Lucas, Erwan; Jost, John D; Kippenberg, Tobias J

    2015-01-01

    The mid-infrared (mid-IR) regime (typically the wavelength regime of $\\lambda \\sim 2.5-20 \\ \\mathrm{\\mu m}$) is an important spectral range for spectroscopy as many molecules have their fundamental rotational-vibrational absorption in this band. Recently optical frequency combs based on optical microresonators ("Kerr" combs) at the onset of the mid-IR region have been generated using crystalline resonators and integrated planar silicon micro-resonators. Here we extend for the first time Kerr combs deep into the mid-IR i.e. the 'molecular fingerprint' region. This is achieved by combining an ultra high quality (Q) factor mid-IR microresonator based on crystalline $\\mathrm{MgF_{2}}$ with the quantum cascade laser (QCL) technology. Using a tapered chalgogenide (ChG) fiber and a QCL continuous wave pump laser, frequency combs at $\\lambda\\sim 4.4\\ \\mathrm{\\mu m}$ (i.e. 2270cm$^{-1}$) are generated, that span over 600nm (i.e. 300cm$^{-1}$) in bandwidth, with a mode spacing of 14.3GHz (0.5cm$^{-1}$), corresponding t...

  19. Measurement of gain and losses of a midinfrared quantum cascade laser by wavelength chirping spectroscopy

    Science.gov (United States)

    Benveniste, E.; Laurent, S.; Vasanelli, A.; Manquest, C.; Sirtori, C.; Teulon, F.; Carras, M.; Marcadet, X.

    2009-02-01

    We present an optimized technique for the measurement of gain and losses of semiconductor lasers. We optically inject the beam of a distributed feedback laser (DFB) inside the cavity of the lasers under study. The DFB laser operates in a pulsed mode and shifts its emission wavelength as a function of time. This frequency chirp creates the Fabry-Pérot fringes of the transmitted intensity that contains all the information on the cavity losses. The setup has been validated by a quantitative study of the losses as a function of the injected current, for a quantum cascade laser emitting at 7.6 μm.

  20. Low power-consumption quantum cascade lasers

    Science.gov (United States)

    Katsuyama, Tsukuru; Hashimoto, Jun-ichi; Yoshinaga, Hiroyuki; Mori, Hiroki; Tsuji, Yukihiro; Murata, Makoto; Ekawa, Mitsuru; Tanahashi, Toshiyuki

    2015-01-01

    Quantum cascade lasers (QCLs) are promising light sources for real time high-sensitivity gas sensing in the mid-infrared region. For the practical use of QCLs as a compact and portable gas sensor, their power-consumption needs to be reduced. We report a successful operation of a low power-consumption distributed feedback (DFB) QCL. For the reduction of power consumption, we introduced a vertical-transition structure in a core region to improve carrier transition efficiency and reduced the core volume. DFB-QCL epitaxial structure was grown by low-pressure OMVPE. The core region consists of AlInAs/GaInAs superlattices lattice-matched to InP. A first-order Bragg-grating was formed near the core region to obtain a large coupling coefficiency. A mesa-strip was formed by reactive ion etching and a buried-heterostructure was fabricated by the regrowth of semi-insulating InP. High-reflective facet coatings were also performed to decrease the mirror loss for the reduction of the threshold current. A device (5x500μm) operated with a single mode in the wavelength region from 7.23μm to 7.27μm. The threshold current and threshold voltage under CW operation at 20 °C were 52mA and 8.4V respectively. A very low threshold power-consumption as low as 0.44 W was achieved, which is among the lowest values at room temperature to our knowledge.

  1. Phase-selective reversible quantum decoherence in cavity QED experiment

    CERN Document Server

    Filip, R

    2001-01-01

    New feasible cavity QED experiment is proposed to analyse reversible quantum decoherence in consequence of quantum complementarity and entanglement. Utilizing the phase selective manipulations with enviroment, it is demonstrated how the complementarity particularly induces a preservation of visibility, whereas quantum decoherence is more progressive due to pronounced entanglement between system and enviroment. This effect can be directly observed using the proposed cavity QED measurements.

  2. Comparison of coherently coupled multi-cavity and quantum dot embedded single cavity systems.

    Science.gov (United States)

    Kocaman, Serdar; Sayan, Gönül Turhan

    2016-12-12

    Temporal group delays originating from the optical analogue to electromagnetically induced transparency (EIT) are compared in two systems. Similar transmission characteristics are observed between a coherently coupled high-Q multi-cavity array and a single quantum dot (QD) embedded cavity in the weak coupling regime. However, theoretically generated group delay values for the multi-cavity case are around two times higher. Both configurations allow direct scalability for chip-scale optical pulse trapping and coupled-cavity quantum electrodynamics (QED).

  3. Applying Quantum Cascade Laser Spectroscopy in Plasma Diagnostics

    Directory of Open Access Journals (Sweden)

    Jürgen Röpcke

    2016-07-01

    Full Text Available The considerably higher power and wider frequency coverage available from quantum cascade lasers (QCLs in comparison to lead salt diode lasers has led to substantial advances when QCLs are used in pure and applied infrared spectroscopy. Furthermore, they can be used in both pulsed and continuous wave (cw operation, opening up new possibilities in quantitative time resolved applications in plasmas both in the laboratory and in industry as shown in this article. However, in order to determine absolute concentrations accurately using pulsed QCLs, careful attention has to be paid to features like power saturation phenomena. Hence, we begin with a discussion of the non-linear effects which must be considered when using short or long pulse mode operation. More recently, cw QCLs have been introduced which have the advantage of higher power, better spectral resolution and lower fluctuations in light intensity compared to pulsed devices. They have proved particularly useful in sensing applications in plasmas when very low concentrations have to be monitored. Finally, the use of cw external cavity QCLs (EC-QCLs for multi species detection is described, using a diagnostics study of a methane/nitrogen plasma as an example. The wide frequency coverage of this type of QCL laser, which is significantly broader than from a distributed feedback QCL (DFB-QCL, is a substantial advantage for multi species detection. Therefore, cw EC-QCLs are state of the art devices and have enormous potential for future plasma diagnostic studies.

  4. Cavity quantum electrodynamics on a nanofiber using a composite photonic crystal cavity.

    Science.gov (United States)

    Yalla, Ramachandrarao; Sadgrove, Mark; Nayak, Kali P; Hakuta, Kohzo

    2014-10-01

    We demonstrate cavity QED conditions in the Purcell regime for single quantum emitters on the surface of an optical nanofiber. The cavity is formed by combining an optical nanofiber and a nanofabricated grating to create a composite photonic crystal cavity. By using this technique, significant enhancement of the spontaneous emission rate into the nanofiber guided modes is observed for single quantum dots. Our results pave the way for enhanced on-fiber light-matter interfaces with clear applications to quantum networks.

  5. Cavity quantum electrodynamics of a quantum dot in a micropillar cavity: comparison between experiment and theory

    DEFF Research Database (Denmark)

    Madsen, Kristian Høeg; Ates, Serkan; Reitzenstein, S.;

    2010-01-01

    The coupling between a quantum dot (QD) and a micropillar cavity is experimentally investigated by performing time-resolved, correlation, and two-photon interference measurements. The Jaynes-Cummings model including dissipative Lindblad terms and dephasing is analyzed, and all the parameters...... for the model are experimentally determined allowing for a complete comparison between experiment and theory....

  6. An Elementary Quantum Network of Single Atoms in Optical Cavities

    CERN Document Server

    Ritter, Stephan; Hahn, Carolin; Reiserer, Andreas; Neuzner, Andreas; Uphoff, Manuel; Mücke, Martin; Figueroa, Eden; Bochmann, Jörg; Rempe, Gerhard

    2012-01-01

    Quantum networks are distributed quantum many-body systems with tailored topology and controlled information exchange. They are the backbone of distributed quantum computing architectures and quantum communication. Here we present a prototype of such a quantum network based on single atoms embedded in optical cavities. We show that atom-cavity systems form universal nodes capable of sending, receiving, storing and releasing photonic quantum information. Quantum connectivity between nodes is achieved in the conceptually most fundamental way: by the coherent exchange of a single photon. We demonstrate the faithful transfer of an atomic quantum state and the creation of entanglement between two identical nodes in independent laboratories. The created nonlocal state is manipulated by local qubit rotation. This efficient cavity-based approach to quantum networking is particularly promising as it offers a clear perspective for scalability, thus paving the way towards large-scale quantum networks and their applicati...

  7. Coherent Dynamics of Quantum Dots in Photonic-Crystal Cavities

    DEFF Research Database (Denmark)

    Madsen, Kristian Høeg

    deviations. Similar measurements on a quantum dot in a photonic-crystal cavity sow a Rabi splitting on resonance, while time-resolved measurements prove that the system is in the weak coupling regime. Whle tuning the quantum dot through resonance of the high-Q mode we observe a strong and surprisingly...... Successfully model the decay rates with a microscopic model that allows us to for the first time extract the effective phonon density of states, which we can model with bulk phonons. Studies on a quantum dot detuned from a low-Q mode of a photonic-crystal cavity show a high collection efficiency at the first......In this thesis we have performed quantum-electrodynamics experiments on quantum dots embedded in photonic-crystal cavities. We perform a quantitative comparison of the decay dynamics and emission spectra of quantum dots embedded in a micropillar cavity and a photonic-crystal cavity. The light...

  8. Applications of absorption spectroscopy using quantum cascade lasers.

    Science.gov (United States)

    Zhang, Lizhu; Tian, Guang; Li, Jingsong; Yu, Benli

    2014-01-01

    Infrared laser absorption spectroscopy (LAS) is a promising modern technique for sensing trace gases with high sensitivity, selectivity, and high time resolution. Mid-infrared quantum cascade lasers, operating in a pulsed or continuous wave mode, have potential as spectroscopic sources because of their narrow linewidths, single mode operation, tunability, high output power, reliability, low power consumption, and compactness. This paper reviews some important developments in modern laser absorption spectroscopy based on the use of quantum cascade laser (QCL) sources. Among the various laser spectroscopic methods, this review is focused on selected absorption spectroscopy applications of QCLs, with particular emphasis on molecular spectroscopy, industrial process control, combustion diagnostics, and medical breath analysis.

  9. Rate equation modelling and investigation of quantum cascade detector characteristics

    Science.gov (United States)

    Saha, Sumit; Kumar, Jitendra

    2016-10-01

    A simple precise transport model has been proposed using rate equation approach for the characterization of a quantum cascade detector. The resonant tunneling transport is incorporated in the rate equation model through a resonant tunneling current density term. All the major scattering processes are included in the rate equation model. The effect of temperature on the quantum cascade detector characteristics has been examined considering the temperature dependent band parameters and the carrier scattering processes. Incorporation of the resonant tunneling process in the rate equation model improves the detector performance appreciably and reproduces the detector characteristics within experimental accuracy.

  10. Efficient method for transport simulations in quantum cascade lasers

    Directory of Open Access Journals (Sweden)

    Maczka Mariusz

    2017-01-01

    Full Text Available An efficient method for simulating quantum transport in quantum cascade lasers is presented. The calculations are performed within a simple approximation inspired by Büttiker probes and based on a finite model for semiconductor superlattices. The formalism of non-equilibrium Green’s functions is applied to determine the selected transport parameters in a typical structure of a terahertz laser. Results were compared with those obtained for a infinite model as well as other methods described in literature.

  11. Efficient method for transport simulations in quantum cascade lasers

    Science.gov (United States)

    Maczka, Mariusz; Pawlowski, Stanislaw

    2016-12-01

    An efficient method for simulating quantum transport in quantum cascade lasers is presented. The calculations are performed within a simple approximation inspired by Büttiker probes and based on a finite model for semiconductor superlattices. The formalism of non-equilibrium Green's functions is applied to determine the selected transport parameters in a typical structure of a terahertz laser. Results were compared with those obtained for a infinite model as well as other methods described in literature.

  12. Terahertz Quantum-Cascade Transmission-Line Metamaterials

    OpenAIRE

    Tavallaee, Amir Ali

    2012-01-01

    Terahertz quantum-cascade (QC) lasers operating at 0.6 − 5 THz (λ ∼ 60 − 500 μm) are poised to become the dominant solid-state sources of continuous-wave (cw) far-infrared radiation enabling applications in terahertz spectroscopy, imaging, and sensing. QC-lasers are the longest wavelength semiconductor laser sources in which terahertz gain is obtained from electronic intersubband radiative transitions in GaAs/AlGaAs heterostructure quantum wells. Since their invent...

  13. Development of GaN/AlGaN Terahertz Quantum Cascade Laser

    Science.gov (United States)

    2008-11-19

    AFOSR-Taiwan Nanoscience Initiative Project Final Report Project Title Development of GaN /AlGaN Terahertz Quantum Cascade Laser...DATES COVERED 14-06-2007 to 13-06-2008 4. TITLE AND SUBTITLE Development of GaN -Based Terahertz Quantum Cascade Laser 5a. CONTRACT NUMBER...the GaN /AlGaN active region for terahertz quantum cascade lasers using MOCVD system based on the quantum cascade structure proposed by Prof. Greg Sun

  14. Ultra-high Q sphere-like cavities for cascaded stimulated Brillouin lasing

    Science.gov (United States)

    Che, Kaijun; Zhang, Pan; Guo, Changlei; Tang, Deyu; Ren, Changyan; Xu, Huiying; Luo, Zhengqian; Cai, Zhiping

    2017-03-01

    High Q microsphere optical cavity is usually fabricated from a single mode fiber. Here, we propose a new method to fabricate sphere-like cavity by melting the tip of rotating quartz-rod with a CO2 laser. The cavities with diameter from 200 μm to 700 μm and resonant Q factors above 108 are obtained. Due to the rich resonances of the sphere-like cavity, up to 15-order cascaded stimulated Brillouin lasings(SBL) near 1.55 μm are observed in a cavity with a diameter of 760 μm by simply tuning the pump wavelength to a finely-selected resonance. We wish the ultra-high Q cavities with rich resonances and bulk rod mount can have practical applications in nonlinear optics and microwave photonics as an optical component.

  15. Scalable photonic quantum computation through cavity-assisted interactions.

    Science.gov (United States)

    Duan, L-M; Kimble, H J

    2004-03-26

    We propose a scheme for scalable photonic quantum computation based on cavity-assisted interaction between single-photon pulses. The prototypical quantum controlled phase-flip gate between the single-photon pulses is achieved by successively reflecting them from an optical cavity with a single-trapped atom. Our proposed protocol is shown to be robust to practical noise and experimental imperfections in current cavity-QED setups.

  16. Quantum correlations in non-inertial cavity systems

    Science.gov (United States)

    Harsij, Zeynab; Mirza, Behrouz

    2016-10-01

    Non-inertial cavities are utilized to store and send Quantum Information between mode pairs. A two-cavity system is considered where one is inertial and the other accelerated in a finite time. Maclaurian series are applied to expand the related Bogoliubov coefficients and the problem is treated perturbatively. It is shown that Quantum Discord, which is a measure of quantumness of correlations, is degraded periodically. This is almost in agreement with previous results reached in accelerated systems where increment of acceleration decreases the degree of quantum correlations. As another finding of the study, it is explicitly shown that degradation of Quantum Discord disappears when the state is in a single cavity which is accelerated for a finite time. This feature makes accelerating cavities useful instruments in Quantum Information Theory.

  17. Intrinsic linewidth of quantum cascade laser frequency combs

    CERN Document Server

    Cappelli, Francesco; Riedi, Sabine; Faist, Jerome

    2015-01-01

    The frequency noise power spectral density of a free-running quantum cascade laser frequency comb is investigated. A plateau is observed at high frequencies, attributed to the quantum noise limit set by the Schawlow-Townes formula for the total laser power on all comb lines. In our experiment, a linewidth of 292 Hz is measured for a total power of 25 mW. This result proves that the four-wave mixing process, responsible for the comb operation, effectively correlates the quantum noise of the individual comb lines.

  18. Integration of a terahertz quantum cascade laser with a hollow waveguide

    Science.gov (United States)

    Wanke, Michael C [Albuquerque, NM; Nordquist, Christopher D [Albuquerque, NM

    2012-07-03

    The present invention is directed to the integration of a quantum cascade laser with a hollow waveguide on a chip to improve both the beam pattern and manufacturability. By coupling the QCL output into a single-mode rectangular waveguide the radiation mode structure can be known and the propagation, manipulation, and broadcast of the QCL radiation can then be entirely controlled by well-established rectangular waveguide techniques. By controlling the impedance of the interface, enhanced functions, such as creating amplifiers, efficient coupling to external cavities, and increasing power output from metal-metal THz QCLs, are also enabled.

  19. Low-loss hollow waveguide fibers for mid-infrared quantum cascade laser sensing applications.

    Science.gov (United States)

    Patimisco, Pietro; Spagnolo, Vincenzo; Vitiello, Miriam S; Scamarcio, Gaetano; Bledt, Carlos M; Harrington, James A

    2013-01-21

    We report on single mode optical transmission of hollow core glass waveguides (HWG) coupled with an external cavity mid-IR quantum cascade lasers (QCLs). The QCL mode results perfectly matched to the hybrid HE(11) waveguide mode and the higher losses TE-like modes have efficiently suppressed by the deposited inner dielectric coating. Optical losses down to 0.44 dB/m and output beam divergence of ~5 mrad were measured. Using a HGW fiber with internal core size of 300 µm we obtained single mode laser transmission at 10.54 µm and successful employed it in a quartz enhanced photoacoustic gas sensor setup.

  20. Low-Loss Hollow Waveguide Fibers for Mid-Infrared Quantum Cascade Laser Sensing Applications

    Directory of Open Access Journals (Sweden)

    James A. Harrington

    2013-01-01

    Full Text Available We report on single mode optical transmission of hollow core glass waveguides (HWG coupled with an external cavity mid-IR quantum cascade lasers (QCLs. The QCL mode results perfectly matched to the hybrid HE11 waveguide mode and the higher losses TE-like modes have efficiently suppressed by the deposited inner dielectric coating. Optical losses down to 0.44 dB/m and output beam divergence of ~5 mrad were measured. Using a HGW fiber with internal core size of 300 µm we obtained single mode laser transmission at 10.54 µm and successful employed it in a quartz enhanced photoacoustic gas sensor setup.

  1. Influence of the material parameters on quantum cascade devices

    Science.gov (United States)

    Benveniste, E.; Vasanelli, A.; Delteil, A.; Devenson, J.; Teissier, R.; Baranov, A.; Andrews, A. M.; Strasser, G.; Sagnes, I.; Sirtori, C.

    2008-09-01

    An experimental investigation on the influence of the material systems on the optical properties of quantum cascade structures is presented. Three electroluminescent quantum cascade devices have been grown using GaAs /AlGaAs, GaInAs /AlInAs, and InAs /AlSb heterostructures. The devices emit at 10μm and are based on a similar bandstructure design. Our results verify that the optical quantum efficiency has the predicted dependence on the electron effective mass. We also demonstrate that the shape of the electroluminescence spectra is independent from the particular material parameters and mainly depends on the tunnel coupling between the injector state and the upper state of the radiative transition.

  2. Separation of Transitions with Two Quantum Jumps from Cascades

    CERN Document Server

    Jentschura, U D

    2010-01-01

    We consider the general scenario of an excited level |i> of a quantum system that can decay via two channels: (i) via a single-quantum jump to an intermediate, resonant level |bar m>, followed by a second single-quantum jump to a final level |f>, and (ii) via a two-quantum transition to a final level |f>. Cascade processes |i> -> |bar m> -> | f> and two-quantum transitions |i> -> |m> -> |f> compete (in the latter case, |m> can be both a nonresonant as well as a resonant level). General expressions are derived within second-order time-dependent perturbation theory, and the cascade contribution is identified. When the one-quantum decay rates of the virtual states are included into the complex resonance energies that enter the propagator denominator, it is found that the second-order decay rate contains the one-quantum decay rate of the initial state as a lower-order term. For atomic transitions, this implies that the differential-in-energy two-photon transition rate with complex resonance energies in the propag...

  3. Frequency combs for cavity cascades: OPO combs and graphene-coupled cavities

    Science.gov (United States)

    Lee, Kevin F.; Kowzan, Grzegorz; Lee, C.-C.; Mohr, C.; Jiang, Jie; Schunemann, Peter G.; Schibli, T. R.; Maslowski, Piotr; Fermann, M. E.

    2017-01-01

    Frequency combs can be used directly, for example as a highly precise spectroscopic light source. They can also be used indirectly, as a bridge between devices whose high precision requirements would normally make them incompatible. Here, we demonstrate two ways that a frequency comb enables new technologies by matching optical cavities. One cavity is the laser oscillator. A second cavity is a low-threshold doubly-resonant optical parametric oscillator (OPO). Extending optical referencing to the doubly-resonant OPO turns the otherwise unstable device into an extremely precise midinfrared frequency comb. Another cavity is an optical enhancement cavity for amplifying spectral absorption in a gas. With the high speed of a graphene-modulated frequency comb, we can couple a frequency comb directly into a high-finesse cavity for trace gas detection.

  4. THz quantum cascade lasers for standoff molecule detection.

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Weng Wah; Wanke, Michael Clement; Lerttamrab, Maytee; Waldmueller, Ines

    2007-10-01

    Remote optical detection of molecules, agents, and energetic materials has many applications to national security interests. Currently there is significant interest in determining under what circumstances THz frequency coverage will aid in a complete sensing package. Sources of coherent THz frequency (i.e. 0.1 to 10 THz) electromagnetic radiation with requisite power levels, frequency agility, compactness and reliability represent the single greatest obstacle in establishing a THz technology base, but recent advances in semiconductor-based quantum cascade lasers (QCLs) offer huge improvements towards the ultimate THz source goals. This project advanced the development of narrow-linewidth THz quantum cascade lasers. We developed theoretical tools to guide the improvement of standard THz quantum cascade lasers, the investigation of nonlinear optics employing infrared QCLs, and the exploration of quantum coherence to improve QCL performance. The latter was aimed especially towards achieving high temperature operation. In addition we developed a computer algorithm capable of shifting the frequencies of an existing THz QCL to a different frequency and invented a new type of laser that may enable room temperature THz generation in a electrically driven solid-state source.

  5. Unconventional geometric quantum phase gates with a cavity QED system

    Science.gov (United States)

    Zheng, Shi-Biao

    2004-11-01

    We propose a scheme for realizing two-qubit quantum phase gates via an unconventional geometric phase shift with atoms in a cavity. In the scheme the atoms interact simultaneously with a highly detuned cavity mode and a classical field. The atoms undergo no transitions during the gate operation, while the cavity mode is displaced along a circle in the phase space, aquiring a geometric phase conditional upon the atomic state. Under certain conditions, the atoms are disentangled with the cavity mode and thus the gate is insensitive to both the atomic spontaneous emission and the cavity decay.

  6. Scheme for Quantum Entanglement Swapping on Cavity QED System

    Institute of Scientific and Technical Information of China (English)

    CHEN Chang-Yong; YU Yan

    2006-01-01

    We propose a scheme for realizing quantum entanglement swapping between the atoms in cavity QED.With only virtual excitation of the cavity during the interaction between the atoms and cavity, the scheme is insensitive to the cavity mode states and the cavity decay. The ideas can also be utilized for realizing entanglement swapping between the atomic levels in a single atom and the atomic levels in the Bell states and between the atomic levels in the Bell states and the atomic levels in the W states.

  7. InAs based terahertz quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Brandstetter, Martin, E-mail: martin.brandstetter@tuwien.ac.at; Kainz, Martin A.; Krall, Michael; Schönhuber, Sebastian; Unterrainer, Karl [Photonics Institute and Center for Micro- and Nanostructures, Technische Universität Wien, Gusshausstrasse 27-29, 1040 Vienna (Austria); Zederbauer, Tobias; Schrenk, Werner; Andrews, Aaron Maxwell; Strasser, Gottfried [Institute for Solid State Electronics and Center for Micro- and Nanostructures, Technische Universität Wien, Floragasse 7, 1040 Vienna (Austria); Detz, Hermann [Austrian Academy of Sciences, Dr. Ignaz Seipel-Platz 2, 1010 Vienna (Austria)

    2016-01-04

    We demonstrate terahertz lasing emission from a quantum cascade structure, realized with InAs/AlAs{sub 0.16}Sb{sub 0.84} heterostructures. Due to the lower effective electron mass, InAs based active regions are expected to provide a higher optical gain compared to structures consisting of GaAs or InGaAs. The growth by molecular beam epitaxy enabled the fabrication of monolayer-thick barriers, required for the active region, which is based on a 3-well resonant phonon depletion design. Devices were processed in a double-metal waveguide geometry to ensure high mode confinement and low optical losses. Lasing emission at 3.8 THz was observed at liquid helium temperatures by applying a magnetic field perpendicular to the layered structure in order to suppress parasitic scattering channels. These results demonstrate the feasibility of InAs based active regions for terahertz quantum cascade lasers, potentially enabling higher operating temperatures.

  8. Emergence of a turbulent cascade in a quantum gas

    Science.gov (United States)

    Navon, Nir; Gaunt, Alexander L.; Smith, Robert P.; Hadzibabic, Zoran

    2016-11-01

    A central concept in the modern understanding of turbulence is the existence of cascades of excitations from large to small length scales, or vice versa. This concept was introduced in 1941 by Kolmogorov and Obukhov, and such cascades have since been observed in various systems, including interplanetary plasmas, supernovae, ocean waves and financial markets. Despite much progress, a quantitative understanding of turbulence remains a challenge, owing to the interplay between many length scales that makes theoretical simulations of realistic experimental conditions difficult. Here we observe the emergence of a turbulent cascade in a weakly interacting homogeneous Bose gas—a quantum fluid that can be theoretically described on all relevant length scales. We prepare a Bose-Einstein condensate in an optical box, drive it out of equilibrium with an oscillating force that pumps energy into the system at the largest length scale, study its nonlinear response to the periodic drive, and observe a gradual development of a cascade characterized by an isotropic power-law distribution in momentum space. We numerically model our experiments using the Gross-Pitaevskii equation and find excellent agreement with the measurements. Our experiments establish the uniform Bose gas as a promising new medium for investigating many aspects of turbulence, including the interplay between vortex and wave turbulence, and the relative importance of quantum and classical effects.

  9. Quantum Dot-Photonic Crystal Cavity QED Based Quantum Information Processing

    Science.gov (United States)

    2012-08-14

    Physical Review A, 2012] 3. Study of the off-resonant quantum dot-cavity coupling in solid-state cavity QED system, and the phonon mediated off...resonant interaction between two quantum dots [Majumdar et al., Physical Review B , 2012] 4. Coherent optical spectroscopy of a single quantum dot via an off...Resonant cavity - much simpler than in conventional approaches [Majumdar et al, Physical Review B, 2011; Papageorge et al., New. Journal of Physics

  10. Rate equations model and optical external efficiency of optically pumped electrically driven terahertz quantum cascade lasers

    Science.gov (United States)

    Hamadou, A.; Thobel, J.-L.; Lamari, S.

    2016-10-01

    A four level rate equations model for a terahertz optically pumped electrically driven quantum cascade laser is here introduced and used to model the system both analytically and numerically. In the steady state, both in the presence and absence of the terahertz optical field, we solve the resulting nonlinear system of equations and obtain closed form expressions for the levels occupation, population inversion as well as the mid-infrared pump threshold intensity in terms of the device parameters. We also derive, for the first time for this system, an analytical formula for the optical external efficiency and analyze the simultaneous effects of the cavity length and pump intensity on it. At moderate to high pump intensities, we find that the optical external efficiency scales roughly as the reciprocal of the cavity length.

  11. Hybrid circuit cavity quantum electrodynamics with a micromechanical resonator.

    Science.gov (United States)

    Pirkkalainen, J-M; Cho, S U; Li, Jian; Paraoanu, G S; Hakonen, P J; Sillanpää, M A

    2013-02-14

    Hybrid quantum systems with inherently distinct degrees of freedom have a key role in many physical phenomena. Well-known examples include cavity quantum electrodynamics, trapped ions, and electrons and phonons in the solid state. In those systems, strong coupling makes the constituents lose their individual character and form dressed states, which represent a collective form of dynamics. As well as having fundamental importance, hybrid systems also have practical applications, notably in the emerging field of quantum information control. A promising approach is to combine long-lived atomic states with the accessible electrical degrees of freedom in superconducting cavities and quantum bits (qubits). Here we integrate circuit cavity quantum electrodynamics with phonons. Apart from coupling to a microwave cavity, our superconducting transmon qubit, consisting of tunnel junctions and a capacitor, interacts with a phonon mode in a micromechanical resonator, and thus acts like an atom coupled to two different cavities. We measure the phonon Stark shift, as well as the splitting of the qubit spectral line into motional sidebands, which feature transitions between the dressed electromechanical states. In the time domain, we observe coherent conversion of qubit excitation to phonons as sideband Rabi oscillations. This is a model system with potential for a quantum interface, which may allow for storage of quantum information in long-lived phonon states, coupling to optical photons or for investigations of strongly coupled quantum systems near the classical limit.

  12. Entangled Photons from Radiative Cascades in Semiconductor Quantum Dots

    CERN Document Server

    Akopian, N; Poem, E; Berlatzky, Y; Avron, J; Gershoni, D; Gerardot, B D; Petroff, P M

    2005-01-01

    We show, for the first time, that polarization-entangled photon pairs can be produced from the biexciton radiative cascade in a semiconductor quantum dot. We select an energy window that erases the ``which path'' information contained in the colors of the emitted photons, and use tomographic analysis to demonstrate that the photon pair violate Bell's inequality and satisfy Peres criterion for entanglement by more than 3 standard deviations of the experimental uncertainty. Our quantitative analysis show that semiconductor quantum dots can be used as sources for ``event-ready'' entangled photons.

  13. Influence of nonparabolicity on electronic structure of quantum cascade laser

    Science.gov (United States)

    Vuković, Nikola; Milanović, Vitomir; Radovanović, Jelena

    2014-06-01

    We analyze the influence of nonparabolicity on the bound electronic states in the conduction-band of quantum wells in external electric field. Numerical results, obtained by transfer matrix method are presented for active region of GaAs/Al0.3Ga0.7As quantum cascade laser. The structure was initially optimized by genetic algorithm, using Kane's model of nonparabolicity, with emission wavelength set to λ≈15.1 μm. However, our numerical results indicate the change in lasing wavelength to 14.04 μm when using a more comprehensive description of nonparabolicity.

  14. Phase-locked array of quantum cascade lasers with an intracavity spatial filter

    CERN Document Server

    Wang, Lei; Jia, Zhiwei; Zhao, Yue; Liu, Chuanwei; Liu, Yinghui; Zhai, Shenqiang; Ning, Zhuo; Liu, Fengqi

    2016-01-01

    Phase-locking an array of quantum cascade lasers is an effective way to achieve higher output power and beam shaping. In this article, based on Talbot effect, we show a new-type phase-locked array of mid-infrared quantum cascade lasers with an integrated spatial- filtering Talbot cavity. All the arrays show stable in-phase operation from the threshold current to full power current. The beam divergence of the array device is smaller than that of a single-ridge laser. We use the multi-slit Fraunhofer diffraction mode to interpret the far-field radiation profile and give a solution to get better beam quality. The maximum power is just about 5 times that of a single-ridge laser for eleven-laser array device and 3 times for seven-laser array device. Considering the great modal selection ability, simple fabricating process and the potential for achieving better beam quality and smaller cavity loss, this new-type phase-locked array may be a hopeful and elegant solution to get high power or beam shaping.

  15. Quantum superdense coding via cavity-assisted interactions

    Institute of Scientific and Technical Information of China (English)

    Pan Guo-Zhu; Yang Ming; Cao Zhuo-Liang

    2009-01-01

    Quantum superdense coding (QSC) is an example of how entanglement can be used to minimize the number of carriers of classical information. This paper proposes two schemes for implementing QSC by means of cavity assisted interactions with single-photon pulses. The schemes are insensitive to the cavity decay and the thermal field, thus it might be realizable based on the current cavity QED techniques.

  16. Linewidth broadening of a quantum dot coupled to an off-resonant cavity

    CERN Document Server

    Majumdar, Arka; Kim, Erik; Englund, Dirk; Kim, Hyochul; Petroff, Pierre; Vuckovic, Jelena

    2010-01-01

    We study the coupling between a photonic crystal cavity and an off-resonant quantum dot under resonant excitation of the cavity or the quantum dot. Linewidths of the quantum dot and the cavity as a function of the excitation laser power are measured. We show that the linewidth of the quantum dot, measured by observing the cavity emission, is significantly broadened compared to the theoretical estimate. This indicates additional incoherent coupling between the quantum dot and the cavity.

  17. Evaluation of quantum-cascade lasers as local oscillators for infrared heterodyne spectroscopy.

    Science.gov (United States)

    Sonnabend, Guido; Wirtz, Daniel; Schieder, Rudolf

    2005-11-20

    We report experiments evaluating the feasibility of quantum-cascade lasers (QCLs) at mid-infrared wavelengths for use as local oscillators (LOs) in a heterodyne receiver. Performance tests with continuous-wave (cw) lasers around 9.6 and 9.2 microm were carried out investigating optical output power, laser linewidth, and tunability. A direct comparison with a CO2 gas laser LO is presented as well. The achieved system sensitivity in a heterodyne spectrometer of only a factor of 2 above the quantum limit together with the measured linewidth of less than 1.5 MHz shows that QCLs are suitable laser sources for heterodyne spectroscopy with sufficient output power to replace gas lasers as LOs even in high-sensitivity astronomical heterodyne receivers. In addition, our experiments show that the tunability of the lasers can be greatly enhanced by use of an external cavity.

  18. Ultra-high-Q toroidal microresonators for cavity quantum electrodynamics

    CERN Document Server

    Spillane, S M; Vahala, K J; Goh, K W; Wilcut, E; Kimble, H J

    2004-01-01

    We investigate the suitability of toroidal microcavities for strong-coupling cavity quantum electrodynamics (QED). Numerical modeling of the optical modes demonstrate a significant reduction of modal volume with respect to the whispering gallery modes of dielectric spheres, while retaining the high quality factors representative of spherical cavities. The extra degree of freedom of toroid microcavities can be used to achieve improved cavity QED characteristics. Numerical results for atom-cavity coupling strength, critical atom number N_0 and critical photon number n_0 for cesium are calculated and shown to exceed values currently possible using Fabry-Perot cavities. Modeling predicts coupling rates g/(2*pi) exceeding 700 MHz and critical atom numbers approaching 10^{-7} in optimized structures. Furthermore, preliminary experimental measurements of toroidal cavities at a wavelength of 852 nm indicate that quality factors in excess of 100 million can be obtained in a 50 micron principal diameter cavity, which w...

  19. Terahertz Quantum Cascade Laser With Efficient Coupling and Beam Profile

    Science.gov (United States)

    Chattopadhyay, Goutam; Kawamura, Jonathan H.; Lin, Robert H.; Williams, Benjamin

    2012-01-01

    Quantum cascade lasers (QCLs) are unipolar semiconductor lasers, where the wavelength of emitted radiation is determined by the engineering of quantum states within the conduction band in coupled multiple-quantum-well heterostructures to have the desired energy separation. The recent development of terahertz QCLs has provided a new generation of solid-state sources for radiation in the terahertz frequency range. Terahertz QCLs have been demonstrated from 0.84 to 5.0 THz both in pulsed mode and continuous wave mode (CW mode). The approach employs a resonant-phonon depopulation concept. The metal-metal (MM) waveguide fabrication is performed using Cu-Cu thermo-compression bonding to bond the GaAs/AlGaAs epitaxial layer to a GaAs receptor wafer.

  20. Mid-infrared interband cascade photodetectors with high quantum efficiency

    Science.gov (United States)

    Tian, Zhao-Bing; Singh, Anjali; Rigg, Kevin; Krishna, Sanjay

    2016-02-01

    Antimony-based Interband Cascade (IC) photodetectors are emerging as viable candidates for highperformance infrared applications, especially at high operating temperatures. In our previous IC detector designs using InAs/GaSb Type-II superlattices, the quantum efficiency was relatively low as the designs were optimized for high signal to noise ratio. Here we report our recent development of low-noise mid-IR IC photodetectors with high external quantum efficiency. By adopting IC detectors with thicker absorber designs, the quantum efficiency of these mid-IR IC detectors has been increased up to 35%. These IC devices continue to have low-dark current and high temperature operations. Some further analysis on the device characteristics is also presented.

  1. Cavity quantum electrodynamics with Anderson-localized modes.

    Science.gov (United States)

    Sapienza, Luca; Thyrrestrup, Henri; Stobbe, Søren; Garcia, Pedro David; Smolka, Stephan; Lodahl, Peter

    2010-03-12

    A major challenge in quantum optics and quantum information technology is to enhance the interaction between single photons and single quantum emitters. This requires highly engineered optical cavities that are inherently sensitive to fabrication imperfections. We have demonstrated a fundamentally different approach in which disorder is used as a resource rather than a nuisance. We generated strongly confined Anderson-localized cavity modes by deliberately adding disorder to photonic crystal waveguides. The emission rate of a semiconductor quantum dot embedded in the waveguide was enhanced by a factor of 15 on resonance with the Anderson-localized mode, and 94% of the emitted single photons coupled to the mode. Disordered photonic media thus provide an efficient platform for quantum electrodynamics, offering an approach to inherently disorder-robust quantum information devices.

  2. Realizing quantum controlled phase flip through cavity QED

    Science.gov (United States)

    Xiao, Yun-Feng; Lin, Xiu-Min; Gao, Jie; Yang, Yong; Han, Zheng-Fu; Guo, Guang-Can

    2004-10-01

    We propose a scheme to realize quantum controlled phase flip (CPF) between two rare-earth ions embedded in the respective microsphere cavity via interacting with a single-photon pulse in sequence. The numerical simulations illuminate that the CPF gate between ions is robust and scalable with extremely high fidelity and low error rate. Our scheme is more applicable than other schemes presented before based on current laboratory cavity-QED technology, and it is possible to be used as an applied unit gate in future quantum computation and quantum communication.

  3. Realizing Quantum Controlled Phase Flip through Cavity-QED

    CERN Document Server

    Xiao, Y F; Gao, J; Yang, Y; Han, Z F; Guo, G C; Xiao, Yun-Feng; Lin, Xiu-Min; Gao, Jie; Yang, Yong; Han, Zheng-Fu; Guo, Guang-Can

    2004-01-01

    We propose a scheme to realize quantum controlled phase flip (CPF) between two rare earth ions embedded in respective microsphere cavity via interacting with a single-photon pulse in sequence. The numerical simulations illuminate that the CPF gate between ions is robust and scalable with extremely high fidelity and low error rate. Our scheme is more applicable than other schemes presented before based on current laboratory cavity-QED technology, and it is possible to be used as an applied unit gate in future quantum computation and quantum communication.

  4. Cavity QED based tuneable, delayed-choice quantum eraser

    Science.gov (United States)

    Imran, Muhammad; Abbas, Tasawar; -ul-Islam, Rameez; Ikram, Manzoor

    2016-01-01

    We propose an experimentally feasible idea for the delayed-choice quantum eraser, having adjustable path distinguishability/fringe visibility. The schematics are based on resonant, dispersive and Ramsey interactions of atoms under cavity QED scenario. The option for tuneability of the fringes in a delayed-choice setup stringently marks the conception of the time in the quantum theory, operational meanings of the state vector reduction and raises questions about Ψ-ontic models while helping to shed out the controversies surrounding the quantum eraser theme. The proposal can be efficiently executed experimentally within the prevailing cavity QED experimental research scenario with good overall success probability and fidelity.

  5. On the quantum (in)stability in cavity QED

    CERN Document Server

    Prants, S V

    2005-01-01

    The stability and instability of quantum motion is studied in the context of cavity quantum electrodynamics (QED). It is shown that the Jaynes-Cummings dynamics can be unstable in the regime of chaotic walking of an atom in the quantized field of a standing wave in the absence of any other interaction with environment. This quantum instability manifests itself in strong variations of quantum purity and entropy and in exponential sensitivity of fidelity of quantum states to small variations in the atom-field detuning. It is quantified in terms of the respective classical maximal Lyapunov exponent that can be estimated in appropriate in-out experiments.

  6. Autonomous quantum thermal machines in atom-cavity systems

    CERN Document Server

    Mitchison, Mark T; Prior, Javier; Woods, Mischa P; Plenio, Martin B

    2016-01-01

    An autonomous quantum thermal machine comprising a trapped atom or ion placed inside an optical cavity is proposed and analysed. Such a machine can operate as a heat engine whose working medium is the quantised atomic motion, or as an absorption refrigerator which cools without any work input. Focusing on the refrigerator mode, we predict that it is possible with state-of-the-art technology to cool a trapped ion almost to its motional ground state using a thermal light source such as sunlight. We nonetheless find that a laser or similar reference system is necessary to stabilise the cavity frequencies. Furthermore, we establish a direct and heretofore unacknowledged connection between the abstract theory of quantum absorption refrigerators and practical sideband cooling techniques. We also highlight and clarify some assumptions underlying several recent theoretical studies on self-contained quantum engines and refrigerators. Our work indicates that cavity quantum electrodynamics is a promising and versatile e...

  7. Emergence of a Turbulent Cascade in a Quantum Gas

    CERN Document Server

    Navon, Nir; Smith, Robert P; Hadzibabic, Zoran

    2016-01-01

    In the modern understanding of turbulence, a central concept is the existence of cascades of excitations from large to small lengthscales, or vice-versa. This concept was introduced in 1941 by Kolmogorov and Obukhov, and the phenomenon has since been observed in a variety of systems, including interplanetary plasmas, supernovae, ocean waves, and financial markets. Despite a lot of progress, quantitative understanding of turbulence remains a challenge due to the interplay of many lengthscales that usually thwarts theoretical simulations of realistic experimental conditions. Here we observe the emergence of a turbulent cascade in a weakly interacting homogeneous Bose gas, a quantum fluid that is amenable to a theoretical description on all relevant lengthscales. We prepare a Bose-Einstein condensate (BEC) in an optical box, drive it out of equilibrium with an oscillating force that pumps energy into the system at the largest lengthscale, study the BEC's nonlinear response to the periodic drive, and observe a gr...

  8. Modelling of GaN quantum dot terahertz cascade laser

    Science.gov (United States)

    Asgari, A.; Khorrami, A. A.

    2013-03-01

    In this paper GaN based spherical quantum dot cascade lasers has been modelled, where the generation of the terahertz waves are obtained. The Schrödinger, Poisson, and the laser rate equations have been solved self-consistently including all dominant physical effects such as piezoelectric and spontaneous polarization in nitride-based QDs and the effects of the temperature. The exact value of the energy levels, the wavefunctions, the lifetimes of electron levels, and the lasing frequency are calculated. Also the laser parameters such as the optical gain, the output power and the threshold current density have been calculated at different temperatures and applied electric fields.

  9. Plasmonic lens enhanced mid-infrared quantum cascade detector

    Energy Technology Data Exchange (ETDEWEB)

    Harrer, Andreas, E-mail: andreas.harrer@tuwien.ac.at; Schwarz, Benedikt; Gansch, Roman; Reininger, Peter; Detz, Hermann; Zederbauer, Tobias; Andrews, Aaron Maxwell; Schrenk, Werner; Strasser, Gottfried [Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, 1040 Vienna (Austria)

    2014-10-27

    We demonstrate monolithic integrated quantum cascade detectors enhanced by plasmonic lenses. Surface normal incident mid-infrared radiation is coupled to surface plasmon polaritons guided to and detected by the active region of the detector. The lens extends the optical effective active area of the device up to a 5 times larger area than for standard mesa detectors or pixel devices while the electrical active region stays the same. The extended optical area increases the absorption efficiency of the presented device as well as the room temperature performance while it offers a flexible platform for various detector geometries. A photocurrent response increase at room temperature up to a factor of 6 was observed.

  10. Higher order nonlinearity and synchronization of quantum cascade lasers

    Institute of Scientific and Technical Information of China (English)

    Taraprasad Chattopadhyay; Prosenjit Bhattacharyya

    2011-01-01

    This paper presents a closed-form analysis of the synchronization phenomenon of the quantum cascade laser (QCL). The analysis has been made with considering higher order nonlinearity of the modal gain of the QCL. The frequency response characteristics of the synchronized QCL along with the stability of the locked state, the effect of nonlinearity on the lockband of the QCL and the amplitude limiting action of the locked QCL have been calculated. The analysis demonstrates the effect of higher order nonlinearity on the properties of the synchronized QCL.

  11. Optical mode control of surface-plasmon quantum cascade lasers

    Science.gov (United States)

    Moreau, V.; Bahriz, M.; Palomo, J.; Wilson, L. R.; Krysa, A. B.; Sirtori, C.; Austin, D. A.; Cockburn, J. W.; Roberts, J. S.; Colombelli, R.

    2007-04-01

    Surface-plasmon waveguides based on metallic strips can provide a two dimensional optical confinement. This concept has been successfully applied to quantum cascade lasers, processed as ridge waveguides, to demonstrate that the lateral extension of the optical mode can be influenced solely by the width of the device top contact. For devices operating at a wavelength of λ ≈7.5 μm, the room-temperature threshold current density was reduced from 6.3 kA/cm2 to 4.4 kA/cm2 with respect to larger devices with full top metallization.

  12. Fully automatized quantum cascade laser design by genetic optimization

    Science.gov (United States)

    Bismuto, A.; Terazzi, R.; Hinkov, B.; Beck, M.; Faist, J.

    2012-07-01

    Using a transport model based on the density matrix formalism, a fully automatized technique to design quantum cascade structures in the mid-infrared is presented that implements a genetic algorithm where the wallplug efficiency has been used as merit factor. Starting from a reference design, the model converges after few generations on an optimized design that presents a better carrier injection in the upper lasing state. Both the designs have been fabricated using buried heterostructure process and the optimized design shows a pronounced increase in the laser operation range and higher output powers. In good agreement with the simulations, the laser efficiency increases from 5% to 12%.

  13. Modelling and fabrication of GaAs photonic-crystal cavities for cavity quantum electrodynamics.

    Science.gov (United States)

    Khankhoje, U K; Kim, S-H; Richards, B C; Hendrickson, J; Sweet, J; Olitzky, J D; Khitrova, G; Gibbs, H M; Scherer, A

    2010-02-10

    In this paper, we present recent progress in the growth, modelling, fabrication and characterization of gallium arsenide (GaAs) two-dimensional (2D) photonic-crystal slab cavities with embedded indium arsenide (InAs) quantum dots (QDs) that are designed for cavity quantum electrodynamics (cQED) experiments. Photonic-crystal modelling and device fabrication are discussed, followed by a detailed discussion of different failure modes that lead to photon loss. It is found that, along with errors introduced during fabrication, other significant factors such as the presence of a bottom substrate and cavity axis orientation with respect to the crystal axis, can influence the cavity quality factor (Q). A useful diagnostic tool in the form of contour finite-difference time domain (FDTD) is employed to analyse device performance.

  14. Geometric phase, quantum Fisher information, geometric quantum correlation and quantum phase transition in the cavity-Bose-Einstein-condensate system

    Science.gov (United States)

    Wu, Wei; Xu, Jing-Bo

    2016-09-01

    We investigate the quantum phase transition of an atomic ensemble trapped in a single-mode optical cavity via the geometric phase and quantum Fisher information of an extra probe atom which is injected into the optical cavity and interacts with the cavity field. We also find that the geometric quantum correlation between two probe atoms exhibits a double sudden transition phenomenon and show this double sudden transition phenomenon is closely associated with the quantum phase transition of the atomic ensemble. Furthermore, we propose a theoretical scheme to prolong the frozen time during which the geometric quantum correlation remains constant by applying time-dependent electromagnetic field.

  15. Scheme for Implementing Quantum Cloning Restoring Machine in Cavity QED

    Institute of Scientific and Technical Information of China (English)

    YU Long-Bao; ZHANG Wen-Hai; YE Liu

    2007-01-01

    We propose an experimentally feasible scheme for implementing quantum restoring machine of the optimal universal 1 → 2 quanturn cloning machine in the context of cavity QED.In our scheme,two atoms (the clones) simultaneously interact with a cavity field,and meanwhile they are driven by a classical field.Then an arbitrary unknown input state can be restored in the ancilla by applying appropriate unitary local operation.

  16. Wavefront Engineering of Quantum Cascade Lasers Using Plasmonics

    Science.gov (United States)

    Yu, Nanfang; Capasso, Federico

    2012-12-01

    We review recent work on beam shaping of mid-infrared and far-infrared (terahertz) quantum cascade lasers using plasmonics. Essentials of quantum cascade lasers (QCLs) are discussed; these include the operating principle based on bandstructure engineering, and beam quality problems associated with laser waveguide design. We explain how metal and semiconductor microstructures can effectively tailor the dispersion properties of mid- and far-infrared surface plasmon polaritons, and therefore can be used as important building blocks for optical devices in these frequencies. The physical principles of three structures are discussed: plasmonic Bragg gratings, designer (spoof) surface plasmon polariton structures, and channel polariton structures. We demonstrate the effectiveness of these structures by realizing various functionalities in QCLs, ranging from beam collimation, polarization control, to multibeam emission, and spatial wavelength demultiplexing. Plasmonics offers a monolithic, compact, and low-loss solution to the problem of poor beam quality of QCLs and may have a large impact on applications such as sensing, light detection and ranging (LIDAR), free-space optical communication, and heterodyne detection of chemicals. The plasmonic designs are scalable and applicable to near-infrared active or passive optical devices.

  17. Photoacoustic Spectroscopy with Quantum Cascade Lasers for Trace Gas Detection

    Directory of Open Access Journals (Sweden)

    Gaetano Scamarcio

    2006-10-01

    Full Text Available Various applications, such as pollution monitoring, toxic-gas detection, noninvasive medical diagnostics and industrial process control, require sensitive and selectivedetection of gas traces with concentrations in the parts in 109 (ppb and sub-ppb range.The recent development of quantum-cascade lasers (QCLs has given a new aspect toinfrared laser-based trace gas sensors. In particular, single mode distributed feedback QCLsare attractive spectroscopic sources because of their excellent properties in terms of narrowlinewidth, average power and room temperature operation. In combination with these lasersources, photoacoustic spectroscopy offers the advantage of high sensitivity and selectivity,compact sensor platform, fast time-response and user friendly operation. This paper reportsrecent developments on quantum cascade laser-based photoacoustic spectroscopy for tracegas detection. In particular, different applications of a photoacoustic trace gas sensoremploying a longitudinal resonant cell with a detection limit on the order of hundred ppb ofozone and ammonia are discussed. We also report two QC laser-based photoacousticsensors for the detection of nitric oxide, for environmental pollution monitoring andmedical diagnostics, and hexamethyldisilazane, for applications in semiconductormanufacturing process.

  18. Quantum cascade laser: Applications in chemical detection and environmental monitoring

    Directory of Open Access Journals (Sweden)

    Radovanović Jelena

    2009-01-01

    Full Text Available In this paper we consider the structural parameter optimization of the active region of a GaAs-based quantum cascade laser in order to maximize the optical gain of the laser at the characteristic wavelengths, which are best suited for detection of pollutant gasses, such as SO2, HNO3, CH4, and NH3, in the ambient air by means of direct absorption. The procedure relies on applying elaborate tools for global optimization, such as the genetic algorithm. One of the important goals is to extend the applicability of a single active region design to the detection of several compounds absorbing at close wave-lengths, and this is achieved by introducing a strong external magnetic field perpendicularly to the epitaxial layers. The field causes two-dimensional continuous energy subbands to split into the series of discrete Landau levels. Since the arrangement of Landau levels depends strongly on the magnitude of the magnetic field, this enables one to control the population inversion in the active region, and hence the optical gain. Furthermore, strong effects of band non-parabolicity result in subtle changes of the lasing wavelength at magnetic fields which maximize the gain, thus providing a path for fine-tuning of the output radiation properties and changing the target compound for detection. The numerical results are presented for quantum cascade laser structures designed to emit at specified wavelengths in the mid-infrared part of the spectrum.

  19. Conditional control of quantum beats in a cavity QED system

    CERN Document Server

    Norris, D G; Orozco, L A; 10.1088/1742-6596/274/1/012143

    2011-01-01

    We probe a ground-state superposition that produces a quantum beat in the intensity correlation of a two-mode cavity QED system. We mix drive with scattered light from an atomic beam traversing the cavity, and effectively measure the interference between the drive and the light from the atom. When a photon escapes the cavity, and upon detection, it triggers our feedback which modulates the drive at the same beat frequency but opposite phase for a given time window. This results in a partial interruption of the beat oscillation in the correlation function, that then returns to oscillate.

  20. Color-Tunable Resonant Photoluminescence and Cavity-Mediated Multistep Energy Transfer Cascade.

    Science.gov (United States)

    Okada, Daichi; Nakamura, Takashi; Braam, Daniel; Dao, Thang Duy; Ishii, Satoshi; Nagao, Tadaaki; Lorke, Axel; Nabeshima, Tatsuya; Yamamoto, Yohei

    2016-07-26

    Color-tunable resonant photoluminescence (PL) was attained from polystyrene microspheres doped with a single polymorphic fluorescent dye, boron-dipyrrin (BODIPY) 1. The color of the resonant PL depends on the assembling morphology of 1 in the microspheres, which can be selectively controlled from green to red by the initial concentration of 1 in the preparation process of the microspheres. Studies on intersphere PL propagation with multicoupled microspheres, prepared by micromanipulation technique, revealed that multistep photon transfer takes place through the microspheres, accompanying energy transfer cascade with stepwise PL color change. The intersphere energy transfer cascade is direction selective, where energy donor-to-acceptor down conversion direction is only allowed. Such cavity-mediated long-distance and multistep energy transfer will be advantageous for polymer photonics device application.

  1. Lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-μm under current pumping

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, A. Yu., E-mail: anton@beam.ioffe.ru; Babichev, A. V.; Karachinsky, L. Ya.; Novikov, I. I. [Ioffe Institute (Russian Federation); Nikitina, E. V. [St. Petersburg Academic University (Russian Federation); Tchernycheva, M. [University Paris Sud XI, Institut d’Electronique Fondamentale (France); Sofronov, A. N.; Firsov, D. A.; Vorobjev, L. E. [Peter the Great St. Petersburg Polytechnic University (Russian Federation); Pikhtin, N. A.; Tarasov, I. S. [Ioffe Institute (Russian Federation)

    2015-11-15

    The lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-μm under current pumping are demonstrated. The quantum-cascade laser heterostructure is grown by molecular-beam epitaxy technique. Despite the relatively short laser cavity length and high level of external loss the laser shows the lasing in the temperature range of 80–220 K. The threshold current density below 4 kA/cm{sup 2} at 220 K with the characteristic temperature T{sub 0} = 123 K was demonstrated.

  2. Quantum feedback in a weakly driven cavity QED system

    Science.gov (United States)

    Reiner, J. E.; Smith, W. P.; Orozco, L. A.; Wiseman, H. M.; Gambetta, Jay

    2004-08-01

    Quantum feedback in strongly coupled systems can probe a regime where one quantum of excitation is a large fluctuation. We present theoretical and experimental studies of quantum feedback in an optical cavity QED system. The time evolution of the conditional state, following a photodetection, can be modified by changing the drive of the cavity. For the appropriate feedback, the conditional state can be captured in a new steady state and then released. The feedback protocol requires resonance operation, and proper amplitude and delay for the change in the drive. We demonstrate the successful use of feedback in the suppression of the vacuum Rabi oscillations for the length of the feedback pulse and their subsequent return to steady state. The feedback works only because we have an entangled quantum system, rather than an analogous correlated classical system.

  3. Quantum entanglement for two qubits in a nonstationary cavity

    CERN Document Server

    Berman, Oleg L; Lozovik, Yurii E

    2016-01-01

    The quantum entanglement and the probability of the dynamical Lamb effect for two qubits caused by non-adiabatic fast change of the boundary conditions are studied. The conditional concurrence of the qubits for each fixed number of created photons in a nonstationary cavity is obtained as a measure of the dynamical quantum entanglement due to the dynamical Lamb effect. We discuss the physical realization of the dynamical Lamb effect, based on superconducting qubits.

  4. Quantum entanglement for two qubits in a nonstationary cavity

    Science.gov (United States)

    Berman, Oleg L.; Kezerashvili, Roman Ya.; Lozovik, Yurii E.

    2016-11-01

    The quantum entanglement and the probability of the dynamical Lamb effect for two qubits caused by nonadiabatic fast change of the boundary conditions are studied. The conditional concurrence of the qubits for each fixed number of created photons in a nonstationary cavity is obtained as a measure of the dynamical quantum entanglement due to the dynamical Lamb effect. We discuss the physical realization of the dynamical Lamb effect, based on superconducting qubits.

  5. Optical feedback effects on terahertz quantum cascade lasers: modelling and applications

    Science.gov (United States)

    Rakić, Aleksandar D.; Lim, Yah Leng; Taimre, Thomas; Agnew, Gary; Qi, Xiaoqiong; Bertling, Karl; Han, She; Wilson, Stephen J.; Kundu, Iman; Grier, Andrew; Ikonić, Zoran; Valavanis, Alexander; Demić, Aleksandar; Keeley, James; Li, Lianhe H.; Linfield, Edmund H.; Davies, A. Giles; Harrison, Paul; Ferguson, Blake; Walker, Graeme; Prow, Tarl; Indjin, Dragan; Soyer, H. Peter

    2016-11-01

    Terahertz (THz) quantum cascade lasers (QCLs) are compact sources of radiation in the 1-5 THz range with significant potential for applications in sensing and imaging. Laser feedback interferometry (LFI) with THz QCLs is a technique utilizing the sensitivity of the QCL to the radiation reflected back into the laser cavity from an external target. We will discuss modelling techniques and explore the applications of LFI in biological tissue imaging and will show that the confocal nature of the QCL in LFI systems, with their innate capacity for depth sectioning, makes them suitable for skin diagnostics with the well-known advantages of more conventional confocal microscopes. A demonstration of discrimination of neoplasia from healthy tissue using a THz, LFI-based system in the context of melanoma is presented using a transgenic mouse model.

  6. Nanoscale displacement sensing based on nonlinear frequency mixing in quantum cascade lasers

    CERN Document Server

    Mezzapesa, F P; De Risi, G; Brambilla, M; Dabbicco, M; Spagnolo, V; Scamarcio, G

    2015-01-01

    We demonstrate a sensor scheme for nanoscale target displacement that relies on a single Quantum Cascade Laser (QCL) subject to optical feedback. The system combines the inherent sensitivity of QCLs to optical re-injection and their ultra-stability in the strong feedback regime where nonlinear frequency mixing phenomena are enhanced. An experimental proof of principle in the micrometer wavelength scale is provided. We perform real-time measurements of displacement with {\\lambda}/100 resolution by inserting a fast-shifting reference etalon in the external cavity. The resulting signal dynamics at the QCL terminals shows a stroboscopic-like effect that relates the sensor resolution with the reference etalon speed. Intrinsic limits to the measurement algorithm and to the reference speed are discussed, disclosing that nanoscale ranges are attainable.

  7. Planar integrated metasurfaces for highly-collimated terahertz quantum cascade lasers

    Science.gov (United States)

    Liang, Guozhen; Dupont, Emmanuel; Fathololoumi, Saeed; Wasilewski, Zbigniew R.; Ban, Dayan; Liang, Hou Kun; Zhang, Ying; Yu, Siu Fung; Li, Lianhe H.; Davies, Alexander Giles; Linfield, Edmund H.; Liu, Hui Chun; Wang, Qi Jie

    2014-01-01

    We report planar integration of tapered terahertz (THz) frequency quantum cascade lasers (QCLs) with metasurface waveguides that are designed to be spoof surface plasmon (SSP) out-couplers by introducing periodically arranged SSP scatterers. The resulting surface-emitting THz beam profile is highly collimated with a divergence as narrow as ~4° × 10°, which indicates a good waveguiding property of the metasurface waveguide. In addition, the low background THz power implies a high coupling efficiency for the THz radiation from the laser cavity to the metasurface structure. Furthermore, since all the structures are in-plane, this scheme provides a promising platform where well-established surface plasmon/metasurface techniques can be employed to engineer the emitted beam of THz QCLs controllably and flexibly. More importantly, an integrated active THz photonic circuit for sensing and communication applications could be constructed by incorporating other optoelectronic devices such as Schottky diode THz mixers, and graphene modulators and photodetectors. PMID:25403796

  8. Quantum dynamic behaviour in a coupled cavities system

    Institute of Scientific and Technical Information of China (English)

    Peng Jun; Wu Yun-Wen; Li Xiao-Juan

    2012-01-01

    The dynamic behaviour of the two-site coupled cavities model which is doped with ta wo-level system is investigated.The exact dynamic solutions in the general condition are obtained via Laplace transform.The simple analytical solutions are obtained in several particular cases,which demonstrate the clear and simple physical picture for the quantum state transition of the system.In the large detuning or hoppling case,the quantum states transferring between qubits follow a slow periodic oscillation induced by the very weak excitation of the cavity mode.In the large coupling case,the system can be interpreted as two Jaynes-Cummings model subsystems which interact through photon hop between the two cavities.In the case of λ≈△(》) g,the quantum states transition of qubits is accompanied by the excitation of the cavity,and the cavity modes have the same dynamic behaviours and the amplitude of probability is equal to 0.25 which does not change with the variation of parameter.

  9. Terahertz Quantum-Cascade Transmission-Line Metamaterials

    Science.gov (United States)

    Tavallaee, Amir Ali

    Terahertz quantum-cascade (QC) lasers operating at 0.6 - 5 THz (λ ˜ 60 - 500 µm) are poised to become the dominant solid-state sources of continuous-wave (cw) far-infrared radiation enabling applications in terahertz spectroscopy, imaging, and sensing. QC-lasers are the longest wavelength semiconductor laser sources in which terahertz gain is obtained from electronic intersubband radiative transitions in GaAs/AlGaAs heterostructure quantum wells. Since their invention in 2001, rapid development has enabled demonstration of cw powers greater than 100 mW. However, challenges still remain in the areas of operating temperature, laser efficiency and power, and beam quality to name a few. The highest-temperature operation of terahertz quantum-cascade lasers (200 K pulsed, 117 K cw) depends on the use of a low-loss "metal-metal" waveguide where the active gain material is sandwiched between two metal cladding layers; a technique similar, in concept, to microstrip transmission line technology at microwave frequencies. Due to the subwavelength transverse dimensions of the metal-metal waveguide, however, obtaining a directive beam pattern and efficient out-coupling of THz power is non-trivial. This thesis reports the demonstration of a one-dimensional waveguide for terahertz quantum-cascade lasers that acts as a leaky-wave antenna and tailors laser radiation in one dimension to a directional beam. This scheme adapts microwave transmission-line metamaterial concepts to a planar structure realized in terahertz metal-metal waveguide technology and is fundamentally different from distributed feedback/photonic crystal structures that work based on Bragg scattering of propagating modes. The leaky-wave metamaterial antenna operates based on a propagating mode with an effective phase index smaller than unity such that it radiates in the surface direction via a leaky-wave mechanism. Surface emission (˜ 40° from broadside) with a single directive beam (FWHM ˜ 15°) at 2.74 THz

  10. Cavity quantum networks for quantum information processing in decoherence-free subspace

    Institute of Scientific and Technical Information of China (English)

    Hua WEI; Zhi-jiao DENG; Wan-li YANG; Fei ZHOU

    2009-01-01

    We give a brief review on the quantum infor- mation processing in decoherence-free subspace (DFS). We show how to realize the initialization of the entangled quantum states, information transfer and teleportation of quantum states, two-qubit Grover search and how to construct the quantum network in DFS, within the cav- ity QED regime based on a cavity-assisted interaction by single-photon pulses.

  11. Efficient scheme for two-atom entanglement and quantum information processing in cavity QED

    Science.gov (United States)

    Zheng; Guo

    2000-09-11

    A scheme is proposed for the generation of two-atom maximally entangled states and realization of quantum logic gates and teleportation with cavity QED. The scheme does not require the transfer of quantum information between the atoms and cavity. In the scheme the cavity is only virtually excited and thus the requirement on the quality factor of the cavities is greatly loosened.

  12. Quantum Logic with Cavity Photons From Single Atoms

    Science.gov (United States)

    Holleczek, Annemarie; Barter, Oliver; Rubenok, Allison; Dilley, Jerome; Nisbet-Jones, Peter B. R.; Langfahl-Klabes, Gunnar; Marshall, Graham D.; Sparrow, Chris; O'Brien, Jeremy L.; Poulios, Konstantinos; Kuhn, Axel; Matthews, Jonathan C. F.

    2016-07-01

    We demonstrate quantum logic using narrow linewidth photons that are produced with an a priori nonprobabilistic scheme from a single 87Rb atom strongly coupled to a high-finesse cavity. We use a controlled-not gate integrated into a photonic chip to entangle these photons, and we observe nonclassical correlations between photon detection events separated by periods exceeding the travel time across the chip by 3 orders of magnitude. This enables quantum technology that will use the properties of both narrow-band single photon sources and integrated quantum photonics.

  13. High-precision molecular interrogation by direct referencing of a quantum-cascade-laser to a near-infrared frequency comb.

    Science.gov (United States)

    Gatti, D; Gambetta, A; Castrillo, A; Galzerano, G; Laporta, P; Gianfrani, L; Marangoni, M

    2011-08-29

    This work presents a very simple yet effective way to obtain direct referencing of a quantum-cascade-laser at 4.3 μm to a near-IR frequency-comb. Precise tuning of the comb repetition-rate allows the quantum-cascade-laser to be scanned across absorption lines of a CO2 gaseous sample and line profiles to be acquired with extreme reproducibility and accuracy. By averaging over 50 acquisitions, line-centre frequencies are retrieved with an uncertainty of 30 kHz in a linear interaction regime. The extension of this methodology to other lines and molecules, by the use of widely tunable extended-cavity quantum-cascade-lasers, paves the way to a wide availability of high-quality and traceable spectroscopic data in the most crucial region for molecular detection and interrogation.

  14. Quantum repeater based on cavity QED evolutions and coherent light

    Science.gov (United States)

    Gonţa, Denis; van Loock, Peter

    2016-05-01

    In the framework of cavity QED, we propose a quantum repeater scheme that uses coherent light and chains of atoms coupled to optical cavities. In contrast to conventional repeater schemes, in our scheme there is no need for an explicit use of two-qubit quantum logical gates by exploiting solely the cavity QED evolution. In our previous work (Gonta and van Loock in Phys Rev A 88:052308, 2013), we already proposed a quantum repeater in which the entanglement between two neighboring repeater nodes was distributed using controlled displacements of input coherent light, while the produced low-fidelity entangled pairs were purified using ancillary (four-partite) entangled states. In the present work, the entanglement distribution is realized using a sequence of controlled phase shifts and displacements of input coherent light. Compared to previous coherent-state-based distribution schemes for two-qubit entanglement, our scheme here relies only upon a simple discrimination of two coherent states with opposite signs, which can be performed in a quantum mechanically optimal fashion via a beam splitter and two on-off detectors. For the entanglement purification, we employ a method that avoids the use of extra entangled ancilla states. Our repeater scheme exhibits reasonable fidelities and repeater rates providing an attractive platform for long-distance quantum communication.

  15. Fast terahertz imaging using a quantum cascade amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Yuan, E-mail: yr235@cam.ac.uk; Wallis, Robert; Jessop, David Stephen; Degl' Innocenti, Riccardo; Klimont, Adam; Beere, Harvey E.; Ritchie, David A. [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2015-07-06

    A terahertz (THz) imaging scheme based on the effect of self-mixing in a 2.9 THz quantum cascade (QC) amplifier has been demonstrated. By coupling an antireflective-coated silicon lens to the facet of a QC laser, with no external optical feedback, the laser mirror losses are enhanced to fully suppress lasing action, creating a THz QC amplifier. The addition of reflection from an external target to the amplifier creates enough optical feedback to initiate lasing action and the resulting emission enhances photon-assisted transport, which in turn reduces the voltage across the device. At the peak gain point, the maximum photon density coupled back leads to a prominent self-mixing effect in the QC amplifier, leading to a high sensitivity, with a signal to noise ratio up to 55 dB, along with a fast data acquisition speed of 20 000 points per second.

  16. Free-space communication based on quantum cascade laser

    Science.gov (United States)

    Chuanwei, Liu; Shenqiang, Zhai; Jinchuan, Zhang; Yuhong, Zhou; Zhiwei, Jia; Fengqi, Liu; Zhanguo, Wang

    2015-09-01

    A free-space communication based on a mid-infrared quantum cascade laser (QCL) is presented. A room-temperature continuous-wave distributed-feedback (DFB) QCL combined with a mid-infrared detector comprise the basic unit of the communication system. Sinusoidal signals at a highest frequency of 40 MHz and modulated video signals with a carrier frequency of 30 MHz were successfully transmitted with this experimental setup. Our research has provided a proof-of-concept demonstration of space optical communication application with QCL. The highest operation frequency of our setup was determined by the circuit-limited modulation bandwidth. A high performance communication system can be obtained with improved modulation circuit system. Project supported by the State Key Development Program for Basic Research of China (Nos. 2013CB632801, 2013CB632803) and the National Natural Science Foundation of China (Nos. 61435014, 61306058, 61274094).

  17. Broadband all-electronically tunable MEMS terahertz quantum cascade lasers.

    Science.gov (United States)

    Han, Ningren; de Geofroy, Alexander; Burghoff, David P; Chan, Chun Wang I; Lee, Alan Wei Min; Reno, John L; Hu, Qing

    2014-06-15

    In this work, we demonstrate all-electronically tunable terahertz quantum cascade lasers (THz QCLs) with MEMS tuner structures. A two-stage MEMS tuner device is fabricated by a commercial open-foundry process performed by the company MEMSCAP. This provides an inexpensive, rapid, and reliable approach for MEMS tuner fabrication for THz QCLs with a high-precision alignment scheme. In order to electronically actuate the MEMS tuner device, an open-loop cryogenic piezo nanopositioning stage is integrated with the device chip. Our experimental result shows that at least 240 GHz of single-mode continuous electronic tuning can be achieved in cryogenic environments (∼4  K) without mode hopping. This provides an important step toward realizing turn-key bench-top tunable THz coherent sources for spectroscopic and coherent tomography applications.

  18. Improved terahertz quantum cascade laser with variable height barriers

    Science.gov (United States)

    Matyas, Alpar; Chashmahcharagh, Reza; Kovacs, Istvan; Lugli, Paolo; Vijayraghavan, Karun; Belkin, Mikhail A.; Jirauschek, Christian

    2012-05-01

    Using an ensemble Monte-Carlo analysis, it is found that relaxing the constraint of identical barrier heights can result in an improved temperature performance. Exploiting this additional design degree of freedom, modified structures with non-uniform barrier heights are developed based on the current record temperature design. For an optimized structure with reduced diagonality, we predict an increase of 31 K for the maximum operating temperature. Furthermore, we develop improved designs with the same oscillator strength as for the reference design. Using a genetic algorithm for optimization, an improvement of the maximum operating temperature by 38 K is obtained. These results aim to show the potential of varying the barrier heigths for the design of high temperature performance terahertz quantum cascade lasers.

  19. Exciton-polariton dynamics in quantum dot-cavity system

    Energy Technology Data Exchange (ETDEWEB)

    Neto, Antonio F.; Lima, William J.; Villas-Boas, Jose M. [Universidade Federal de Uberlandia (UFU), MG (Brazil). Inst. de Fisica

    2012-07-01

    Full text: One of the basic requirement for quantum information processing systems is the ability to completely control the state of a single qubit. This imply in know all sources of decoherence and elaborate ways to avoid them. In recent work, A. Laucht et al. [1] presented detailed theoretical and experimental investigations of electrically tunable single quantum dot (QD) - photonic crystal (PhC) nanocavity systems operating in the strong coupling regime of the light matter interaction. Unlike previous studies, where the exciton-cavity spectral detuning was varied by changing the lattice temperature, or by the adsorption of inert gases at low temperatures, they employ the quantum confined Stark-effect to electro-optically control the exciton-cavity detuning. The new built device enabled them to systematically probe the emission spectrum of the strongly coupled system as a function of external control parameters, as for example the incoherent excitation power density or the lattice temperature. Those studies reveal for the first time insights in dephasing mechanisms of 0D exciton polaritons [1]. In another study [2], using a similar device, they investigate the coupling between two different QDs with a single cavity mode. In both works, incoherent pumping was used, but for quantum information, coherent and controlled excitations are necessary. Here, we theoretically investigate the dynamics a single quantum dot inside a cavity under coherent pulse excitation and explore a wide range of parameters, as for example, the exciton-cavity detunings, the excitation power, the spontaneous decay, and pure dephasing. We use density matrix formalism in the Lindblad form, and we solve it numerically. Our results show that coherent excitation can be used to probe strong coupling between exciton and cavity mode by monitoring the exciton Rabi oscillation as function of the cavity detuning. This can give new insights for future experimental measurement focusing on quantum

  20. Efficient method for the calculation of dissipative quantum transport in quantum cascade lasers.

    Science.gov (United States)

    Greck, Peter; Birner, Stefan; Huber, Bernhard; Vogl, Peter

    2015-03-09

    We present a novel and very efficient method for calculating quantum transport in quantum cascade lasers (QCLs). It follows the nonequilibrium Green's function (NEGF) framework but sidesteps the calculation of lesser self-energies by replacing them by a quasi-equilibrium expression. This method generalizes the phenomenological Büttiker probe model by taking into account individual scattering mechanisms. It is orders of magnitude more efficient than a fully self-consistent NEGF calculation for realistic devices. We apply this method to a new THz QCL design which works up to 250 K - according to our calculations.

  1. A Monolithic Filter Cavity for Experiments in Quantum Optics

    CERN Document Server

    Palittapongarnpim, Pantita; Lvovsky, A I

    2012-01-01

    By applying a high-reflectivity dielectric coating on both sides of a commercial plano-convex lens, we produce a stable monolithic Fabry-Perot cavity suitable for use as a narrow band filter in quantum optics experiments. The resonant frequency is selected by means of thermal expansion. Owing to the long term mechanical stability, no optical locking techniques are required. We characterize the cavity performance as an optical filter, obtaining a 45 dB suppression of unwanted modes while maintaining a transmission of 60%.

  2. New quantum cascade laser architectures: II-VI quantum cascade emitters, high k-space lasing, and short injectors

    Science.gov (United States)

    Franz, Kale J.

    Quantum cascade (QC) lasers are today's most capable mid-infrared light sources. With up to watt-level room temperature emission over a broad swath of mid-infrared wavelengths, these tiny semiconductor devices enable a variety of applications and technologies such as ultra-sensitive systems for detecting trace molecules in the vapor phase. The foundation of a QC structure lies in alternating hundreds of wide- and narrow-bandgap semiconductor layers to form a coupled quantum well system. In this way, the laws of quantum mechanics are used to precisely engineer electron transport and create artificial optical transitions. The result is a material with capabilities not found in nature, a truly "designer" material. As a central theme in this thesis, we stress the remarkable flexibility of the quantum cascade---the ability to highly tailor device structure for creative design concepts. The QC idea, in fact, relies on no particular material system for its implementation. While all QC lasers to date have been fabricated from III--V materials such as InGaAs/AlInAs, I detail our preliminary work on ZnCdSe/ZnCdMgSe---a II--VI materials system---where we have demonstrated electroluminescence. We then further discuss how the inherent QC flexibility can be exploited for new devices that extend QC performance and capabilities. In this regard, we offer the examples of excited state transitions and short injectors. Excited state transitions are an avenue to enhancing optical gain, which is especially needed for longer-wavelength devices where optical losses hinder performance. Likewise, shortening the QC injector length over a conventional QC structure has powerful implications for threshold current, output power, and wall-plug efficiency. In both cases, novel physical effects are discovered. Pumping electrons into highly excited states led to the discovery of high k-space lasing from highly non-equilibrium electron distributions. Shortening QC injector regions allowed us to

  3. Measuring the effective phonon density of states of a quantum dot in cavity quantum electrodynamics

    DEFF Research Database (Denmark)

    Madsen, Kristian Høeg; Nielsen, Per Kær; Kreiner-Møller, Asger;

    2013-01-01

    We employ detuning-dependent decay-rate measurements of a quantum dot in a photonic-crystal cavity to study the influence of phonon dephasing in a solid-state quantum-electrodynamics experiment. The experimental data agree with a microscopic non-Markovian model accounting for dephasing from longi...

  4. Quantitative analysis of quantum dot dynamics and emission spectra in cavity quantum electrodynamics

    DEFF Research Database (Denmark)

    Madsen, Kristian Høeg; Lodahl, Peter

    2013-01-01

    –Cummings model, whereas systematic deviations are observed for the emission spectra. The discrepancy for the spectra is attributed to the coupling of other exciton lines to the cavity and interference of different propagation paths toward the detector of the fields emitted by the quantum dot. In contrast......We present detuning-dependent spectral and decay-rate measurements to study the difference between the spectral and dynamical properties of single quantum dots embedded in micropillar and photonic crystal cavities. For the micropillar cavity, the dynamics is well described by the dissipative Jaynes......, quantitative information about the system can readily be extracted from the dynamical measurements. In the case of photonic crystal cavities, we observe an anti-crossing in the spectra when detuning a single quantum dot through resonance, which is the spectral signature of a strong coupling. However, time...

  5. Quantum Cavity Optomechanics with Phononic Bandgap Shielded Silicon Nitride Membranes

    DEFF Research Database (Denmark)

    Nielsen, William Hvidtfelt Padkær

    Cavity optomechanics, a field which has matured tremendously over the last decade,has conclusively reached the quantum regime. Noteworthy experimentalachievements include cooling of the vibrational motion of macroscopic objects tothe quantum ground state, the observation of shot noise of radiation...... two highly reflective mirrors, all of which are embedded in a helium flowcryostat. In order to reach truly quantum territory, severe shielding of the membranefrom the environment is required, as well as meticulous concern for auxiliarysources of noise, both from the laser and mirrors used.The purpose...... of this thesis is to document the development of the experimentfrom its initial stages to its final quantum enabled incarnation, as well as to providethe necessary theoretical machinery to interpret the experimental results. A strongemphasis is placed on the unique challenges posed by our unique monolithic...

  6. From quantum feedback to probabilistic error correction: manipulation of quantum beats in cavity QED

    Energy Technology Data Exchange (ETDEWEB)

    Barberis-Blostein, P [Instituto de Investigaciones en Matematicas Aplicadas y en Sistemas, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, 04510, Mexico, DF (Mexico); Norris, D G; Orozco, L A; Carmichael, H J [Joint Quantum Institute, Department of Physics, University of Maryland and National Institute of Standards and Technology, College Park, MD 20742 (United States)], E-mail: lorozco@umd.edu

    2010-02-15

    It is shown how one can implement quantum feedback and probabilistic error correction in an open quantum system consisting of a single atom, with ground- and excited-state Zeeman structure, in a driven two-mode optical cavity. The ground-state superposition is manipulated and controlled through conditional measurements and external fields, which shield the coherence and correct quantum errors. Modeling an experimentally realistic situation demonstrates the robustness of the proposal for realization in the laboratory.

  7. Giant and broadband circular asymmetric transmission based on two cascading polarization conversion cavities

    Science.gov (United States)

    Ji, Ruonan; Wang, Shao-Wei; Liu, Xingxing; Lu, Wei

    2016-04-01

    In this paper, a three-layered sandwiched metamaterial is proposed to achieve giant and broadband asymmetric transmission of circularly polarized waves at the near-infrared communication band. The metamaterial consists of two layers of identical 45° tilted chiral S-shaped metasurfaces sandwiched with a subwavelength metallic grating. Based on the delicate combination of broadband polarization conversion and a cavity-enhanced effect, the asymmetric parameter can reach a maximum value of 0.87 and over 0.6 in a wide range from 1.2 to 2.0 μm, which has not been found in previous reports. Furthermore, a perfect robustness to misalignments is obtained as the effect originated from function-independent cascading cavities, which effectively reduce the requirement of alignment precision in layer-by-layer photolithography processes. The proposed nanostructure has a great potential to be used as a circular polarization rotator or diode-like device in optical communication systems.In this paper, a three-layered sandwiched metamaterial is proposed to achieve giant and broadband asymmetric transmission of circularly polarized waves at the near-infrared communication band. The metamaterial consists of two layers of identical 45° tilted chiral S-shaped metasurfaces sandwiched with a subwavelength metallic grating. Based on the delicate combination of broadband polarization conversion and a cavity-enhanced effect, the asymmetric parameter can reach a maximum value of 0.87 and over 0.6 in a wide range from 1.2 to 2.0 μm, which has not been found in previous reports. Furthermore, a perfect robustness to misalignments is obtained as the effect originated from function-independent cascading cavities, which effectively reduce the requirement of alignment precision in layer-by-layer photolithography processes. The proposed nanostructure has a great potential to be used as a circular polarization rotator or diode-like device in optical communication systems. Electronic supplementary

  8. Generation of an Entangled State of Two Three-Level Superconducting Quantum Interference Devices in Cavity

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    We propose a scheme for generating a maximally entangled state of two three-level superconducting quantum interference devices (SQUIDs) by using a quantized cavity field and classical microwave pluses in cavity. In this scheme, no quantum information will be transferred from the SQUIDs to the cavity since the cavity field is only virtually excited. Thus, the cavity decay is suppressed during the entanglement generation.

  9. Sound-based analogue of cavity quantum electrodynamics in silicon.

    Science.gov (United States)

    Soykal, Ö O; Ruskov, Rusko; Tahan, Charles

    2011-12-01

    A quantum mechanical superposition of a long-lived, localized phonon and a matter excitation is described. We identify a realization in strained silicon: a low-lying donor transition (P or Li) driven solely by acoustic phonons at wavelengths where high-Q phonon cavities can be built. This phonon-matter resonance is shown to enter the strongly coupled regime where the "vacuum" Rabi frequency exceeds the spontaneous phonon emission into noncavity modes, phonon leakage from the cavity, and phonon anharmonicity and scattering. We introduce a micropillar distributed Bragg reflector Si/Ge cavity, where Q≃10(5)-10(6) and mode volumes V≲25λ(3) are reachable. These results indicate that single or many-body devices based on these systems are experimentally realizable.

  10. Optimization of optical nonlinearities in quantum cascade lasers

    Science.gov (United States)

    Bai, Jing

    Nonlinearities in quantum cascade lasers (QCL's) have wide applications in wavelength tunability and ultra-short pulse generation. In this thesis, optical nonlinearities in InGaAs/AlInAs-based mid-infrared (MIR) QCL's with quadruple resonant levels are investigated. Design optimization for the second-harmonic generation (SHG) of the device is presented. Performance characteristics associated with the third-order nonlinearities are also analyzed. The design optimization for SHG efficiency is obtained utilizing techniques from supersymmetric quantum mechanics (SUSYQM) with both material-dependent effective mass and band nonparabolicity. Current flow and power output of the structure are analyzed by self-consistently solving rate equations for the carriers and photons. Nonunity pumping efficiency from one period of the QCL to the next is taken into account by including all relevant electron-electron (e-e) and longitudinal (LO) phonon scattering mechanisms between the injector/collector and active regions. Two-photon absorption processes are analyzed for the resonant cascading triple levels designed for enhancing SHG. Both sequential and simultaneous two-photon absorption processes are included in the rate-equation model. The current output characteristics for both the original and optimized structures are analyzed and compared. Stronger resonant tunneling in the optimized structure is manifested by enhanced negative differential resistance. Current-dependent linear optical output power is derived based on the steady-state photon populations in the active region. The second-harmonic (SH) power is derived from the Maxwell equations with the phase mismatch included. Due to stronger coupling between lasing levels, the optimized structure has both higher linear and nonlinear output powers. Phase mismatch effects are significant for both structures leading to a substantial reduction of the linear-to-nonlinear conversion efficiency. The optimized structure can be fabricated

  11. Optical dynamics in low-dimensional semiconductor heterostructures. Quantum dots and quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Carsten

    2008-07-01

    This work is focused on the optical dynamics of mesoscopic semiconductor heterostructures, using as prototypes zero-dimensional quantum dots and quantum cascade lasers which consist of quasitwo- dimensional quantum wells. Within a density matrix theory, a microscopic many-particle theory is applied to study scattering effects in these structures: the coupling to external as well as local fields, electron-phonon coupling, coupling to impurities, and Coulomb coupling. For both systems, the investigated effects are compared to experimentally observed results obtained during the past years. In quantum dots, the three-dimensional spatial confinement leads to the necessity to consider a quantum kinetic description of the dynamics, resulting in non-Markovian electron-phonon effects. This can be seen in the spectral phonon sidebands due to interaction with acoustic phonons as well as a damping of nonlinear Rabi oscillations which shows a nonmonotonous intensity and pulse duration dependence. An analysis of the inclusion of the self-interaction of the quantum dot shows that no dynamical local field terms appear for the simple two-level model. Considering local fields which have their origin in many quantum dots, consequences for a two-level quantum dot such as a zero-phonon line broadening and an increasing signal in photon echo experiments are found. For the use of quantum dots in an optical spin control scheme, it is found that the dephasing due to the electron-phonon interaction can be dominant in certain regimes. Furthermore, soliton and breather solutions are studied analytically in nonlinear quantum dot ensembles. Generalizing to quasi-two-dimensional structures, the intersubband dynamics of quantum cascade laser structures is investigated. A dynamical theory is considered in which the temporal evolution of the subband populations and the current density as well as the influence of scattering effects is studied. In the nonlinear regime, the scattering dependence and

  12. Interference control of perfect photon absorption in cavity quantum electrodynamics

    CERN Document Server

    Wang, Liyong; Zhu, Yifu; Agarwal, G S

    2016-01-01

    We propose and analyze a scheme for controlling coherent photon transmission and reflection in a cavity-quantum-electrodynamics (CQED) system consisting of an optical resonator coupled with three-level atoms coherently prepared by a control laser from free space. When the control laser is off and the cavity is excited by two identical light fields from two ends of the cavity, the two input light fields can be completely absorbed by the CQED system and the light energy is converted into the excitation of the polariton states, but no light can escape from the cavity. Two distinct cases of controlling the perfect photon absorption are analyzed: (a) when the control laser is tuned to the atomic resonance and creates electromagnetically induced transparency, the prefect photon absorption is suppressed and the input light fields are nearly completely transmitted through the cavity; (b) when the control laser is tuned to the polariton state resonance and inhibits the polariton state excitation, the perfect photon ab...

  13. GaN-based terahertz quantum cascade lasers

    Science.gov (United States)

    Terashima, Wataru; Hirayama, Hideki

    2015-05-01

    III-nitride semiconductors having huge longitudinal optical phonon energies are promising as materials to solve a problem of "development of operational frequency range (5-12 THz)" on THz-QCLs. In this study, for the purpose of THz lasing from target subband levels, we designed unique quantum cascade (QC) structures whose active regions consisted of two quantum wells (QWs) for one period and the number of wave-functions contributed to lasing is limited to minimum 3 subband levels. (i.e., Pure 3-level laser system). We fabricated THz-QCLs with QC structures of a pure 3- level laser system (100-200 periods) through a radio-frequency molecular beam epitaxy (RF-MBE) and a metal organic chemical vapor deposition (MOCVD) on MOCVD-growth AlGaN/AlN templates grown on c-plane sapphire substrates. Clear satellite peaks in XRD analyses could be observed, indicating that layer structures were stacked with a good periodicity. By comparing data with simulation spectra, it was found that error of film thicknesses were 1-3 %. We observed sharp lasing spectra with peaks at frequencies of ~5.5 THz and ~7.0 THz whose full width at half maximum (FWHM) values were close to those of resolution of FTIR spectrometer, when we tried pulse current injection measurements into THz-QCL devices. We successfully for the first time realized GaN-based THz-QCL devices lasing at almost the same frequencies as the target ones by designing a 2QWs-type QC structure with a pure 3-level laser system. We also successfully achieved lasing at ~5.5 and ~7.0 THz, which are highest reported to date for any kinds of THz- QCLs.

  14. Quantum cascade laser-based photoacoustic sulfuryl fluoride sensing

    Science.gov (United States)

    Minini, Kariza Mayra Silva; Bueno, Sâmylla Cristina Espécie; da Silva, Marcelo Gomes; Sthel, Marcelo Silva; Vargas, Helion; Angster, Judit; Miklós, András

    2017-02-01

    Although sulfuryl fluoride (SO2F2) is an efficient fumigant that does not react with the surface of indoor materials and does not reduce the stratospheric ozone shield, there are some concerns about its use. It is a toxic gas that attacks the central nervous system, and its global warming potential (GWP) value is 4780 for 100 years' time. Therefore, it is a clear necessity of implementing detection methods for tracing such a molecule. In this work a sensitive photoacoustic setup was built to detect SO2F2 at concentrations of parts per billion by volume (ppbv). The symmetric S-O stretching mode was excited by a continuous-wave quantum cascade laser with radiation wavenumber ranging from 1275.7 to 1269.3 cm-1. The photoacoustic signal was generated by modulating the laser wavenumber at the first longitudinal mode of the photoacoustic cell with amplitude depth of 5 × 10-3 cm-1. The detection of a minimum SO2F2 concentration of 20 ppbv was achieved.

  15. Fast automotive diesel exhaust measurement using quantum cascade lasers

    Science.gov (United States)

    Herbst, J.; Brunner, R.; Lambrecht, A.

    2013-12-01

    Step by step, US and European legislations enforce the further reduction of atmospheric pollution caused by automotive exhaust emissions. This is pushing automotive development worldwide. Fuel efficient diesel engines with SCRtechnology can impede NO2-emission by reduction with NH3 down to the ppm range. To meet the very low emission limits of the Euro6 resp. US NLEV (National Low Emission Vehicle) regulations, automotive manufacturers have to optimize continuously all phases of engine operation and corresponding catalytic converters. Especially nonstationary operation holds a high potential for optimizing gasoline consumption and further reducing of pollutant emissions. Test equipment has to cope with demanding sensitivity and speed requirements. In the past Fraunhofer IPM has developed a fast emission analyzer called DEGAS (Dynamic Exhaust Gas Analyzer System), based on cryogenically cooled lead salt lasers. These systems have been used at Volkswagen AG`s test benches for a decade. Recently, IPM has developed DEGAS-Next which is based on cw quantum cascade lasers and thermoelectrically cooled detectors. The system is capable to measure three gas components (i.e. NO, NO2, NH3) in two channels with a time resolution of 20 ms and 1 ppm detection limits. We shall present test data and a comparison with fast FTIR measurements.

  16. Probing anharmonicity of a quantum oscillator in an optomechanical cavity

    Science.gov (United States)

    Latmiral, Ludovico; Armata, Federico; Genoni, Marco G.; Pikovski, Igor; Kim, M. S.

    2016-05-01

    We present a way of measuring with high precision the anharmonicity of a quantum oscillator coupled to an optical field via radiation pressure. Our protocol uses a sequence of pulsed interactions to perform a loop in the phase space of the mechanical oscillator, which is prepared in a thermal state. We show how the optical field acquires a phase depending on the anharmonicity. Remarkably, one only needs small initial cooling of the mechanical motion to probe even small anharmonicities. Finally, by applying tools from quantum estimation theory, we calculate the ultimate bound on the estimation precision posed by quantum mechanics and compare it with the precision obtainable with feasible measurements such as homodyne and heterodyne detection on the cavity field. In particular we demonstrate that homodyne detection is nearly optimal in the limit of a large number of photons of the field and we discuss the estimation precision of small anharmonicities in terms of its signal-to-noise ratio.

  17. Cavity-assisted dynamical quantum phase transition in superconducting quantum simulators

    Science.gov (United States)

    Tian, Lin

    Coupling a quantum many-body system to a cavity can create bifurcation points in the phase diagram, where the many-body system switches between different phases. Here I will discuss the dynamical quantum phase transitions at the bifurcation points of a one-dimensional transverse field Ising model coupled to a cavity. The Ising model can be emulated with various types of superconducting qubits connected in a chain. With a time-dependent Bogoliubov method, we show that an infinitesimal quench of the driving field can cause gradual evolution of the transverse field on the Ising spins to pass through the quantum critical point. Our calculation shows that the cavity-induced nonlinearity plays an important role in the dynamics of this system. Quasiparticles can be excited in the Ising chain during this process, which results in the deviation of the system from its adiabatic ground state. This work is supported by the National Science Foundation under Award Number 0956064.

  18. Numerical investigation of the interaction between upstream cavity purge flow and main flow in low aspect ratio turbine cascade

    Institute of Scientific and Technical Information of China (English)

    Jia Wei; Liu Huoxing

    2013-01-01

    In modem gas turbines,rim seal located between the stator-disc and rotor-disc is used to prevent hot-gas ingestion into the inner stage-gap of high pressure turbine.However,the purge flow supplied to the cavity through the rim seal interacts with the main flow,producing additional aerodynamic loss due to the mixing process which plays a significant role in the formation,development and evolution of downstream secondary flow.In this paper,a set of cascade representative of low aspect ratio turbine is selected to numerically investigate the influence of upstream cavity purge flow on the hub secondary flow structure and aerodynamic loss.Cascade with/without upstream cavity and four different purge mass flow rates are all taken into account in this simulation.Then,a deep insight into the loss mechanism of interaction between purge flow and main flow is gained.The results show that the presence of cavity and purge flow has a significant impact on the main flow which not only changes the vortex structure in both the passage and upstream cavity,but also alters the cascade exit flow angle distribution along the spanwise.Moreover,aerodynamic loss in the cascade rises with the increase of purge flow rate while the sealing effect is also enhanced.Therefore,the effect of upstream cavity purge flow must be considered in the process of turbine aerodynamic design.What is more,it is necessary to minimize the purge flow rate in order to reduce aerodynamic loss on the premise of satisfying cooling requirements.

  19. Quantum frequency doubling based on tripartite entanglement with cavities

    Science.gov (United States)

    Juan, Guo; Zhi-Feng, Wei; Su-Ying, Zhang

    2016-02-01

    We analyze the entanglement characteristics of three harmonic modes, which are the output fields from three cavities with an input tripartite entangled state at fundamental frequency. The entanglement properties of the input beams can be maintained after their frequencies have been up-converted by the process of second harmonic generation. We have calculated the parametric dependences of the correlation spectrum on the initial squeezing factor, the pump power, the transmission coefficient, and the normalized analysis frequency of cavity. The numerical results provide references to choose proper experimental parameters for designing the experiment. The frequency conversion of the multipartite entangled state can also be applied to a quantum communication network. Project supported by the National Natural Science Foundation of China (Grant No. 91430109), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20111401110004), and the Natural Science Foundation of Shanxi Province, China (Grant No. 2014011005-3).

  20. Quantum state transfer and logic gates with two 3-level atoms in cavity QED

    Science.gov (United States)

    Yang, Chui-Ping; Chu, Shih-I.

    2004-08-01

    We present a new way to implement quantum controlled phase-shift gate, quantum exchange gate (SWAP gate), and quantum state transfer with two 3-level atoms in cavity QED. The method does not involve real excitation of a cavity photon during the operation, thus decoherence induced due to the cavity-photon decay is minimized. In addition, it is remarkable that for all present purposes, no auxiliary atoms or any measurement is needed. Therefore, the operation is significantly simplified.

  1. Quantum Interference Induced Photon Blockade in a Coupled Single Quantum Dot-Cavity System

    CERN Document Server

    Tang, Jing; Xu, Xiulai

    2015-01-01

    We propose an experimental scheme to implement a strong photon blockade with a single quantum dot coupled to a nanocavity. The photon blockade effect can be tremendously enhanced by driving the cavity and the quantum dot simultaneously with two classical laser fields. This enhancement of photon blockade is ascribed to the quantum interference effect to avoid two-photon excitation of the cavity field. Comparing with Jaynes-Cummings model, the second-order correlation function at zero time delay $g^{(2)}(0)$ in our scheme can be reduced by two orders of magnitude and the system sustains a large intracavity photon number. A red (blue) cavity-light detuning asymmetry for photon quantum statistics with bunching or antibunching characteristics is also observed. The photon blockade effect has a controllable flexibility by tuning the relative phase between the two pumping laser fields and the Rabi coupling strength between the quantum dot and the pumping field. Moreover, the photon blockade scheme based on quantum in...

  2. Experimental investigation of terahertz quantum cascade laser with variable barrier heights

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Aiting; Vijayraghavan, Karun; Belkin, Mikhail A., E-mail: mbelkin@ece.utexas.edu [Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758 (United States); Matyas, Alpar; Jirauschek, Christian [Institute for Nanoelectronics, Technische Universität München, D-80333 Munich (Germany); Wasilewski, Zbig R. [Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario N2L 3G (Canada)

    2014-04-28

    We report an experimental study of terahertz quantum cascade lasers with variable barrier heights based on the Al{sub x}Ga{sub 1–x}As/GaAs material system. Two new designs are developed based on semiclassical ensemble Monte Carlo simulations using state-of-the-art Al{sub 0.15}Ga{sub 0.85}As/GaAs three-quantum-well resonant phonon depopulation active region design as a reference. The new designs achieved maximum lasing temperatures of 188 K and 172 K, as compared to the maximum lasing temperature of 191 K for the reference structure. These results demonstrate that terahertz quantum cascade laser designs with variable barrier heights provide a viable alternative to the traditional active region designs with fixed barrier composition. Additional design space offered by using variable barriers may lead to future improvements in the terahertz quantum cascade laser performance.

  3. Multiparty Quantum Secret Sharing of Classical Message using Cavity Quantum Electrodynamic System

    Institute of Scientific and Technical Information of China (English)

    HAN Lian-Fang; LIU Yi-Min; ZHANG Zhan-Jun

    2006-01-01

    @@ An experimental feasible scheme of multiparty secret sharing of classical messages is proposed, based on a cavity quantum electrodynamic system. The secret messages are imposed on atomic Bell states initially in the sender's possession by local unitary operations. By swapping quantum entanglement of atomic Bell states, the secret messages are split into several parts and each part is distributed to a separate party. In this case, any subset of the entire party group can not read out the secret message but the entirety via mutual cooperations. In this scheme, to discriminate atomic Bell states, additional classical fields are employed besides the same highly-detuned single-mode cavities used to prepare atomic Bell states. This scheme is insensitive to the cavity decay and the thermal field, and usual joint Bell-state measurements are unnecessary.

  4. Quantum cascade laser-based sensors for the detection of exhaled carbon monoxide

    Science.gov (United States)

    Pakmanesh, Nahid; Cristescu, Simona M.; Ghorbanzadeh, Atamalek; Harren, Frans J. M.; Mandon, Julien

    2016-01-01

    Carbon monoxide (CO) is an important biomarker as it originates in the human body from the heme (component of hemoglobin) degradation. Tunable laser absorption spectroscopy in the mid-infrared wavelength region is used for sensitive trace gas sensing of exhaled carbon monoxide (CO). Based on a quantum cascade laser emitting at 4.61 µm, two different spectroscopic methods are investigated: off-axis integrated cavity output spectroscopy (OA-ICOS) and wavelength modulation 2f/1f spectroscopy (WMS). The optical sensors integrate a slow feedback system to correct for wavelength drifts improving their stability over days. Both approaches demonstrate a high reproducibility and sensitivity during online measurements of exhaled human breath. Considering the detection limit to be the equal to the standard deviation of the background fluctuations, the noise-equivalent detection limit for both OA-ICOS and WMS is 7 ppbv (1-s averaging time), leading to a noise-equivalent absorption sensitivity of 3.1 × 10-7 cm-1 Hz-1/2, which is sufficient for measurements of exhaled CO (eCO). Collection and measurements of eCO samples were investigated, and different exhalation flow rates and breath-holding time were explored, to provide a reliable sampling method for future medical investigations.

  5. Quantum computation in decoherence-free subspace via cavity-decay-assisted adiabatic passage

    Directory of Open Access Journals (Sweden)

    FENG Xunli

    2015-08-01

    Full Text Available In this work,a scheme for quantum computation based on cavity QED in a decoherence-free subspaces via using the technique of stimulated Raman adiabatic passage (STIRAP is proposed.To implement universal quantum logic gates that form basic blocks of quantum computation,we suppose two atoms are trapped in a single-mode cavity with large decay rates and are driven by the laser fields.The relatively large cavity decay can be used for the continuous detection of the cavity mode as so-called ″cavity-decay-induced quantum Zeno effect″.The results show that,decoherence induced by the atomic spontaneous emission and cavity decay can be efficiently suppress with the STIRAP technique and the quantum Zeno effect.

  6. Mid-infrared quantum cascade laser integrated with distributed Bragg reflector

    Science.gov (United States)

    Yoshinaga, Hiroyuki; Hashimoto, Jun-ichi; Mori, Hiroki; Tsuji, Yukihiro; Murata, Makoto; Ekawa, Mitsuru; Katsuyama, Tsukuru

    2016-02-01

    Quantum cascade lasers (QCLs) are promising as compact light sources in the mid-infrared region. In order to put them into a practical use, their relatively high threshold currents should be reduced. Facet reflectivity increase by distributed Bragg reflector (DBR) is effective for this purpose, but there have been few reports on DBR-integrated QCLs (DBRQCLs). In this paper, we report a successful operation of a DBR-QCL in 7 μm wavelength region. With the fabrication, an n-InP buffer layer, a core region consisting of AlInAs/GaInAs superlattices, an n-InP cladding layer, and an n-GaInAs contact layer were successively grown on an n-InP substrate using OMVPE in the first growth. Then, the wafer was processed into a mesa-stripe, and it was buried by an Fe-doped InP current-blocking layer to form a buriedheterostructure (BH) waveguide. After that, a DBR in which semiconductor-walls and air-gaps were alternately arranged was formed at the front or end of the cavity by dry-etching the epitaxial layers of the air-gap regions, and thus a DBRQCL was fabricated. A DBR-QCL chip (Mesa-width:10 μm, Cavity-legth:2 mm) which had a DBR-structure consisting of 1 pair of a 3λ/4-thick semiconductor-wall/3λ/4-thick air-gap at the front end and a high reflective facet at the rear end oscillated successfully under continuous-wave condition at 15°C. This is the first report on the InP-based DBR-QCL to our knowledge. The facet reflectivity at the DBR was 66%, which was about two times larger than that of the cleaved facet. This result clearly shows that the DBR-structure is effective for threshold current reduction of QCL.

  7. Single photon delayed feedback: a way to stabilize intrinsic quantum cavity electrodynamics.

    Science.gov (United States)

    Carmele, Alexander; Kabuss, Julia; Schulze, Franz; Reitzenstein, Stephan; Knorr, Andreas

    2013-01-01

    We propose a scheme to control cavity quantum electrodynamics in the single photon limit by delayed feedback. In our approach a single emitter-cavity system, operating in the weak coupling limit, can be driven into the strong coupling-type regime by an external mirror: The external loop produces Rabi oscillations directly connected to the electron-photon coupling strength. As an expansion of typical cavity quantum electrodynamics, we treat the quantum correlation of external and internal light modes dynamically and demonstrate a possible way to implement a fully quantum mechanical time-delayed feedback. Our theoretical approach proposes a way to experimentally feedback control quantum correlations in the single photon limit.

  8. Quantum State Engineering by Superpositions of Coherent States along aStraight Line in Cavity Quantum Electrodynamics

    Institute of Scientific and Technical Information of China (English)

    郑仕标

    2001-01-01

    A scheme is proposed for generating the superpositions of several coherent states in a cavity field with dispersive cavity quantum electrodynamics (QED). In the scheme, a sequence of atoms interacts dispersively with the cavity field, connected with a microwave source, and is manipulated by classical fields, followed by state-selective measurements. In this way, the cavity field is collapsed onto a superposition of several coherent states along a straight line with controllable coefficients. This scheme provides the possibility for quantum state engineering via coherent-state superpositions along a straight line in cavity QED for the first time.

  9. Analysis of adiabatic transfer in cavity quantum electrodynamics

    Indian Academy of Sciences (India)

    Joyee Ghosh; R Ghosh; Deepak Kumar

    2011-10-01

    A three-level atom in a configuration trapped in an optical cavity forms a basic unit in a number of proposed protocols for quantum information processing. This system allows for efficient storage of cavity photons into long-lived atomic excitations, and their retrieval with high fidelity, in an adiabatic transfer process through the ‘dark state’ by a slow variation of the control laser intensity. We study the full quantum mechanics of this transfer process with a view to examine the non-adiabatic effects arising from inevitable excitations of the system to states involving the upper level of , which is radiative. We find that the fidelity of storage is better, the stronger the control field and the slower the rate of its switching off. On the contrary, unlike the adiabatic notion, retrieval is better with faster rates of switching on of an optimal control field. Also, for retrieval, the behaviour with dissipation is non-monotonic. These results lend themselves to experimental tests. Our exact computations, when applied to slow variations of the control intensity for strong atom–photon couplings, are in very good agreement with Berry’s superadiabatic transfer results without dissipation.

  10. Efficient Dielectric Metasurface Collimating Lenses for Mid-Infrared Quantum Cascade Lasers

    CERN Document Server

    Arbabi, Amir; Horie, Yu; Bagheri, Mahmood; Faraon, Andrei

    2015-01-01

    Light emitted from single-mode semiconductor lasers generally has large divergence angles, and high numerical aperture lenses are required for beam collimation. Visible and near infrared lasers are collimated using aspheric glass or plastic lenses, yet collimation of mid-infrared quantum cascade lasers typically requires more costly aspheric lenses made of germanium, chalcogenide compounds, or other infrared-transparent materials. Here we report mid-infrared dielectric metasurface flat lenses that efficiently collimate the output beam of single-mode quantum cascade lasers. The metasurface lenses are composed of amorphous silicon posts on a flat sapphire substrate and can be fabricated at low cost using a single step conventional UV binary lithography. Mid-infrared radiation from a 4.8 $\\mu$m distributed-feedback quantum cascade laser is collimated using a polarization insensitive metasurface lens with 0.86 numerical aperture and 79% transmission efficiency. The collimated beam has a half divergence angle of 0...

  11. A scheme for implementing quantum clock synchronization algorithm in cavity QED

    Institute of Scientific and Technical Information of China (English)

    Wu Qin-Qin; Kuang Le-Man

    2006-01-01

    In this paper, we propose a scheme for implementing the quantum clock synchronization (QCS) algorithm in cavity quantum electrodynamic (QED) formalism. Our method is based on three-level ladder-type atoms interacting with classical and quantized cavity fields. Atom-qubit realizations of three-qubit and four-qubit QCS algorithms are explicitly presented.

  12. Quantum Logic Network for Cloning a State Near a Given One Based on Cavity QED

    Institute of Scientific and Technical Information of China (English)

    ZHANG Da-Wei; SHAO Xiao-Qiang; ZHU Ai-Dong

    2008-01-01

    A quantum logic network is constructed to simulate a cloning machine which copies states near a given one. Meanwhile, a scheme for implementing this cloning network based on the technique of cavity quantum electrody-namics (QED) is presented. It is easy to implement this network of cloning machine in the framework of cavity QED and feasible in the experiment.

  13. Environment-Assisted Speed-up of the Field Evolution in Cavity Quantum Electrodynamics.

    Science.gov (United States)

    Cimmarusti, A D; Yan, Z; Patterson, B D; Corcos, L P; Orozco, L A; Deffner, S

    2015-06-12

    We measure the quantum speed of the state evolution of the field in a weakly driven optical cavity QED system. To this end, the mode of the electromagnetic field is considered as a quantum system of interest with a preferential coupling to a tunable environment: the atoms. By controlling the environment, i.e., changing the number of atoms coupled to the optical cavity mode, an environment-assisted speed-up is realized: the quantum speed of the state repopulation in the optical cavity increases with the coupling strength between the optical cavity mode and this non-Markovian environment (the number of atoms).

  14. Scheme for splitting quantum information via W states in cavity QED systems

    Institute of Scientific and Technical Information of China (English)

    Yu Xi-Mei; Gu Yong-Jian; Ma Li-Zhen; Zhou Bang-An

    2008-01-01

    Assisted by multipartite entanglement,Quantum information may be split so that the original qubit can be reconstructed if and only if the recipients cooperate.This paper proposes an experimentally feasible scheme for splitting quantum information via W-type entangled states in cavity QED systems,where three-level Rydberg atoms interact with nonresonant cavities.Since W-type states are used as the quantum channel and the cavities are only virtually excited,the scheme is easy to implement and robust against decoherence,and the dependence on the quality factor of the cavities is greatly reduced.

  15. Possible Realization of Cluster States and Quantum Information Transfer in Cavity QED via Raman Transition

    Institute of Scientific and Technical Information of China (English)

    ZHAN Zhi-Ming; LI Wei-Bin

    2007-01-01

    We present a scheme to generate cluster states with many atoms in cavity QED via Raman transition. In this scheme, no transfer of quantum information between the atoms and cavities is required, the cavity fields are only virtually excited and thus the cavity decay is suppressed during the generation of cluster states. The atoms are always populated in the two ground states. Therefore, the scheme is insensitive to the atomic spontaneous emission and cavity decay. We also show how to transfer quantum information from one atom to another.

  16. A Coherence Preservation Control Strategy in Cavity QED Based on Classical Quantum Feedback

    Directory of Open Access Journals (Sweden)

    Ming Li

    2013-01-01

    Full Text Available For eliminating the unexpected decoherence effect in cavity quantum electrodynamics (cavity QED, the transfer function of Rabi oscillation is derived theoretically using optical Bloch equations. In particular, the decoherence in cavity QED from the atomic spontaneous emission is especially considered. A feedback control strategy is proposed to preserve the coherence through Rabi oscillation stabilization. In the scheme, a classical quantum feedback channel for the quantum information acquisition is constructed via the quantum tomography technology, and a compensation system based on the root locus theory is put forward to suppress the atomic spontaneous emission and the associated decoherence. The simulation results have proved its effectiveness and superiority for the coherence preservation.

  17. Frequency-locking and threshold current-lowering effects of quantum cascade laser and an application in gas detection field

    Institute of Scientific and Technical Information of China (English)

    陈伟根; 万福; 邹经鑫; 顾朝亮; 周渠

    2015-01-01

    In this paper, the frequency-locking and threshold current-lowering effects of quantum cascade laser are studied and achieved. Combined with cavity-enhanced absorption spectroscopy, the noninvasive detection of H2 with a pre-pared concentration of 500 ppm in multiple dissolved gases is performed and evaluated. The high frequency selectivity of 0.0051 cm−1 at an acquisition time of 1 s allows the sensitive detection of the (1-0) S(1) band of H2 with a high ac-curacy of (96.53±0.29)%and shows that the detection limit to an absorption line of 4712.9046 cm−1 is approximately (17.26±0.63) ppm at an atmospheric pressure and a temperature of 20◦C.

  18. Cavity QED and quantum computation in the weak coupling regime

    Science.gov (United States)

    Fujii, Kazuyuki; Higashida, Kyoko; Kato, Ryosuke; Wada, Yukako

    2004-12-01

    In this paper we consider a model of quantum computation based on n atoms, laser cooled and trapped linearly in a cavity, and realize it as the n-atom Tavis-Cummings Hamiltonian interacting with n external (laser) fields. We solve the Schrödinger equation of the model in the case of n = 2 and construct the controlled NOT gate by making use of a resonance condition and the rotating wave approximation associated with it. Our method is not heuristic but completely mathematical, and the significant feature is the consistent use of Rabi oscillations. We also present an idea for the construction of three controlled NOT gates in the case of n = 3 which gives a controlled-controlled NOT gate.

  19. Cavity QED and Quantum Computation in the Weak Coupling Regime

    CERN Document Server

    Fujii, K; Kato, R; Wada, Y; Fujii, Kazuyuki; Higashida, Kyoko; Kato, Ryosuke; Wada, Yukako

    2004-01-01

    In this paper we consider a model of quantum computation based on n atoms of laser--cooled and trapped linearly in a cavity and realize it as the n atoms Tavis--Cummings Hamiltonian interacting with n external (laser) fields. We solve the Schr{\\" o}dinger equation of the model in the case of n=2 and construct the controlled NOT gate by making use of a resonance condition and rotating wave approximation associated to it. Our method is not heuristic but completely mathematical, and the significant feature is a consistent use of Rabi oscillations. We also present a problem related to the construction of (three) controlled NOT gates in the case of n=3 which gives the controlled-controlled NOT gate.

  20. Cavity QED and quantum computation in the weak coupling regime

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Kazuyuki; Higashida, Kyoko; Kato, Ryosuke; Wada, Yukako [Department of Mathematical Sciences, Yokohama City University, Yokohama 236-0027 (Japan)

    2004-12-01

    In this paper we consider a model of quantum computation based on n atoms, laser cooled and trapped linearly in a cavity, and realize it as the n-atom Tavis-Cummings Hamiltonian interacting with n external (laser) fields. We solve the Schroedinger equation of the model in the case of n = 2 and construct the controlled NOT gate by making use of a resonance condition and the rotating wave approximation associated with it. Our method is not heuristic but completely mathematical, and the significant feature is the consistent use of Rabi oscillations. We also present an idea for the construction of three controlled NOT gates in the case of n = 3 which gives a controlled-controlled NOT gate.

  1. Cavity quantum electrodynamics studies with site-controlled InGaAs quantum dots integrated into high quality microcavities

    DEFF Research Database (Denmark)

    Reitzenstein, S.; Schneider, C.; Albert, F.;

    2011-01-01

    Semiconductor quantum dots (QDs) are fascinating nanoscopic structures for photonics and future quantum information technology. However, the random position of self-organized QDs inhibits a deterministic coupling in devices relying on cavity quantum electrodynamics (cQED) effects which complicates...

  2. Scheme for implementing perfect quantum teleportation with four-qubit entangled states in cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Tang Jing-Wu; Zhao Guan-Xiang; He Xiong-Hui

    2011-01-01

    Recently, Peng et al. [2010 Eur. Phys. J. D 58 403] proposed to teleport an arbitrary two-qubit state with a family of four-qubit entangled states, which simultaneously include the tensor product of two Bell states, linear cluster state and Dicke-class state. This paper proposes to implement their scheme in cavity quantum electrodynamics and then presents a new family of four-qubit entangled state |Ω4)1234. It simultaneously includes all the well-known four-qubit entangled states which can be used to teleport an arbitrary two-qubit state. The distinct advantage of the scheme is that it only needs a single setup to prepare the whole family of four-qubit entangled states, which will be very convenient for experimental realization. After discussing the experimental condition in detail, we show the scheme may be feasible based on present technology in cavity quantum electrodynamics.

  3. Preparation of Genuinely Entangled Six-Atom State via Cavity Quantum Electrodynamics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wen; LIU Yi-Min; YIN Xiao-Feng; ZHANG Zhan-Jun

    2011-01-01

    A cavity quantum electrodynamics scheme for preparing a genuinely entangled state [A. Borras, et al., J. Phys. A 40 (2007) 13407] on six two-level atoms is proposed. In the scheme, the atom-cavity detuning is much bigger than the atom-cavity coupling strength and the necessary preparation time is much shorter than the Rydberg-atom lifespan. Hence the scheme has two distinct features, i.e., insensitive to the cavity decay and the atom radiation.

  4. Scheme to Implement Optimal Asymmetric Economical Phase-Covariant Quantum Cloning in Cavity QED

    Institute of Scientific and Technical Information of China (English)

    YANG Chun-Nuan; ZHANG Wen-Hai; HE Jin-Chun; DAI Jie-Lin; HUANG Nian-Ning; YE Liu

    2008-01-01

    We propose an experimentally feasible scheme to implement the optimal asymmetric economical 1 → 2 phase-covariant quantum cloning in two dimensions based on the cavity QED technique. The protocol is very simple and only two atoms are required. Our scheme is insensitive to the cavity field states and cavity decay. During the processes, the cavity is only virtually excited and it thus greatly prolongs the efficient decoherent time. Therefore, it may be realized in experiment.

  5. On the cascade approach to the quantum multiscattering problem

    Energy Technology Data Exchange (ETDEWEB)

    Salcedo, L.L. [Departamento de Fisica Moderna, Universidad de Granada, E-18071 Granada (Spain)

    2003-01-01

    The multiscattering problem is studied in the matrix density formalism. We study how to isolate the quasi-classical degrees of freedom in order to connect them with a cascade approach. The different problems that arise, as well as their possible solutions, are discussed and exemplified with a pion-nucleus model. (orig.)

  6. Quantum Transport Simulation of High-Power 4.6-μm Quantum Cascade Lasers

    Directory of Open Access Journals (Sweden)

    Olafur Jonasson

    2016-06-01

    Full Text Available We present a quantum transport simulation of a 4.6- μ m quantum cascade laser (QCL operating at high power near room temperature. The simulation is based on a rigorous density-matrix-based formalism, in which the evolution of the single-electron density matrix follows a Markovian master equation in the presence of applied electric field and relevant scattering mechanisms. We show that it is important to allow for both position-dependent effective mass and for effective lowering of very thin barriers in order to obtain the band structure and the current-field characteristics comparable to experiment. Our calculations agree well with experiments over a wide range of temperatures. We predict a room-temperature threshold field of 62 . 5 kV/cm and a characteristic temperature for threshold-current-density variation of T 0 = 199 K . We also calculate electronic in-plane distributions, which are far from thermal, and show that subband electron temperatures can be hundreds to thousands of degrees higher than the heat sink. Finally, we emphasize the role of coherent tunneling current by looking at the size of coherences, the off-diagonal elements of the density matrix. At the design lasing field, efficient injection manifests itself in a large injector/upper lasing level coherence, which underscores the insufficiency of semiclassical techniques to address injection in QCLs.

  7. Toward the Realization of a Compact Chemical Sensor Platform using Quantum Cascade Lasers

    Science.gov (United States)

    2015-09-01

    ARL-RP-0550 ● SEP 2015 US Army Research Laboratory Toward the Realization of a Compact Chemical Sensor Platform using Quantum...ARL-RP-0550 ● SEP 2015 US Army Research Laboratory Toward the Realization of a Compact Chemical Sensor Platform using Quantum Cascade...Lasers by Ellen L Holthoff, Logan S Marcus, and Paul M Pellegrino Sensors and Electron Devices Directorate, ARL A reprint from Proc

  8. Numerical Study on Quantum Walks Implemented on the Cascade Rotational Transitions in a Diatomic Molecule

    CERN Document Server

    Matsuoka, Leo; Hashimoto, Masashi; Yokoyama, Keiichi

    2011-01-01

    We propose an implementation scheme for the continuous-time quantum walk using a diatomic molecule and an optical frequency comb. We show an analogy between the quantum walk and the cascade rotational transitions induced by the optical frequency comb whose frequency peaks are tuned to the pure rotational transitions in the molecule. The strategy to compensate for the centrifugal distortion of the real molecule is also demonstrated.

  9. Macroscopic quantum electrodynamics of high-Q cavities

    Energy Technology Data Exchange (ETDEWEB)

    Khanbekyan, Mikayel

    2009-10-27

    In this thesis macroscopic quantum electrodynamics in linear media was applied in order to develop an universally valid quantum theory for the description of the interaction of the electromagnetic field with atomic sources in high-Q cavities. In this theory a complete description of the characteristics of the emitted radiation is given. The theory allows to show the limits of the applicability of the usually applied theory. In order to establish an as possible generally valid theory first the atom-field interaction was studied in the framework of macroscopic quantum electrodynamics in dispersive and absorptive media. In order to describe the electromagnetic field from Maxwell's equations was started, whereby the noise-current densities, which are connected with the absorption of the medium, were included. The solution of these equations expresses the electromagnetic field variables by the noise-current densities by means of Green's tensor of the macroscopic Maxwell equations. The explicit quantization is performed by means of the noise-current densities, whereby a diagonal Hamiltonian is introduced, which then guarantees the time development according to Maxwell's equation and the fulfillment of the fundamental simultaneous commutation relations of the field variables. In the case of the interaction of the medium-supported field with atoms the Hamiltonian must be extended by atom-field interactions energies, whereby the canonical coupling schemes of the minimal or multipolar coupling can be used. The dieelectric properties of the material bodies as well as their shape are coded in the Green tensor of the macroscopic Maxwell equations. As preparing step first the Green tensor was specified in order to derive three-dimensional input-output relations for the electromagnetic field operators on a plane multilayer structure. Such a general dewscription of the electromagnetic field allows the inclusion both of dispersion and absorption of the media and the

  10. Cavity-photon-switched coherent transient transport in a double quantum waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Nzar Rauf, E-mail: nra1@hi.is; Gudmundsson, Vidar, E-mail: vidar@raunvis.hi.is [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Tang, Chi-Shung [Department of Mechanical Engineering, National United University, 1, Lienda, 36003 Miaoli, Taiwan (China); Manolescu, Andrei [School of Science and Engineering, Reykjavik University, Menntavegur 1, IS-101 Reykjavik (Iceland)

    2014-12-21

    We study a cavity-photon-switched coherent electron transport in a symmetric double quantum waveguide. The waveguide system is weakly connected to two electron reservoirs, but strongly coupled to a single quantized photon cavity mode. A coupling window is placed between the waveguides to allow electron interference or inter-waveguide transport. The transient electron transport in the system is investigated using a quantum master equation. We present a cavity-photon tunable semiconductor quantum waveguide implementation of an inverter quantum gate, in which the output of the waveguide system may be selected via the selection of an appropriate photon number or “photon frequency” of the cavity. In addition, the importance of the photon polarization in the cavity, that is, either parallel or perpendicular to the direction of electron propagation in the waveguide system is demonstrated.

  11. Applications of cw quantum cascade laser near 8 μm in gas sensing research

    KAUST Repository

    Sajid, Muhammad Bilal

    2014-01-01

    Quantum cascade laser based sensors operating near 8 μm to detect H2O2, C2H2, CH4, N2O and H2O are discussed and demonstrated for applications in chemical kinetics, combustion and spectroscopic measurements.

  12. Electron transport in n-doped Si/SiGe quantum cascade structures

    NARCIS (Netherlands)

    Lazic, I.; Ikonic, Z.; Milanovic, V.; Kelsall, R.W.; Indjin, D.; Harrison, P.

    2007-01-01

    An electron transport model in n-Si/SiGe quantum cascade or superlattice structures is described. The model uses the electronic structure calculated within the effective-mass complex-energy framework, separately for perpendicular (Xz) and in-plane (Xxy) valleys, the degeneracy of which is lifted by

  13. Exhaled nitric oxide monitoring by quantum cascade laser: comparison with chemiluminescent and electrochemical sensors.

    NARCIS (Netherlands)

    Mandon, J.; Hogman, M.; Merkus, P.J.F.M.; Amsterdam, J. van; Harren, F.J.M.; Cristescu, S.M.

    2012-01-01

    Fractional exhaled nitric oxide (F(E)NO) is considered an indicator in the diagnostics and management of asthma. In this study we present a laser-based sensor for measuring F(E)NO. It consists of a quantum cascade laser (QCL) combined with a multi-pass cell and wavelength modulation spectroscopy for

  14. On the cascade capture of electrons at donors in GaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Aleshkin, V. Ya., E-mail: aleshkin@ipmras.ru [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

    2015-09-15

    The impact parameter for the cascade capture of electrons at a charged donor in a GaAs quantum well is calculated. A simple approximate analytical expression for the impact parameter is suggested. The temperature dependence of the impact parameter for the case of electron scattering by the piezoelectric potential of acoustic phonons is determined.

  15. Application of step-scan FTIR to the research of quantum cascade lasers

    Institute of Scientific and Technical Information of China (English)

    Junqi Liu; Xiuzhen Lu; Yu Guo; Xiuqi Huang; Xiaoling Che; Wen Lei; Fengqi Liu

    2005-01-01

    The principle of step-scan Fourier transform infrared (FTIR) spectroscopy is introduced. Double modulation step-scan FTIR technique is used to obtain the quantum cascade laser's stacked emission spectra in the time domain. Optical property and thermal accumulation of devices due to large drive current are analyzed.

  16. Phase-locking of a 2.7-THz quantum cascade laser

    NARCIS (Netherlands)

    Gao, J. R.; Khosropanah, P.; Baryshev, A.; Zhang, W.; Jellema, W.; Hovenier, J. N.; Klapwijk, T. M.; Paveliev, D. G.; Williams, B. S.; Kumar, S.; Hu, Q.; Reno, L.; Klein, B.; Hesler, J. L.; Rastogi, PK; Hack, E

    2010-01-01

    We successfully realized phase-locking of a 2.7-THz metal-metal waveguide quantum cascade laser (QCL) to a reference, which is generated from an external microwave signal by applying two stages of frequency multiplication. The reference is the 15th harmonic of a signal at 182 GHz, which is produced

  17. Phase locking of a 2.7 THz quantum cascade laser to a microwave reference

    NARCIS (Netherlands)

    Khosropanah, P.; Baryshev, A.; Zhang, W.; Jellema, W.; Hovenier, J. N.; Gao, J. R.; Klapwijk, T. M.; Paveliev, D. G.; Williams, B. S.; Kumar, S.; Hu, Q.; Reno, J. L.; Klein, B.; Hesler, J. L.

    2009-01-01

    We demonstrate the phase locking of a 2.7 THz metal-metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain (x1

  18. Phase locking of a 2.7 THz quantum cascade laser to a microwave reference

    NARCIS (Netherlands)

    Khosropanah, P.; Baryshev, A.; Zhang, W.; Jellema, W.; Hovenier, J.N.; Gao, J.R.; Klapwijk, T.M.; Paveliev, D.G.; Williams, B.S.; Kumar, S.; Hu, Q.; Reno, J.L.; Klein, B.; Hesler, J.L.

    2009-01-01

    We demonstrate the phase locking of a 2.7 THz metal–metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain (x1

  19. Phase locking and spectral linewidth of a two-mode terahertz quantum cascade laser

    NARCIS (Netherlands)

    Baryshev, A.; Hovenier, J.N.; Adam, A.J.L.; Kašalynas, I.; Gao, J.R.; Klaassen, T.O.; Williams, B.S.; Kumar, S.; Hu,Q.; Reno, J.L.

    2006-01-01

    We have studied the phase locking and spectral linewidth of an ∼ 2.7 THz quantum cascade laser by mixing its two lateral lasing modes. The beat signal at about 8 GHz is compared with a microwave reference by applying conventional phase lock loop circuitry with feedback to the laser bias current. Pha

  20. Photon Cascade from a Single Crystal Phase Nanowire Quantum Dot

    DEFF Research Database (Denmark)

    Bouwes Bavinck, Maaike; Jöns, Klaus D; Zieliński, Michal;

    2016-01-01

    We report the first comprehensive experimental and theoretical study of the optical properties of single crystal phase quantum dots in InP nanowires. Crystal phase quantum dots are defined by a transition in the crystallographic lattice between zinc blende and wurtzite segments and therefore offer....... We notice that the emission spectra consist often of two peaks close in energy, which we explain with a comprehensive theory showing that the symmetry of the system plays a crucial role for the hole levels forming hybridized orbitals. Our results state that crystal phase quantum dots have promising...

  1. Hollow fiber based quantum cascade laser spectrometer for fast and sensitive drug identification

    Science.gov (United States)

    Herbst, J.; Scherer, B.; Ruf, A.; Erb, J.; Lambrecht, A.

    2012-01-01

    Sensitive and fast identification of drugs or drug precursors is important and necessary in scenarios like baggage or container check by customs or police. Fraunhofer IPM is developing a laser spectrometer using external cavity quantum cascade lasers (EC-QCL) to obtain mid-infrared (IR) absorption spectra in the wavelength range of the specific vibrational bands of amphetamines and their precursors. The commercial EC-QCL covers a tuning range of about 225 cm-1 within 1.4 s. The system could be used for different sample types like bulk samples or liquid solutions. A sampling unit evaporates the sample. Because of small sample amounts a 3 m long hollow fiber with an inner volume smaller than 1ml is used as gas cell and wave guide for the laser beam. This setup is suitable as a detector of a gas chromatograph instead of a standard detector (TCD or FID). The advantage is the selective identification of drugs by their IR spectra in addition to the retention time in the gas chromatographic column. In comparison to Fourier Transform IR systems the EC-QCL setup shows a good mechanical robustness and has the advantage of a point light source. Because of the good fiber incoupling performance of the EC-QCL it is possible to use hollow fibers. So, a good absorption signal is achieved because of the long optical path in the small cell volume without significant dilution. In first laboratory experiments a detection limit in the microgram range for pseudo ephedrine is achieved.

  2. Quantum cascade laser-based measurement of metal alkylamide density during atomic layer deposition.

    Science.gov (United States)

    Maslar, James E; Kimes, William A; Sperling, Brent A

    2012-03-01

    An in situ gas-phase diagnostic for the metal alkylamide compound tetrakis(ethylmethylamido) hafnium (TEMAH), Hf[N(C(2)H(5))(CH(3))](4), was demonstrated. This diagnostic is based on direct absorption measurement of TEMAH vapor using an external cavity quantum cascade laser emitting at 979 cm(-1), coinciding with the most intense TEMAH absorption in the mid-infrared spectral region, and employing 50 kHz amplitude modulation with synchronous detection. Measurements were performed in a single-pass configuration in a research-grade atomic layer deposition (ALD) chamber. To examine the detection limit of this technique for use as a TEMAH delivery monitor, this technique was demonstrated in the absence of any other deposition reactants or products, and to examine the selectivity of this technique in the presence of deposition products that potentially interfere with detection of TEMAH vapor, it was demonstrated during ALD of hafnium oxide using TEMAH and water. This technique successfully detected TEMAH at molecular densities present during simulated industrial ALD conditions. During hafnium oxide ALD using TEMAH and water, absorbance from gas-phase reaction products did not interfere with TEMAH measurements while absorption by reaction products deposited on the optical windows did interfere, although interfering absorption by deposited reaction products corresponded to only ≈4% of the total derived TEMAH density. With short measurement times and appropriate signal averaging, estimated TEMAH minimum detectable densities as low as ≈2 × 10(12) molecules/cm(3) could be obtained. While this technique was demonstrated specifically for TEMAH delivery and hafnium oxide ALD using TEMAH and water, it should be readily applicable to other metal alkylamide compounds and associated metal oxide and nitride deposition chemistries, assuming similar metal alkylamide molar absorptivity and molecular density in the measurement chamber.

  3. A scheme for transferring an unknown atomic entangled state via cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Wu Tao; Ye Liu; Ni Zhi-Xiang

    2006-01-01

    In this paper, we propose a scheme for transferring an unknown atomic entangled state via cavity quantum electrodynamics (QED). This scheme, which has a successful probability of 100 percent, does not require Bell-state measurement and performing any operations to reconstruct an initial state. Meanwhile, the scheme only involves atomfield interaction with a large detuning and does not require the transfer of quantum information between the atoms and cavity. Thus the scheme is insensitive to the cavity field states and cavity decay. This scheme can also be extended to transfer ring an entangled state of n-atom.

  4. Interference control of nonlinear excitation in a multi-atom cavity quantum electrodynamics system.

    Science.gov (United States)

    Yang, Guoqing; Tan, Zheng; Zou, Bichen; Zhu, Yifu

    2014-12-01

    We show that by manipulating quantum interference in a multi-atom cavity quantum electrodynamics (CQED) system, the nonlinear excitation of the cavity-atom polariton can be resonantly enhanced while the linear excitation is suppressed. Under the appropriate conditions, it is possible to selectively enhance or suppress the polariton excitation with two free-pace laser fields. We report on an experiment with cold Rb atoms in an optical cavity and present experimental results that demonstrate such interference control of the CQED excitation and its direct application to studies of all-optical switching and cross-phase modulation of the cavity-transmitted light.

  5. Classical and Quantum Theory of Photothermal Cavity Cooling of a Mechanical Oscillator

    CERN Document Server

    Restrepo, Juan; Ciuti, Cristiano; Favero, Ivan

    2010-01-01

    Photothermal effects allow very efficient optomechanical coupling between mechanical degrees of freedom and photons. In the context of cavity cooling of a mechanical oscillator, the question of if the quantum ground state of the oscillator can be reached using photothermal back-action has been debated and remains an open question. Here we address this problem by complementary classical and quantum calculations. Both lead us to conclude that: first, the ground-state can indeed be reached using photothermal cavity cooling, second, it can be reached in a regime where the cavity detuning is small allowing a large amount of photons to enter the cavity.

  6. Coupled carrier-phonon nonequilibrium dynamics in terahertz quantum cascade lasers: a Monte Carlo analysis

    Science.gov (United States)

    Iotti, Rita C.; Rossi, Fausto

    2013-07-01

    The operation of state-of-the-art optoelectronic quantum devices may be significantly affected by the presence of a nonequilibrium quasiparticle population to which the carrier subsystem is unavoidably coupled. This situation is particularly evident in new-generation semiconductor-heterostructure-based quantum emitters, operating both in the mid-infrared as well as in the terahertz (THz) region of the electromagnetic spectrum. In this paper, we present a Monte Carlo-based global kinetic approach, suitable for the investigation of a combined carrier-phonon nonequilibrium dynamics in realistic devices, and discuss its application with a prototypical resonant-phonon THz emitting quantum cascade laser design.

  7. Macroscopic quantum electrodynamics of high-Q cavities

    Energy Technology Data Exchange (ETDEWEB)

    Khanbekyan, Mikayel

    2009-10-27

    In this thesis macroscopic quantum electrodynamics in linear media was applied in order to develop an universally valid quantum theory for the description of the interaction of the electromagnetic field with atomic sources in high-Q cavities. In this theory a complete description of the characteristics of the emitted radiation is given. The theory allows to show the limits of the applicability of the usually applied theory. In order to establish an as possible generally valid theory first the atom-field interaction was studied in the framework of macroscopic quantum electrodynamics in dispersive and absorptive media. In order to describe the electromagnetic field from Maxwell's equations was started, whereby the noise-current densities, which are connected with the absorption of the medium, were included. The solution of these equations expresses the electromagnetic field variables by the noise-current densities by means of Green's tensor of the macroscopic Maxwell equations. The explicit quantization is performed by means of the noise-current densities, whereby a diagonal Hamiltonian is introduced, which then guarantees the time development according to Maxwell's equation and the fulfillment of the fundamental simultaneous commutation relations of the field variables. In the case of the interaction of the medium-supported field with atoms the Hamiltonian must be extended by atom-field interactions energies, whereby the canonical coupling schemes of the minimal or multipolar coupling can be used. The dieelectric properties of the material bodies as well as their shape are coded in the Green tensor of the macroscopic Maxwell equations. As preparing step first the Green tensor was specified in order to derive three-dimensional input-output relations for the electromagnetic field operators on a plane multilayer structure. Such a general dewscription of the electromagnetic field allows the inclusion both of dispersion and absorption of the media and the

  8. Coherent quantum state storage and transfer between two phase qubits via a resonant cavity.

    Science.gov (United States)

    Sillanpää, Mika A; Park, Jae I; Simmonds, Raymond W

    2007-09-27

    As with classical information processing, a quantum information processor requires bits (qubits) that can be independently addressed and read out, long-term memory elements to store arbitrary quantum states, and the ability to transfer quantum information through a coherent communication bus accessible to a large number of qubits. Superconducting qubits made with scalable microfabrication techniques are a promising candidate for the realization of a large-scale quantum information processor. Although these systems have successfully passed tests of coherent coupling for up to four qubits, communication of individual quantum states between superconducting qubits via a quantum bus has not yet been realized. Here, we perform an experiment demonstrating the ability to coherently transfer quantum states between two superconducting Josephson phase qubits through a quantum bus. This quantum bus is a resonant cavity formed by an open-ended superconducting transmission line of length 7 mm. After preparing an initial quantum state with the first qubit, this quantum information is transferred and stored as a nonclassical photon state of the resonant cavity, then retrieved later by the second qubit connected to the opposite end of the cavity. Beyond simple state transfer, these results suggest that a high-quality-factor superconducting cavity could also function as a useful short-term memory element. The basic architecture presented here can be expanded, offering the possibility for the coherent interaction of a large number of superconducting qubits.

  9. A high carrier injection terahertz quantum cascade laser based on indirectly pumped scheme

    Energy Technology Data Exchange (ETDEWEB)

    Razavipour, S. G., E-mail: sgrazavi@uwaterloo.ca; Xu, C.; Wasilewski, Z. R.; Ban, D. [Department of Electrical and Computer Engineering, Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Ave. W., Waterloo, Ontario N2L3G1 (Canada); Dupont, E.; Laframboise, S. R. [National Research Council, Blg. M-50, 1200 Montreal Rd., Ottawa, Ontario K1A0R6 (Canada); Chan, C. W. I.; Hu, Q. [Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2014-01-27

    A Terahertz quantum cascade laser with a rather high injection coupling strength based on an indirectly pumped scheme is designed and experimentally implemented. To effectively suppress leakage current, the chosen quantum cascade module of the device is based on a five-well GaAs/Al{sub 0.25}Ga{sub 0.75}As structure. The device lases up to 151 K with a lasing frequency of 2.67 THz. This study shows that the effect of higher energy states in carrier transport and the long-range tunnel coupling between states that belong to non-neighbouring modules have to be considered in quantum design of structures with a narrow injector barrier. Moreover, the effect of interface roughness scattering between the lasing states on threshold current is crucial.

  10. Compact photonic crystal circulator with flat-top transmission band created by cascading magneto-optical resonance cavities.

    Science.gov (United States)

    Wang, Qiong; Ouyang, Zhengbiao; Lin, Mi; Liu, Qiang

    2015-11-20

    A new type of compact three-port circulator with flat-top transmission band (FTTB) in a two-dimensional photonic crystal has been proposed, through coupling the cascaded magneto-optical resonance cavities to waveguides. The coupled-mode theory is applied to investigate the coupled structure and analyze the condition to achieve FTTB. According to the theoretical analysis, the structure is further optimized to ensure that the condition for achieving FTTB can be satisfied for both cavity-cavity coupling and cavity-waveguide coupling. Through the finite-element method, it is demonstrated that the design can realize a high quality, nonreciprocal circulating propagation of waves with an insertion loss of 0.023 dB and an isolation of 23.3 dB, covering a wide range of operation frequency. Such a wideband circulator has potential applications in large-scale integrated photonic circuits for guiding or isolating harmful optical reflections from load elements.

  11. Efficient scheme of quantum SWAP gate and multi-atom cluster state via cavity QED

    Institute of Scientific and Technical Information of China (English)

    Jiang Chun-Lei; Fang Mao-Fa; Hu Yao-Hua

    2008-01-01

    In this paper,we propose a physical scheme to realize quantum SWAP gate by using a large-detuned single-mode cavity field and two identical Rydberg atoms.It is shown that the scheme can also be used to create multi-atom cluster state.During the interaction between atom and cavity,the cavity is only virtually excited and thus the scheme is insensitive to the cavity field states and cavity decay.With the help of our scheme it is very simple to prepare the N-atom cluster state with perfect fidelity and probability.The practical feasibility of this method is also discussed.

  12. Quantum Statistical Properties of the Exciton in a Leaky Quasi-Mode Cavity

    Institute of Scientific and Technical Information of China (English)

    YU Zhao-Xian; JIAO Zhi-Yong

    2002-01-01

    We have studied quantum statistical properties of the exciton in a leaky quasi-mode cavity. It is shown that when the exciton is initially in a squeezed coherent state whereas cavity initially in a vacuum state, there is energy exchange between the exciton and cavity. Both the exciton and cavity may exhibit sub-Poissonian distribution and exist quadrature squeezing. Calculation shows that correlation between the exciton and cavity is classical, which implies that there is not the violation of the Cauchy-Schwartz inequality.

  13. Scheme to Implement Optimal Symmetric 1 → 2 Universal Quantum Telecloning Through Cavity-Assisted Interaction

    Institute of Scientific and Technical Information of China (English)

    YANG Zhen; ZHANG Wen-Hai; HE Juan; YE Liu

    2008-01-01

    We propose a scheme to implement the optimal symmetric 1 → 2 universal quantum telecloning through cavity-assisted interaction. In our scheme, an arbitrary single atomic state can be telecloned to two single atomic states. And three atoms are trapped in three spatially separated cavities respectively. With a particular multiparticle entangled state acting as a quantum information channel and the trapped single atom acting as a quantum network node for its long-lived internal state, quantum information can be telecloned among nodes and can stored in the nodes.

  14. Optical scatter of quantum noise filter cavity optics

    CERN Document Server

    Vander-Hyde, Daniel; Smith, Joshua R

    2014-01-01

    We report on measurements of light scattering from two two-inch super-polished fused silica substrates before and after applying (ATFilms) ion-beam sputtered highly-reflective dielectric coatings. We used an imaging scatterometer, that illuminates the sample with a linearly polarized 1064 nm wavelength laser at a fixed angle of incidence and records images of back scatter for azimuthal angles in the plane of the laser beam, to measure the Bidirectional Reflectance Distribution Function (BRDF) and estimate the total integrated scatter for both samples, before and after coating. We find application of these highly reflective coatings leads to an increase of the integrated scatter of the primary surface by more than 50 %. In addition, the BRDF function of the coated optics takes on a pattern of maxima and zeroes versus azimuthal angle that is qualitatively consistent with bulk scattering from the coating layers. These results are part of a broader study to understand optical loss in quantum noise filter cavities...

  15. Quantum repeater with Rydberg-blocked atomic ensembles in fiber-coupled cavities

    DEFF Research Database (Denmark)

    Brion, Etienne; Carlier, F.; Akulin, M.;

    2012-01-01

    We propose and analyze a quantum repeater architecture in which Rydberg-blocked atomic ensembles inside optical cavities are linked by optical fibers. Entanglement generation, swapping, and purification are achieved through collective laser manipulations of the ensembles and photon transmission...

  16. Nonradiating and radiating modes excited by quantum emitters in open epsilon-near-zero cavities

    CERN Document Server

    Liberal, Iñigo

    2015-01-01

    Controlling the emission and interaction properties of quantum emitters (QEs) embedded within an optical cavity is a key technique in engineering light-matter interactions at the nanoscale, as well as in the development of quantum information processing. State-of-the-art optical cavities are based on high Q photonics crystals and dielectric resonators. However, wealthier responses might be attainable with cavities carved in more exotic materials. Here, we theoretically investigate the emission and interaction properties of QEs embedded in open epsilon-near-zero (ENZ) cavities. Using analytical methods and numerical simulations, it is demonstrated that open ENZ cavities present the unique property of supporting nonradiating modes independently of the geometry of the external boundary of the cavity (shape, size, topology...). Moreover, the possibility of switching between radiating and nonradiating modes enables a dynamic control of both the emission by, and the interaction between, QEs. These phenomena provide...

  17. Thermal Analysis of InAs/A1Sb Short Wavelength Mid-IR Quantum Cascade Lasers

    Institute of Scientific and Technical Information of China (English)

    WEI Lin; LI Ai-Zhen; XU Gang-Yi

    2009-01-01

    We present the effects of hereto-interfaces and major key parameters on the thermal behaviors and performance of short wavelength mid-IR InAs/AlSb quantum cascade lasers (QCLs).We use a finite element method (FEM) with commercial software,ANSYS,to simulate the heat dissipation in QCLs in cw operation mode with an epilayer-down mounting package.The thermal performance is characterized by the temperature increase △T (self-heating effect) between the active region of QCLs and the heatsink.Results show that (1) the self-heating effects of InAs/AlSb QCLs are much less than those in AllnAs/GaInAs QCLs,(2) narrower ridges lead to significantly cooler active regions of InAs/AlSb QCLs due to poor heat transport in the cross-plane direction (across interfaces) and that most of the heat flows out of the active region in the lateral direction,and (3) the cavity length of the laser has little influence on the self-heating effect of the device,but the long cavity reduces mirror loss and threshold current density.

  18. Teleportation of Atomic States via Cavity Quantum Electrodynamics

    CERN Document Server

    Guerra, E S

    2004-01-01

    In this article we discuss a scheme of teleportation of atomic states. The experimental realization proposed makes use of cavity Quatum Electrodynamics involving the interaction of Rydberg atoms with a micromaser cavity prepared in a coherent state. We start presenting a scheme to prepare atomic Bell states via the interaction of atoms with a cavity. In our scheme the cavity and some atoms play the role of auxiliary systems used to achieve the teleportation.

  19. Three-qubit Fredkin gate based on cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Shao Xiao-Qiang; Chen Li; Zhang Shou

    2009-01-01

    This paper presents a scheme for implementing a Fredkin gate on three modes of a cavity.The scheme is based on the dispersive atom-cavity interaction.By modulating the cavity frequency and the atomic transition frequency appropriately,it obtains the effective form of nonlinear interaction between photons in the three-mode cavity.This availability is testified via numerical analysis.It also considers both the situations with and without dissipation.

  20. Bloch-wave engineering of quantum dot-micropillars for cavity quantum electrodynamics experiments

    CERN Document Server

    Lermer, Matthias; Dunzer, Florian; Reitzenstein, Stephan; Höfling, Sven; Mørk, Jesper; Worschech, Lukas; Kamp, Martin; Forchel, Alfred

    2011-01-01

    We have employed Bloch-wave engineering to realize submicron diameter ultra-high quality factor GaAs/AlAs micropillars (MPs). The design features a tapered cavity in which the fundamental Bloch mode is subject to an adiabatic transition to match the Bragg mirror Bloch mode. The resulting reduced scattering loss leads to record-high visibility of the strong coupling in MPs with modest oscillator strength quantum dots. A quality factor of 13,600 and a Rabi splitting of 85 \\mueV with an estimated visibility v of 0.38 are observed for a small mode volume MP with a diameter dc of 850 nm.

  1. Spatial mode effects in a cavity-EIT based quantum memory with ion Coulomb crystals

    DEFF Research Database (Denmark)

    Zangenberg, Kasper Rothe; Dantan, Aurelien Romain; Drewsen, Michael

    2012-01-01

    Quantum storage and retrieval of light in ion Coulomb crystals using cavity electromagnetically induced transparency are investigated theoretically. It is found that when both the control and the probe fields are coupled to the same spatial cavity mode, their transverse mode profile affects the q...... the quantum memory efficiency in a non-trivial way. Under such conditions, the control-field parameters and crystal dimensions that maximize the memory efficiency are calculated....

  2. Spatial mode effects in a cavity EIT-based quantum memory with ion Coulomb crystals

    CERN Document Server

    Zangenberg, Kasper R; Drewsen, Michael

    2012-01-01

    Quantum storage and retrieval of light in ion Coulomb crystals using cavity electromagnetically induced transparency is investigated theoretically. It is found that, when both the control and probe fields are coupled to the same cavity mode, their transverse mode profile affects the quantum memory efficiency in a non-trivial way. Under such conditions the control field parameters and crystal dimensions that maximize the memory efficiency are calculated.

  3. Quantum Photonic in Hybrid Cavity Systems with Strong Matter-Light Couplings

    Science.gov (United States)

    2015-08-24

    AFRL-AFOSR-VA-TR-2015-0246 Quantum Photonic in Hybrid Cavity Systems with Strong Matter-Light Couplings Hui Deng UNIVERSITY OF MICHIGAN Final Report...TITLE AND SUBTITLE Quantum Photonic in Hybrid Cavity Systems with Strong Matter-Light Couplings 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-12-1-0256... photons was demonstrated in the designable microcavity structure for the first time, establishing a robust light-matter hybrid states with designable

  4. A Scheme for Atomic Entangled States and Quantum Gate Operations in Cavity QED

    Institute of Scientific and Technical Information of China (English)

    LI Peng-Bo; GU Ying; GONG Qi-Huang; GUO Guang-Can

    2009-01-01

    We propose a scheme for controllably entangling the ground states of five-state W-type atoms confined in a cavity and realizing swap gate and phase gate operations.In this scheme the cavity is only virtually excited and the atomic excited states are almost not occupied,so the produced entangled states and quantum logic operations are very robust against the cavity decay and atomic spontaneous emission.

  5. Quantum atomic lithography via cross-cavity optical Stern-Gerlach setup

    Science.gov (United States)

    Máximo, C. E.; Batalhão, T. B.; Bachelard, R.; de Moraes Neto, G. D.; de Ponte, M. A.; Moussa, M. H. Y.

    2014-10-01

    We present a fully quantum scheme to perform 2D atomic lithography based on a cross-cavity optical Stern-Gerlach setup: an array of two mutually orthogonal cavities crossed by an atomic beam perpendicular to their optical axes, which is made to interact with two identical modes. After deriving an analytical solution for the atomic momentum distribution, we introduce a protocol allowing us to control the atomic deflection by manipulating the amplitudes and phases of the cavity field states.

  6. Quantum state engineering in a cavity by Stark chirped rapid adiabatic passage

    CERN Document Server

    Amniat-Talab, M; Guérin, S

    2006-01-01

    We propose a robust scheme to generate single-photon Fock states and atom-photon and atom-atom entanglement in atom-cavity systems. We also present a scheme for quantum networking between two cavity nodes using an atomic channel. The mechanism is based on Stark-chirped rapid adiabatic passage (SCRAP) and half-SCRAP processes in a microwave cavity. The engineering of these states depends on the design of the adiabatic dynamics through the static and dynamic Stark shifts.

  7. Efficient scheme for preparation of the multi-atom W state via cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Zhang Jin; Ye Liu

    2004-01-01

    We present an efficient scheme for preparation of the multi-atom W state via cavity quantum electrodynamics.Involved in this scheme are n identical two-level atoms and a single-mode cavity field. Discussion indicates that this scheme can be realized easily by current technologies.

  8. Generation of Entangled States of Multiple Superconducting Quantum Interference Devices in Cavity

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    We propose a scheme for generating the maximally entangled states of many superconducting quantum interference devices (SQUIDs) by using a quantized cavity field and classicalmicrowave pulses in cavity. In the scheme,the maximally entangled states can be generated without requiring the measurement and individual addressing of the SQUIDs.

  9. Proposed Coupling of an Electron Spin in a Semiconductor Quantum Dot to a Nanosize Optical Cavity

    DEFF Research Database (Denmark)

    Majumdar, Arka; Nielsen, Per Kær; Bajcsy, Michal

    2013-01-01

    We propose a scheme to efficiently couple a single quantum dot electron spin to an optical nano-cavity, which enables us to simultaneously benefit from a cavity as an efficient photonic interface, as well as to perform high fidelity (nearly 100%) spin initialization and manipulation achievable in...

  10. Reducing dephasing in coupled quantum dot-cavity systems by engineering the carrier wavefunctions

    DEFF Research Database (Denmark)

    Nysteen, Anders; Nielsen, Per Kær; Mørk, Jesper

    2012-01-01

    We demonstrate theoretically how photon-assisted dephasing by the electron-phonon interaction in a coupled cavity-quantum dot system can be significantly reduced for specific QD-cavity detunings. Our starting point is a recently published theory,1 which considers longitudinal acoustic phonons, de...

  11. Preparation of W state in resonant bimodal cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A scheme is proposed for generating entangled W states with four cavity modes. In this scheme, we send a Ⅴ-type three-level atom through two identical two-mode cavities in succession. After the atom exits from the second cavity,the four cavity modes are prepared in the W state. On the other hand we can obtain three-atom W states by sending three Ⅴ-type three-level atoms through a two-mode cavity in turn. The present scheme does not require conditional measurement, and it is easily generalized to preparing 2n-mode W states and n-atom W states.

  12. Vacuum Rabi splitting in a plasmonic cavity at the single quantum emitter limit

    CERN Document Server

    Santhosh, Kotni; Chuntonov, Lev; Haran, Gilad

    2015-01-01

    The strong interaction of individual quantum emitters with resonant cavities is of fundamental interest for understanding light matter interactions, as well as for quantum information processing and quantum communication applications. Plasmonic cavities hold the promise of attaining the strong coupling regime even under ambient conditions and within subdiffraction volumes. Recent experiments revealed strong coupling between individual plasmonic structures and multiple organic molecules, but so far strong coupling at the limit of a single quantum emitter has not been reported. Here we demonstrate vacuum Rabi splitting, a manifestation of strong coupling, using silver bowtie plasmonic cavities loaded with semiconductor quantum dots (QDs). A transparency dip is observed in the scattering spectra of individual bowties with one to a few QDs in their gaps. Rabi splitting values as high as 180 meV are registered with a single QD. These observations are verified by polarization-dependent experiments and validated by ...

  13. An integrated quantum repeater at telecom wavelength with single atoms in optical fiber cavities

    Science.gov (United States)

    Uphoff, Manuel; Brekenfeld, Manuel; Rempe, Gerhard; Ritter, Stephan

    2016-03-01

    Quantum repeaters promise to enable quantum networks over global distances by circumventing the exponential decrease in success probability inherent in direct photon transmission. We propose a realistic, functionally integrated quantum-repeater implementation based on single atoms in optical cavities. Entanglement is directly generated between the single-atom quantum memory and a photon at telecom wavelength. The latter is collected with high efficiency and adjustable temporal and spectral properties into a spatially well-defined cavity mode. It is heralded by a near-infrared photon emitted from a second, orthogonal cavity. Entanglement between two remote quantum memories can be generated via an optical Bell-state measurement, while we propose entanglement swapping based on a highly efficient, cavity-assisted atom-atom gate. Our quantum-repeater scheme eliminates any requirement for wavelength conversion such that only a single system is needed at each node. We investigate a particular implementation with rubidium and realistic parameters for Fabry-Perot cavities based on hbox {CO}_2 laser-machined optical fibers. We show that the scheme enables the implementation of a rather simple quantum repeater that outperforms direct entanglement generation over large distances and does not require any improvements in technology beyond the state of the art.

  14. Above room temperature continuous wave operation of a broad-area quantum-cascade laser

    Science.gov (United States)

    Semtsiv, M. P.; Masselink, W. T.

    2016-11-01

    We describe the design and implementation of a broad-area (w ≈ 30 μm) quantum-cascade laser operating in a continuous wave mode up to heat-sink temperatures beyond +100 °C. The room-temperature emission wavelength is 4.6 μm. The temperature gradient in the active region of such a wide laser stripe is essentially perpendicular to the epitaxial layers and the resulting steady-state active region temperature offset scales approximately with the square of the number of cascades. With only 10 cascades in the active region, the threshold electrical power density in the current quantum-cascade laser in the continuous-wave mode is as low as Vth × Ith = 3.8 V × 0.9 kA/cm2 = 3.4 kW/cm2 at room temperature for 2 mm-long two-side high-reflectivity coated laser stripe. A 4 mm-long one-side high-reflectivity coated laser stripe delivers in continuous-wave mode above 0.6 W at +20 °C and above 1.3 W at -27 °C (cooled with a single-stage Peltier element). A 2 mm-long two-side high-reflectivity coated laser stripe demonstrates continuous-wave lasing up to at least +102 °C (375 K). The thermal conductance, Gth, ranges between 235 W/K cm2 and 140 W/K cm2 for temperatures between -33 °C and +102 °C. This demonstration opens the route for continuous-wave power scaling of quantum-cascade lasers via broad-area laser ridges.

  15. Cavity Quantum Electrodynamics: The Strange Theory of Light in a Box

    Science.gov (United States)

    Dutra, Sergio M.

    2004-12-01

    What happens to light when it is trapped in a box? Cavity Quantum Electrodynamics addresses a fascinating question in physics: what happens to light, and in particular to its interaction with matter, when it is trapped inside a box? With the aid of a model-building approach, readers discover the answer to this question and come to appreciate its important applications in computing, cryptography, quantum teleportation, and opto-electronics. Instead of taking a traditional approach that requires readers to first master a series of seemingly unconnected mathematical techniques, this book engages the readers' interest and imagination by going straight to the point, introducing the mathematics along the way as needed. Appendices are provided for the additional mathematical theory. Researchers, scientists, and students of modern physics can refer to Cavity Quantum Electrodynamics and examine the field thoroughly. Several key topics covered that readers cannot find in any other quantum optics book include: * Introduction to the problem of the "vacuum catastrophe" and the cosmological constant * Detailed up-to-date account of cavity QED lasers and thresholdless lasing * Examination of cavities with movable walls * First-principles discussion about cavity QED in open cavities * Pedagogical account of microscopic quantization in dielectrics Complementing the coverage of the most advanced theory and techniques, the author provides context by discussing the historical evolution of the field and its discoveries. In that spirit, "recommended reading," provided in each chapter, leads readers to both contemporary literature as well as key historical papers. Despite being one of many specialties within physics, cavity quantum electrodynamics serves as a window to many of the fundamental issues of physics. Cavity Quantum Electrodynamics will serve as an excellent resource for advanced undergraduate quantum mechanics courses as well as for graduate students, researchers, and

  16. Self-formed cavity quantum electrodynamics in coupled dipole cylindrical-waveguide systems.

    Science.gov (United States)

    Afshar V, S; Henderson, M R; Greentree, A D; Gibson, B C; Monro, T M

    2014-05-01

    An ideal optical cavity operates by confining light in all three dimensions. We show that a cylindrical waveguide can provide the longitudinal confinement required to form a two dimensional cavity, described here as a self-formed cavity, by locating a dipole, directed along the waveguide, on the interface of the waveguide. The cavity resonance modes lead to peaks in the radiation of the dipole-waveguide system that have no contribution due to the skew rays that exist in longitudinally invariant waveguides and reduce their Q-factor. Using a theoretical model, we evaluate the Q-factor and modal volume of the cavity formed by a dipole-cylindrical-waveguide system and show that such a cavity allows access to both the strong and weak coupling regimes of cavity quantum electrodynamics.

  17. Far-infrared quantum cascade lasers operating in AlAs phonon Reststrahlen band

    CERN Document Server

    Ohtani, K; Süess, M J; Faist, J; Andrews, A M; Zederbauer, T; Detz, H; Schrenk, W; Strasser, G

    2016-01-01

    We report on the operation of a double metal waveguide far-infrared quantum cascade laser emitting at 28 $\\mu$m, corresponding to the AlAs-like phonon Reststrahlen band. To avoid absorption by AlAs-like optical phonons, the Al-free group-V alloy GaAs$_{0.51}$Sb$_{0.49}$ is used as a barrier layer in the bound-to-continuum based active region. Lasing occurs at a wavelength of 28.3 $\\mu$m, which is the longest wavelength among the quantum cascade lasers operating from mid-infrared to far-infrared. The threshold current density at 50 K is 5.5 kA/cm$^{2}$ and maximum operation temperature is 175 K. We also discuss the feasibility that operation wavelength cover the whole spectral range bridging between mid-infrared and terahertz by choosing suited group III-V materials.

  18. Origin of the inverse energy cascade in two-dimensional quantum turbulence

    CERN Document Server

    Skaugen, Audun

    2016-01-01

    We unravel the intimate connection between fundamental characteristics of two dimensional turbulence, i.e. the large-scale coherent structures and the inverse energy cascade. We propose a driven, dissipative point vortex model that is able to capture the dynamics of two-dimensional quantum turbulence by the emergent clustering of same-sign vortices, which form a non-equilibrium analogue of Onsager vortex equilibria. The inverse energy cascade developing in a statistically neutral system originates from this clustering of co-rotating and counter-rotating vortices. The Kolmogorov energy spectrum $k^{-5/3}$ is attributed to the scale-free correlations in the vorticity field fluctuations, here measured by the weighted pair correlation function that has a power-law decay as $r^{-4/3}$ on inertial separation lengthscales $r$. This scale-invariant statistics of vorticity, attributed to a conformal symmetry of two-dimensional classical turbulence, draws further analogies between classical and quantum turbulence beyon...

  19. A Sulfur Hexafluoride Sensor Using Quantum Cascade and CO2 Laser-Based Photoacoustic Spectroscopy

    Directory of Open Access Journals (Sweden)

    Helion Vargas

    2010-10-01

    Full Text Available The increase in greenhouse gas emissions is a serious environmental problem and has stimulated the scientific community to pay attention to the need for detection and monitoring of gases released into the atmosphere. In this regard, the development of sensitive and selective gas sensors has been the subject of several research programs. An important greenhouse gas is sulphur hexafluoride, an almost non-reactive gas widely employed in industrial processes worldwide. Indeed it is estimated that it has a radiative forcing of 0.52 W/m2. This work compares two photoacoustic spectrometers, one coupled to a CO2 laser and another one coupled to a Quantum Cascade (QC laser, for the detection of SF6. The laser photoacoustic spectrometers described in this work have been developed for gas detection at small concentrations. Detection limits of 20 ppbv for CO2 laser and 50 ppbv for quantum cascade laser were obtained.

  20. Exploring negative refraction conditions for quantum cascade semiconductor metamaterials in the terahertz spectral range

    Science.gov (United States)

    Daničić, A.; Radovanović, J.; Ramović, S.; Milanović, V.

    2016-03-01

    In order to avoid losses in metamaterial unit cells at frequencies of interest, caused by metallic inclusions, an active medium design has been proposed. As candidate structures for this active medium, we have chosen quantum cascade lasers because of their high output gain. Here we analyze and compare two quantum cascade structures that emit at 4.6 THz and 3.9 THz, respectively, placed under the influence of a strong magnetic field. We first solve the full system of rate equations for all relevant Landau levels, and obtain the necessary information about carrier distribution among the levels, after which we are able to evaluate the permittivity component along the growth direction of the structure. With these data one can determine the conditions under which negative refraction occurs, and calculate the values of the refractive index of the structure, as well as the range of frequencies at which the structure exhibits negative refraction for a predefined total electron sheet density.

  1. Strong coupling and stimulated emission in single parabolic quantum well microcavity for terahertz cascade

    Energy Technology Data Exchange (ETDEWEB)

    Tzimis, A.; Savvidis, P. G. [Department of Materials Science and Technology, University of Crete, 71003 Heraklion, Crete (Greece); Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, 71110 Heraklion, Crete (Greece); Trifonov, A. V.; Ignatiev, I. V. [Spin Optics Laboratory, State University of Saint-Petersburg, 1 Ulianovskaya, 198504 St. Petersburg (Russian Federation); Christmann, G.; Tsintzos, S. I. [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, 71110 Heraklion, Crete (Greece); Hatzopoulos, Z. [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, 71110 Heraklion, Crete (Greece); Department of Physics, University of Crete, 71003 Heraklion, Crete (Greece); Kavokin, A. V. [Spin Optics Laboratory, State University of Saint-Petersburg, 1 Ulianovskaya, 198504 St. Petersburg (Russian Federation); School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)

    2015-09-07

    We report observation of strong light-matter coupling in an AlGaAs microcavity (MC) with an embedded single parabolic quantum well. The parabolic potential is achieved by varying aluminum concentration along the growth direction providing equally spaced energy levels, as confirmed by Brewster angle reflectivity from a reference sample without MC. It acts as an active region of the structure which potentially allows cascaded emission of terahertz (THz) light. Spectrally and time resolved pump-probe spectroscopy reveals characteristic quantum beats whose frequencies range from 0.9 to 4.5 THz, corresponding to energy separation between relevant excitonic levels. The structure exhibits strong stimulated nonlinear emission with simultaneous transition to weak coupling regime. The present study highlights the potential of such devices for creating cascaded relaxation of bosons, which could be utilized for THz emission.

  2. Spectral gain profile of a multi-stack terahertz quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Bachmann, D., E-mail: dominic.bachmann@tuwien.ac.at; Deutsch, C.; Krall, M.; Unterrainer, K.; Darmo, J. [Photonics Institute, Vienna University of Technology, Gußhausstraße 27-29, 1040 Vienna (Austria); Center for Micro- and Nanostructures, Vienna University of Technology, Floragasse 7, 1040 Vienna (Austria); Rösch, M.; Scalari, G.; Beck, M.; Faist, J. [Institute for Quantum Electronics, ETH Zürich, Auguste-Piccard-Hof 1, 8093 Zürich (Switzerland)

    2014-11-03

    The spectral gain of a multi-stack terahertz quantum cascade laser, composed of three active regions with emission frequencies centered at 2.3, 2.7, and 3.0 THz, is studied as a function of driving current and temperature using terahertz time-domain spectroscopy. The optical gain associated with the particular quantum cascade stacks clamps at different driving currents and saturates to different values. We attribute these observations to varying pumping efficiencies of the respective upper laser states and to frequency dependent optical losses. The multi-stack active region exhibits a spectral gain full width at half-maximum of 1.1 THz. Bandwidth and spectral position of the measured gain match with the broadband laser emission. As the laser action ceases with increasing operating temperature, the gain at the dominant lasing frequency of 2.65 THz degrades sharply.

  3. Mode-resolved Photon Counting via Cascaded Quantum Frequency Conversion

    CERN Document Server

    Huang, Yu-Ping

    2012-01-01

    Resources for the manipulation and measurements of high-dimensional photonic signals are crucial for implementing qu$d$it-based applications. Here we propose potentially high-performance, chip-compatible devices for such purposes by exploiting quantum-frequency conversion in nonlinear optical media. Specifically, by using sum-frequency generation in a $\\chi^{(2)}$ waveguide we show how mode-resolved photon counting can be accomplished for telecom-band photonic signals subtending multiple temporal modes. Our method is generally applicable to any nonlinear medium with arbitrary dispersion property.

  4. Porous waveguide facilitated low divergence quantum cascade laser*

    Institute of Scientific and Technical Information of China (English)

    Yin Wen; Lu Quanyong; Liu Wannfeng; Zhang Jinchuan; Wang Lijun; Liu Junqi; Li Lu; Liu Fengqi; Wang Zhanguo

    2011-01-01

    A quantum cscade laser with a porous waveguide structure emitting at 4.5 μm is reported. A branchlike porous structure filled with metal material was fabricated on both sides of the laser ridge by an electrochemical etching process. In contrast to the common ridge waveguide laser, devices with a porous structure give rather better beam quality. Utilizing this porous structure as a high-order mode absorber, the device exhibited fundamental transverse mode emission with a nearly diffraction limited far-field beam divergence angle of 4.9°.

  5. Terahertz inverse synthetic aperture radar imaging using self-mixing interferometry with a quantum cascade laser.

    Science.gov (United States)

    Lui, H S; Taimre, T; Bertling, K; Lim, Y L; Dean, P; Khanna, S P; Lachab, M; Valavanis, A; Indjin, D; Linfield, E H; Davies, A G; Rakić, A D

    2014-05-01

    We propose a terahertz (THz)-frequency synthetic aperture radar imaging technique based on self-mixing (SM) interferometry, using a quantum cascade laser. A signal processing method is employed which extracts and exploits the radar-related information contained in the SM signals, enabling the creation of THz images with improved spatial resolution. We demonstrate this by imaging a standard resolution test target, achieving resolution beyond the diffraction limit.

  6. Entangled photon pairs from a quantum dot cascade decay: the effect of time-reordering

    OpenAIRE

    F. Troiani; Tejedor, C.

    2008-01-01

    Coulomb interactions between confined carriers remove degeneracies in the excitation spectra of quantum dots. This provides a which path information in the cascade decay of biexcitons, thus spoiling the energy-polarization entanglement of the emitted photon pairs. We theoretically analyze a strategy of color coincidence across generation (AG), recently proposed as an alternative to the previous, within generation (WG) approach. We simulate the system dynamics and compute the correlation funct...

  7. Effects of quantum interference in spectra of cascade spontaneous emission from multilevel systems

    Science.gov (United States)

    Makarov, A. A.; Yudson, V. I.

    2016-12-01

    A general expression for the spectrum of cascade spontaneous emission from an arbitrary multilevel system is presented. Effects of the quantum interference of photons emitted in different transitions are analyzed. These effects are especially essential when the transition frequencies are close. Several examples are considered: (i) Three-level system; (ii) Harmonic oscillator; (iii) System with equidistant levels and equal rates of the spontaneous decay for all the transitions; (iv) Dicke superradiance model.

  8. Infrared absorption nano-spectroscopy using sample photoexpansion induced by tunable quantum cascade lasers.

    Science.gov (United States)

    Lu, Feng; Belkin, Mikhail A

    2011-10-10

    We report a simple technique that allows obtaining mid-infrared absorption spectra with nanoscale spatial resolution under low-power illumination from tunable quantum cascade lasers. Light absorption is detected by measuring associated sample thermal expansion with an atomic force microscope. To detect minute thermal expansion we tune the repetition frequency of laser pulses in resonance with the mechanical frequency of the atomic force microscope cantilever. Spatial resolution of better than 50 nm is experimentally demonstrated.

  9. Cavity-mediated coupling of mechanical oscillators limited by quantum backaction

    CERN Document Server

    Spethmann, Nicolas; Schreppler, Sydney; Buchmann, Lukas; Stamper-Kurn, Dan M

    2015-01-01

    A complex quantum system can be constructed by coupling simple quantum elements to one another. For example, trapped-ion or superconducting quantum bits may be coupled by Coulomb interactions, mediated by the exchange of virtual photons. Alternatively quantum objects can be coupled by the exchange of real photons, particularly when driven within resonators that amplify interactions with a single electro-magnetic mode. However, in such an open system, the capacity of a coupling channel to convey quantum information or generate entanglement may be compromised. Here, we realize phase-coherent interactions between two spatially separated, near-ground-state mechanical oscillators within a driven optical cavity. We observe also the noise imparted by the optical coupling, which results in correlated mechanical fluctuations of the two oscillators. Achieving the quantum backaction dominated regime opens the door to numerous applications of cavity optomechanics with a complex mechanical system. Our results thereby illu...

  10. Virtual-photon-induced quantum phase gates for two distant atoms trapped in separate cavities

    CERN Document Server

    Zheng, Shi-Biao

    2012-01-01

    We propose a scheme for implementing quantum gates for two atoms trapped in distant cavities connected by an optical fiber. The effective long-distance coupling between the two distributed qubits is achieved without excitation and transportation of photons through the optical fiber. Since the cavity modes and fiber mode are never populated and the atoms undergo no transitions, the gate operation is insensitive to the decoherence effect when the thermal photons in the environment are negligible. The scheme opens promising perspectives for networking quantum information processors and implementing distributed and scalable quantum computation.

  11. Controlled phase gates based on two nonidentical quantum dots trapped in separate cavities

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Xia; Zhang Jian-Qi; Yu Ya-Fei; Zhang Zhi-Ming

    2011-01-01

    We propose a scheme for realizing two-qubit controlled phase gates on two nonidentical quantum dots trapped in separate cavities.In our scheme,each dot simultaneously interacts with one highly detuned cavity mode and two strong driven classical fields.During the gate operation,the quantum dots undergo no transition,while the system can acquire different phases conditional on different states of the quantum dots.With the application of the single-qubit operations,two-qubit controlled phase gates can be realized.

  12. Long-range energy transfer in self-assembled quantum dot-DNA cascades

    Science.gov (United States)

    Goodman, Samuel M.; Siu, Albert; Singh, Vivek; Nagpal, Prashant

    2015-11-01

    The size-dependent energy bandgaps of semiconductor nanocrystals or quantum dots (QDs) can be utilized in converting broadband incident radiation efficiently into electric current by cascade energy transfer (ET) between layers of different sized quantum dots, followed by charge dissociation and transport in the bottom layer. Self-assembling such cascade structures with angstrom-scale spatial precision is important for building realistic devices, and DNA-based QD self-assembly can provide an important alternative. Here we show long-range Dexter energy transfer in QD-DNA self-assembled single constructs and ensemble devices. Using photoluminescence, scanning tunneling spectroscopy, current-sensing AFM measurements in single QD-DNA cascade constructs, and temperature-dependent ensemble devices using TiO2 nanotubes, we show that Dexter energy transfer, likely mediated by the exciton-shelves formed in these QD-DNA self-assembled structures, can be used for efficient transport of energy across QD-DNA thin films.The size-dependent energy bandgaps of semiconductor nanocrystals or quantum dots (QDs) can be utilized in converting broadband incident radiation efficiently into electric current by cascade energy transfer (ET) between layers of different sized quantum dots, followed by charge dissociation and transport in the bottom layer. Self-assembling such cascade structures with angstrom-scale spatial precision is important for building realistic devices, and DNA-based QD self-assembly can provide an important alternative. Here we show long-range Dexter energy transfer in QD-DNA self-assembled single constructs and ensemble devices. Using photoluminescence, scanning tunneling spectroscopy, current-sensing AFM measurements in single QD-DNA cascade constructs, and temperature-dependent ensemble devices using TiO2 nanotubes, we show that Dexter energy transfer, likely mediated by the exciton-shelves formed in these QD-DNA self-assembled structures, can be used for efficient

  13. Distinctive signature of indium gallium nitride quantum dot lasing in microdisk cavities.

    Science.gov (United States)

    Woolf, Alexander; Puchtler, Tim; Aharonovich, Igor; Zhu, Tongtong; Niu, Nan; Wang, Danqing; Oliver, Rachel; Hu, Evelyn L

    2014-09-30

    Low-threshold lasers realized within compact, high-quality optical cavities enable a variety of nanophotonics applications. Gallium nitride materials containing indium gallium nitride (InGaN) quantum dots and quantum wells offer an outstanding platform to study light-matter interactions and realize practical devices such as efficient light-emitting diodes and nanolasers. Despite progress in the growth and characterization of InGaN quantum dots, their advantages as the gain medium in low-threshold lasers have not been clearly demonstrated. This work seeks to better understand the reasons for these limitations by focusing on the simpler, limited-mode microdisk cavities, and by carrying out comparisons of lasing dynamics in those cavities using varying gain media including InGaN quantum wells, fragmented quantum wells, and a combination of fragmented quantum wells with quantum dots. For each gain medium, we use the distinctive, high-quality (Q ∼ 5,500) modes of the cavities, and the change in the highest-intensity mode as a function of pump power to better understand the dominant radiative processes. The variations of threshold power and lasing wavelength as a function of gain medium help us identify the possible limitations to lower-threshold lasing with quantum dot active medium. In addition, we have identified a distinctive lasing signature for quantum dot materials, which consistently lase at wavelengths shorter than the peak of the room temperature gain emission. These findings not only provide better understanding of lasing in nitride-based quantum dot cavity systems but also shed insight into the more fundamental issues of light-matter coupling in such systems.

  14. Theory of quantum light emission from a strongly-coupled single quantum dot photonic-crystal cavity system.

    Science.gov (United States)

    Hughes, Stephen; Yao, P

    2009-03-02

    We present a rigorous medium-dependent theory for describing the quantum field emitted and detected from a single quantum dot exciton, strongly coupled to a planar photonic crystal nanocavity, from which the exact spectrum is derived. By using simple mode decomposition techniques, this exact spectrum is subsequently reduced to two separate user-friendly forms, in terms of the leaky cavity mode emission and the radiation mode emission. On application to study exciton-cavity coupling in the strong coupling regime, besides a pronounced modification of the usual vacuum Rabi spectral doublet, we predict several new effects associated with the leaky cavity mode emission, including the appearance of an off-resonance cavity mode and a loss-induced on-resonance spectral triplet. The cavity mode emission is shown to completely dominate the emitted spectrum, even for large cavity-exciton detunings, whereby the usual cavity-QED formulas developed for radiation-mode emission drastically fail. These predictions are in qualitative agreement with several "mystery observations" reported in recent experiments, and apply to a wide range of semiconductor cavities.

  15. Fano-resonance boosted cascaded field enhancement in a plasmonic nanoparticle-in-cavity nanoantenna array and its SERS application

    CERN Document Server

    Zhu, Zhendong; You, Oubo; Li, Qunqing; Fan, Shoushan

    2015-01-01

    Cascaded optical field enhancement (CFE) can be realized in some specially designed multiscale plasmonic nanostructures, where the generation of extremely strong field at nanoscale volume is crucial for many applications, for example, surface enhanced Raman spectroscopy (SERS). Here, we propose a strategy of realizing a high-quality plasmonic nanoparticle-in-cavity (PIC) nanoantenna array, where strong coupling between a nanoparticle dark mode with a high order nanocavity bright mode can produce Fano resonance at a target wavelength. The Fano resonance can effectively boost the CFE in the PIC, with a field enhancement factor up to 5X10^2. A cost-effective and reliable nanofabrication method is developed with room temperature nanoimprinting lithography to manufacture high-quality PIC arrays. This technique guarantees the generation of only one gold nanoparticle at the bottom of each nanocavity, which is crucial for the generation of the expected CFE. As a demonstration of the performance and application of the...

  16. Quantum-enhanced metrology with the single-mode coherent states of an optical cavity inside a quantum feedback loop

    Science.gov (United States)

    Clark, Lewis A.; Stokes, Adam; Beige, Almut

    2016-08-01

    In this paper, we use the nonlinear generator of dynamics of the individual quantum trajectories of an optical cavity inside an instantaneous quantum feedback loop to measure the phase shift between two pathways of light with a precision above the standard quantum limit. The feedback laser provides a reference frame and constantly increases the dependence of the state of the resonator on the unknown phase. Since our quantum metrology scheme can be implemented with current technology and does not require highly efficient single photon detectors, it should be of practical interest until highly entangled many-photon states become more readily available.

  17. Universal quantum gates for photon-atom hybrid systems assisted by bad cavities.

    Science.gov (United States)

    Wang, Guan-Yu; Liu, Qian; Wei, Hai-Rui; Li, Tao; Ai, Qing; Deng, Fu-Guo

    2016-01-01

    We present two deterministic schemes for constructing a CNOT gate and a Toffoli gate on photon-atom and photon-atom-atom hybrid quantum systems assisted by bad cavities, respectively. They are achieved by cavity-assisted photon scattering and work in the intermediate coupling region with bad cavities, which relaxes the difficulty of their implementation in experiment. Also, bad cavities are feasible for fast quantum operations and reading out information. Compared with previous works, our schemes do not need any auxiliary qubits and measurements. Moreover, the schematic setups for these gates are simple, especially that for our Toffoli gate as only a quarter wave packet is used to interact the photon with each of the atoms every time. These atom-cavity systems can be used as the quantum nodes in long-distance quantum communication as their relatively long coherence time is suitable for multi-time operations between the photon and the system. Our calculations show that the average fidelities and efficiencies of our two universal hybrid quantum gates are high with current experimental technology.

  18. Bloch-wave engineering of quantum dot micropillars for cavity quantum electrodynamics experiments.

    Science.gov (United States)

    Lermer, M; Gregersen, N; Dunzer, F; Reitzenstein, S; Höfling, S; Mørk, J; Worschech, L; Kamp, M; Forchel, A

    2012-02-01

    We have employed Bloch-wave engineering to realize submicron diameter high quality factor GaAs/AlAs micropillars (MPs). The design features a tapered cavity in which the fundamental Bloch mode is subject to an adiabatic transition to match the Bragg mirror Bloch mode. The resulting reduced scattering loss leads to record-high vacuum Rabi splitting of the strong coupling in MPs with modest oscillator strength quantum dots. A quality factor of 13, 600 and a splitting of 85  μeV with an estimated visibility v of 0.41 are observed for a small mode volume MP with a diameter d{c} of 850 nm.

  19. Enhancing Quantum Discord in Cavity QED by Applying Classical Driving Field

    Institute of Scientific and Technical Information of China (English)

    QIAN Yi; XU Jing-Bo

    2012-01-01

    We investigate the quantum discord dynamics in a cavity quantum electrodynamics system, which consists of two noninteracting two-level atoms driven by independent optical Gelds and classical fields, and find that the quantum discord vanishes only asymptotically although entanglement disappears suddenly during the time evolution in the absence of classical fields. It is shown that the amount of quantum discord can be increased by adjusting the classical driving fields because the increasing degree of the amount of quantum mutual information is greater than classical correlation by applying the classical driving fields. Finally, the influence of the classical driving field on the fidelity of the system is also examined.%We investigate the quantum discord dynamics in a cavity quantum electrodynamics system,which consists of two noninteracting two-level atoms driven by independent optical fields and classical fields,and find that the quantum discord vanishes only asymptotically although entanglement disappears suddenly during the time evolution in the absence of classical fields.It is shown that the amount of quantum discord can be increased by adjusting the classical driving fields because the increasing degree of the amount of quantum mutual information is greater than classical correlation by applying the classical driving fields.Finally,the influence of the classical driving field on the fidelity of the system is also examined.

  20. Quantum simulation of Dirac fermion mode, Majorana fermion mode and Majorana-Weyl fermion mode in cavity QED lattice

    OpenAIRE

    Sarkar, Sujit

    2014-01-01

    Quantum simulation aims to simulate a quantum system using a controble laboratory system that underline the same mathematical model. Cavity QED lattice system is that prescribe system to simulate the relativistic quantum effect. We quantum simulate the Dirac fermion mode, Majorana fermion mode and Majorana-Weyl fermion mode and a crossover between them in cavity QED lattice. We also present the different analytical relations between the field operators for different mode excitations.

  1. Long-distance quantum state transfer through cavity-assisted interaction

    Institute of Scientific and Technical Information of China (English)

    Li Yu-Ning; Mei Feng; Yu Ya-Fei; and Zhang Zhi-Ming

    2011-01-01

    We propose a scheme for long-distance quantum state transfer between different atoms based on cavity-assisted interactions.In our scheme,a coherent optical pulse sequentially interacts with two distant atoms trapped in separated cavities. Through the measurement of the state of the first atom and the homodyne detection of the final output coherent light,the quantum state can be transferred into the second atom with a success probability of unity and a fidelity of unity.In addition,our scheme neither requires the high-Q cavity working in the strong coupling regime nor employs the single-photon quantum channel,which greatly relaxes the experimental requirements.

  2. Vacuum Rabi splitting in a plasmonic cavity at the single quantum emitter limit.

    Science.gov (United States)

    Santhosh, Kotni; Bitton, Ora; Chuntonov, Lev; Haran, Gilad

    2016-06-13

    The strong interaction of individual quantum emitters with resonant cavities is of fundamental interest for understanding light-matter interactions. Plasmonic cavities hold the promise of attaining the strong coupling regime even under ambient conditions and within subdiffraction volumes. Recent experiments revealed strong coupling between individual plasmonic structures and multiple organic molecules; however, strong coupling at the limit of a single quantum emitter has not been reported so far. Here we demonstrate vacuum Rabi splitting, a manifestation of strong coupling, using silver bowtie plasmonic cavities loaded with semiconductor quantum dots (QDs). A transparency dip is observed in the scattering spectra of individual bowties with one to a few QDs, which are directly counted in their gaps. A coupling rate as high as 120 meV is registered even with a single QD, placing the bowtie-QD constructs close to the strong coupling regime. These observations are verified by polarization-dependent experiments and validated by electromagnetic calculations.

  3. Scheme for Remote Implementation of Partially Unknown Quantum Operation of Two Qubits in Cavity QED

    Institute of Scientific and Technical Information of China (English)

    QIU Liang; WANG An-Min

    2008-01-01

    By constructing the recovery operations of the protocol of remote implementation of partially unknown quantum operation of two qubits [An-Min Wang: Phys. Rev. A 74 (2006) 032317] with two-qubit Cnot gate and single qubit logic gates, we present a scheme to implement it in cavity QED. Long-lived Rydberg atoms are used as qubits, and the interaction between the atoms and the field of cavity is a nonresonant one. Finally, we analyze the experimental feasibility of this scheme.

  4. Scheme for implementing quantum dense coding with W-class state in cavity QED

    Institute of Scientific and Technical Information of China (English)

    He Juan; Ye Liu; Ni Zhi-Xiang

    2008-01-01

    An experimentally feasible protocol for realizing dense coding by using a class of W-state in cavity quantum electrodynamics (QED) is proposed in this paper.The prominent advantage of our scheme is that the succeasful probability of the dense coding with a W-class state can reach 1.In addition,the scheme can be implemented by the present cavity QED techniques.

  5. Low-threshold terahertz molecular laser optically pumped by a quantum cascade laser

    Directory of Open Access Journals (Sweden)

    A. Pagies

    2016-06-01

    Full Text Available We demonstrate a low-threshold, compact, room temperature, and continuous-wave terahertz molecular laser optically pumped by a mid-infrared quantum cascade laser. These characteristics are obtained, thanks to large dipole transitions of the active medium: NH3 (ammonia in gas state. The low-power (<60 mW laser pumping excites the molecules, thanks to intense mid-infrared transitions around 10.3 μm. The molecules de-excite by stimulated emission on pure inversion “umbrella-mode” quantum transitions allowed by the tunnel effect. The tunability of the quantum cascade laser gives access to several pure inversion transitions with different rotation states: we demonstrate the continuous-wave generation of ten laser lines around 1 THz. At 1.07 THz, we measure a power of 34 μW with a very low-threshold of 2 mW and a high differential efficiency of 0.82 mW/W. The spectrum was measured showing that the linewidth is lower than 1 MHz. To our knowledge, this is the first THz molecular laser pumped by a solid-state source and this result opens the way for compact, simple, and efficient THz source at room temperature for imaging applications.

  6. Propene concentration sensing for combustion gases using quantum-cascade laser absorption near 11 μm

    KAUST Repository

    Chrystie, Robin

    2015-05-29

    We report on a strategy to measure, in situ, the concentration of propene (C3H6) in combustion gases using laser absorption spectroscopy. Pyrolysis of n-butane was conducted in a shock tube, in which the resultant gases were probed using an extended cavity quantum-cascade laser. A differential absorption approach using online and offline wavelengths near λ = 10.9 μm enabled discrimination of propene, cancelling the effects of spectral interference from the simultaneous presence of intermediate hydrocarbon species during combustion. Such interference-free measurements were facilitated by exploiting the =C–H bending mode characteristic to alkenes (olefins). It was confirmed, for intermediate species present during pyrolysis of n-butane, that their absorption cross sections were the same magnitude for both online and offline wavelengths. Hence, this allowed time profiles of propene concentration to be measured during pyrolysis of n-butane in a shock tube. Time profiles of propene subsequent to a passing shock wave exhibit trends similar to that predicted by the well-established JetSurF 1.0 chemical kinetic mechanism, albeit lower by a factor of two. Such a laser diagnostic is a first step to experimentally determining propene in real time with sufficient time resolution, thus aiding the refinement and development of chemical kinetic models for combustion. © 2015 Springer-Verlag Berlin Heidelberg

  7. Probing organometallic reactions by time-resolved infrared spectroscopy in solution and in the solid state using quantum cascade lasers.

    Science.gov (United States)

    Calladine, James A; Horvath, Raphael; Davies, Andrew J; Wriglesworth, Alisdair; Sun, Xue-Zhong; George, Michael W

    2015-05-01

    The photochemistry and photophysics of metal carbonyl compounds (W(CO)6, Cp*Rh(CO)2 (Cp* = η(5)-C5Me5), and fac-[Re(CO)3(4,4'-bpy)2Br] [bpy = bipyridine]) have been examined on the nanosecond timescale using a time-resolved infrared spectrometer with an external cavity quantum cascade laser (QCL) as the infrared source. We show the photochemistry of W(CO)6 in alkane solution is easily monitored, and very sensitive measurements are possible with this approach, meaning it can monitor small transients with absorbance changes less than 10(-6) ΔOD. The C-H activation of Cp*Rh(CO)(C6H12) to form Cp*Rh(CO)(C6H11)H occurs within the first few tens of nanoseconds following photolysis, and we demonstrate that kinetics obtained following deconvolution are in excellent agreement with those measured using an ultrafast laser-based spectrometer. We also show that the high flux and tunability of QCLs makes them suited for solid-state and time-resolved measurements.

  8. Quantum phase gate based on electromagnetically induced transparency in optical cavities

    Science.gov (United States)

    Borges, Halyne S.; Villas-Bôas, Celso J.

    2016-11-01

    We theoretically investigate the implementation of a quantum controlled-phase gate in a system constituted by a single atom inside an optical cavity, based on the electromagnetically induced transparency effect. First we show that a probe pulse can experience a π phase shift due to the presence or absence of a classical control field. Considering the interplay of the cavity-EIT effect and the quantum memory process, we demonstrated a controlled-phase gate between two single photons. To this end, first one needs to store a (control) photon in the ground atomic states. In the following, a second (target) photon must impinge on the atom-cavity system. Depending on the atomic state, this second photon will be either transmitted or reflected, acquiring different phase shifts. This protocol can then be easily extended to multiphoton systems, i.e., keeping the control photon stored, it may induce phase shifts in several single photons, thus enabling the generation of multipartite entangled states. We explore the relevant parameter space in the atom-cavity system that allows the implementation of quantum controlled-phase gates using the recent technologies. In particular, we have found a lower bound for the cooperativity of the atom-cavity system which enables the implementation of phase shift on single photons. The induced shift on the phase of a photonic qubit and the controlled-phase gate between single photons, combined with optical devices, enable one to perform universal quantum computation.

  9. Temperature tunability of quantum emitter - cavity coupling in a photonic wire microcavity with shielded sidewall loss

    CERN Document Server

    Bernard, M

    2016-01-01

    Recent technological advancements have allowed to implement in solid-state cavity-based devices phenomena of quantum nature such as vacuum Rabi splitting, controllable single photon emission and quantum entanglement. For a sufficiently strong coupling between a quantum emitter and a cavity, large quality factors ($Q$) along with small modal volume ($V_{eff}$) are essential. Here we show that by applying a 5nm Al coating to the sidewalls of a submicrometer-sized Fabry-P\\'{e}rot microcavity, the cavity $Q$ can be temperature-tuned from few hundreds at room temperatures to 2$\\times$10$^5$ below 30~K. This is achieved by, first, a complete shielding of the sidewall loss with ideally reflecting lateral metallic mirrors and, secondly, a dramatic decrease of the cavity's axial loss for small-sized devices due to the largely off-axis wavevector within the multilayered structure. Our findings offer a novel temperature-tunable platform to study quantum electrodynamical phenomena of emitter-cavity coupling. We demonstra...

  10. Cavity quantum electrodynamics with Anderson-localized modes

    DEFF Research Database (Denmark)

    Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren;

    2010-01-01

    by a factor of 15 on resonance with the Anderson-localized mode, and 94% of the emitted single photons coupled to the mode. Disordered photonic media thus provide an efficient platform for quantum electrodynamics, offering an approach to inherently disorder-robust quantum information devices....

  11. Bloch Oscillations of Cold Atoms in a Cavity: Effects of Quantum Noise

    CERN Document Server

    Venkatesh, B Prasanna

    2013-01-01

    In this communication we extend our theory of Bloch oscillations of cold atoms inside an optical cavity [Venkatesh et al., Phys. Rev. A 80, 063834 (2009)] to include the effects of quantum noise. By solving the coupled dynamics of linearized fluctuations about the atomic and optical meanfields, we are able to include the effects of quantum measurement backaction upon the atoms and ultimately examine how this influences the signal-to-noise ratio of a measurement of external forces using this system. One of the hurdles we overcome along the way is the proper treatment of fluctuations about time-dependent meanfields in the cold atom cavity-QED context.

  12. Capture cavity cryomodule for quantum beam experiment at KEK superconducting RF test facility

    Science.gov (United States)

    Tsuchiya, K.; Hara, K.; Hayano, H.; Kako, E.; Kojima, Y.; Kondo, Y.; Nakai, H.; Noguchi, S.; Ohuchi, N.; Terashima, A.; Horikoshi, A.; Semba, T.

    2014-01-01

    A capture cavity cryomodule was fabricated and used in a beam line for quantum beam experiments at the Superconducting RF Test Facility (STF) of the High Energy Accelerator Research Organization in Japan. The cryomodule is about 4 m long and contains two nine-cell cavities. The cross section is almost the same as that of the STF cryomodules that were fabricated to develop superconducting RF cavities for the International Linear Collider. An attempt was made to reduce the large deflection of the helium gas return pipe (GRP) that was observed in the STF cryomodules during cool-down and warm-up. This paper briefly describes the structure and cryogenic performance of the captures cavity cryomodule, and also reports the measured displacement of the GRP and the cavity-containing helium vessels during regular operation.

  13. Capture cavity cryomodule for quantum beam experiment at KEK superconducting RF test facility

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, K.; Hara, K.; Hayano, H.; Kako, E.; Kojima, Y.; Kondo, Y.; Nakai, H.; Noguchi, S.; Ohuchi, N.; Terashima, A. [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801 (Japan); Horikoshi, A.; Semba, T. [Hitachi, Ltd., Hitachi Works, Hitachi, Ibaraki 317-8511 (Japan)

    2014-01-29

    A capture cavity cryomodule was fabricated and used in a beam line for quantum beam experiments at the Superconducting RF Test Facility (STF) of the High Energy Accelerator Research Organization in Japan. The cryomodule is about 4 m long and contains two nine-cell cavities. The cross section is almost the same as that of the STF cryomodules that were fabricated to develop superconducting RF cavities for the International Linear Collider. An attempt was made to reduce the large deflection of the helium gas return pipe (GRP) that was observed in the STF cryomodules during cool-down and warm-up. This paper briefly describes the structure and cryogenic performance of the captures cavity cryomodule, and also reports the measured displacement of the GRP and the cavity-containing helium vessels during regular operation.

  14. Quantum Nondemolition Measurement and Preparation of Fock States with Electromagnetically Induced Transparency in an Optical Cavity

    CERN Document Server

    Lin, G W; Huang, T; Lin, X M; Wang, Z Y; Gong, S Q

    2012-01-01

    We propose a technique for quantum nondemolition (QND) measurement and preparation of fock states by dynamics of electromagnetically induced transparency (EIT). An atomic medium trapped in an optical cavity is driven by two continuous-wave classical fields under steady-state EIT. The weak coherent fields are sequently injected into the cavity. During the process of photons passing through the cavity, a measurement on the changes of absorption loss of the probe field will be used for QND measurement of the small photon number, and thus create photon fock states, in particular single-photon states, in a heralded way.

  15. Implementation of quantum controlled phase gate and preparation of multiparticle entanglement in cavity QED

    Institute of Scientific and Technical Information of China (English)

    Wu Xi; Chen Zhi-Hua; Zhang Yong; Chen Yue-Hua; Ye Ming-Yong; Lin Xiu-Min

    2011-01-01

    Schemes are presented for realizing quantum controlled phase gate and preparing an N-qubit W-like state, which are based on the large-detuned interaction among three-state atoms, dual-mode cavity and a classical pulse. In particular, a class of W states that can be used for perfect teleportation and superdense coding is generated by only one step.Compared with the previous schemes, cavity decay is largely suppressed because the cavity is only virtually excited and always in the vacuum state and the atomic spontaneous emission is strongly restrained due to a large atom-field detuning.

  16. Cavity quantum electrodynamics with a Rydberg-blocked atomic ensemble

    DEFF Research Database (Denmark)

    Guerlin, Christine; Brion, Etienne; Esslinger, Tilman

    2010-01-01

    The realization of a Jaynes-Cummings model in the optical domain is proposed for an atomic ensemble. The scheme exploits the collective coupling of the atoms to a quantized cavity mode and the nonlinearity introduced by coupling to high-lying Rydberg states. A two-photon transition resonantly...... effective Jaynes-Cummings model. We use numerical simulations to show that the cavity transmission can be used to reveal detailed properties of the Jaynes-Cummings ladder of excited states and that the atomic nonlinearity gives rise to highly nontrivial photon emission from the cavity. Finally, we suggest...... couples the single-atom ground state |g> to a Rydberg state |e>via a nonresonant intermediate state |i>, but due to the interaction between Rydberg atoms only a single atom can be resonantly excited in the ensemble. This restricts the state space of the ensemble to the collective ground state |G...

  17. Cavity-Based Single-Atom Quantum Memory

    CERN Document Server

    Dilley, Jerome; Shore, Bruce W; Kuhn, Axel

    2011-01-01

    We show how to capture a single photon of arbitrary temporal shape with one atom coupled to an optical cavity. Our model applies to Raman transitions in three-level atoms with one branch of the transition controlled by a (classical) laser pulse, and the other coupled to the cavity. Photons impinging on the cavity normally exhibit partial reflection, transmission, and/or absorption by the atom. Only a control pulse of suitable temporal shape ensures impedance matching throughout the pulse, resulting in complete state mapping from photon to atom. For most possible photon shapes, we derive an unambiguous analytic expression for the temporal shape of the required control pulse. The process is subject to some inherent limitations, which we also discuss briefly.

  18. High Temperature Operation of 5.5μm Strain-Compensated Quantum Cascaded Lasers

    Institute of Scientific and Technical Information of China (English)

    LU Xiu-Zhen; LIU Feng-Qi; LIU Jun-Qi; JIN Peng; WANG Zhan-Guo

    2005-01-01

    @@ We develop 5.5-μm Inx Ga1-xAs/InyAl1-yAs strain-compensated quantum cascade lasers with InP and InGaAs cladding layers by using solid-source molecular-beam epitaxy. Pulse operation has been achieved up to 323K (50℃) for uncoated 20-μm-wide and 2-mm-long devices. These devices display an output power of 36mW with a duty cycle of 1% at room temperature. In continuous wave operation a record peak optical power of 10mW per facet has been measured at 83 K.

  19. Continuous wave operation of quantum cascade lasers with frequency-shifted feedback

    Energy Technology Data Exchange (ETDEWEB)

    Lyakh, A., E-mail: arkadiy.lyakh@ucf.edu [Pranalytica, Inc., 1101 Colorado Ave., Santa Monica, CA 90401 (United States); NanoScience Technology Center, University of Central Florida, 12424 Research Pkwy, Orlando, FL 32826 (United States); College of Optics and Photonics, University of Central Florida, 304 Scorpius St, Orlando, FL 32826 (United States); Barron-Jimenez, R.; Dunayevskiy, I.; Go, R.; Tsvid, G.; Patel, C. Kumar N., E-mail: patel@pranalytica.com [Pranalytica, Inc., 1101 Colorado Ave., Santa Monica, CA 90401 (United States)

    2016-01-15

    Operation of continuous wave quantum cascade lasers with a frequency-shifted feedback provided by an acousto-optic modulator is reported. Measured linewidth of 1.7 cm{sup −1} for these devices, under CW operating conditions, was in a good agreement with predictions of a model based on frequency-shifted feedback seeded by spontaneous emission. Linewidth broadening was observed for short sweep times, consistent with sound wave grating period variation across the illuminated area on the acousto-optic modulator. Standoff detection capability of the AOM-based QCL setup was demonstrated for several solid materials.

  20. High frequency modulation capabilities and quasi single-sideband emission from a quantum cascade laser.

    Science.gov (United States)

    Hangauer, Andreas; Spinner, Georg; Nikodem, Michal; Wysocki, Gerard

    2014-09-22

    Both intensity- (IM) and frequency-modulation (FM) behavior of a directly modulated quantum cascade laser (QCL) are measured from 300 Hz to 1.7 GHz. Quantitative measurements of tuning coefficients has been performed and the transition from thermal- to electronic-tuning is clearly observed. A very specific FM behavior of QCLs has been identified which allows for optical quasi single sideband (SSB) modulation through current injection and has not been observed in directly modulated semiconductor lasers before. This predestines QCLs in applications where SSB is required, such as telecommunication or high speed spectroscopy. The experimental procedure and theoretical modeling for data extraction is discussed.

  1. Rectified diode response of a multimode quantum cascade laser integrated terahertz transceiver

    CERN Document Server

    Dyer, Gregory C; Cich, Michael J; Grine, Albert D; Fuller, Charles T; Reno, John L; Wanke, Michael C

    2016-01-01

    We characterized the DC transport response of a diode embedded in a THz quantum cascade laser as the laser current was changed. The overall response is described by parallel contributions from the rectification of the laser field due to the non-linearity of the diode I-V and from thermally activated transport. Sudden jumps in the diode response when the laser changes from single mode to multi-mode operation, with no corresponding jumps in output power, suggest that the coupling between the diode and laser field depends on the spatial distribution of internal fields. The results demonstrate conclusively that the internal laser field couples directly to the integrated diode.

  2. Distributed feedback terahertz frequency quantum cascade lasers with dual periodicity gratings

    CERN Document Server

    Castellano, F; Li, L H; Pitanti, A; Tredicucci, A; Linfield, E H; Davies, A G; Vitiello, M S

    2016-01-01

    We have developed terahertz frequency quantum cascade lasers that exploit a double-periodicity distributed feedback grating to control the emission frequency and the output beam direction independently. The spatial refractive index modulation of the gratings necessary to provide optical feedback at a fixed frequency and, simultaneously, a far-field emission pattern centered at controlled angles, was designed through use of an appropriate wavevector scattering model. Single mode THz emission at angles tuned by design between 0{\\deg} and 50{\\deg} was realized, leading to an original phase-matching approach, lithographically independent, for highly collimated THz QCLs.

  3. Towards a compact THz local oscillator based on a quantum cascade laser

    OpenAIRE

    Richter, Heiko; Greiner-Bär, Michael; Pavlov, Sergey; Semenov, Alexei D.; Wienold, Martin; Schrottke, Lutz; Giehler, M.; Hey, R.; Grahn, H.T.; Huebers, H. -W.

    2010-01-01

    Heterodyne spectroscopy of molecular rotational lines and atomic fine-structure lines is a powerful tool in astronomy and planetary research. One example is the OI fine-structure line at 4.7 THz. This is a main target to be observed with GREAT, the German Receiver for Astronomy at Terahertz Frequencies, which will be operated on board of SOFIA. We report on the development of a compact, easy-to-use source, which combines a quantum-cascade laser (QCL) a compact, lowinput- power Stirling cooler...

  4. Extracting fundamental transverse mode operation in broad area quantum cascade lasers

    Science.gov (United States)

    Kaspi, R.; Luong, S.; Yang, C.; Lu, C.; Newell, T. C.; Bate, T.

    2016-11-01

    Power scaling in broad area quantum cascade lasers results in the operation of high order transverse modes with a far-field profile consisting of two lobes propagating at large angles relative to the optical axis. We report a method of suppressing the high order transverse modes that can extract the fundamental mode and provide emission along the optical axis. By generating a lateral constriction in the waveguide in the form of short trenches defined by the focused ion beam milling technique, we report broad area devices in which most of the power is contained in a near diffraction-limited beam that provides high brightness.

  5. Room-temperature operation of mid-infrared surface-plasmon quantum cascade lasers

    Science.gov (United States)

    Bahriz, M.; Moreau, V.; Palomo, J.; Krysa, A. B.; Austin, D.; Cockburn, J. W.; Roberts, J. S.; Wilson, L. R.; Julien, F.; Colombelli, R.

    2007-04-01

    We report the pulsed, room-temperature operation of an InGaAs/AllnAs quantum cascade laser at an operating wavelength of ≈ 7.5 μm in which the optical mode is a surface-plasmon polariton excitation. The use of a silver-based electrical contact with reduced optical losses at the laser emission wavelength allows for a reduction of the laser threshold current by a factor of two relative to samples with a gold-based contact layer.

  6. On-chip focusing in the mid-infrared: Demonstrated with ring quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Szedlak, Rolf, E-mail: rolf.szedlak@tuwien.ac.at; Schwarzer, Clemens; Zederbauer, Tobias; Detz, Hermann; Maxwell Andrews, Aaron; Schrenk, Werner; Strasser, Gottfried [Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, 1040 Vienna (Austria)

    2014-04-14

    We report on collimated emission beams from substrate emitting ring quantum cascade lasers with an on-chip focusing element fabricated into the bottom side of the device. It is formed by a gradient index metamaterial layer, realized by etching subwavelength holes into the substrate. The generated optical path length difference for rays emitted under different angles from the ring waveguide flattens the wavefront and focuses the light. Our far field measurements show an increased peak intensity corresponding to 617% of the initial value without the focusing element. Far field calculations, based on a Fourier transformation of the metamaterial area, are in good agreement with our experimental data.

  7. Real-time quantum cascade laser-based infrared microspectroscopy in-vivo

    Science.gov (United States)

    Kröger-Lui, N.; Haase, K.; Pucci, A.; Schönhals, A.; Petrich, W.

    2016-03-01

    Infrared microscopy can be performed to observe dynamic processes on a microscopic scale. Fourier-transform infrared spectroscopy-based microscopes are bound to limitations regarding time resolution, which hampers their potential for imaging fast moving systems. In this manuscript we present a quantum cascade laser-based infrared microscope which overcomes these limitations and readily achieves standard video frame rates. The capabilities of our setup are demonstrated by observing dynamical processes at their specific time scales: fermentation, slow moving Amoeba Proteus and fast moving Caenorhabditis elegans. Mid-infrared sampling rates between 30 min and 20 ms are demonstrated.

  8. Indirect absorption spectroscopy using quantum cascade lasers: mid-infrared refractometry and photothermal spectroscopy.

    Science.gov (United States)

    Pfeifer, Marcel; Ruf, Alexander; Fischer, Peer

    2013-11-04

    We record vibrational spectra with two indirect schemes that depend on the real part of the index of refraction: mid-infrared refractometry and photothermal spectroscopy. In the former, a quantum cascade laser (QCL) spot is imaged to determine the angles of total internal reflection, which yields the absorption line via a beam profile analysis. In the photothermal measurements, a tunable QCL excites vibrational resonances of a molecular monolayer, which heats the surrounding medium and changes its refractive index. This is observed with a probe laser in the visible. Sub-monolayer sensitivities are demonstrated.

  9. Monitoring Hydrogen Sulfide Using a Quantum Cascade Laser Based Trace Gas Sensing System

    Institute of Scientific and Technical Information of China (English)

    WANG Ling-Fang; SHARPLES Thomas-Roben

    2011-01-01

    @@ We present the detection of hydrogen sulfide (HS) in a quantum cascade laser (QCL) based gas sensing system employing direct laser absorption spectroscopy.The sensitivity is obtained to be 3.61 × 10 cm Hz and the HS broadening coefficient in N is analyzed by fitting to the plot of the Lorentzian half width at the half maximum as a function of N pressure is 0.1124±0.0031 cm.atm.A simulation based on data from the HITRAN database shows broad agreement with the experimentally obtained spectrum.

  10. Quantum Cascade Laser-Based Photoacoustic Sensor for Trace Detection of Formaldehyde Gas

    Directory of Open Access Journals (Sweden)

    Pietro Mario Lugarà

    2009-04-01

    Full Text Available We report on the development of a photoacoustic sensor for the detection of formaldehyde (CH2O using a thermoelectrically cooled distributed-feedback quantum cascade laser operating in pulsed mode at 5.6 mm. A resonant photoacoustic cell, equipped with four electret microphones, is excited in its first longitudinal mode at 1,380 Hz. The absorption line at 1,778.9 cm-1 is selected for CH2O detection. A detection limit of 150 parts per billion in volume in nitrogen is achieved using a 10 seconds time constant and 4 mW laser power. Measurements in ambient air will require water vapour filters.

  11. Hyperparallel optical quantum computation assisted by atomic ensembles embedded in double-sided optical cavities

    Science.gov (United States)

    Li, Tao; Long, Gui-Lu

    2016-08-01

    We propose an effective, scalable, hyperparallel photonic quantum computation scheme in which photonic qubits are hyperencoded both in the spatial degrees of freedom (DOF) and the polarization DOF of each photon. The deterministic hyper-controlled-not (hyper-cnot) gate on a two-photon system is attainable with our interesting interface between the polarized photon and the collective spin wave (magnon) of an atomic ensemble embedded in a double-sided optical cavity, and it doubles the operations in the conventional quantum cnot gate. Moreover, we present a compact hyper-cnotN gate on N +1 hyperencoded photons with only two auxiliary cavity-magnon systems, not more, and it can be faithfully constituted with current experimental techniques. Our proposal enables various applications with the hyperencoded photons in quantum computing and quantum networks.

  12. Epitaxial lift-off for solid-state cavity quantum electrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Greuter, Lukas; Najer, Daniel; Kuhlmann, Andreas V.; Starosielec, Sebastian; Warburton, Richard J. [Department of Physics, University of Basel, Klingelbergstrasse 82, Basel 4056 (Switzerland); Valentin, Sascha R.; Ludwig, Arne; Wieck, Andreas D. [Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany)

    2015-08-21

    We demonstrate an approach to incorporate self-assembled quantum dots into a Fabry-Pérot-like microcavity. Thereby, a 3λ/4 GaAs layer containing quantum dots is epitaxially removed and attached by van der Waals bonding to one of the microcavity mirrors. We reach a finesse as high as 4100 with this configuration limited by the reflectivity of the dielectric mirrors and not by scattering at the semiconductor-mirror interface, demonstrating that the epitaxial lift-off procedure is a promising procedure for cavity quantum electrodynamics in the solid state. As a first step in this direction, we demonstrate a clear cavity-quantum dot interaction in the weak coupling regime with a Purcell factor in the order of 3. Estimations of the coupling strength via the Purcell factor suggest that we are close to the strong coupling regime.

  13. Epitaxial lift-off for solid-state cavity quantum electrodynamics

    CERN Document Server

    Greuter, Lukas; Kuhlmann, Andreas V; Valentin, Sascha; Ludwig, Arne; Wieck, Andreas D; Starosielec, Sebastian; Warburton, Richard J

    2015-01-01

    We present a new approach to incorporate self-assembled quantum dots into a Fabry-P\\'{e}rot-like microcavity. Thereby a 3$\\lambda$/4 GaAs layer containing quantum dots is epitaxially removed and attached by van der Waals bonding to one of the microcavity mirrors. We reach a finesse as high as 4,100 with this configuration limited by the reflectivity of the dielectric mirrors and not by scattering at the semiconductor - mirror interface, demonstrating that the epitaxial lift-off procedure is a promising procedure for cavity quantum electrodynamics in the solid state. As a first step in this direction, we demonstrate a clear cavity-quantum dot interaction in the weak coupling regime with a Purcell factor in the order of 3. Estimations of the coupling strength via the Purcell factor suggests that we are close to the strong coupling regime.

  14. Dispersive readout of valley splittings in cavity-coupled silicon quantum dots

    Science.gov (United States)

    Burkard, Guido; Petta, J. R.

    2016-11-01

    The band structure of bulk silicon has a sixfold valley degeneracy. Strain in the Si/SiGe quantum well system partially lifts the valley degeneracy, but the materials factors that set the splitting of the two lowest lying valleys are still under intense investigation. Using cavity input-output theory, we propose a method for accurately determining the valley splitting in Si/SiGe double quantum dots embedded in a superconducting microwave resonator. We show that low lying valley states in the double quantum dot energy level spectrum lead to readily observable features in the cavity transmission. These features generate a "fingerprint" of the microscopic energy level structure of a semiconductor double quantum dot, providing useful information on valley splittings and intervalley coupling rates.

  15. A scheme for conditional quantum phase gate via bimodal cavity and a Λ-type three-level atom

    Institute of Scientific and Technical Information of China (English)

    Cai Jian-Wu; Fang Mao-Fa; Liao Xiang-Ping; Zheng Xiao-Juan

    2006-01-01

    We propose a scheme to implement a two-qubit conditional quantum phase gate for the intracavity field via a single three-level Λ-type atom driven by two modes in a high-Q cavity. The quantum information is encoded on the Fock states of the bimodal cavity. The gate's averaged fidelity is expected to reach 99.8%.

  16. PT-symmetric quantum oscillator in an optical cavity

    CERN Document Server

    Longhi, Stefano

    2016-01-01

    The quantum harmonic oscillator with parity-time ($\\mathcal{PT}$) symmetry, obtained from the ordinary (Hermitian) quantum harmonic oscillator by an imaginary displacement of the spatial coordinate, provides an important and exactly-solvable model to investigate non-Hermitian extension of the Ehrenfest theorem. Here it is shown that transverse light dynamics in an optical resonator with off-axis longitudinal pumping can emulate a $\\mathcal{PT}$-symmetric quantum harmonic oscillator, providing an experimentally accessible system to investigate non-Hermitian coherent state propagation.

  17. An Efficient Scheme for Implementing an N-Qubit Toffoli Gate with Superconducting Quantum-Interference Devices in Cavity QED

    Institute of Scientific and Technical Information of China (English)

    ZHENG An-Shou; LIU Ji-Bing; XIANG Dong; LIU Cui-Lan; YUAN Hong

    2007-01-01

    An alternative approach is proposed to realize an n-qubit Toffoli gate with superconducting quantum-interference devices (SQUIDs) in cavity quantum electrodynamics (QED). In the proposal, we represent two logical gates of a qubit with the two lowest levels of a SQUID while a higher-energy intermediate level of each SQUID is utilized for the gate manipulation. During the operating process, because the cavity field is always in vacuum state, the requirement on the cavity is greatly loosened and there is no transfer of quantum information between the cavity and SQUIDs.

  18. Holonomic quantum computation with superconducting charge-phase qubits in a cavity

    Energy Technology Data Exchange (ETDEWEB)

    Feng Zhibo [National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093 (China) and Institute for Condensed Matter Physics, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China)], E-mail: zbfeng010@163.com; Zhang Xinding [Institute for Condensed Matter Physics, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China)

    2008-03-03

    We theoretically propose a feasible scheme to realize holonomic quantum computation with charge-phase qubits placed in a microwave cavity. By appropriately adjusting the controllable parameters, each charge-phase qubit is set as an effective four-level subsystem, based on which a universal set of holonomic quantum gates can be realized. Further analysis shows that our system is robust to the first-order fluctuation of the gate charges, and the intrinsic leakages between energy levels can be ignored.

  19. Ultrafast photon-photon interaction in a strongly coupled quantum dot-cavity system

    CERN Document Server

    Englund, Dirk; Bajcsy, Michal; Faraon, Andrei; Petroff, Pierre; vuckovic, Jelena

    2011-01-01

    We study dynamics of the interaction between two weak light beams mediated by a strongly coupled quantum dot-photonic crystal cavity system. First, we perform all optical switching of a weak continuous-wave signal with a pulsed control beam, and then perform switching between two pulsed beams (40ps pulses) at the single photon level. Our results show that the quantum dot-nanocavity system creates strong, controllable interactions at the single photon level.

  20. The Oscillator Strength of the Quantum Transitions in Multi-Resonant-Tunneling Structures Tours as Basic Elements of Quantum Cascade Lasers and Detectors in a Transverse Magnetic Field

    Directory of Open Access Journals (Sweden)

    I.V. Boyko

    2014-04-01

    Full Text Available Using the model of a closed resonant tunneling structure developed the theory of the electron energy spectrum and oscillator strengths of the quantum electronic transitions between energy levels of this nanostructure. It is shown that by changing the intensity of the magnetic field can be in a wide range of electromagnetic waves to adjust the operating frequency of the radiation of a quantum cascade laser or detector, working on quantum transitions between the first and the third energy electronic states.

  1. Terahertz dual-wavelength quantum cascade laser based on GaN active region

    Science.gov (United States)

    Mirzaei, B.; Rostami, A.; Baghban, H.

    2012-03-01

    In this paper a novel terahertz (THz) quantum cascade laser (QCL) based on GaN/AlGaN quantum wells has been proposed, which emits at two widely separated wavelengths 33 and 52 μm simultaneously in a single active region. The large LO-phonon energy (˜90 meV), the ultrafast resonant phonon depopulation of the lower radiative levels, suppression of the electrons that escape to the continuum states and selective carrier injection and extraction all together lead to a considerable enhancement in the operating temperature of the structure. All calculations have been done at a temperature of 265 K. Moreover, similar behavior of the output optical powers is another remarkable feature, which makes both wavelengths useful for special applications.

  2. Monte Carlo study of GaN versus GaAs terahertz quantum cascade structures

    Science.gov (United States)

    Bellotti, Enrico; Driscoll, Kristina; Moustakas, Theodore D.; Paiella, Roberto

    2008-03-01

    Due to their large optical phonon energies, nitride semiconductors are promising for the development of terahertz quantum cascade lasers with dramatically improved high-temperature performance relative to existing GaAs devices. Here, we present a rigorous Monte Carlo study of carrier dynamics in two structures based on the same design scheme for emission at 2THz, consisting of GaN /AlGaN or GaAs /AlGaAs quantum wells. The population inversion and hence the gain coefficient of the nitride device are found to exhibit a much weaker (by a factor of over 3) temperature dependence and to remain large enough for laser action even without cryogenic cooling.

  3. Quantum cascade emission in the III-nitride material system designed with effective interface grading

    Energy Technology Data Exchange (ETDEWEB)

    Song, Alex Y., E-mail: alexys@stanford.edu; Huang, Tzu-Yung; Zah, Chung-En; Gmachl, Claire F. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08540 (United States); Bhat, Rajaram; Wang, Jie [Corning Incorporated, Corning, New York 14831 (United States); Allerman, Andrew A. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2015-09-28

    We report the realization of quantum cascade (QC) light emission in the III-nitride material system, designed with effective interface grading (EIG). EIG induces a continuous transition between wells and barriers in the quantum confinement, which alters the eigenstate system and even delocalizes the states with higher energy. Fully transverse-magnetic spontaneous emission is observed from the fabricated III-nitride QC structure, with a center wavelength of ∼4.9 μm and a full width at half maximum of ∼110 meV, both in excellent agreement with theoretical predictions. A multi-peak photo-response spectrum is also measured from the QC structure, which again agrees well with theoretical calculations and verifies the effects of EIG.

  4. Cavity quantum electrodynamics in the Anderson-localized regime

    DEFF Research Database (Denmark)

    Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren;

    2010-01-01

    We experimentally measure, by means of time-resolved photoluminescence spectroscopy, a 15-fold enhancement of the spontaneous emission decay rate of single semiconductor quantum dots coupled to disorder-induced Anderson-localized modes with efficiencies reaching 94%....

  5. High quantum efficiency mid-wavelength interband cascade infrared photodetectors with one and two stages

    Science.gov (United States)

    Zhou, Yi; Chen, Jianxin; Xu, Zhicheng; He, Li

    2016-08-01

    In this paper, we report on mid-wavelength infrared interband cascade photodetectors grown on InAs substrates. We studied the transport properties of the photon-generated carriers in the interband cascade structures by comparing two different detectors, a single stage detector and a two-stage cascade detector. The two-stage device showed quantum efficiency around 19.8% at room temperature, and clear optical response was measured even at a temperature of 323 K. The two detectors showed similar Johnson-noise limited detectivity. The peak detectivity of the one- and two-stage devices was measured to be 2.15 × 1014 cm·Hz1/02/W and 2.19 × 1014 cm·Hz1/02/W at 80 K, 1.21 × 109 cm·Hz1/02/W and 1.23 × 109 cm·Hz1/02/W at 300 K, respectively. The 300 K background limited infrared performance (BLIP) operation temperature is estimated to be over 140 K.

  6. Non-classical light generated by quantum-noise-driven cavity optomechanics.

    Science.gov (United States)

    Brooks, Daniel W C; Botter, Thierry; Schreppler, Sydney; Purdy, Thomas P; Brahms, Nathan; Stamper-Kurn, Dan M

    2012-08-23

    Optomechanical systems, in which light drives and is affected by the motion of a massive object, will comprise a new framework for nonlinear quantum optics, with applications ranging from the storage and transduction of quantum information to enhanced detection sensitivity in gravitational wave detectors. However, quantum optical effects in optomechanical systems have remained obscure, because their detection requires the object’s motion to be dominated by vacuum fluctuations in the optical radiation pressure; so far, direct observations have been stymied by technical and thermal noise. Here we report an implementation of cavity optomechanics using ultracold atoms in which the collective atomic motion is dominantly driven by quantum fluctuations in radiation pressure. The back-action of this motion onto the cavity light field produces ponderomotive squeezing. We detect this quantum phenomenon by measuring sub-shot-noise optical squeezing. Furthermore, the system acts as a low-power, high-gain, nonlinear parametric amplifier for optical fluctuations, demonstrating a gain of 20 dB with a pump corresponding to an average of only seven intracavity photons. These findings may pave the way for low-power quantum optical devices, surpassing quantum limits on position and force sensing, and the control and measurement of motion in quantum gases.

  7. Quantum state engineering and reconstruction in cavity QED. An analytical approach

    Energy Technology Data Exchange (ETDEWEB)

    Lougovski, P.

    2004-09-25

    The models of a strongly-driven micromaser and a one-atom laser are developed. Their analytical solutions are obtained by means of phase space techniques. It is shown how to exploit the model of a one-atom laser for simultaneous generation and monitoring of the decoherence of the atom-field ''Schroedinger cat'' states. The similar machinery applied to the problem of the generation of the maximally-entangled states of two atoms placed inside an optical cavity permits its analytical solution. The steady-state solution of the problem exhibits a structure in which the two-atom maximally-entangled state correlates with the vacuum state of the cavity. As a consequence, it is demonstrated that the atomic maximally-entangled state, depending on a coupling regime, can be produced via a single or a sequence of no-photon measurements. The question of the implementation of a quantum memory device using a dispersive interaction between the collective internal ground state of an atomic ensemble and two orthogonal modes of a cavity is addressed. The problem of quantum state reconstruction in the context of cavity quantum electrodynamics is considered. The optimal operational definition of the Wigner function of a cavity field is worked out. It is based on the Fresnel transform of the atomic inversion of a probe atom. The general integral transformation for the Wigner function reconstruction of a particle in an arbitrary symmetric potential is derived.

  8. Optimizing optical nonlinearities in GaInAs/AlInAs quantum cascade lasers

    Directory of Open Access Journals (Sweden)

    Gajić Aleksandra D.

    2014-01-01

    Full Text Available Regardless of the huge advances made in the design and fabrication of mid-infrared and terahertz quantum cascade lasers, success in accessing the ~3-4 mm region of the electromagnetic spectrum has remained limited. This fact has brought about the need to exploit resonant intersubband transitions as powerful nonlinear oscillators, consequently enabling the occurrence of large nonlinear optical susceptibilities as a means of reaching desired wavelengths. In this work, we present a computational model developed for the optimization of second-order optical nonlinearities in In0.53Ga0.47As/Al0.48In0.52As quantum cascade laser structures based on the implementation of the Genetic algorithm. The carrier transport and the power output of the structure were calculated by self-consistent solutions to the system of rate equations for carriers and photons. Both stimulated and simultaneous double-photon absorption processes occurring between the second harmonic generation-relevant levels are incorporated into rate equations and the material-dependent effective mass and band non-parabolicity are taken into account, as well. The developed method is quite general and can be applied to any higher order effect which requires the inclusion of the photon density equation. [Projekat Ministarstva nauke Republike Srbije, br. III 45010

  9. Long term reliability study and life time model of quantum cascade lasers

    Science.gov (United States)

    Xie, Feng; Nguyen, Hong-Ky; Leblanc, Herve; Hughes, Larry; Wang, Jie; Wen, Jianguo; Miller, Dean J.; Lascola, Kevin

    2016-09-01

    Here, we present results of quantum cascade laser lifetime tests under various aging conditions including an accelerated life test. The total accumulated life time exceeds 1.5 × 106 device hours. The longest single device aging time was 46 500 hours without failure in the room temperature aging test. Four failures were found in a group of 19 devices subjected to the accelerated life test with a heat-sink temperature of 60 °C and a continuous-wave current of 1 A. Failure mode analyses revealed that thermally induced oxidation of InP in the semi-insulating layer is the cause of failure. An activation energy of 1.2 eV is derived from the dependence of the failure rate on laser core temperature. The mean time to failure of the quantum cascade lasers operating at a typical condition with the current density of 5 kA/cm2 and heat-sink temperature of 25 °C is expected to be 809 000 hours.

  10. Short pulse generation and mode control of broadband terahertz quantum cascade lasers

    CERN Document Server

    Bachmann, Dominic; Süess, Martin J; Beck, Mattias; Unterrainer, Karl; Darmo, Juraj; Faist, Jérôme; Scalari, Giacomo

    2016-01-01

    We report on a waveguide engineering technique that enables the generation of a bandwidth up to 1 THz and record ultra-short pulse length of 2.5 ps in injection seeded terahertz quantum cascade lasers. The reported technique is able to control and fully suppress higher order lateral modes in broadband terahertz quantum cascade lasers by introducing side-absorbers to metal-metal waveguides. The side-absorbers consist of a top metalization set-back with respect to the laser ridge and an additional lossy metal layer. In continuous wave operation the side-absorbers lead to octave spanning laser emission, ranging from 1.63 to 3.37 THz, exhibiting a 725 GHz wide at top within a 10 dB intensity range as well as frequency comb operation with a bandwidth of 442 GHz. Numerical and experimental studies have been performed to optimize the impact of the side-absorbers on the emission properties and to determine the required increase of waveguide losses. Furthermore, these studies have led to a better understanding of the ...

  11. An indirectly pumped terahertz quantum cascade laser with low injection coupling strength operating above 150 K

    Science.gov (United States)

    Razavipour, S. G.; Dupont, E.; Fathololoumi, S.; Chan, C. W. I.; Lindskog, M.; Wasilewski, Z. R.; Aers, G.; Laframboise, S. R.; Wacker, A.; Hu, Q.; Ban, D.; Liu, H. C.

    2013-05-01

    We designed and demonstrated a terahertz quantum cascade laser based on indirect pump injection to the upper lasing state and phonon scattering extraction from the lower lasing state. By employing a rate equation formalism and a genetic algorithm, an optimized active region design with four-well GaAs/Al0.25Ga0.75As cascade module was obtained and epitaxially grown. A figure of merit which is defined as the ratio of modal gain versus injection current was maximized at 150 K. A fabricated device with a Au metal-metal waveguide and a top n+ GaAs contact layer lased at 2.4 THz up to 128.5 K, while another one without the top n+ GaAs lased up to 152.5 K (1.3ℏω /kB). The experimental results have been analyzed with rate equation and nonequilibrium Green's function models. A high population inversion is achieved at high temperature using a small oscillator strength of 0.28, while its combination with the low injection coupling strength of 0.85 meV results in a low current. The carefully engineered wavefunctions enhance the quantum efficiency of the device and therefore improve the output optical power even with an unusually low injection coupling strength.

  12. Influences of strong exciton-phonon interaction on two coupled quantum dots within cavity QED

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Xiaozhong [Department of Physics, Institute of Quantum Optics and Quantum Information, Shanghai Jiao Tong University, Shanghai 200240 (China)]. E-mail: yxz@sjtu.edu.cn; Zhu Kadi [Department of Physics, Institute of Quantum Optics and Quantum Information, Shanghai Jiao Tong University, Shanghai 200240 (China); Li Waisang [Department of Electronic and Information Engineering, Hong Kong Polytechnic University, Hong Kong (China)

    2004-08-30

    For two coupled quantum dots within cavity QED, we show that the exciton-phonon interaction reduces the Rabi frequency and Foerster interaction even at absolute zero temperature. The exciton-phonon interaction also makes an additional contribution to the static exciton-exciton dipole interaction energy.

  13. Influences of strong exciton-phonon interaction on two coupled quantum dots within cavity QED

    Science.gov (United States)

    Yuan, Xiao-Zhong; Zhu, Ka-Di; Li, Wai-Sang

    2004-08-01

    For two coupled quantum dots within cavity QED, we show that the exciton-phonon interaction reduces the Rabi frequency and Förster interaction even at absolute zero temperature. The exciton-phonon interaction also makes an additional contribution to the static exciton-exciton dipole interaction energy.

  14. Observation of Non-Markovian Dynamics of a Single Quantum Dot in a Micropillar Cavity

    DEFF Research Database (Denmark)

    Madsen, Kristian Høeg; Ates, Serkan; Lund-Hansen, Toke;

    2011-01-01

    We measure the detuning-dependent dynamics of a quasiresonantly excited single quantum dot coupled to a micropillar cavity. The system is modeled with the dissipative Jaynes-Cummings model where all experimental parameters are determined by explicit measurements. We observe non-Markovian dynamics...

  15. Classical correlation and quantum discord mediated by cavity in two coupled qubits

    NARCIS (Netherlands)

    Wang, Cheng-Zhi; Li, Chun-Xian; Nie, Liu-Ying; Li, Jiang-Fan

    2011-01-01

    We study the dynamics of classical correlation and quantum discord of two coupled two-level atoms interacting with a cavity initially in vacuum, coherent and thermal equilibrium states, respectively. The interplay between the atom-atom coupling and mean number of photons is considered. We find that,

  16. Hidden Markov Model of atomic quantum jump dynamics in an optically probed cavity

    DEFF Research Database (Denmark)

    Gammelmark, S.; Molmer, K.; Alt, W.

    2014-01-01

    We analyze the quantum jumps of an atom interacting with a cavity field. The strong atom- field interaction makes the cavity transmission depend on the time dependent atomic state, and we present a Hidden Markov Model description of the atomic state dynamics which is conditioned in a Bayesian......, the atomic state is determined in a Bayesian manner from the measurement data, and we present an iterative protocol, which determines both the atomic state and the model parameters. As a new element in the treatment of observed quantum systems, we employ a Bayesian approach that conditions the atomic state...... manner on the detected signal. We suggest that small variations in the observed signal may be due to spatial motion of the atom within the cavity, and we represent the atomic system by a number of hidden states to account for both the small variations and the internal state jump dynamics. In our theory...

  17. Cavity quantum electrodynamics with separate photon storage and qubit readout modes.

    Science.gov (United States)

    Leek, P J; Baur, M; Fink, J M; Bianchetti, R; Steffen, L; Filipp, S; Wallraff, A

    2010-03-12

    We present the realization of a cavity quantum electrodynamics setup in which photons of strongly different lifetimes are engineered in different harmonic modes of the same cavity. We achieve this in a superconducting transmission line resonator with superconducting qubits coupled to the different modes. One cavity mode is strongly coupled to a detection line for qubit state readout, while a second long lifetime mode is used for photon storage and coherent quantum operations. We demonstrate sideband-based measurement of photon coherence, generation of n photon Fock states and the scaling of the sideband Rabi frequency with square root of n using a scheme that may be extended to realize sideband-based two-qubit logic gates.

  18. Photon antibunching and nonlinear effects for a quantum dot coupled to a semiconductor cavity

    Science.gov (United States)

    Bello, F.; Whittaker, D. M.

    2010-09-01

    The models presented simulate pumping techniques that can be used on modern semiconductor devices which are capable of coupling a quantum dot and cavity mode in order to determine a more efficient method of producing a single-photon emitter while taking into consideration typical parameters which are achievable given today’s standards of coupling strength. Cavity quantum electrodynamics are incorporated in the calculations as we compare various pumping schemes for the system that either use on-resonant laser excitation or nonresonant excitation due to a wetting layer. In particular, we look to study how antibunching effects change for each method as the cavity finesse is increased toward the strong coupling regime. Experimentally these studies are equivalent to nonlinear pump-probe measurements, where a strong pump, either resonant or nonresonant, is used to excite the coupled system, and the resulting state is characterized using a weak, resonant probe beam.

  19. Quantum Dot Cavity-QED in the Presence of Strong Electron-Phonon Interactions

    CERN Document Server

    Wilson-Rae, I

    2001-01-01

    A quantum dot strongly coupled to a single high finesse optical microcavity mode constitutes a new fundamental system for quantum optics. Here, the effect of exciton-phonon interactions on reversible quantum-dot cavity coupling is analysed without making Born-Markov approximation. The analysis is based on techniques that have been used to study the ``spin boson'' Hamiltonian. Observability of vacuum-Rabi splitting depends on the strength and the frequency dependence of the spectral density function characterizing the interactions with phonons, both of which can be influenced by phonon confinement.

  20. Cavity Ring-down Spectroscopic System And Method

    KAUST Repository

    Alquaity, Awad Bin Saud

    2015-05-14

    A system and method for cavity ring-down spectroscopy can include a pulsed quantum cascade laser, an optical ring-down cavity, a photodetector, and an oscilloscope. The system and method can produce pulse widths of less than 200 ns with bandwidths greater than 300 pm, as well as provide temporal resolution of greater than 10 .mu.s.

  1. Classical stochastic measurement trajectories: Bosonic atomic gases in an optical cavity and quantum measurement backaction

    Science.gov (United States)

    Lee, Mark D.; Ruostekoski, Janne

    2014-08-01

    We formulate computationally efficient classical stochastic measurement trajectories for a multimode quantum system under continuous observation. Specifically, we consider the nonlinear dynamics of an atomic Bose-Einstein condensate contained within an optical cavity subject to continuous monitoring of the light leaking out of the cavity. The classical trajectories encode within a classical phase-space representation a continuous quantum measurement process conditioned on a given detection record. We derive a Fokker-Planck equation for the quasiprobability distribution of the combined condensate-cavity system. We unravel the dynamics into stochastic classical trajectories that are conditioned on the quantum measurement process of the continuously monitored system. Since the dynamics of a continuously measured observable in a many-atom system can be closely approximated by classical dynamics, the method provides a numerically efficient and accurate approach to calculate the measurement record of a large multimode quantum system. Numerical simulations of the continuously monitored dynamics of a large atom cloud reveal considerably fluctuating phase profiles between different measurement trajectories, while ensemble averages exhibit local spatially varying phase decoherence. Individual measurement trajectories lead to spatial pattern formation and optomechanical motion that solely result from the measurement backaction. The backaction of the continuous quantum measurement process, conditioned on the detection record of the photons, spontaneously breaks the symmetry of the spatial profile of the condensate and can be tailored to selectively excite collective modes.

  2. Quantum logic operations on two distant atoms trapped in two optical-fibre-connected cavities

    Institute of Scientific and Technical Information of China (English)

    Zhang Ying-Qiao; Zhang Shou; Yeon Kyu-Hwang; Yu Seong-Cho

    2011-01-01

    Based on the coupling of two distant three-level atoms in two separate optical cavities connected with two optical fibres,schemes on the generation of several two-qubit logic gates are discussed under the conditions of △ =δ -2v cos πk/2 (》) g/2 and (v~ g).Discussion and analysis of the fidelity,gate time and experimental setups show that our schemes are feasible with current optical cavity,atomic trap and optical fibre techniques.Moreover,the atom-cavityfibre coupling can be used to generate an N-qubit nonlocal entanglement and transfer quantum information among N distant atoms by arranging N atom-cavity assemblages in a line and connecting each two adjacent cavities with two optical fibres.

  3. Two-photon gateway in one-atom cavity quantum electrodynamics.

    Science.gov (United States)

    Kubanek, A; Ourjoumtsev, A; Schuster, I; Koch, M; Pinkse, P W H; Murr, K; Rempe, G

    2008-11-14

    Single atoms absorb and emit light from a resonant laser beam photon by photon. We show that a single atom strongly coupled to an optical cavity can absorb and emit resonant photons in pairs. The effect is observed in a photon correlation experiment on the light transmitted through the cavity. We find that the atom-cavity system transforms a random stream of input photons into a correlated stream of output photons, thereby acting as a two-photon gateway. The phenomenon has its origin in the quantum anharmonicity of the energy structure of the atom-cavity system. Future applications could include the controlled interaction of two photons by means of one atom.

  4. Cavity-photon contribution to the effective interaction of electrons in parallel quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Gudmundsson, Vidar [Science Institute, University of Iceland, Reykjavik (Iceland); Sitek, Anna [Science Institute, University of Iceland, Reykjavik (Iceland); Department of Theoretical Physics, Faculty of Fundamental Problems of Technology, Wroclaw University of Technology (Poland); Abdullah, Nzar Rauf [Science Institute, University of Iceland, Reykjavik (Iceland); Physics Department, Faculty of Science and Science Education, School of Science, University of Sulaimani, Kurdistan Region (Iraq); Tang, Chi-Shung [Department of Mechanical Engineering, National United University, Miaoli (China); Manolescu, Andrei [School of Science and Engineering, Reykjavik University (Iceland)

    2016-05-15

    A single cavity photon mode is expected to modify the Coulomb interaction of an electron system in the cavity. Here we investigate this phenomena in a parallel double quantum dot system. We explore properties of the closed system and the system after it has been opened up for electron transport. We show how results for both cases support the idea that the effective electron-electron interaction becomes more repulsive in the presence of a cavity photon field. This can be understood in terms of the cavity photons dressing the polarization terms in the effective mutual electron interaction leading to nontrivial delocalization or polarization of the charge in the double parallel dot potential. In addition, we find that the effective repulsion of the electrons can be reduced by quadrupolar collective oscillations excited by an external classical dipole electric field. (copyright 2015 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Teleportation of two-atom entangled state in resonant cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Yang Zhen-Biao

    2007-01-01

    An alternative scheme is presented for teleportation of a two-atom entangled state in cavity quantum electrodynamics (QED). It is based on the resonant atom-cavity field interaction. In the scheme, only one cavity is involved, and the number of the atoms needed to be detected is decreased compared with the previous scheme. Since the resonant atom-cavity field interaction greatly reduces the interaction time, the decoherence effect can be effectively suppressed during the teleportation process. The experimental feasibility of the scheme is discussed. The scheme can easily be generalized to the teleportation of N-atom Greeninger-Horne-Zeilinger (GHZ) entangled states. The number of atoms needed to be detected does not increase as the number of the atoms in the GHZ state increases.

  6. A nanophotonic probe for quantum electrodynamics in random cavities

    DEFF Research Database (Denmark)

    Huisman, S. R.; Frater, E. H.; Korterik, J. P.;

    2011-01-01

    Disorder in photonic-crystal slab waveguides can cause localization of light [1, 2]. Sapienza et al. observed that the interaction of localized light with embedded quantum dots is so strong that it yields a considerable Purcell enhancement of the emission rate [3]. This coupling between emitters...

  7. Statistics of quantum transport in weakly nonideal chaotic cavities.

    Science.gov (United States)

    Rodríguez-Pérez, Sergio; Marino, Ricardo; Novaes, Marcel; Vivo, Pierpaolo

    2013-11-01

    We consider statistics of electronic transport in chaotic cavities where time-reversal symmetry is broken and one of the leads is weakly nonideal; that is, it contains tunnel barriers characterized by tunneling probabilities Γ(i). Using symmetric function expansions and a generalized Selberg integral, we develop a systematic perturbation theory in 1-Γ(i) valid for an arbitrary number of channels and obtain explicit formulas up to second order for the average and variance of the conductance and for the average shot noise. Higher moments of the conductance are considered to leading order.

  8. Quantum chaos and fractals with atoms in cavities

    CERN Document Server

    Uleysky, M; Prants, S V

    2002-01-01

    We study the coupled translational, electronic, and field dynamics of the combined system "a two-level atom + a single-mode quantized field + a standing-wave ideal cavity". We derive Hamilton -- Schr\\"odinger equations for probability amplitudes and averaged position and momentum of a point-like atom interacting with the quantized field in a standing-wave cavity. They constitute, in general, an infinite-dimensional set of equations with an infinite number of integrals of motion which may be reduced to a dynamical system with four degrees of freedom if the quantized field is supposed to be initially prepared in a Fock state. This system is found to produce semiquantum chaos with positive values of the maximal Lyapunov exponent. At large values of detuning $|\\delta|\\gg 1$, the Rabi atomic oscillations are usually shallow, and the dynamics is found to be almost regular. The Doppler -- Rabi resonance, deep Rabi oscillations that may occur at any large value of $|\\delta|$ to be equal to $|\\alpha p_0|$, is found nu...

  9. Optimization of a Quantum Cascade Laser Operating in the Terahertz Frequency Range Using a Multiobjective Evolutionary Algorithm

    Science.gov (United States)

    2004-06-01

    laser fundamentals , semiconductors, quantum wells and finally ending with a discussion of generic QC lasers. With the a priori knowledge that...quantum cascade laser structure and operation. It begins, in Chapter 2, with a discussion of the atom, continus with laser fundamentals , semiconductors...Aerospace Engineering, Arizona State University. 102 15. Chow, W. W. and Koch, S. W. Semiconductor- Laser Fundamentals . New York: Springer-Verlag

  10. Quantum aspects of cavity optomechanics with atomic ensembles and ensemble arrays

    Science.gov (United States)

    Stamper-Kurn, Dan

    2012-06-01

    While the motion of a many-atom ensemble of atoms interacting strongly with a single mode of an optical resonator can be devilishly complicated, under favorable conditions, the cavity can be made to interact with and to sense just one, or just a few, normal modes of the gaseous system. This leads to an atoms-based realization of cavity optomechanics, directly analogous to experiments in which one seeks to observe the motion of suspended mirrors, cantilevers, and membranes at the quantum limits of precision. I will discuss our progress toward demonstrating and understanding the distinctively quantum mechanical aspects of both the ``opto'' and ``mechanical'' portions of cavity optomechanical systems. Specifically, I will report on the observation of the ponderomotive squeezing of light by a mechanical oscillator, and of strong motional sideband asymmetry that demonstrates the quantization of collective atomic motion and quantifies the energy flux into the mechanical system due to quantum measurement backaction. I will conclude by describing our approach to realizing strong cavity coupling to a multi-mode mechanical system, specifically to an array of distinguishable mechanical oscillators. [4pt] The work reported in this talk was performed in collaboration with members of my research group, including Thierry Botter, Nathaniel Brahms, Daniel Brooks, Thomas Purdy and Sydney Schreppler, and was supported by the AFOSR and NSF.

  11. Multi-species trace gas analysis with dual-wavelength quantum cascade laser

    Science.gov (United States)

    Jágerská, Jana; Tuzson, Béla; Looser, Herbert; Jouy, Pierre; Hugi, Andreas; Mangold, Markus; Soltic, Patrik; Faist, Jérôme; Emmenegger, Lukas

    2015-04-01

    Simultaneous detection of multiple gas species using mid-IR laser spectroscopy is highly appealing for a large variety of applications ranging from air quality monitoring, medical breath analysis to industrial process control. However, state-of-the-art distributed-feedback (DFB) mid-IR lasers are usually tunable only within a narrow spectral range, which generally leads to one-laser-one-compound measurement strategy. Thus, multi-species detection involves several lasers and elaborate beam combining solutions [1]. This makes them bulky, costly, and highly sensitive to optical alignment, which limits their field deployment. In this paper, we explore an alternative measurement concept based on a dual-wavelength quantum cascade laser (DW-QCL) [2]. Such a laser can emit at two spectrally distinct wavelengths using a succession of two DFB gratings with different periodicities and a common waveguide to produce one output beam. The laser design was optimized for NOx measurements and correspondingly emits single-mode at 5.26 and 6.25 μm. Electrical separation of the respective laser sections makes it possible to address each wavelength independently. Thereby, it is possible to detect NO and NO2 species with one laser using the same optical path, without any beam combining optics, i.e. in a compact and cost-efficient single-path optical setup. Operated in a time-division multiplexed mode, the spectrometer reaches detection limits at 100 s averaging of 0.5 and 1.5 ppb for NO2 and NO, respectively. The performance of the system was validated against the well-established chemiluminescence detection while measuring the NOx emissions on an automotive test-bench, as well as monitoring the pollution at a suburban site. [1] B. Tuzson, K. Zeyer, M. Steinbacher, J. B. McManus, D. D. Nelson, M. S. Zahniser, and L. Emmenegger, 'Selective measurements of NO, NO2 and NOy in the free troposphere using quantum cascade laser spectroscopy,' Atmospheric Measurement Techniques 6, 927-936 (2013

  12. Efficient and long-lived quantum memory with cold atoms inside a ring cavity

    CERN Document Server

    Bao, Xiao-Hui; Dietrich, Peter; Rui, Jun; Dück, Alexander; Strassel, Thorsten; Li, Li; Liu, Nai-Le; Zhao, Bo; Pan, Jian-Wei; 10.1038/nphys2324

    2012-01-01

    Quantum memories are regarded as one of the fundamental building blocks of linear-optical quantum computation and long-distance quantum communication. A long standing goal to realize scalable quantum information processing is to build a long-lived and efficient quantum memory. There have been significant efforts distributed towards this goal. However, either efficient but short-lived or long-lived but inefficient quantum memories have been demonstrated so far. Here we report a high-performance quantum memory in which long lifetime and high retrieval efficiency meet for the first time. By placing a ring cavity around an atomic ensemble, employing a pair of clock states, creating a long-wavelength spin wave, and arranging the setup in the gravitational direction, we realize a quantum memory with an intrinsic spin wave to photon conversion efficiency of 73(2)% together with a storage lifetime of 3.2(1) ms. This realization provides an essential tool towards scalable linear-optical quantum information processing.

  13. Nonequilibrium Green's functions theory for the alpha factor of quantum cascade lasers (Conference Presentation)

    Science.gov (United States)

    Pereira, Mauro F.; Winge, David O.; Wacker, Andreas; Jumpertz, Louise; Michel, Florian; Pawlus, Robert; Elsaesser, Wolfgang E.; Schires, Kevin; Carras, Mathieu; Grillot, Frédéric

    2016-10-01

    The linewidth of a conventional laser is due to fluctuations in the laser field due to spontaneous emission and described by the Schalow-Townes formula. In addition to that, in a semiconductor laser there is a contribution arising from fluctuations in the refractive index induced by carrier density fluctuations. The later are quantitatively described by the linewidth enhancement or alpha factor [C. H. Henry, IEEE J. Quantum Electron. 18 (2), 259 (1982), W. W. Chow, S. W. Koch and M. Sargent III, Semiconductor-Laser Physics, Springer-Verlag (1994), M.F. Pereira Jr et al, J. Opt. Soc. Am. B10, 765 (1993). In this paper we investigate the alpha factor of quantum cascade lasers under actual operating conditions using the Nonequilibrium Greens Functions approach [A. Wacker et a, IEEE Journal of Sel. Top. in Quantum Electron.,19 1200611, (2013), T. Schmielau and M.F. Pereira, Appl. Phys. Lett. 95 231111, (2009)]. The simulations are compared with recent results obtained with different optical feedback techniques [L. Jumpertz et al, AIP ADVANCES 6, 015212 (2016)].

  14. Cavity quantum electrodynamics with three-dimensional photonic bandgap crystals

    CERN Document Server

    Vos, W L

    2015-01-01

    This paper gives an overview of recent work on three-dimensional (3D) photonic crystals with a "full and complete" 3D photonic band gap. We review five main aspects: 1) spontaneous emission inhibition, 2) spatial localization of light within a tiny nanoscale volume (aka "a nanobox for light"), 3) the introduction of a gain medium leading to thresholdless lasers, 4) breaking of the weak-coupling approximation of cavity QED, both in the frequency and in the time-domain, 5) decoherence, in particular the shielding of vacuum fluctuations by a 3D photonic bandgap. In addition, we list and evaluate all known photonic crystal structures with a demonstrated 3D band gap.

  15. Impurity-free quantum well intermixing for large optical cavity high-power laser diode structures

    Science.gov (United States)

    Kahraman, Abdullah; Gür, Emre; Aydınlı, Atilla

    2016-08-01

    We report on the correlation of atomic concentration profiles of diffusing species with the blueshift of the quantum well luminescence from both as-grown and impurity free quantum wells intermixed on actual large optical cavity high power laser diode structures. Because it is critical to suppress catastrophic optical mirror damage, sputtered SiO2 and thermally evaporated SrF2 were used both to enhance and suppress quantum well intermixing, respectively, in these (Al)GaAs large optical cavity structures. A luminescence blueshift of 55 nm (130 meV) was obtained for samples with 400 nm thick sputtered SiO2. These layers were used to generate point defects by annealing the samples at 950 °C for 3 min. The ensuing Ga diffusion observed as a shifting front towards the surface at the interface of the GaAs cap and AlGaAs cladding, as well as Al diffusion into the GaAs cap layer, correlates well with the observed luminescence blue shift, as determined by x-ray photoelectron spectroscopy. Although this technique is well-known, the correlation between the photoluminescence peak blue shift and diffusion of Ga and Al during impurity free quantum well intermixing on actual large optical cavity laser diode structures was demonstrated with both x ray photoelectron and photoluminescence spectroscopy, for the first time.

  16. Nonlinear optical effects and Hong-Ou-Mandel interference in cavity quantum electrodynamics

    Science.gov (United States)

    Mirza, Imran M.; van Enk, Steven J.

    Pure quantum interference among single photons is one of the key ingredients to perform linear optics quantum computation (LOQC). The Hong-Ou-Mandel interference (HOMI) [C. K. Hong, Z. Y. Ou and L. Mandel, Phys. Rev. Lett. 59, (18), 2044-2046 (1987)] i.e. complete destructive interference between two identical and indistinguishable photons simultaneously entering input ports of a 50/50 beam splitter, is a well-known example in this context. In this talk, I'll present our theoretical study of HOMI in a coupled Jaynes-Cummings array. In particular and by applying quantum jump/trajectory formalism, I'll focus on how partial quantum interference between two photons survive both non-linearities produced by two-level emitter and spectral filtering due to optical cavities in our coupled cavity array setup [Imran M. Mirza and Steven J. van Enk, Opt. Comm. 343, 172-177 (2015)]. Along with LOQC, this work is crucial from the perspective of exploiting coupled cavity arrays to store single photons reliably (without altering their temporal and spectral traits) [Imran M. Mirza, Steven J. van Enk and Jeff Kimble, JOSA B, 10, 2640-2649, (2013)].

  17. Quantum Gate Operations in Decoherence-Free Subspace with Superconducting Charge Qubits inside a Cavity

    Institute of Scientific and Technical Information of China (English)

    WANG Yi-Min; ZHOU Yan-Li; LIANG Lin-Mei; LI Cheng-Zu

    2009-01-01

    We propose a feasible scheme to achieve universal quantum gate operations in decoherence-free subspace with superconducting charge qubits placed in a microwave cavity.Single-logic-qubit gates can be realized with cavity assisted interaction, which possesses the advantages of unconventional geometric gate operation.The two-logic-qubit controlled-phase gate between subsystems can be constructed with the help of a variable electrostatic transformer, The collective decoherence can be successfully avoided in our well-designed system.Moreover, GHZ state for logical qubits can also be easily produced in this system.

  18. Entanglement and quantum state transfer between two atoms trapped in two indirectly coupled cavities

    Science.gov (United States)

    Zheng, Bin; Shen, Li-Tuo; Chen, Ming-Feng

    2016-05-01

    We propose a one-step scheme for implementing entanglement generation and the quantum state transfer between two atomic qubits trapped in two different cavities that are not directly coupled to each other. The process is realized through engineering an effective asymmetric X-Y interaction for the two atoms involved in the gate operation and an auxiliary atom trapped in an intermediate cavity, induced by virtually manipulating the atomic excited states and photons. We study the validity of the scheme as well as the influences of the dissipation by numerical simulation and demonstrate that it is robust against decoherence.

  19. Real-time imaging using a 2.8 THz quantum cascade laser and uncooled infrared microbolometer camera

    OpenAIRE

    Behnken, Barry N.; Karunasiri, Gamani; Chamberlin, Danielle R.; Robrish, Peter R.; Faist, Jerome

    2008-01-01

    Optics Letters, Volume 33, No. 5, pp. 440-442 (March 1, 2008) Real-time imaging in the terahertz (THz) spectral range was achieved using a milliwatt-scale, 2.8 THz quantum cascade laser and an uncooled, 160 120 pixel microbolometer camera modified with Picarin optics... This work is supported by the Air Force Office of Scientific Research (AFOSR).

  20. Frequency locking of single-mode 3.5-THz quantum cascade lasers using a gas cell

    NARCIS (Netherlands)

    Ren, Y.; Hovenier, J.N.; Cui, M.; Hayton, D.J.; Gao, J.R.; Klapwijk, T.M.; Shi, S.C.; Kao, T.Y.; Hu, Q.; Reno, J.L.

    2012-01-01

    We report frequency locking of two 3.5-THz third-order distributed feedback (DFB) quantum cascade lasers (QCLs) by using methanol molecular absorption lines, a proportional-integral-derivative controller, and a NbN bolometer. We show that the free-running linewidths of the QCLs are dependent on the

  1. Quantum optics and cavity QED Quantum network with individual atoms and photons

    Directory of Open Access Journals (Sweden)

    Rempe G.

    2013-08-01

    Full Text Available Quantum physics allows a new approach to information processing. A grand challenge is the realization of a quantum network for long-distance quantum communication and large-scale quantum simulation. This paper highlights a first implementation of an elementary quantum network with two fibre-linked high-finesse optical resonators, each containing a single quasi-permanently trapped atom as a stationary quantum node. Reversible quantum state transfer between the two atoms and entanglement of the two atoms are achieved by the controlled exchange of a time-symmetric single photon. This approach to quantum networking is efficient and offers a clear perspective for scalability. It allows for arbitrary topologies and features controlled connectivity as well as, in principle, infinite-range interactions. Our system constitutes the largest man-made material quantum system to date and is an ideal test bed for fundamental investigations, e.g. quantum non-locality.

  2. Terahertz inverse synthetic aperture radar (ISAR) imaging with a quantum cascade laser transmitter.

    Science.gov (United States)

    Danylov, Andriy A; Goyette, Thomas M; Waldman, Jerry; Coulombe, Michael J; Gatesman, Andrew J; Giles, Robert H; Qian, Xifeng; Chandrayan, Neelima; Vangala, Shivashankar; Termkoa, Krongtip; Goodhue, William D; Nixon, William E

    2010-07-19

    A coherent transceiver using a THz quantum cascade (TQCL) laser as the transmitter and an optically pumped molecular laser as the local oscillator has been used, with a pair of Schottky diode mixers in the receiver and reference channels, to acquire high-resolution images of fully illuminated targets, including scale models and concealed objects. Phase stability of the received signal, sufficient to allow coherent image processing of the rotating target (in azimuth and elevation), was obtained by frequency-locking the TQCL to the free-running, highly stable optically pumped molecular laser. While the range to the target was limited by the available TQCL power (several hundred microwatts) and reasonably strong indoor atmospheric attenuation at 2.408 THz, the coherence length of the TQCL transmitter will allow coherent imaging over distances up to several hundred meters. Image data obtained with the system is presented.

  3. III-nitride quantum cascade detector grown by metal organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yu, E-mail: yusong@princeton.edu; Huang, Tzu-Yung; Badami, Pranav; Gmachl, Claire [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08540 (United States); Bhat, Rajaram; Zah, Chung-En [Corning Incorporated, Corning, New York 14831 (United States)

    2014-11-03

    Quantum cascade (QC) detectors in the GaN/Al{sub x}Ga{sub 1−x}N material system grown by metal organic chemical vapor deposition are designed, fabricated, and characterized. Only two material compositions, i.e., GaN as wells and Al{sub 0.5}Ga{sub 0.5}N as barriers are used in the active layers. The QC detectors operates around 4 μm, with a peak responsivity of up to ∼100 μA/W and a detectivity of up to 10{sup 8} Jones at the background limited infrared performance temperature around 140 K.

  4. Surface Emitting Distributed Feedback Quantum Cascade Laser around 8.3μm

    Institute of Scientific and Technical Information of China (English)

    GUO Wan-Hong; LIU Jun-Qi; LU Quan-Yong; ZHANG Wei; JIANG Yu-Chao; LI Lu; WANG Li-Jun; LIU Feng-Qi; WANG Zhan-Guo

    2010-01-01

    @@ We demonstrate surface emitting distributed feedback quantum cascade lasers emitting at wavelengths from8.1 μm at 90 K to 8.4 μm at 210K.The second-order metalized grating is carefully designed using a modified coupled-mode theory and fabricated by contact lithography.The devices show single mode behavior with a side mode suppression ratio above 18dB at all working temperatures.At 90K,the device emits an optical power of 101 mW from the surface and 199mW from the edge.In addition,a double-lobe far-field pattern with a separation of 2.2° is obtained in the direction along the waveguide.

  5. Nonresonant tunneling phonon depopulated GaN based terahertz quantum cascade structures

    Science.gov (United States)

    Freeman, Will; Karunasiri, Gamani

    2013-04-01

    GaN based terahertz quantum cascade structures are theoretically studied. Since the Fröhlich interaction is ˜15 times higher in GaN than in GaAs, level broadening makes obtaining appreciable optical gain difficult even with a large population inversion. A density matrix Monte Carlo method is used to calculate the broadening of the optical gain spectra as a function of lattice temperature. We find by using a proposed method of nonresonant tunneling and electron-longitudinal-optical phonon scattering for depopulation of the lower lasing state, that it is possible to sufficiently isolate the upper lasing state and control the lower lasing state lifetime to obtain high optical gain in GaN. The results predict lasing out to 300 K which is significantly higher than for GaAs based structures.

  6. Extended and quasi-continuous tuning of quantum cascade lasers using superstructure gratings and integrated heaters

    Energy Technology Data Exchange (ETDEWEB)

    Bidaux, Yves, E-mail: yves.bidaux@alpeslasers.ch [Alpes Lasers SA, 1-3 Passsage Max Meuron, CH-2001 Neuchâtel (Switzerland); Institute for Quantum Electronics, ETH-Zurich, CH-8093 Zurich (Switzerland); Bismuto, Alfredo, E-mail: alfredo.bismuto@alpeslasers.ch; Tardy, Camille; Terazzi, Romain; Gresch, Tobias; Blaser, Stéphane; Muller, Antoine [Alpes Lasers SA, 1-3 Passsage Max Meuron, CH-2001 Neuchâtel (Switzerland); Faist, Jerome [Institute for Quantum Electronics, ETH-Zurich, CH-8093 Zurich (Switzerland)

    2015-11-30

    In this work, we demonstrate broad electrical tuning of quantum cascade lasers at 9.25 μm, 8.5 μm, and 4.4 μm in continuous wave operation using Vernier-effect distributed Bragg reflectors based on superstructure gratings. Integrated micro-heaters allow to switch from one Vernier channel to the other, while predictable and mode-hop free tuning can be obtained in each channel modulating the laser current with a side mode suppression ratio as high as 30 dB. The resulting device behaves effectively as a switchable multicolour tunable source. Tuning up to 6.5% of the central wavelength is observed. To prove the importance of the developed devices for high resolution molecular spectroscopy, a N{sub 2}O absorption spectrum has been measured.

  7. Quantum cascade laser-based spectrometer for high sensitive measurements of trace gases in air

    Institute of Scientific and Technical Information of China (English)

    Yuanyuan Tang; Wenqing Liu; Ruifeng Kan; Yujun Zhang; Dong Chen; Shuai Zhang; Jun Ruan

    2012-01-01

    A quantum cascade (QC) laser-based spectrometer is developed to measure trace gases in air.The proposed spectrometer is tested for N2O,and the results presented in this letter.This system takes advantage of recent technology in QC lasers by utilizing intra-pulse scan spectroscopy,which allows high sensitive measurement.Without calibration gases,the gas concentration can be calculated with scan integration and the corresponding values from the HITRAN04 database.By analyzing the Allan variance,a detection limit of 2 ppb is obtained.Continuous measurement of N2O sampled from ambient air shows the applicability of the proposed system for the field measurements of gases of environmental concern.

  8. A Polarization-Dependent Normal Incident Quantum Cascade Detector Enhanced Via Metamaterial Resonators

    Science.gov (United States)

    Wang, Lei; Zhai, Shen-Qiang; Wang, Feng-Jiao; Liu, Jun-Qi; Liu, Shu-Man; Zhuo, Ning; Zhang, Chuan-Jin; Wang, Li-Jun; Liu, Feng-Qi; Wang, Zhan-Guo

    2016-12-01

    The design, fabrication, and characterization of a polarization-dependent normal incident quantum cascade detector coupled via complementary split-ring metamaterial resonators in the infrared regime are presented. The metamaterial structure is designed through three-dimensional finite-difference time-domain method and fabricated on the top metal contact, which forms a double-metal waveguide together with the metallic ground plane. With normal incidence, significant enhancements of photocurrent response are obtained at the metamaterial resonances compared with the 45° polished edge coupling device. The photocurrent response enhancements exhibit clearly polarization dependence, and the largest response enhancement factor of 165% is gained for the incident light polarized parallel to the split-ring gap.

  9. Comb-assisted subkilohertz linewidth quantum cascade laser for high-precision mid-infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Galli, I.; Cappelli, F.; Bartalini, S.; Mazzotti, D.; Giusfredi, G.; Cancio, P.; De Natale, P. [CNR-INO-Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI (Italy); LENS-European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI (Italy); Siciliani de Cumis, M. [CNR-INO-Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI (Italy); Borri, S. [CNR-IFN-Istituto di Fotonica e Nanotecnologie, Via Amendola 173, 70126 Bari, BA (Italy); Montori, A. [LENS-European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI (Italy); Akikusa, N. [Development Bureau Laser Device R and D Group, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan); Yamanishi, M. [Central Research Laboratories, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan)

    2013-03-25

    We report on the linewidth narrowing of a room-temperature mid-infrared quantum cascade laser by phase-locking to a difference-frequency-generated radiation referenced to an optical frequency comb synthesizer. A locking bandwidth of 250 kHz, with a residual rms phase-noise of 0.56 rad, has been achieved. The laser linewidth is narrowed by more than 2 orders of magnitude below 1 kHz, and its frequency is stabilized with an absolute traceability of 2 Multiplication-Sign 10{sup -12}. This source has allowed the measurement of the absolute frequency of a CO{sub 2} molecular transition with an uncertainty of about 1 kHz.

  10. Quantum cascade laser photoacoustic detection of nitrous oxide released from soils for biofuel production

    Science.gov (United States)

    Couto, F. M.; Sthel, M. S.; Castro, M. P. P.; da Silva, M. G.; Rocha, M. V.; Tavares, J. R.; Veiga, C. F. M.; Vargas, H.

    2014-12-01

    In order to investigate the generation of greenhouse gases in sugarcane ethanol production chain, a comparative study of N2O emission in artificially fertilized soils and soils free from fertilizers was carried out. Photoacoustic spectroscopy using quantum cascade laser with an emission ranging from 7.71 to 7.88 µm and differential photoacoustic cell were applied to detect nitrous oxide (N2O), an important greenhouse gas emitted from soils cultivated with sugar cane. Owing to calibrate the experimental setup, an initial N2O concentration was diluted with pure nitrogen and detection limit of 50 ppbv was achieved. The proposed methodology was selective and sensitive enough to detect N2O from no fertilized and artificially fertilized soils. The measured N2O concentration ranged from ppmv to ppbv.

  11. The MBE growth and optimization of high performance terahertz frequency quantum cascade lasers.

    Science.gov (United States)

    Li, L H; Zhu, J X; Chen, L; Davies, A G; Linfield, E H

    2015-02-09

    The technique of molecular beam epitaxy has recently been used to demonstrate the growth of terahertz frequency GaAs/AlGaAs quantum cascade lasers (QCL) with Watt-level optical output powers. In this paper, we discuss the critical importance of achieving accurate layer thicknesses and alloy compositions during growth, and demonstrate that precise growth control as well as run-to-run growth reproducibility is possible. We also discuss the importance of minimizing background doping level in maximizing QCL performance. By selecting high-performance active region designs, and optimizing the injection doping level and device fabrication, we demonstrate total optical (two-facet) output powers as high as 1.56 W.

  12. Detection of acrolein and acrylonitrile with a pulsed room temperature quantum cascade laser

    Science.gov (United States)

    Manne, J.; Jäger, W.; Tulip, J.

    2010-06-01

    We investigated the use of a pulsed, distributed feedback quantum cascade laser centered at 957 cm-1 in combination with an astigmatic Herriot cell with 250 m path length for the detection of acrolein and acrylonitrile. These molecules have been identified as hazardous air-pollutants because of their adverse health effects. The spectrometer utilizes the intra-pulse method, where a linear frequency down-chirp, that is induced when a top-hat current pulse is applied to the laser, is used for sweeping across the absorption line. Up to 450 ns long pulses were used for these measurements which resulted in a spectral window of ~2.2 cm-1. A room temperature mercury-cadmium-telluride detector was used, resulting in a completely cryogen free spectrometer. We demonstrated detection limits of ~3 ppb for acrylonitrile and ~6 ppb for acrolein with ~10 s averaging time. Laser characterization and optimization of the operational parameters for sensitivity improvement are discussed.

  13. Ultrasonic photoacoustic spectroscopy of trace hazardous chemicals using quantum cascade laser

    Science.gov (United States)

    Kumar, Deepak; Ghai, Devinder Pal; Soni, R. K.

    2016-12-01

    We report an ultrasonic sensor based on open-cell photoacoustic spectroscopy method for the detection of explosive agents in traces. Experimentally, we recorded photoacoustic spectra of traces of hazardous explosives and molecules. Tunable mid-infrared quantum cascade lasers in the wavelength range 7.0-8.8 μm lying in the molecular fingerprint region are used as optical source. Samples of Pentaerylthirol Tetranitrate (PETN), Tetranitro-triazacyclohexane (RDX), Dinitrotoluene, p-Nitrobenzoic acid and other chemicals like Ibuprofen having quantity 1.0 mg were detected using a custom made photoacoustic cells in both open and closed configurations. The explosive traces were swiped using paper from contaminated surface and detected. Finite element mesh based simulation of photoacoustic cell is carried out for optimization of geometry at ultrasonic frequency (40 kHz). A point sensor based on above approach will be very effective for forensic applications and suspicious material screening.

  14. On-chip dual-comb based on quantum cascade laser frequency combs

    Energy Technology Data Exchange (ETDEWEB)

    Villares, G., E-mail: gustavo.villares@phys.ethz.ch; Wolf, J.; Kazakov, D.; Süess, M. J.; Beck, M.; Faist, J., E-mail: jfaist@phys.ethz.ch [Institute for Quantum Electronics, ETH Zürich, CH-8093 Zürich (Switzerland); Hugi, A. [IRsweep GmbH, CH-8093 Zürich (Switzerland)

    2015-12-21

    Dual-comb spectroscopy is emerging as an appealing application of mid-infrared frequency combs for high-resolution molecular spectroscopy, as it leverages on the unique coherence properties of frequency combs. Here, we present an on-chip dual-comb source based on mid-infrared quantum cascade laser frequency combs. Control of the combs repetition and offset frequencies is obtained by integrating micro-heaters next to each laser. We show that a full control of the dual-comb system is possible, by measuring a multi-heterodyne beating corresponding to an optical bandwidth of 32 cm{sup −1} centered at 1330 cm{sup −1} (7.52 μm), demonstrating that this device represents a critical step towards compact dual-comb systems.

  15. Proton implantation for the isolation of AlGaAs/GaAs quantum cascade lasers

    Science.gov (United States)

    Szerling, A.; Kosiel, K.; Kozubal, M.; Myśliwiec, M.; Jakieła, R.; Kuc, M.; Czyszanowski, T.; Kruszka, R.; Pągowska, K.; Karbownik, P.; Barcz, A.; Kamińska, E.; Piotrowska, A.

    2016-07-01

    The novel fabrication scheme of the mid-infrared (∼9.5 μm) Al0.45Ga0.55As/GaAs plasmon-enhanced-waveguide quantum cascade laser (QCL) is reported. The electric isolation was made exclusively by 6.5 μm-deep proton implantation. The applied implantation allowed us to suppress the current spreading and at the same time enabled the laser radiation confinement without any mesa formation. A galvanic gold layer at least 3.5 μm thick covering the top ohmic contact was used as a mask for implantation. This mask was not removed after the implantation, but it served for heat spreading from the laser. A considerable reduction in the necessary technological steps was obtained with the presented novel fabrication scheme, in comparison with the standard mesa-etching-based method.

  16. Quantum Cascade Laser-Based Photoacoustic Spectroscopy for Trace Vapor Detection and Molecular Discrimination

    Directory of Open Access Journals (Sweden)

    Almon Fisher

    2010-03-01

    Full Text Available We report on the development of a microelectromechanical systems (MEMS-scale photoacoustic sensor for the detection of trace gases. A mid-infrared quantum cascade laser (QCL was used to determine detection limits for acetic acid, acetone, 1,4-dioxane, and vinyl acetate. The source was continuously tunable from 1015 cm-1 to 1240 cm-1, allowing for the collection of photoacoustic vibrational spectra for these gases. Exceptional agreement between the measured photoacoustic spectra and the infrared spectra for acetic acid, acetone, 1,4-dioxane, and vinyl acetate was observed. Partial least-squares (PLS regression was used to develop an algorithm for classification of these compounds based solely on photoacoustic spectra.

  17. A phonon scattering assisted injection and extraction based terahertz quantum cascade laser

    Science.gov (United States)

    Dupont, E.; Fathololoumi, S.; Wasilewski, Z. R.; Aers, G.; Laframboise, S. R.; Lindskog, M.; Razavipour, S. G.; Wacker, A.; Ban, D.; Liu, H. C.

    2012-04-01

    A lasing scheme for terahertz quantum cascade lasers, based on consecutive phonon-photon-phonon emissions per module, is proposed and experimentally demonstrated. The charge transport of the proposed structure is modeled using a rate equation formalism. An optimization code based on a genetic algorithm was developed to find a four-well design in the GaAs/Al0.25Ga0.75As material system that maximizes the product of population inversion and oscillator strength at 150 K. The fabricated devices using Au double-metal waveguides show lasing at 3.2 THz up to 138 K. The electrical characteristics display no sign of differential resistance drop at lasing threshold, which, in conjunction with the low optical power of the device, suggest—thanks to the rate equation model—a slow depopulation rate of the lower lasing state, a hypothesis confirmed by non-equilibrium Green's function calculations.

  18. Phase Locking of a 2.7 THz Quantum Cascade Laser to a Microwave Reference

    Science.gov (United States)

    Khosropanah, P.; Baryshev, A.; Zhang, W.; Jellema, W.; Hovenier, J. N.; Gao, J. R.; Klapwijk, T. M.; Paveliev, D. G.; Williams, B. S.; Hu, Q.; Reno, J. L.; Klein, B.; Hesler, J. L.

    2009-01-01

    We demonstrate the phase locking of a 2.7 THz metal-metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain (x 12) from a microwave synthesizer at approx. 15 GHz. Both laser and reference radiations are coupled into a bolometer mixer, resulting in a beat signal, which is fed into a phase-lock loop. The spectral analysis of the beat signal confirms that the QCL is phase locked. This result opens the possibility to extend heterodyne interferometers into the far-infrared range.

  19. Electronic temperatures of terahertz quantum cascade active regions with phonon scattering assisted injection and extraction scheme.

    Science.gov (United States)

    Patimisco, Pietro; Scamarcio, Gaetano; Santacroce, Maria Vittoria; Spagnolo, Vincenzo; Vitiello, Miriam Serena; Dupont, Emmanuel; Laframboise, Sylvain R; Fathololoumi, Saeed; Razavipour, Ghasem S; Wasilewski, Zbigniew

    2013-04-22

    We measured the lattice and subband electronic temperatures of terahertz quantum cascade devices based on the optical phonon-scattering assisted active region scheme. While the electronic temperature of the injector state (j = 4) significantly increases by ΔT = T(e)(4) - T(L) ~40 K, in analogy with the reported values in resonant phonon scheme (ΔT ~70-110 K), both the laser levels (j = 2,3) remain much colder with respect to the latter (by a factor of 3-5) and share the same electronic temperature of the ground level (j = 1). The electronic population ratio n(2)/n(1) shows that the optical phonon scattering efficiently depopulates the lower laser level (j = 2) up to an electronic temperature T(e) ~180 K.

  20. Quantum-coherent coupling of a mechanical oscillator to an optical cavity mode.

    Science.gov (United States)

    Verhagen, E; Deléglise, S; Weis, S; Schliesser, A; Kippenberg, T J

    2012-02-01

    Optical laser fields have been widely used to achieve quantum control over the motional and internal degrees of freedom of atoms and ions, molecules and atomic gases. A route to controlling the quantum states of macroscopic mechanical oscillators in a similar fashion is to exploit the parametric coupling between optical and mechanical degrees of freedom through radiation pressure in suitably engineered optical cavities. If the optomechanical coupling is 'quantum coherent'--that is, if the coherent coupling rate exceeds both the optical and the mechanical decoherence rate--quantum states are transferred from the optical field to the mechanical oscillator and vice versa. This transfer allows control of the mechanical oscillator state using the wide range of available quantum optical techniques. So far, however, quantum-coherent coupling of micromechanical oscillators has only been achieved using microwave fields at millikelvin temperatures. Optical experiments have not attained this regime owing to the large mechanical decoherence rates and the difficulty of overcoming optical dissipation. Here we achieve quantum-coherent coupling between optical photons and a micromechanical oscillator. Simultaneously, coupling to the cold photon bath cools the mechanical oscillator to an average occupancy of 1.7 ± 0.1 motional quanta. Excitation with weak classical light pulses reveals the exchange of energy between the optical light field and the micromechanical oscillator in the time domain at the level of less than one quantum on average. This optomechanical system establishes an efficient quantum interface between mechanical oscillators and optical photons, which can provide decoherence-free transport of quantum states through optical fibres. Our results offer a route towards the use of mechanical oscillators as quantum transducers or in microwave-to-optical quantum links.

  1. Point and standoff detection of trace explosives using quantum cascade lasers

    Science.gov (United States)

    Kim, Seonghwan; Lee, Dongkyu; Liu, Xunchen; Van Neste, C. W.; Thundat, Thomas

    2014-06-01

    Chemical sensors based on micro/nanoelectromechanical systems (M/NEMS) offer many advantages. However, obtaining chemical selectivity in M/NEMS sensors using chemoselective interfaces has been a longstanding challenge. Despite their many advantages, M/NEMS devices relying on chemoselective interfaces do not have sufficient selectivity. Therefore, highly sensitive and selective detection and quantification of chemical molecules using real-time, miniature sensor platforms still remains as a crucial challenge. Incorporating photothermal/photoacoustic spectroscopic techniques with M/NEMS using quantum cascade lasers can provide the chemical selectivity without sacrificing the sensitivity of the miniaturized sensing system. Point sensing is defined as sensing that requires collection and delivery of the target molecules to the sensor for detection and analysis. For example, photothermal cantilever deflection spectroscopy, which combines the high thermomechanical sensitivity of a bimetallic microcantilever with high selectivity of the mid infrared (IR) spectroscopy, is capable of obtaining molecular signatures of extremely small quantities of adsorbed explosive molecules (tens of picogram). On the other hand, standoff sensing is defined as sensing where the sensor and the operator are at distance from the target samples. Therefore, the standoff sensing is a non-contact method of obtaining molecular signatures without sample collection and processing. The distance of detection depends on the power of IR source, the sensitivity of a detector, and the efficiency of the collecting optics. By employing broadly tunable, high power quantum cascade lasers and a boxcar averager, molecular recognition of trace explosive compounds (1 μg/cm2 of RDX) on a stainless steel surface has been achieved at a distance of five meters.

  2. Vacuum-Induced Abelian and Non-Abelian Gauge Potentials in Cavity Quantum Electrodynamics

    Institute of Scientific and Technical Information of China (English)

    张海龙; 梁奇锋; 俞立先; 陈刚

    2011-01-01

    Gauge potential plays an important role in exploring exotic phenomena in the single- and many-body quantum systems. In this paper, we propose a scheme to create both new Abelian and non-Abelian gauge potentials by adiabatically controlling the degenerate Dicke model in cavity quantum electrodynamics. It is shown that a non-Abelian gauge potential is achieved only for a single atom, whereas an Abelianizen diagonal gauge potential is realized for the atomic ensemble. More importantly, two interesting quantum phenomena such as the geometric phase and the magnetic monopole induced by our created gauge potentials are also predicted. The possible physical realization is presented in the macroscopic circuit quantum electrodynamics with the Cooper pair boxes, which act as the artificial two-level atoms controlled by the gate voltage and the external magnetic flux.

  3. Atoms and molecules in cavities, from weak to strong coupling in quantum-electrodynamics (QED) chemistry.

    Science.gov (United States)

    Flick, Johannes; Ruggenthaler, Michael; Appel, Heiko; Rubio, Angel

    2017-03-21

    In this work, we provide an overview of how well-established concepts in the fields of quantum chemistry and material sciences have to be adapted when the quantum nature of light becomes important in correlated matter-photon problems. We analyze model systems in optical cavities, where the matter-photon interaction is considered from the weak- to the strong-coupling limit and for individual photon modes as well as for the multimode case. We identify fundamental changes in Born-Oppenheimer surfaces, spectroscopic quantities, conical intersections, and efficiency for quantum control. We conclude by applying our recently developed quantum-electrodynamical density-functional theory to spontaneous emission and show how a straightforward approximation accurately describes the correlated electron-photon dynamics. This work paves the way to describe matter-photon interactions from first principles and addresses the emergence of new states of matter in chemistry and material science.

  4. Quantum-dot nano-cavity lasers with Purcell-enhanced stimulated emission

    DEFF Research Database (Denmark)

    Gregersen, Niels; Skovgård, Troels Suhr; Lorke, Michael;

    2012-01-01

    We present a rate equation model for quantum-dot light-emitting devices that take into account Purcell enhancement of both spontaneous emission and stimulated emission as well as the spectral profile of the optical and electronic density-of-states. We find that below threshold the b-factor in a q......We present a rate equation model for quantum-dot light-emitting devices that take into account Purcell enhancement of both spontaneous emission and stimulated emission as well as the spectral profile of the optical and electronic density-of-states. We find that below threshold the b......-factor in a quantum-dot nanolaser depends strongly on the pump. For quantum dots with linewidth comparable to that of the cavity, we then show that an otherwise non-lasing device can lase due to Purcell enhancement of the stimulated emission. Finally, we compare the rate equation model to a microscopic model...

  5. Backaction-limited cavity-sideband spectroscopy of quantum collective motion

    CERN Document Server

    Brahms, Nathan; Schreppler, Sydney; Brooks, Daniel W C; Stamper-Kurn, Dan M

    2011-01-01

    The motion of sub-atomic particles is characteristically quantum mechanical in nature. In contrast, quantum aspects of the motion of massive, many-atom objects are typically obscured by high phonon occupation and thermal noise. This contrast is now diminishing, owing to research efforts to bring the control and measurement of macroscopic motion fully into the quantum regime, using objects with masses from attograms to kilograms. This achievement will be critical for constructing force detectors sensitive to gravitational waves, verifying the correspondence principle at macroscopic scales, and realizing protocols that mechanically store and exchange quantum information. Here, we directly observe the quantization of the collective motion of an ultracold atomic ensemble by measuring the inability of a 0.6 attogram centre-of-mass mode to emit energy from its ground state. Moreover, the optical output of our strongly coupled cavity-optomechanical system contains a spectroscopic record of the energy exchanged betwe...

  6. Preservation of quantum correlation between separated nitrogen-vacancy centers embedded in photonic-crystal cavities

    Science.gov (United States)

    Yang, Wanli; An, Jun-Hong; Zhang, Chengjie; Feng, Mang; Oh, C. H.

    2014-03-01

    We investigate the non-Markovian dynamics of quantum correlation between two initially entangled nitrogen-vacancy centers (NVC) embedded in photonic crystal cavities (PCC). We find that a finite quantum correlation is preserved even asymptotically when the transition frequency ofthe NVC is within the band gap of the PCC, which is quantitatively different from the result of approaching zero under the Born-Markovian approximation. In addition, once the transition frequency of NVC is far beyond the bad gap of the PCC, the quantum correlation initially prepared in NVC will be fully transferred to the reservoirs in the long-time limit. Our result reveals that the interplay between the non-Markovian effect of the structured reservoirs and the existence of emitter-field bound state plays an essential role in such quantum correlation preservation. This feature may open new perspectives for devising active decoherence-immune solid-state optical devices.

  7. Quantum entanglement and teleportation in pulsed cavity optomechanics

    Energy Technology Data Exchange (ETDEWEB)

    Hofer, Sebastian G. [Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Institute for Theoretical Physics, Institute for Gravitational Physics, Leibniz University Hannover, Callinstrasse 38, 30167 Hannover (Germany); Wieczorek, Witlef; Aspelmeyer, Markus [Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Hammerer, Klemens [Institute for Theoretical Physics, Institute for Gravitational Physics, Leibniz University Hannover, Callinstrasse 38, 30167 Hannover (Germany)

    2011-11-15

    Entangling a mechanical oscillator with an optical mode is an enticing and yet a very challenging goal in cavity optomechanics. Here we consider a pulsed scheme to create Einstein-Podolsky-Rosen-type entanglement between a traveling-wave light pulse and a mechanical oscillator. The entanglement can be verified unambiguously by a pump-probe sequence of pulses. In contrast to schemes that work in a steady-state regime under a continuous-wave drive, this protocol is not subject to stability requirements that normally limit the strength of achievable entanglement. We investigate the protocol's performance under realistic conditions, including mechanical decoherence, in full detail. We discuss the relevance of a high mechanical Qf product for entanglement creation and provide a quantitative statement on which magnitude of the Qf product is necessary for a successful realization of the scheme. We determine the optimal parameter regime for its operation and show it to work in current state-of-the-art systems.

  8. Long-distance entanglement and quantum communication in coupled cavity arrays

    CERN Document Server

    Giampaolo, S M

    2009-01-01

    We introduce quantum spin models that allow for long-distance end-to-end entanglement and long-distance, high-fidelity teleportation, even at moderately high temperatures. We show how these models, that realize an optimal compromise between scalability and resilience to decoherence, can be implemented in simply engineered arrays of coupled optical cavities. We demonstrate how the latter can be used to realize a quasi-deterministic scheme of long-distance quantum communication with high success rate, without direct projection on Bell states and Bell measurements.

  9. Two-Qubit Geometric Phase Gate for Quantum Dot Spins using Cavity Polariton Resonance

    CERN Document Server

    Puri, Shruti; Yamamoto, Yoshihisa

    2012-01-01

    We describe a design to implement a two-qubit geometric phase gate, by which a pair of electrons confined in adjacent quantum dots are entangled. The entanglement is a result of the Coulomb exchange interaction between the optically excited exciton-polaritons and the localized spins. This optical coupling, resembling the electron-electron Ruderman-Kittel-Kasuya-Yosida (RKKY) inter- actions, offers high speed, high fidelity two-qubit gate operation with moderate cavity quality factor Q. The errors due to the finite lifetime of the polaritons can be minimized by optimizing the optical pulse parameters (duration and energy). The proposed design, using electrostatic quantum dots, maximizes entanglement and ensures scalability.

  10. Encoding quantum information in a stabilized manifold of a superconducting cavity

    Science.gov (United States)

    Touzard, S.; Leghtas, Z.; Mundhada, S. O.; Axline, C.; Reagor, M.; Chou, K.; Blumoff, J.; Sliwa, K. M.; Shankar, S.; Frunzio, L.; Schoelkopf, R. J.; Mirrahimi, M.; Devoret, M. H.

    In a superconducting Josephson circuit architecture, we activate a multi-photon process between two modes by applying microwave drives at specific frequencies. This creates a pairwise exchange of photons between a high-Q cavity and the environment. The resulting open dynamical system develops a two-dimensional quasi-energy ground state manifold. Can we encode, protect and manipulate quantum information in this manifold? We experimentally investigate the convergence and escape rates in and out of this confined subspace. Finally, using quantum Zeno dynamics, we aim to perform gates which maintain the state in the protected manifold at all times. Work supported by: ARO, ONR, AFOSR and YINQE.

  11. Cavity quantum electrodynamics with many-body states of a two-dimensional electron gas.

    Science.gov (United States)

    Smolka, Stephan; Wuester, Wolf; Haupt, Florian; Faelt, Stefan; Wegscheider, Werner; Imamoglu, Ataç

    2014-10-17

    Light-matter interaction has played a central role in understanding as well as engineering new states of matter. Reversible coupling of excitons and photons enabled groundbreaking results in condensation and superfluidity of nonequilibrium quasiparticles with a photonic component. We investigated such cavity-polaritons in the presence of a high-mobility two-dimensional electron gas, exhibiting strongly correlated phases. When the cavity was on resonance with the Fermi level, we observed previously unknown many-body physics associated with a dynamical hole-scattering potential. In finite magnetic fields, polaritons show distinct signatures of integer and fractional quantum Hall ground states. Our results lay the groundwork for probing nonequilibrium dynamics of quantum Hall states and exploiting the electron density dependence of polariton splitting so as to obtain ultrastrong optical nonlinearities.

  12. Realization of quantum gates with multiple control qubits or multiple target qubits in a cavity

    Science.gov (United States)

    Waseem, Muhammad; Irfan, Muhammad; Qamar, Shahid

    2015-06-01

    We propose a scheme to realize a three-qubit controlled phase gate and a multi-qubit controlled NOT gate of one qubit simultaneously controlling n-target qubits with a four-level quantum system in a cavity. The implementation time for multi-qubit controlled NOT gate is independent of the number of qubit. Three-qubit phase gate is generalized to n-qubit phase gate with multiple control qubits. The number of steps reduces linearly as compared to conventional gate decomposition method. Our scheme can be applied to various types of physical systems such as superconducting qubits coupled to a resonator and trapped atoms in a cavity. Our scheme does not require adjustment of level spacing during the gate implementation. We also show the implementation of Deutsch-Joza algorithm. Finally, we discuss the imperfections due to cavity decay and the possibility of physical implementation of our scheme.

  13. Genetic algorithm applied to the optimization of quantum cascade lasers with second harmonic generation

    Science.gov (United States)

    Gajić, A.; Radovanović, J.; Milanović, V.; Indjin, D.; Ikonić, Z.

    2014-02-01

    A computational model for the optimization of the second order optical nonlinearities in GaInAs/AlInAs quantum cascade laser structures is presented. The set of structure parameters that lead to improved device performance was obtained through the implementation of the Genetic Algorithm. In the following step, the linear and second harmonic generation power were calculated by self-consistently solving the system of rate equations for carriers and photons. This rate equation system included both stimulated and simultaneous double photon absorption processes that occur between the levels relevant for second harmonic generation, and material-dependent effective mass, as well as band nonparabolicity, were taken into account. The developed method is general, in the sense that it can be applied to any higher order effect, which requires the photon density equation to be included. Specifically, we have addressed the optimization of the active region of a double quantum well In0.53Ga0.47As/Al0.48In0.52As structure and presented its output characteristics.

  14. High-power quantum cascade lasers (QCLs) grown by GasMBE

    Science.gov (United States)

    Razeghi, Manijeh; Slivken, Steven

    2003-10-01

    This paper is a brief summary of the technological development and state-of-the-art performance of quantum cascade lasers produced at the Centre for Quantum Devices. Laser design will be discussed, as well as experimental details of device fabrication. Recent work has focused on the development of high peak and average power QCLs emitting at room temperature and above. Scaling of the output is demonstrated by increasing the number of emitting regions in the waveguide core. At λ = 9 μm, over 7 W of peak power has been demonstrated at room temperature for a single diode, with an average power of 300 mW at 6% duty cycle. At shorter wavelengths, laser development includes the use of highly strain-balanced heterostructures in order to maintain a high conduction band offset and minimize leakage current. At λ = 6 μm, utilizing a high reflective coating and epilayer-down mounting of the laser, we have demonstrated 225 mW of average power from a single facet at room temperature. Lastly, these results are put in perspective of other reported results and possible future directions are discussed.

  15. Investigations of repetition rate stability of a mode-locked quantum dot semiconductor laser in an auxiliary optical fiber cavity

    DEFF Research Database (Denmark)

    Breuer, Stefan; Elsässer, Wolfgang; McInerney, J.G.

    2010-01-01

    We have investigated experimentally the pulse train (mode beating) stability of a monolithic mode-locked multi-section quantum-dot laser with an added passive auxiliary optical fiber cavity. Addition of the weakly coupled (¿ -24dB) cavity reduces the current-induced shift d¿/dI of the principal...

  16. Auger Processes Mediating the Nonresonant Optical Emission from a Semiconductor Quantum Dot Embedded Inside an Optical Cavity

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Nielsen, Per Kær; Lund, Anders Mølbjerg;

    2013-01-01

    We show that Auger processes involving wetting layer transitions mediate emission from a cavity that is detuned from a quantum dot by even tens of meV. The wetting layer thus acts as a reservoir, which by Coulomb scattering can supply or absorb the energy difference between emitter and cavity. We...

  17. Trojan Wave Packets in the Quantum Cavity within the Extended Jaynes-Cummings Model

    Science.gov (United States)

    Kalinski, Matt

    2016-05-01

    Some time ago we have developed the theory of the Trojan Wave Packets (TWP) in the classical strong Circularly Polarized electromagnetic field in terms of the Mathieu generating functions. We have discovered that by the proper partitioning of the Coulomb spectrum i.e. by considering the deviation from the circularity and the vertical tilt of the undressed states as the new quantum numbers we can reduce the problem to the problem of several non-interacting quantum pendula for the Stark-Zeeman field dressed states. The TWP in the infinite physical space however turned out to be weakly unstable due to the spontaneous emission. Here we develop the theory in which the TWP is truly eternal when the electromagnetic interactions are considered quantum and the field is confined by the perfect quantum cavity boundary conditions. First we extend the Jaynes-Cummings (JC) model from the two to the infinite number of levels interacting with the one or two perfectly resonant quantum modes of the electromagnetic field. Similarly the model of JC and our previous pendular model the dressed electron-field eigenstates are constructed within the weakly interacting manifolds. Superpositions of those states are possible with the quantum electron density moving on the circular trajectories.

  18. Quantum Key Distribution Based on a Weak-Coupling Cavity QED Regime

    Institute of Scientific and Technical Information of China (English)

    李春燕; 李岩松

    2011-01-01

    We present a quantum key distribution scheme using a weak-coupling cavity QED regime based on quantum dense coding.Hybrid entanglement states of photons and electrons are used to distribute information.We just need to transmit photons without storing them in the scheme.The electron confined in a quantum dot,which is embedded in a microcavity,is held by one of the legitimate users throughout the whole communication process.Only the polarization of a single photon and spin of electron measurements are applied in this protocol,which are easier to perform than collective-Bell state measurements.Linear optical apparatus,such as a special polarizing beam splitter in a circular basis and single photon operations,make it more flexible to realize under current technology.Its efficiency will approach 100% in the ideal case.The security of the scheme is also discussed.%We present a quantum key distribution scheme using a weak-coupling cavity QED regime based on quantum dense coding. Hybrid entanglement states of photons and electrons are used to distribute information. We just need to transmit photons without storing them in the scheme. The electron confined in a quantum dot, which is embedded in a microcavity, is held by one of the legitimate users throughout the whole communication process. Only the polarization of a single photon and spin of electron measurements are applied in this protocol, which are easier to perform than collective-Bell state measurements. Linear optical apparatus, such as a speciai polarizing beam splitter in a circular basis and single photon operations, make it more flexible to realize under current technology. Its efficiency will approach 100% in the ideal case. The security of the scheme is also discussed.

  19. Proposal for manipulating and detecting spin and orbital States of trapped electrons on helium using cavity quantum electrodynamics.

    Science.gov (United States)

    Schuster, D I; Fragner, A; Dykman, M I; Lyon, S A; Schoelkopf, R J

    2010-07-23

    We propose a hybrid architecture in which an on-chip high finesse superconducting cavity is coupled to the lateral motion and spin state of a single electron trapped on the surface of superfluid helium. We estimate the motional coherence times to exceed 15  μs, while energy will be coherently exchanged with the cavity photons in less than 10 ns for charge states and faster than 1  μs for spin states, making the system attractive for quantum information processing and strong coupling cavity quantum electrodynamics experiments. The cavity is used for nondestructive readout and as a quantum bus mediating interactions between distant electrons or an electron and a superconducting qubit.

  20. Interband cascade light emitting devices based on type-II quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui Q.; Lin, C.H.; Murry, S.J. [Univ. of Houston, TX (United States). Space Vacuum Epitaxy Center] [and others

    1997-06-01

    The authors discuss physical processes in the newly developed type-II interband cascade light emitting devices, and review their recent progress in the demonstration of the first type-II interband cascade lasers and the observation of interband cascade electroluminescence up to room temperature in a broad mid-infrared wavelength region (extended to 9 {mu}m).

  1. Quantum Electrodynamics with Semiconductor Quantum Dots Coupled to Anderson‐localized Random Cavities

    DEFF Research Database (Denmark)

    Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren;

    2011-01-01

    of the spontaneous emission decay rate by up to a factor 15 and an efficiency of channeling single photons into Anderson-localized modes reaching values as high as 94%. These results prove that disordered photonic media provide an efficient platform for quantum electrodynamics, offering a novel route to quantum...

  2. X-ray quantum optics with Moessbauer nuclei in thin-film cavities

    Energy Technology Data Exchange (ETDEWEB)

    Heeg, Kilian Peter

    2014-12-09

    In this thesis thin-film cavities with embedded Moessbauer nuclei probed by near-resonant X-ray light are studied from a quantum optical perspective. A theoretical framework is developed and compact expressions for the observables are derived for the linear excitation regime, which is encountered in current experiments. Even advanced cavity layouts can be modeled in excellent agreement with the results of previous experiments and semi-classical approaches. In the absence of magnetic hyperfine splitting, the spectral response of the system is found to be formed by tunable Fano profiles. An experimental implementation of this line shape control allows to extract spectroscopic signatures with high precision and to reconstruct the phase of the nuclear transition in good agreement with the theoretical predictions. The alignment of medium magnetization and polarization control of the X-rays enable to engineer advanced quantum optical level schemes, in which vacuum induced coherence effects are predicted and successfully demonstrated in an experiment. Furthermore, it is shown that group velocity control for x-ray pulses can be achieved in the cavity. A scheme for its observation is proposed and then employed to experimentally confirm sub-luminal X-ray propagation. Finally, non-linear effects, which could become accessible with future light sources, are explored and a non-linear line shape control mechanism is discussed.

  3. Quantum Noise Limits in White-Light-Cavity-Enhanced Gravitational Wave Detectors

    CERN Document Server

    Zhou, Minchuan; Shahriar, Selim M

    2014-01-01

    Previously, we had proposed a gravitational wave detector that incorporates the white light cavity (WLC) effect using a compound cavity for signal recycling (CC-SR). Here, we first calculate the quantum noise (QN) limited sensitivity curves for this design, and find that the broadening of sensitivity predicted by the classical analysis is also present in these curves, but is somewhat reduced. Furthermore, we find that the curves always stay above the standard quantum limit (SQL). To circumvent this limitation, we modify the dispersion to compensate the non-linear phase variation produced by the opto-mechanical (OM) resonance effects by making use of the single sideband approximation (SSA). We find that the resonance dips in the resulting QN curves entails a 14 times higher sensitivity-bandwidth product compared to the highest sensitivity result presented by Bunanno and Chen. We also present a simpler scheme (WLC-SR) where a dispersion medium is inserted in the SR cavity. Compared to the highest sensitivity re...

  4. Exciton dynamics in a site-controlled quantum dot coupled to a photonic crystal cavity

    Energy Technology Data Exchange (ETDEWEB)

    Jarlov, C., E-mail: clement.jarlov@epfl.ch; Lyasota, A.; Ferrier, L.; Gallo, P.; Dwir, B.; Rudra, A.; Kapon, E. [Laboratory of Physics of Nanostructures, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

    2015-11-09

    Exciton and cavity mode (CM) dynamics in site-controlled pyramidal quantum dots (QDs), integrated with linear photonic crystal membrane cavities, are investigated for a range of temperatures and photo-excitation power levels. The absence of spurious multi-excitonic effects, normally observed in similar structures based on self-assembled QDs, permits the observation of effects intrinsic to two-level systems embedded in a solid state matrix and interacting with optical cavity modes. The coupled exciton and CM dynamics follow the same trend, indicating that the CM is fed only by the exciton transition. The Purcell reduction of the QD and CM decay times is reproduced well by a theoretical model that includes exciton linewidth broadening and temperature dependent non-radiative processes, from which we extract a Purcell factor of 17 ± 5. For excitation powers above QD saturation, we show the influence of quantum wire barrier states at short delay time, and demonstrate the absence of multiexcitonic background emission.

  5. Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing

    Directory of Open Access Journals (Sweden)

    Simone Borri

    2016-02-01

    Full Text Available The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF2 microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line.

  6. Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing

    Science.gov (United States)

    Borri, Simone; Siciliani de Cumis, Mario; Insero, Giacomo; Bartalini, Saverio; Cancio Pastor, Pablo; Mazzotti, Davide; Galli, Iacopo; Giusfredi, Giovanni; Santambrogio, Gabriele; Savchenkov, Anatoliy; Eliyahu, Danny; Ilchenko, Vladimir; Akikusa, Naota; Matsko, Andrey; Maleki, Lute; De Natale, Paolo

    2016-01-01

    The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF2 microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line. PMID:26901199

  7. Measurements of the linewidth enhancement factor of mid-infrared quantum cascade lasers by different optical feedback techniques

    Directory of Open Access Journals (Sweden)

    L. Jumpertz

    2016-01-01

    Full Text Available Precise knowledge of the linewidth enhancement factor of a semiconductor laser under actual operating conditions is of prime importance since this parameter dictates various phenomena such as linewidth broadening or optical nonlinearities enhancement. The above-threshold linewidth enhancement factor of a mid-infrared quantum cascade laser structure operated at 10∘C is determined experimentally using two different methods based on optical feedback. Both Fabry-Perot and distributed feedback quantum cascade lasers based on the same active area design are studied, the former by following the wavelength shift as a function of the feedback strength and the latter by self-mixing interferometry. The results are consistent and unveil a clear pump current dependence of the linewidth enhancement factor, with values ranging from 0.8 to about 3.

  8. Measurements of the linewidth enhancement factor of mid-infrared quantum cascade lasers by different optical feedback techniques

    Energy Technology Data Exchange (ETDEWEB)

    Jumpertz, L., E-mail: louise.jumpertz@telecom-paristech.fr [Université Paris-Saclay, Télécom ParisTech, CNRS LTCI, 46 rue Barrault, F-75013 Paris (France); MirSense, 8 avenue de la Vauve, F-91120 Palaiseau (France); Michel, F.; Pawlus, R.; Elsässer, W. [Technische Universität Darmstadt, Schlossgartenstr. 7, D-64289 Darmstadt (Germany); Schires, K. [Université Paris-Saclay, Télécom ParisTech, CNRS LTCI, 46 rue Barrault, F-75013 Paris (France); Carras, M. [MirSense, 8 avenue de la Vauve, F-91120 Palaiseau (France); Grillot, F. [Université Paris-Saclay, Télécom ParisTech, CNRS LTCI, 46 rue Barrault, F-75013 Paris (France); also with Center for High Technology Materials, University of New-Mexico, 1313 Goddard SE, Albuquerque, NM (United States)

    2016-01-15

    Precise knowledge of the linewidth enhancement factor of a semiconductor laser under actual operating conditions is of prime importance since this parameter dictates various phenomena such as linewidth broadening or optical nonlinearities enhancement. The above-threshold linewidth enhancement factor of a mid-infrared quantum cascade laser structure operated at 10{sup ∘}C is determined experimentally using two different methods based on optical feedback. Both Fabry-Perot and distributed feedback quantum cascade lasers based on the same active area design are studied, the former by following the wavelength shift as a function of the feedback strength and the latter by self-mixing interferometry. The results are consistent and unveil a clear pump current dependence of the linewidth enhancement factor, with values ranging from 0.8 to about 3.

  9. Phonon-dressed Mollow triplet in the regime of cavity quantum electrodynamics: excitation-induced dephasing and nonperturbative cavity feeding effects.

    Science.gov (United States)

    Roy, C; Hughes, S

    2011-06-17

    We study the resonance fluorescence spectra of a driven quantum dot placed inside a high-Q semiconductor cavity and interacting with an acoustic phonon bath. The dynamics is calculated using a time-convolutionless master equation in the polaron frame. We predict pronounced spectral broadening of the Mollow sidebands through off-resonant cavity emission which, for small cavity-coupling rates, increases quadratically with the Rabi frequency in direct agreement with recent experiments using semiconductor micropillars [S. M. Ulrich et al., preceding Letter, Phys. Rev. Lett. 106, 247402 (2011)]. We also demonstrate that, surprisingly, phonon coupling actually helps resolve signatures of the elusive second rungs of the Jaynes-Cummings ladder states via off-resonant cavity feeding. Both multiphonon and multiphoton effects are shown to play a qualitatively important role on the fluorescence spectra.

  10. Thermal effects on sudden changes and freezing of correlations between remote atoms in a cavity quantum electrodynamics network.

    Science.gov (United States)

    Eremeev, Vitalie; Ciobanu, Nellu; Orszag, Miguel

    2014-05-01

    We investigate thermal effects on sudden changes and freezing of the quantum and classical correlations of remote qubits in a cavity quantum electrodynamics (CQED) network with losses. We find that the detrimental effect of thermal reservoirs on the freezing of correlations can be compensated via an efficient coupling of the fiber connecting the two cavities of the system. Furthermore, for certain initial conditions, we find a double sudden transition in the dynamics of Bures geometrical quantum discord. The second transition tends to disappear at a critical temperature, hence freezing the discord. Finally, we discuss the feasibility of the experimental realization of the present proposal.

  11. High-temperature operation of broadband bidirectional terahertz quantum-cascade lasers

    Science.gov (United States)

    Khanal, Sudeep; Gao, Liang; Zhao, Le; Reno, John L.; Kumar, Sushil

    2016-09-01

    Terahertz quantum cascade lasers (QCLs) with a broadband gain medium could play an important role for sensing and spectroscopy since then distributed-feedback schemes could be utilized to produce laser arrays on a single semiconductor chip with wide spectral coverage. QCLs can be designed to emit at two different frequencies when biased with opposing electrical polarities. Here, terahertz QCLs with bidirectional operation are developed to achieve broadband lasing from the same semiconductor chip. A three-well design scheme with shallow-well GaAs/Al0.10Ga0.90As superlattices is developed to achieve high-temperature operation for bidirectional QCLs. It is shown that shallow-well heterostructures lead to optimal quantum-transport in the superlattice for bidirectional operation compared to the prevalent GaAs/Al0.15Ga0.85As material system. Broadband lasing in the frequency range of 3.1-3.7 THz is demonstrated for one QCL design, which achieves maximum operating temperatures of 147 K and 128 K respectively in opposing polarities. Dual-color lasing with large frequency separation is demonstrated for a second QCL, that emits at ~3.7 THz and operates up to 121 K in one polarity, and at ~2.7 THz up to 105 K in the opposing polarity. These are the highest operating temperatures achieved for broadband terahertz QCLs at the respective emission frequencies, and could lead to commercial development of broadband terahertz laser arrays.

  12. Development of a Multi-Objective Evolutionary Algorithm for Strain-Enhanced Quantum Cascade Lasers

    Directory of Open Access Journals (Sweden)

    David Mueller

    2016-07-01

    Full Text Available An automated design approach using an evolutionary algorithm for the development of quantum cascade lasers (QCLs is presented. Our algorithmic approach merges computational intelligence techniques with the physics of device structures, representing a design methodology that reduces experimental effort and costs. The algorithm was developed to produce QCLs with a three-well, diagonal-transition active region and a five-well injector region. Specifically, we applied this technique to Al x Ga 1 - x As/In y Ga 1 - y As strained active region designs. The algorithmic approach is a non-dominated sorting method using four aggregate objectives: target wavelength, population inversion via longitudinal-optical (LO phonon extraction, injector level coupling, and an optical gain metric. Analysis indicates that the most plausible device candidates are a result of the optical gain metric and a total aggregate of all objectives. However, design limitations exist in many of the resulting candidates, indicating need for additional objective criteria and parameter limits to improve the application of this and other evolutionary algorithm methods.

  13. Toward a compact THz local oscillator based on a quantum-cascade laser

    Science.gov (United States)

    Richter, H.; Greiner-Baer, M.; Pavlov, S. G.; Semenov, A. D.; Wienold, M.; Schrottke, L.; Giehler, M.; Hey, R.; Grahn, H. T.; Hübers, H.-W.

    2010-07-01

    Heterodyne spectroscopy of molecular rotational lines and atomic fine-structure lines is a powerful tool in astronomy and planetary research. One example is the OI fine structure line at 4.7 THz. This is a main target for the observation with GREAT, the German Receiver for Astronomy at Terahertz Frequencies, which will be operated on board of SOFIA. We report on the development of a compact, easy-to-use source, which combines a quantum-cascade laser (QCL) with a compact, low-input-power Stirling cooler. This work is part of the local-oscillator development for GREAT/SOFIA. The QCL, which is based on a two-miniband design, has been developed for high output power and low electrical pump power. Efficient carrier injection is achieved by resonant longitudinal optical phonon scattering. The amount of generated heat complies with the cooling capacity of the Stirling cooler. The whole system weighs less than 15 kg including cooler, power supplies etc. The output power is above 1 mW. With an appropriate optical beam shaping, the emission profile of the laser becomes a fundamental Gaussian one. Sub-MHz frequency accuracy can be achieved by locking the emission of the QCL to a molecular resonance.

  14. Quantum cascade laser frequency stabilisation at the sub-Hz level

    CERN Document Server

    Argence, Bérengère; Lopez, Olivier; Nicolodi, Daniele; Abgrall, Michel; Chardonnet, Christian; Daussy, Christophe; Darquié, Benoît; Coq, Yann Le; Amy-Klein, Anne

    2014-01-01

    Quantum Cascade Lasers (QCL) are increasingly being used to probe the mid-infrared "molecular fingerprint" region. This prompted efforts towards improving their spectral performance, in order to reach ever-higher resolution and precision. Here, we report the stabilisation of a QCL onto an optical frequency comb. We demonstrate a relative stability and accuracy of 2x10-15 and 10-14, respectively. The comb is stabilised to a remote near-infrared ultra-stable laser referenced to frequency primary standards, whose signal is transferred via an optical fibre link. The stability and frequency traceability of our QCL exceed those demonstrated so far by two orders of magnitude. As a demonstration of its capability, we then use it to perform high-resolution molecular spectroscopy. We measure absorption frequencies with an 8x10-13 relative uncertainty. This confirms the potential of this setup for ultra-high precision measurements with molecules, such as our ongoing effort towards testing the parity symmetry by probing ...

  15. Operation of a Wideband Terahertz Superconducting Bolometer Responding to Quantum Cascade Laser Pulses

    Science.gov (United States)

    Cibella, S.; Beck, M.; Carelli, P.; Castellano, M. G.; Chiarello, F.; Faist, J.; Leoni, R.; Ortolani, M.; Sabbatini, L.; Scalari, G.; Torrioli, G.; Turcinkova, D.

    2012-06-01

    We make use of a niobium film to produce a micrometric vacuum-bridge superconducting bolometer responding to THz frequency. The bolometer works anywhere in the temperature range 2-7 K, which can be easily reached in helium bath cryostats or closed-cycle cryocoolers. In this work the bolometer is mounted on a pulse tube refrigerator and operated to measure the equivalent noise power (NEP) and the response to fast (μs) terahertz pulses. The NEP above 100 Hz equals that measured in a liquid helium cryostat showing that potential drawbacks related to the use of a pulse tube refrigerator (like mechanical and thermal oscillations, electromagnetic interference, noise) are irrelevant. At low frequency, instead, the pulse tube expansion-compression cycles originate lines at 1 Hz and harmonics in the noise spectrum. The bolometer was illuminated with THz single pulses coming either from a Quantum Cascade Laser operating at liquid nitrogen temperature or from a frequency-multiplied electronic oscillator. The response of the bolometer to the single pulses show that the device can track signals with a rise time as fast as about 450 ns.

  16. Open-path, quantum cascade laser-based sensor for high resolution atmospheric ammonia measurements

    Directory of Open Access Journals (Sweden)

    D. J. Miller

    2013-07-01

    Full Text Available We demonstrate a compact, open-path, quantum cascade laser-based atmospheric ammonia sensor operating at 9.06 μm for high sensitivity, high temporal resolution, ground-based measurements. Atmospheric ammonia (NH3 is a gas-phase precursor to fine particulate matter, with implications for air quality and climate change. Currently, NH3 sensing challenges have led to a lack of widespread in-situ measurements. Our open-path sensor configuration avoids sampling artifacts associated with NH3 surface adsorption onto inlet tubing and reduced pressure sampling cells, as well as condensed-phase partitioning ambiguities. Multi-harmonic wavelength modulation spectroscopy allows for selective and sensitive detection of atmospheric-pressure broadened absorption features. An in-line ethylene reference cell provides real-time calibration (±20% accuracy and normalization for instrument drift under rapidly changing field conditions. The sensor has a sensitivity and minimum detection limit of 0.15 ppbv NH3 at 10 Hz, a mass of ~ 5 kg and consumes ~ 50 W of electrical power. In-situ field performance of this open-path NH3 sensor is demonstrated, with 10 Hz time resolution and a large dynamic response for in-situ NH3 measurements. This sensor provides the capabilities for improved in-situ gas phase NH3 sensing relevant for emission source characterization and flux measurements.

  17. Sensitive detection of acrolein and acrylonitrile with a pulsed quantum-cascade laser

    Science.gov (United States)

    Manne, J.; Lim, A.; Tulip, J.; Jäger, W.

    2012-05-01

    We report on spectroscopic measurements of acrolein and acrylonitrile at atmospheric pressure using a pulsed distributed feedback quantum-cascade laser in combination with intra- and inter-pulse techniques and compare the results. The measurements were done in the frequency region around 957 cm-1. In the inter-pulse technique, the laser is excited with short current pulses (5-10 ns), and the pulse amplitude is modulated with an external current ramp resulting in a ˜2.3 cm-1 frequency scan. In the intra-pulse technique, a linear frequency down-chirp during the pulse is used for sweeping across the absorption line. Long current pulses up to 500 ns were used for these measurements which resulted in a spectral window of ˜2.2 cm-1 during the down-chirp. These comparatively wide spectral windows facilitated the measurements of the relatively broad absorption lines (˜1 cm-1) of acrolein and acrylonitrile. The use of a room-temperature mercury-cadmium-telluride detector resulted in a completely cryogen-free spectrometer. We demonstrate ppb level detection limits within a data acquisition time of ˜10 s with these methodologies.

  18. Multi-modal, ultrasensitive detection of trace explosives using MEMS devices with quantum cascade lasers

    Science.gov (United States)

    Zandieh, Omid; Kim, Seonghwan

    2016-05-01

    Multi-modal chemical sensors based on microelectromechanical systems (MEMS) have been developed with an electrical readout. Opto-calorimetric infrared (IR) spectroscopy, capable of obtaining molecular signatures of extremely small quantities of adsorbed explosive molecules, has been realized with a microthermometer/microheater device using a widely tunable quantum cascade laser. A microthermometer/microheater device responds to the heat generated by nonradiative decay process when the adsorbed explosive molecules are resonantly excited with IR light. Monitoring the variation in microthermometer signal as a function of illuminating IR wavelength corresponds to the conventional IR absorption spectrum of the adsorbed molecules. Moreover, the mass of the adsorbed molecules is determined by measuring the resonance frequency shift of the cantilever shape microthermometer for the quantitative opto-calorimetric IR spectroscopy. In addition, micro-differential thermal analysis, which can be used to differentiate exothermic or endothermic reaction of heated molecules, has been performed with the same device to provide additional orthogonal signal for trace explosive detection and sensor surface regeneration. In summary, we have designed, fabricated and tested microcantilever shape devices integrated with a microthermometer/microheater which can provide electrical responses used to acquire both opto-calorimetric IR spectra and microcalorimetric thermal responses. We have demonstrated the successful detection, differentiation, and quantification of trace amounts of explosive molecules and their mixtures (cyclotrimethylene trinitramine (RDX) and pentaerythritol tetranitrate (PETN)) using three orthogonal sensing signals which improve chemical selectivity.

  19. Exhaled nitric oxide monitoring by quantum cascade laser: comparison with chemiluminescent and electrochemical sensors.

    Science.gov (United States)

    Mandon, Julien; Högman, Marieann; Merkus, Peter J F M; van Amsterdam, Jan; Harren, Frans J M; Cristescu, Simona M

    2012-01-01

    Fractional exhaled nitric oxide (F(E)NO) is considered an indicator in the diagnostics and management of asthma. In this study we present a laser-based sensor for measuring F(E)NO. It consists of a quantum cascade laser (QCL) combined with a multi-pass cell and wavelength modulation spectroscopy for the detection of NO at the sub-part-per-billion by volume (ppbv, 110(-9)) level. The characteristics and diagnostic performance of the sensor were assessed. A detection limit of 0.5 ppbv was demonstrated with a relatively simple design. The QCL-based sensor was compared with two market sensors, a chemiluminescent analyzer (NOA 280, Sievers) and a portable hand-held electrochemical analyzer (MINO, Aerocrine AB, Sweden). F(E)NO from 20 children diagnosed with asthma and treated with inhaled corticosteroids were measured. Data were found to be clinically acceptable within 1.1 ppbv between the QCL-based sensor and chemiluminescent sensor and within 1.7 ppbv when compared to the electrochemical sensor. The QCL-based sensor was tested on healthy subjects at various expiratory flow rates for both online and offline sampling procedures. The extended NO parameters, i.e. the alveolar region, airway wall, diffusing capacity, and flux were calculated and showed a good agreement with the previously reported values.

  20. Exhaled nitric oxide monitoring by quantum cascade laser: comparison with chemiluminescent and electrochemical sensors

    Science.gov (United States)

    Mandon, Julien; Högman, Marieann; Merkus, Peter J. F. M.; van Amsterdam, Jan; Harren, Frans J. M.; Cristescu, Simona M.

    2012-01-01

    Fractional exhaled nitric oxide (FENO) is considered an indicator in the diagnostics and management of asthma. In this study we present a laser-based sensor for measuring FENO. It consists of a quantum cascade laser (QCL) combined with a multi-pass cell and wavelength modulation spectroscopy for the detection of NO at the sub-part-per-billion by volume (ppbv, 1∶10-9) level. The characteristics and diagnostic performance of the sensor were assessed. A detection limit of 0.5 ppbv was demonstrated with a relatively simple design. The QCL-based sensor was compared with two market sensors, a chemiluminescent analyzer (NOA 280, Sievers) and a portable hand-held electrochemical analyzer (MINO®, Aerocrine AB, Sweden). FENO from 20 children diagnosed with asthma and treated with inhaled corticosteroids were measured. Data were found to be clinically acceptable within 1.1 ppbv between the QCL-based sensor and chemiluminescent sensor and within 1.7 ppbv when compared to the electrochemical sensor. The QCL-based sensor was tested on healthy subjects at various expiratory flow rates for both online and offline sampling procedures. The extended NO parameters, i.e. the alveolar region, airway wall, diffusing capacity, and flux were calculated and showed a good agreement with the previously reported values.

  1. A study of different metals employed in metal-metal waveguides for terahertz quantum cascade lasers

    Science.gov (United States)

    Szymański, Michał; Szerling, Anna; Kosiel, Kamil; Płuska, Mariusz

    2016-07-01

    We consider the possibility of improvement of metal-metal waveguides designed for terahertz quantum cascade lasers (THz QCL) with respect to waveguide losses. We calculate {α\\text{wg}} solving Helmholtz equation by transfer matrix method. The essence of our work is the error analysis. We notice that the refractive indices of metals in THz range are known with very poor accuracy. We present divergences among numerous measurements and calculations reported in the literature. In addition, we point out that optical properties of metals and semiconductors depend on temperature which varies throughout the working device. At last, we present our scanning electron microscope photos showing that semiconductor-metal and metal-metal interfaces are not perfect. In adjacent areas mixing of materials occurs and hence the spatial refractive index distribution is perturbed. Our error analysis shows that today’s accuracy of refractive index data (±37% is the best reported in the literature) makes the problem of optimization of considered waveguides ambiguous. According to our calculations the precision level of about  ±10% is required. Once improving the precision turns out to be impossible, we suggest focusing the design works on criteria such as choosing metals minimizing the risk of damaging the active region by atom migration, providing the best ohmic contact or allowing the most effective heat removal.

  2. Bloch-wave engineering of quantum dot-micropillars for cavity quantum electrodynamics experiments

    DEFF Research Database (Denmark)

    Lermer, Matthias; Gregersen, Niels; Dunzer, Florian;

    2012-01-01

    We have employed Bloch-wave engineering to realize submicron diameter ultra-high quality factor GaAs/AlAs micropillars (MPs). The design features a tapered cavity in which the fundamental Bloch mode is subject to an adiabatic transition to match the Bragg mirror Bloch mode. The resulting reduced ...

  3. Metasurface external cavity laser

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Luyao, E-mail: luyaoxu.ee@ucla.edu; Curwen, Christopher A.; Williams, Benjamin S. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Hon, Philip W. C.; Itoh, Tatsuo [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Chen, Qi-Sheng [Northrop Grumman Aerospace Systems, Redondo Beach, California 90278 (United States)

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  4. Nanofiber Fabry-Perot microresonator for nonlinear optics and cavity quantum electrodynamics.

    Science.gov (United States)

    Wuttke, C; Becker, M; Brückner, S; Rothhardt, M; Rauschenbeutel, A

    2012-06-01

    We experimentally realize a Fabry-Perot-type optical microresonator near the cesium D2 line wavelength based on a tapered optical fiber, equipped with two fiber Bragg gratings that enclose a subwavelength diameter waist. Owing to the very low taper losses, the finesse of the resonator reaches F=86 while the on-resonance transmission is T=11%. The characteristics of our resonator fulfill the requirements of nonlinear optics and cavity quantum electrodynamics in the strong coupling regime. These characteristics, combined with the demonstrated ease of use and advantageous mode geometry, open a realm of applications.

  5. Nanofiber Fabry-Perot microresonator for non-linear optics and cavity quantum electrodynamics

    CERN Document Server

    Wuttke, C; Brückner, S; Rothhardt, M; Rauschenbeutel, A

    2012-01-01

    We experimentally realize a Fabry-Perot-type optical microresonator near the cesium D2 line wavelength based on a tapered optical fiber, equipped with two fiber Bragg gratings which enclose a sub-wavelength diameter waist. Owing to the very low taper losses, the finesse of the resonator reaches F = 86 while the on-resonance transmission is T = 11 %. The characteristics of our resonator fulfill the requirements of non-linear optics and cavity quantum electrodynamics in the strong coupling regime. In combination with its demonstrated ease of use and its advantageous mode geometry, it thus opens a realm of applications.

  6. Tunable single and dual mode operation of an external cavity quantum-dot injection laser

    Energy Technology Data Exchange (ETDEWEB)

    Biebersdorf, A [Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universitaet, Amalienstrasse 54, D-80799 Munich (Germany); Lingk, C [Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universitaet, Amalienstrasse 54, D-80799 Munich (Germany); De Giorgi, M [Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universitaet, Amalienstrasse 54, D-80799 Munich (Germany); Feldmann, J [Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universitaet, Amalienstrasse 54, D-80799 Munich (Germany); Sacher, J [Sacher Lasertechnik GmbH, Hannah Arendt Strasse 3-7, D-35037 Marburg (Germany); Arzberger, M [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall, D-85748 Garching (Germany); Ulbrich, C [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall, D-85748 Garching (Germany); Boehm, G [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall, D-85748 Garching (Germany); Amann, M-C [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall, D-85748 Garching (Germany); Abstreiter, G [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall, D-85748 Garching (Germany)

    2003-08-21

    We investigate quantum-dot (QD) lasers in an external cavity using Littrow and Littman configurations. Here, we report on a continuously tunable QD laser with a broad tuning range from 1047 to 1130 nm with high stability and efficient side mode suppression. The full-width at half-maximum of the laser line is 0.85 nm determined mainly by the quality of the external grating. This laser can be operated in a dual-mode modus, where the mode-spacing can be tuned continuously between 1.1 and 34 nm. Simultaneous emission of the two laser modes is shown by sum frequency generation experiments.

  7. Cavity QED quantum phase gates for a single longitudinal mode of the intracavity field

    Science.gov (United States)

    García-Maraver, R.; Corbalán, R.; Eckert, K.; Rebić, S.; Artoni, M.; Mompart, J.

    2004-12-01

    A single three-level atom driven by a longitudinal mode of a high- Q cavity is used to implement two-qubit quantum phase gates for the intracavity field. The two qubits are associated with the zero- and one-photon Fock states of each of the two opposite circular polarization states of the field. The three-level atom mediates the conditional phase gate provided the two polarization states and the atom interact in a V-type configuration and the two-photon resonance condition is satisfied. Microwave and optical implementations are discussed with gate fidelities being evaluated against several decoherence mechanisms such as atomic velocity fluctuations or the presence of a weak magnetic field. The use of coherent states for both polarization states is investigated to assess the entanglement capability of the proposed quantum gates.

  8. Feedback in a cavity QED system for control of quantum beats

    Directory of Open Access Journals (Sweden)

    Cimmarusti A.D.

    2013-08-01

    Full Text Available Conditional measurements on the undriven mode of a two-mode cavity QED system prepare a coherent superposition of ground states which generate quantum beats. The continuous system drive induces decoherence through the phase interruptions from Rayleigh scattering, which manifests as a decrease of the beat amplitude and an increase of the frequency of oscillation. We report recent experiments that implement a simple feedback mechanism to protect the quantum beat. We continuously drive the system until a photon is detected, heralding the presence of a coherent superposition. We then turn off the drive and let the superposition evolve in the dark, protecting it against decoherence. At a later time we reinstate the drive to measure the amplitude, phase, and frequency of the beats. The amplitude can increase by more than fifty percent, while the frequency is unchanged by the feedback.

  9. Quantum simulation of 2D topological physics in a 1D array of optical cavities.

    Science.gov (United States)

    Luo, Xi-Wang; Zhou, Xingxiang; Li, Chuan-Feng; Xu, Jin-Shi; Guo, Guang-Can; Zhou, Zheng-Wei

    2015-07-06

    Orbital angular momentum of light is a fundamental optical degree of freedom characterized by unlimited number of available angular momentum states. Although this unique property has proved invaluable in diverse recent studies ranging from optical communication to quantum information, it has not been considered useful or even relevant for simulating nontrivial physics problems such as topological phenomena. Contrary to this misconception, we demonstrate the incredible value of orbital angular momentum of light for quantum simulation by showing theoretically how it allows to study a variety of important 2D topological physics in a 1D array of optical cavities. This application for orbital angular momentum of light not only reduces required physical resources but also increases feasible scale of simulation, and thus makes it possible to investigate important topics such as edge-state transport and topological phase transition in a small simulator ready for immediate experimental exploration.

  10. Cavity QED quantum phase gates for a single longitudinal mode of the intracavity field

    CERN Document Server

    García-Maraver, R; Eckert, K; Rebic, S; Artoni, M; Mompart, J

    2004-01-01

    A single three-level atom driven by a longitudinal mode of a high-Q cavity is used to implement two-qubit quantum phase gates for the intracavity field. The two qubits are associated to the zero-and one-photon Fock states of each of the two opposite circular polarization states of the field. The three-level atom yields the conditional phase gate provided the two polarization states and the atom interact in a $V$-type configuration and the two photon resonance condition is fulfilled. Microwave and optical implementations are discussed with gate fidelities being evaluated against several decoherence mechanisms such as atomic velocity fluctuations or the presence of a weak magnetic field. The use of coherent states for both polarization states is investigated to assess the entanglement capability of the proposed quantum gates.

  11. Microscopic theory of indistinguishable single-photon emission from a quantum dot coupled to a cavity: The role of non-Markovian phonon-induced decoherence

    DEFF Research Database (Denmark)

    Nielsen, Per Kær; Lodahl, Peter; Jauho, Antti-Pekka;

    2013-01-01

    We study the fundamental limit on single-photon indistinguishability imposed by decoherence due to phonon interactions in semiconductor quantum dot-cavity quantum electrodynamics systems. Employing an exact diagonalization approach we find large differences compared to standard methods...

  12. The transition from quantum Zeno to anti-Zeno effects for a qubit in a cavity by varying the cavity frequency

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xiufeng, E-mail: xfcao@xmu.edu.cn [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China); Advanced Science Institute, RIKEN, Wako-shi 351-0198 (Japan); Ai, Qing; Sun, Chang-Pu [Advanced Science Institute, RIKEN, Wako-shi 351-0198 (Japan); Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China); Nori, Franco [Advanced Science Institute, RIKEN, Wako-shi 351-0198 (Japan); Physics Department, The University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2012-01-09

    We propose a strategy to demonstrate the transition from the quantum Zeno effect (QZE) to the anti-Zeno effect (AZE) using a superconducting qubit coupled to a transmission line cavity, by varying the central frequency of the cavity mode. Our results are obtained without the rotating wave approximation (RWA), and the initial state (a dressed state) is easy to prepare. Moreover, we find that in the presence of both qubit's intrinsic bath and the cavity bath, the emergence of the QZE and the AZE behaviors relies not only on the match between the qubit energy-level-spacing and the central frequency of the cavity mode, but also on the coupling strength between the qubit and the cavity mode. -- Highlights: ► We propose how to demonstrate the transition from Zeno effect to anti-Zeno effect. ► Our results are beyond the RWA, and the initial state is easy to prepare. ► The case of both qubit's intrinsic bath and cavity bath coexist is also studied.

  13. Unconventional Geometric Phase-Shift Gates Based on Superconducting Quantum Interference Devices Coupled to a Single-Mode Cavity

    Institute of Scientific and Technical Information of China (English)

    SONG Ke-Hui; ZHOU Zheng-Wei; GUO Guang-Can

    2006-01-01

    We present a scheme to realize geometric phase-shift gate for two superconducting quantum interference device (SQUID) qubits coupled to a single-mode microwave field. The geometric phase-shift gate operation is performed transitions during the gate operation. Thus, the docoherence due to energy spontaneous emission based on the levels of SQUIDs are suppressed. The gate is insensitive to the cavity decay throughout the operation since the cavity mode is displaced along a circle in the phase space, acquiring a phase conditional upon the two lower flux states of the SQUID qubits, and the cavity mode is still in the original vacuum state. Based on the SQUID qubits interacting with the cavity mode, our proposed approach may open promising prospects for quantum logic in SQUID-system.

  14. Two simple schemes for implementing Toffoli gate via atom-cavity field interaction in cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Shao Xiao-Qiang; Chen Li; Zhang Shou

    2009-01-01

    This paper proposes two schemes for implementing three-qubit Toffoli gate with an atom (as target qubit) sent through a two-mode cavity (as control qubits). The first scheme is based on the large-detuning atom-cavity field interaction and the second scheme is based on the resonant atom-field interaction. Both the situations with and without cavity decay and atomic spontaneous emission are considered. The advantages and the experimental feasibility of these two schemes are discussed.

  15. Measuring intensity correlations of a THz quantum cascade laser around its threshold at sub-cycle timescales

    CERN Document Server

    Chelmus, Ileana Cristina Benea; Maissen, Curdin; Scalari, Giacomo; Beck, Mattias; Faist, Jerome

    2016-01-01

    The quantum nature of photonic systems is reflected in the photon statistics of the light they emit. Therefore, the development of quantum optics tools with single photon sensitivity and excellent temporal resolution is paramount to the development of exotic sources, and is particularly challenging in the THz range where photon energies approach kbT at T=300 K. Here, we report on the first room temperature measurement of field g1({\\tau}) and intensity correlations g2({\\tau}) in the THz range with sub-cycle temporal resolution (146 fs) over the bandwidth 0.3-3 THz, based on electro-optic sampling. With this system, we are able to measure the photon statistics at threshold of a THz Quantum Cascade Laser.

  16. Eddy covariance carbonyl sulfide flux measurements with a quantum cascade laser absorption spectrometer

    Science.gov (United States)

    Gerdel, Katharina; Spielmann, Felix M.; Hammerle, Albin; Wohlfahrt, Georg

    2016-04-01

    Carbonyl sulfide (COS) is the most abundant sulfur containing trace gas present in the troposphere at concentrations of around 500 ppt. Recent interest in COS by the ecosystem-physiological community has been sparked by the fact that COS co-diffuses into plant leaves pretty much the same way as carbon dioxide (CO2) does, but in contrast to CO2, COS is not known to be emitted by plants. Thus uptake of COS by vegetation has the potential to be used as a tracer for canopy gross photosynthesis, which cannot be measured directly, however represents a key term in the global carbon cycle. Since a few years, quantum cascade laser absorption spectrometers (QCLAS) are commercially available with the precision, sensitivity and time response suitable for eddy covariance (EC) flux measurements. While there exist a handful of published reports on EC flux measurements in the recent literature, no rigorous investigation of the applicability of QCLAS for EC COS flux measurements has been carried out so far, nor have been EC processing and QA/QC steps developed for carbon dioxide and water vapor flux measurements within FLUXNET been assessed for COS. The aim of this study is to close this knowledge gap, to discuss critical steps in the post-processing chain of COS EC flux measurements and to devise best-practice guidelines for COS EC flux data processing. To this end we collected EC COS (and CO2, H2O and CO) flux measurements above a temperate mountain grassland in Austria over the vegetation period 2015 with a commercially available QCLAS. We discuss various aspects of EC data post-processing, in particular issues with the time-lag estimation between sonic anemometer and QCLAS signals and QCLAS time series detrending, as well as QA/QC, in particular flux detection limits, random flux uncertainty, the interaction of various processing steps with common EC QA/QC filters (e.g. detrending and stationarity tests), u*-filtering, etc.

  17. Development of a Quantum Cascade Laser-Based Detector for Ammonia and Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Zahniser, Mark S.; Nelson, David D.; McManus, J. Barry; Shorter, Joanne H.; Herndon, Scott C.; Jimenez, Rodrigo

    2005-12-31

    We have developed a compact, robust, atmospheric trace gas detector based on mid-infrared absorption spectroscopy using pulsed quantum cascade (QC) lasers. The spectrometer is suitable for airborne measurements of ammonia, nitric acid, formaldehyde, formic acid, methane, nitrous oxide, carbon monoxide, nitrogen dioxide and other gases that have line-resolved absorption spectra in the mid-infrared spectral region. The QC laser light source operates near room temperature with thermal electric cooling instead of liquid nitrogen which has been previously required for semiconductor lasers in the mid-infrared spectral region. The QC lasers have sufficient output power so that thermal electric cooled detectors may be used in many applications with lower precision requirements. The instrument developed in this program has been used in several field campaigns from both the Aerodyne Mobile Laboratory and from the NOAA WP3 aircraft. The Phase II program has resulted in more than 10 archival publications describing the technology and its applications. Over 12 instruments based on this design have been sold to research groups in Europe and the United States making the program both a commercial as well as a technological success. Anticipated Benefits The development of a sensitive, cryogen-free, mid-infrared absorption method for atmospheric trace gas detection will have wide benefits for atmospheric and environmental research and broader potential commercial applications in areas such as medical diagnostic and industrial process monitoring of gaseous compounds. Examples include air pollution monitoring, breath analysis, combustion exhaust diagnostics, and plasma diagnostics for semi-conductor fabrication. The substitution of near-room temperature QC lasers for cryogenic lead salt TDLs and the resulting simplifications in instrument design and operation will greatly expand the range of applications.

  18. Applications of a Mid-IR Quantum Cascade Laser in Gas Sensing Research

    KAUST Repository

    Sajid, Muhammad Bilal

    2015-05-01

    Laser absorption based sensors are extensively used in a variety of gas sensing areas such as combustion, atmospheric research, human breath analysis, and high resolution infrared spectroscopy. Quantum cascade lasers have recently emerged as high resolution, high power laser sources operating in mid infrared region and can have wide tunability range. These devices provide an opportunity to access stronger fundamental and combination vibrational bands located in mid infrared region than previously accessible weaker overtone vibrational bands located in near infrared region. Spectroscopic region near 8 µm contains strong vibrational bands of methane, acetylene, hydrogen peroxide, water vapor and nitrous oxide. These molecules have important applications in a wide range of applications. This thesis presents studies pertaining to spectroscopy and combustion applications. Advancements in combustion research are imperative to achieve lower emissions and higher efficiency in practical combustion devices such as gas turbines and engines. Accurate chemical kinetic models are critical to achieve predictive models which contain several thousand reactions and hundreds of species. These models need highly reliable experimental data for validation and improvements. Shock tubes are ideal devices to obtain such information. A shock tube is a homogenous, nearly constant volume, constant pressure, adiabatic and 0-D reactor. In combination with laser absorption sensors, shock tubes can be used to measure reaction rates and species time histories of several intermediates and products formed during pyrolysis and oxidation of fuels. This work describes measurement of the decomposition rate of hydrogen peroxide which is an important intermediate species controlling reactivity of combustion system in the intermediate temperature range. Spectroscopic parameters (linestrengths, broadening coefficients and temperature dependent coefficients) are determined for various transitions of

  19. Multiplexed Chirped Pulse Quantum Cascade Laser Measurements of Ammonia and Other Small Molecules

    Science.gov (United States)

    Picken, Craig; Langford, Nigel; Duxbury, Geoffrey

    2014-06-01

    Spectrometers based on Quantum Cascade (QC) lasers can be run in either continuous or pulsed operation. Although the instrumentation based upon the most recent versions of continuously operating QC lasers can have higher resolution than chirped lasers, using chirped pulse QC lasers can give an advantage when rapid changes in gas composition occur. For example, when jet engines are being tested, a variety of temperature dependent effects on the trace gas concentrations of the plume may be observed. Most pulsed QC lasers are operated in the down chirped mode, in which the chirp rate slows during the pulse. In our spectrometer the changes in frequency are recorded using two Ge etalons, one with a free spectral range of 0.0495 cm-1, and the other with a fringe spacing of 0.0195 cm-1.They can also be deployed in multiplex schemes in which two or more down-chirped lasers are used. In this paper we wish to show examples of the use of multiplexed chirped pulse lasers to allow overlapping spectra to be recorded. The examples of multiplex methods used are taken partly from measurements of 14NH3 and 15NH3 in the region from 1630 to 1622 cm-1, and partly from the use of other chirped pulse lasers operating in the 8 μm region. Among the effects seen are rapid passage effects caused by the rapid down-chirp, and the use of gases such as nitrogen to cause variation in the shape of the collisional broadened absorption lines.

  20. Improvements in quantum cascade laser performance through comprehensive modeling and experiments

    Science.gov (United States)

    Howard, Scott Sheridan

    Prior to the invention of the quantum cascade (QC) laser, many applications based on mid-infrared (mid-IR) laser absorption spectroscopy were not be explored. Development of the QC laser provided an inherently compact, semiconductor based, and tunable mid-IR source that could be used for laser absorption spectroscopy. Additionally, QC lasers can be designed to emit at a specific wavelength within a very wide wavelength range from between 3 and 30 mum and can be fabricated to operate single-mode to clearly scan mid-IR absorption "fingerprints" [1]. This allows lasers to be tailored to the exact wavelength of an absorption feature. Two examples of absorption spectroscopy experiments were carried out as part of this dissertation and described herein: C60 in space and dissolved gasses in living tissue. Although QC lasers allow for application development in the mid-IR, they are inefficient and heat dissipation is problematic. First generation QC lasers relied on either bulky cryogenic cooling systems for continuous wave operation or large, expensive pulse generators [2]. Later, advances in QC laser design, growth, and fabrication led to room-temperature continuous wave operation [3]. These advances promoted additional applications of QC lasers where cryogenic cooling was impossible or highly inconvenient. This dissertation presents comprehensive self-consistent models permitting the optimization of high operating temperature QC lasers. These models employ strategies counter to those used in designing low temperature devices and were used to design, fabricate, and demonstrate high-performance QC lasers. By self-consistently solving the temperature dependent threshold current density and heat equations, including temperature dependent thermal conductivities, phonon lifetimes, thermal "backfilling," thermionic emission, and energy level broadening, we calculated the effects of doping level, material choice, and waveguide layer thickness on the laser threshold performance

  1. Schemes generating entangled states and entanglement swapping between photons and three-level atoms inside optical cavities for quantum communication

    Science.gov (United States)

    Heo, Jino; Kang, Min-Sung; Hong, Chang-Ho; Yang, Hyeon; Choi, Seong-Gon

    2017-01-01

    We propose quantum information processing schemes based on cavity quantum electrodynamics (QED) for quantum communication. First, to generate entangled states (Bell and Greenberger-Horne-Zeilinger [GHZ] states) between flying photons and three-level atoms inside optical cavities, we utilize a controlled phase flip (CPF) gate that can be implemented via cavity QED). Subsequently, we present an entanglement swapping scheme that can be realized using single-qubit measurements and CPF gates via optical cavities. These schemes can be directly applied to construct an entanglement channel for a communication system between two users. Consequently, it is possible for the trust center, having quantum nodes, to accomplish the linked channel (entanglement channel) between the two separate long-distance users via the distribution of Bell states and entanglement swapping. Furthermore, in our schemes, the main physical component is the CPF gate between the photons and the three-level atoms in cavity QED, which is feasible in practice. Thus, our schemes can be experimentally realized with current technology.

  2. Real-time path-integral approach for dissipative quantum dot-cavity quantum electrodynamics: impure dephasing-induced effects

    Science.gov (United States)

    Nahri, Davoud G.; Mathkoor, Faisal H. A.; Ooi, C. H. Raymond

    2017-02-01

    A dissipative quantum dot (QD)-cavity system, where the QD is initially prepared in the excited state with no photon in the cavity, coupled to a longitudinal acoustic (LA) phonon reservoir is studied using a numerically exact real-time path-integral approach. Three distinct dynamical regimes of weak (WC), strong (SC), and coherent coupling (CC) are discussed and more accurate conditions identifying them are presented. Our results show that to have the CC regime, which is characterized by clear vacuum Rabi oscillation (VRO), vacuum Rabi splitting (VRS) should be larger than the sum of the widths of the corresponding peaks. In order to distinguish between contributions of population decay and impure dephasing, induced by LA phonon bath and the dissipations, we propose a two-part phenomenological expression, corresponding to the population decay and impure dephasing, which fits the QD-cavity decay curves perfectly and is used to calculate the corresponding spectra. We demonstrate that the effective population decay rate (the emission rate) increases from the carrier recombination rate to a maximum value, which is the mean of the QD and cavity dissipation rates, with QD-cavity coupling strength. To study the role of the effective impure dephasing rate on the width of the central peak of the spectra we introduce a quantity that can also be applied in determining the distinct coupling regimes. This quantity enables us to identify the onset of the SC regime as the point where the impure dephasing term begins to contribute to the central band of the spectrum significantly, as a result of the existence of VRO with a very small frequency (unclear VRO) at the corresponding decay curve. Its contribution to the width of the central peak increases with the coupling strength up to the onset of the CC regime, then reduces as a result of the appearance of sidebands in the spectra, which originates from clear VRO. The effective population decay and impure dephasing rate contribute

  3. A grating-coupled external cavity InAs/InP quantum dot laser with 85-nm tuning range

    Science.gov (United States)

    Wei, Heng; Jin, Peng; Luo, Shuai; Ji, Hai-Ming; Yang, Tao; Li, Xin-Kun; Wu, Jian; An, Qi; Wu, Yan-Hua; Chen, Hong-Mei; Wang, Fei-Fei; Wu, Ju; Wang, Zhan-Guo

    2013-09-01

    The optical performance of a grating-coupled external cavity laser based on InAs/InP quantum dots is investigated. Continuous tuning from 1391 nm to 1468 nm is realized at an injection current of 1900 mA. With the injection current increasing to 2300 mA, the tuning is blue shifted to some extent to the range from 1383 nm to 1461 nm. By combining the effect of the injection current with the grating tuning, the total tuning bandwidth of the external cavity quantum-dot laser can reach up to 85 nm. The dependence of the threshold current on the tuning wavelength is also presented.

  4. Simplified realization of two-qubit quantum phase gate with four-level systems in cavity QED

    Science.gov (United States)

    Yang, Chui-Ping; Chu, Shih-I.; Han, Siyuan

    2004-10-01

    We propose a method for realizing two-qubit quantum phase gate with 4-level systems in cavity QED. In this proposal, the two logical states of a qubit are represented by the two lowest levels of each system, and two intermediate levels of each system are utilized to facilitate coherent control and manipulation of quantum states of the qubits. The present method does not involve cavity-photon population during the operation. In addition, we show that the gate can be achieved using only two-step operations.

  5. One-Step Realization of SWAP Gate with Superconducting Quantum-Interference Devices and Atoms in Cavity QED

    Institute of Scientific and Technical Information of China (English)

    ZHAN Zhi-Ming

    2008-01-01

    We put forward a simple scheme for one-step realization of a two-qubit SWAP gate with SQUIDs (super-conducting quantum-interference devices) in cavity QED via Raman transition. In this scheme, the cavity field is only virtually excited and thus the cavity decay is suppressed. The SWAP gate is realized by using only two lower flux states of the SQUID system and the excited state would not be excited. Therefore, the effect of decoherence caused from the levels of the SQUID system is possibly minimized. The scheme can also be used to implement the SWAP gate with atoms.

  6. Development of Miniaturized Difference Frequency Generation, Fiber Optic, and Quantum Cascade Laser Systems in Conjunction With Integrated Electronics for Global Studies of Atmospheric Tracers Using UAVs.

    Science.gov (United States)

    Witinski, M. F.; Lapson, L. B.; Anderson, J. G.

    2007-12-01

    In order to harness the power of UAVs (Unmanned Aerial Vehicles) for in situ atmospheric monitoring of tracers such as CO2, N2O, CH4, and H2O, we have developed small, lightweight, single mode laser systems with co- developed integrated electronics. The laser sources are of various types including newly developed cavity- enhanced difference frequency generation (CE DFG), distributed feedback quantum cascade lasers (DFB QCLs), and new types of commercially available DFB diode lasers. All are continuous wave (cw) and thermo-electrically cooled, ensuring a high instrument duty cycle in a compact, low maintenance package. The light sources are collimated with miniature aspherical lenses and coupled into a home-built astigmatic Herriott cell for detection of the various targets using direct absorption. In parallel with the optical components, we have developed integrated electrical systems for laser control, data processing, and acquisition. A prototype instrument suite is described that illustrates the importance of parallel development of optical and electrical components in achieving an apparatus that is compact, fully automated, and highly capable scientifically. Although the emphasis here is on atmospheric tracers, this technology could be applied to spectroscopic measurements of other atmospheric species such as isotopes, free radicals, and reactive intermediates.

  7. Direct determination of glucose, lactate and triglycerides in blood serum by a tunable quantum cascade laser-based mid-IR sensor

    Science.gov (United States)

    Brandstetter, M.; Volgger, L.; Genner, A.; Jungbauer, C.; Lendl, B.

    2013-02-01

    This work reports on a compact sensor for fast and reagent-free point-of-care determination of glucose, lactate and triglycerides in blood serum based on a tunable (1030-1230 cm-1) external-cavity quantum cascade laser (EC-QCL). For simple and robust operation a single beam set-up was designed and only thermoelectric cooling was used for the employed laser and detector. Full computer control of analysis including liquid handling and data analysis facilitated routine measurements. A high optical pathlength (>100 μm) is a prerequisite for robust measurements in clinical practice. Hence, the optimum optical pathlength for transmission measurements in aqueous solution was considered in theory and experiment. The experimentally determined maximum signal-to-noise ratio (SNR) was around 140 μm for the QCL blood sensor and around 50 μm for a standard FT-IR spectrometer employing a liquid nitrogen cooled mercury cadmium telluride (MCT) detector. A single absorption spectrum was used to calculate the analyte concentrations simultaneously by using a partial-least-squares (PLS) regression analysis. Glucose was determined in blood serum with a prediction error (RMSEP) of 6.9 mg/dl and triglycerides with an error of cross-validation (RMSECV) of 17.5 mg/dl in a set of 42 different patients. In spiked serum samples the lactate concentration could be determined with an RMSECV of 8.9 mg/dl.

  8. Reagent-free monitoring of multiple clinically relevant parameters in human blood plasma using a mid-infrared quantum cascade laser based sensor system.

    Science.gov (United States)

    Brandstetter, Markus; Sumalowitsch, Tamara; Genner, Andreas; Posch, Andreas E; Herwig, Christoph; Drolz, Andreas; Fuhrmann, Valentin; Perkmann, Thomas; Lendl, Bernhard

    2013-07-21

    We present a semi-automated point-of-care (POC) sensor approach for the simultaneous and reagent-free determination of clinically relevant parameters in blood plasma. The portable sensor system performed direct mid-infrared (MIR) transmission measurements of blood plasma samples using a broadly tunable external-cavity quantum cascade laser source with high spectral power density. This enabled the use of a flow cell with a long path length (165 μm) which resulted in high signal-to-noise ratios and a rugged system, insensitive to clogging. Multivariate calibration models were built using well established Partial-Least-Squares (PLS) regression analysis. Selection of spectral pre-processing procedures was optimized by an automated evaluation algorithm. Several analytes, including glucose, lactate, triglycerides, cholesterol, total protein as well as albumin, were successfully quantified in routinely taken blood plasma samples from 67 critically ill patients. Although relying on a spectral range from 1030 cm(-1) to 1230 cm(-1), which is optimal for glucose and lactate but rather unusual for protein analysis, it was possible to selectively determine the albumin and total protein concentrations with sufficient accuracy for POC application.

  9. High-efficiency atomic entanglement concentration for quantum communication network assisted by cavity QED

    Science.gov (United States)

    Wang, Guan-Yu; Li, Tao; Deng, Fu-Guo

    2015-04-01

    Quantum entanglement is the key resource in quantum information processing, especially in quantum communication network. However, affected by the environment noise, the maximally entangled states usually collapse into nonmaximally entangled ones or even mixed states. Here we present two high-efficiency schemes to complete the entanglement concentration of nonlocal two-atom systems. Our first scheme is used to concentrate the nonlocal atomic systems in the partially entangled states with known parameters, and it has the optimal success probability. The second scheme is used to concentrate the entanglement of the nonlocal two-atom systems in the partially entangled states with unknown parameters. Compared with the other schemes for the entanglement concentration of atomic systems, our two protocols are more efficient and practical. They require only an ancillary single photon to judge whether they succeed or not, and they work in a heralded way with detection inefficiency and absence of sophisticated single-photon detectors in practical applications. Moreover, they are insensitive to both the cavity decay and atomic spontaneous emission.

  10. Fano-resonance induced strong-coupling of a hyperbolic cavity to a quantum emitter

    CERN Document Server

    Hasan, Mehedi; Belov, Pavel

    2015-01-01

    Light-matter interaction is studied for an open quantum system in the strong-coupling regime. A quantum dot and a hyperbolic cavity of spherical geometry is shown to couple light with large Rabi frequency and the role of Fano resonance is shown in the coupling mechanism. High Purcell factor and large Lamb shift are outlined. In the near-field spectrum, two distinct anti-crossings are evident, namely -- the one near the epsilon near zero (ENZ) frequency (from the effective medium description) which is detectable in the far-field, and the second anti-crossing is a pseudomode that does not appear in the far-field spectrum. This delineates the phenomenon `farfield propagating large Purcell factor'. Finally, we remark the fidelity of the strong-coupling, i.e. how prone the strong-coupling with respect to the loss mechanisms. This study on strong-coupling will have applications for spectroscopy, control over chemical reaction rate, microcavity, and in quantum information technology.

  11. Coupling of erbium dopants to yttrium orthosilicate photonic crystal cavities for on-chip optical quantum memories

    CERN Document Server

    Miyazono, Evan; Craiciu, Ioana; Kindem, Jonathan M; Faraon, Andrei

    2016-01-01

    Erbium dopants in crystals exhibit highly coherent optical transitions well suited for solid-state optical quantum memories operating in the telecom band. Here we demonstrate coupling of erbium dopant ions in yttrium orthosilicate to a photonic crystal cavity fabricated directly in the host crystal using focused ion beam milling. The coupling leads to reduction of the photoluminescence lifetime and enhancement of the optical depth in microns-long devices, which will enable on-chip quantum memories.

  12. Suppressing gate errors in frequency-domain quantum computation through extra physical systems coupled to a cavity

    Science.gov (United States)

    Nakamura, Satoshi; Goto, Hayato; Kujiraoka, Mamiko; Ichimura, Kouichi

    2016-12-01

    We propose a scheme for frequency-domain quantum computation (FDQC) in which the errors due to crosstalk are suppressed using extra physical systems coupled to a cavity. FDQC is a promising method to realize large-scale quantum computation, but crosstalk is a major problem. When physical systems employed as qubits satisfy specific resonance conditions, gate errors due to crosstalk increase. In our scheme, the errors are suppressed by controlling the resonance conditions using extra physical systems.

  13. Generation of Two-Mode Nonclassical States via Dispersive Interaction in Trapped-Ion Cavity Quantum Electrodynamics

    Institute of Scientific and Technical Information of China (English)

    YANG Wen-Xing; ZHAN Zhi-Ming; LI Jia-Hua

    2004-01-01

    @@ We propose a simple method to generate a practical SU(2)-Schrodinger-cat state of a single trapped-ion vibration mode and the light field state, using the method based on a quantum system, which is composed of the onedimensional trapped-ion motion and a single cavity field mode. Moreover, the method proposed can be used for the generation two-mode maximal quantum entangled state. The detection of such a state is also briefly discussed.

  14. Coupling of erbium dopants to yttrium orthosilicate photonic crystal cavities for on-chip optical quantum memories

    Energy Technology Data Exchange (ETDEWEB)

    Miyazono, Evan; Zhong, Tian; Craiciu, Ioana; Kindem, Jonathan M.; Faraon, Andrei, E-mail: faraon@caltech.edu [T. J. Watson Laboratory of Applied Physics, California Institute of Technology, 1200 E California Blvd, Pasadena, California 91125 (United States)

    2016-01-04

    Erbium dopants in crystals exhibit highly coherent optical transitions well suited for solid-state optical quantum memories operating in the telecom band. Here, we demonstrate coupling of erbium dopant ions in yttrium orthosilicate to a photonic crystal cavity fabricated directly in the host crystal using focused ion beam milling. The coupling leads to reduction of the photoluminescence lifetime and enhancement of the optical depth in microns-long devices, which will enable on-chip quantum memories.

  15. Characterization and Dynamic Analysis of Long-Cavity Multi-Section Gain- Levered Quantum-Dot Lasers

    Science.gov (United States)

    2013-03-01

    linewidth-enhancement factor to values greater than one [19]. This is combined with the original quantum-dot emission wavelength being blueshifted ...16]. Figure 12: Blueshift of the quantum-dot emission due to state filling. Each spectrum is marked with the corresponding laser cavity length...distinct second peak near 1222 nm. This spectral feature continues to blueshift as biasing is increased to 500 mA. The fundamental spectral feature widens

  16. Non-equilibrium Green's function calculation for GaN-based terahertz-quantum cascade laser structures

    Science.gov (United States)

    Yasuda, H.; Kubis, T.; Hosako, I.; Hirakawa, K.

    2012-04-01

    We theoretically investigated GaN-based resonant phonon terahertz-quantum cascade laser (QCL) structures for possible high-temperature operation by using the non-equilibrium Green's function method. It was found that the GaN-based THz-QCL structures do not necessarily have a gain sufficient for lasing, even though the thermal backfilling and the thermally activated phonon scattering are effectively suppressed. The main reason for this is the broadening of the subband levels caused by a very strong interaction between electrons and longitudinal optical (LO) phonons in GaN.

  17. A compact, continuous-wave terahertz source based on a quantum-cascade laser and a miniature cryocooler

    OpenAIRE

    Richter, Heiko; Greiner-Bär, Michael; Pavlov, Sergey; Semenov, Alexei D.; Wienold, Martin; Schrottke, Lutz; Giehler, M.; Hey, R.; Grahn, H.T.; Huebers, H. -W.

    2010-01-01

    We report on the development of a compact, easy-to-use terahertz radiation source, which combines a quantum cascade laser (QCL) operating at 3.1 THz with a compact, low input-power Stirling cooler. The QCL, which is based on a two miniband design, has been developed for high output and low electrical pump power. The amount of generated heat complies with the nominal cooling capacity of the Stirling cooler of 7 W at 65 K with 240 W of electrical input power. Special care has been taken to achi...

  18. Recent Advances in Room Temperature, High-Power Terahertz Quantum Cascade Laser Sources Based on Difference-Frequency Generation

    OpenAIRE

    Quanyong Lu; Manijeh Razeghi

    2016-01-01

    We present the current status of high-performance, compact, THz sources based on intracavity nonlinear frequency generation in mid-infrared quantum cascade lasers. Significant performance improvements of our THz sources in the power and wall plug efficiency are achieved by systematic optimizing the device’s active region, waveguide, and chip bonding strategy. High THz power up to 1.9 mW and 0.014 mW for pulsed mode and continuous wave operations at room temperature are demonstrated, respectiv...

  19. Generation of Kerr combs centered at 4.5{\\mu}m in crystalline microresonators pumped by quantum cascade lasers

    CERN Document Server

    Savchenkov, Anatoliy A; Di Teodoro, Fabio; Belden, Paul M; Lotshaw, William T; Matsko, Andrey B; Maleki, Lute

    2015-01-01

    We report on the generation of mid-infrared Kerr frequency combs in high-finesse CaF$_2$ and MgF$_2$ whispering-gallery mode resonators pumped with continuous wave room temperature quantum cascade lasers. The combs were centered at 4.5$\\mu$m, the longest wavelength to date. A frequency comb wider than a half of an octave was demonstrated when approximately 20mW of pump power was coupled to an MgF2 resonator characterized with quality factor exceeding 10$^8$.

  20. Real-time diagnostics of a jet engine exhaust using an intra-pulse quantum cascade laser spectrometer

    Science.gov (United States)

    Duxbury, Geoffrey; Hay, Kenneth G.; Langford, Nigel; Johnson, Mark P.; Black, John D.

    2011-09-01

    It has been demonstrated that an intra-pulse scanned quantum cascade laser spectrometer may be used to obtain real-time diagnostics of the amounts of carbon monoxide, carbon dioxide, and water, in the exhaust of an aero gas turbine (turbojet) engine operated in a sea level test cell. Measurements have been made of the rapid changes in composition following ignition, the composition under steady state operating conditions, and the composition changes across the exhaust plume. The minimum detection limit for CO in a double pass through a typical gas turbine plume of 50 cm in diameter, with 0.4 seconds integration time, is approximately 2 ppm.

  1. Quantum cascade lasers operating from 1.4 to 4 THz

    Institute of Scientific and Technical Information of China (English)

    Sushil Kumar

    2011-01-01

    The development of teranertz (THz) quantum cascade lasers (QCLs) has progressed considerably since their advent almost a decade ago. THz QCLs operating in a frequency range from 1.4 to 4 THz with electron-phonon scattering mediated depopulation schemes are described. Several different types of GaAs/AlGaAs superlattice designs are reviewed. Some of the best temperature performances are obtained by the so-called resonant-phonon designs that are described. Operation above a temperature of 160 K has been obtained across the spectrum for THz QCLs operating at v > 1.8 THz. The maximum operating temperature of previously reported THz QCLs has empirically been limited to a value of ~ hω/kB- A new design scheme for THz QCLs with scattering-assisted injection is shown to surpass this empirical temperature barrier, and is promising to improve the maximum operating temperatures of THz QCLs even further.%1.IntroductionHigh-power sources of terahertz (THz) radiation are required for a multitude of applications in sensing,imaging,and spectroscopy in fields as diverse as astronomy,medicine,security,pharmaceuticals and so-forth.THz science and technology has advanced significantly in the recent years[1,2] especially toward the realization of novel THz radiation sources.In comparison to narrow-band sources such as lasers,broadband sources of terahertz radiation are more widely available;however,such sources are inherently low power (average power is of the order of few micro-Watts).They are useful nevertheless because of room temperature operation and for their ability to be detected coherently.Techniques such as generation of THz bandwidth time-domain pulses in high resistivity semiconductors[3],non-linear generation by electrooptical-rectification in crystals such as ZnTe[4],or nonlinear generation by optical parametric conversion in materials such as LiNbO3[5] or by difference-frequency generation in semiconductors[6],have been used for various raster-scanned imaging and

  2. Pulse delay measurements in cascaded quantum well gain and absorber media

    DEFF Research Database (Denmark)

    Hansen, Per Lunnemann; Poel, Mike van der; Yvind, Kresten

    2010-01-01

    A tunable delay of ultrashort laser pulses in semiconductor waveguide structures are demonstrated in cascaded amplifying and absorbing semiconductor waveguides and compared with a single sectioned waveguide. The single sectioned waveguide shows a low transmission at the maximum delay. This is eff......A tunable delay of ultrashort laser pulses in semiconductor waveguide structures are demonstrated in cascaded amplifying and absorbing semiconductor waveguides and compared with a single sectioned waveguide. The single sectioned waveguide shows a low transmission at the maximum delay...

  3. Influence of atomic motion on the population and dipole squeezing of a cascade three-level atom in cavity field

    Institute of Scientific and Technical Information of China (English)

    Zhu Ai-Dong; Zhang Shou

    2004-01-01

    The dynamical property of a cascade three-level atom is investigated in the condition of atomic motion. The influence of atomic motion on the population and dipole squeezing is discussed. The results show that atomic motion makes the amplitude of atomic population be steady and increasing the parameter ep which denotes the atomic motion and the structure of field mode can shorten the period of collapse-revivals. By choosing an appropriate paramenter ep, we can obtain a dipole squeezed atom of long standing.

  4. Thermal entanglement in two-atom cavity QED and the entangled quantum Otto engine

    Science.gov (United States)

    Wang, Hao; Liu, Sanqiu; He, Jizhou

    2009-04-01

    The simple system of two two-level identical atoms couple to single-mode optical cavity in the resonance case is studied for investigating the thermal entanglement. It is interesting to see that the critical temperature is only dependent on the coefficient of atom-atom dipole-dipole interaction. Based on the mode, we construct and investigate a entangled quantum Otto engine (QOE). Expressions for several important performance parameters such as the heat transferred, the work done in a cycle, and the efficiency of the entangled QOE in zero G are derived in terms of thermal concurrence. Some intriguing features and their qualitative explanations are given. Furthermore, the validity of the second law of thermodynamics is confirmed in the entangled QOE. The results obtained here have general significance and will be helpful to understand deeply the performance of an entangled QOE.

  5. Quantum modeling of semiconductor gain materials and vertical-external-cavity surface-emitting laser systems

    Energy Technology Data Exchange (ETDEWEB)

    Bueckers, Christina; Kuehn, Eckhard; Schlichenmaier, Christoph; Koch, Stephan W. [Department of Physics and Material Sciences Center, Philipps-University Marburg (Germany); Imhof, Sebastian; Thraenhardt, Angela [Faculty of Natural Sciences, Chemnitz University of Technology, Chemnitz (Germany); Hader, Joerg; Moloney, Jerome V. [Nonlinear Control Strategies, Inc., Tucson, AZ (United States); College of Optical Sciences, University of Arizona, Tucson, AZ (United States); Rubel, Oleg [Thunder Bay Regional Research Institute, Thunder Bay, ON (Canada); Department of Physics, Lakehead University, Thunder Bay, ON (Canada); Zhang, Wei [Centre for Biophotonics, SIPBS, University of Strathclyde, Glasgow, Scotland (United Kingdom); Ackemann, Thorsten [SUPA and Department of Physics, University of Strathclyde, Glasgow, Scotland (United Kingdom)

    2010-04-15

    This article gives an overview of the microscopic theory used to quantitatively model a wide range of semiconductor laser gain materials. As a snapshot of the current state of research, applications to a variety of actual quantum-well systems are presented. Detailed theory-experiment comparisons are shown and it is analyzed how the theory can be used to extract poorly known material parameters. The intrinsic laser loss processes due to radiative and nonradiative Auger recombination are evaluated microscopically. The results are used for realistic simulations of vertical-external-cavity surface-emitting laser systems. To account for nonequilibrium effects, a simplified model is presented using pre-computed microscopic scattering and dephasing rates. Prominent deviations from quasi-equilibrium carrier distributions are obtained under strong in-well pumping conditions. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  6. Hot electron bolometer heterodyne receiver with a 4.7-THz quantum cascade laser as a local oscillator

    CERN Document Server

    Kloosterman, Jenna L; Ren, Yuan; Kao, Tsung-Yu; Hovenier, Neils; Gao, Jian-Rong; Klapwijk, Teun M; Hu, Qing; Walker, Christopher K; Reno, John L

    2012-01-01

    We report on a heterodyne receiver designed to observe the astrophysically important neutral atomic oxygen [OI] line at 4.7448 THz. The local oscillator is a third-order distributed feedback Quantum Cascade Laser operating in continuous wave mode at 4.756 THz. A quasi-optical, superconducting NbN hot electron bolometer is used as the mixer. We recorded a double sideband receiver noise temperature (T^DSB_rec) of 815 +/- 12 K, which is ~7 times the quantum noise limit (hf/2kB) and an Allan variance time of 15 s at an effective noise fluctuation bandwidth of 18 MHz. Heterodyne performance was confirmed by measuring a methanol line spectrum.

  7. Inter-subbandspectroscopy on silicon-germanium quantum cascade structures; Intersubband Spektroskopie an Silizium-Germanium-Quantenkaskadenstrukturen

    Energy Technology Data Exchange (ETDEWEB)

    Bormann, I.

    2006-02-15

    This work refers to the design, the fabrication and the structural, electrical and optical characterization of light emitters based on SiGe quantum cascade structures (QCS). In a first step two Si/SiGe quantum cascade structures without waveguides were designed using a 6-band k x p calculation of the subband structure including Si/Ge segregation effects during molecular beam epitaxy (MBE) growth. After growth on (001) Si substrates they were characterized by transmission electron microscopy (TEM). Although the structures are strongly strained due to the average Ge content of 18%, they show no signs of strain relaxation. The interface roughness amounts to three monolayers in good agreement with the segregation model. Both structures show well resolved intersubband electroluminescence (EL) at 146 meV and 159 meV respectively in excellent agreement with the band structure calculations. The line width is 30 meV. The transversal magnetic polarization and photocurrent measurements prove that the intersubband transition is the source of the emitted luminescence. Numerical calculations of the upper state nonradiative hole lifetime determined by the deformation potential scattering of holes with optical phonons reveal a lifetime of about 400 fs for both structures. The feasibility to enhance the upper state lifetime in 'diagonal' transitions between heavy hole states in neighboring quantum wells is investigated. Therefore the Si barrier thickness between the quantum wells was varied and accordingly the wave function overlap using a second sample series. From EL measurements the lifetime of the 35 A barrier sample was found to be 17 times longer than for a 15 A barrier. It is possible to reduce the strong strain in Si/SiGe structures by using a virtual Si{sub 1-x}Ge{sub x} substrate. For this purpose a thin Si{sub 0.72}Ge{sub 0.28} relaxed buffer with a threading dislocation density of 10{sup 7} cm{sup -2} and a RMS surface roughness of 13 A was developed and

  8. Optical Design of Dilute Nitride Quantum Wells Vertical Cavity Semiconductor Optical Amplifiers for Communication Systems

    Directory of Open Access Journals (Sweden)

    Faten A. Chaqmaqchee

    2016-04-01

    Full Text Available III-V semiconductors components such as Gallium Arsenic (GaAs, Indium Antimony (InSb, Aluminum Arsenic (AlAs and Indium Arsenic (InAs have high carrier mobilities and direct energy gaps. This is making them indispensable for today’s optoelectronic devices such as semiconductor lasers and optical amplifiers at 1.3 μm wavelength operation. In fact, these elements are led to the invention of the Gallium Indium Nitride Arsenic (GaInNAs, where the lattice is matched to GaAs for such applications. This article is aimed to design dilute nitride GaInNAs quantum wells (QWs enclosed between top and bottom of Aluminum (Gallium Arsenic Al(GaAs distributed bragg mirrors (DBRs using MATLAB® program. Vertical cavity semiconductor optical amplifiers (VCSOAs structures are based on Fabry Perot (FP method to design optical gain and bandwidth gain to be operated in reflection and transmission modes. The optical model gives access to the contact layer of epitaxial structure and the reflectivity for successive radiative modes, their lasing thresholds, emission wavelengths and optical field distributions in the laser cavity.

  9. Tuning of Detection Wavelength in a Resonant-Cavity-Enhanced Quantum-Dot-Embedded Photodiode by Changing Detection Angle

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hao; ZHU Hui; ZHENG Hou-Zhi; XU Ping; PENG Hong-Ling; TAN Ping-Heng; YANG Fu-Hua; NI Hai-Qiao; ZENG Yu-Xin; GAN Hua-Dong

    2005-01-01

    @@ We have Fabricated a resonant-cavity-enhanced photodiode (RCE-PD) with InGaAs quantum dots (QDs) as an active medium. This sort of QD-embedded RCE-PD is capable of a peak external quantum efficiency of 32%and responsivity of 0.27 A/W at 1.058 μm with a full width at half maximum (FWHM) of 5nm. Angle-resolved photocurrent response eventually proves that with the detection angle changing from 0° to 60°, the peak-current wavelength shifts towards the short wavelength side by 37nm, while the quantum efficiency remains larger than 15%.

  10. Cavity QED and Quantum Computation in the Weak Coupling Regime II Complete Construction of the Controlled-Controlled NOT Gate

    CERN Document Server

    Fujii, K; Kato, R; Wada, Y; Fujii, Kazuyuki; Higashida, Kyoko; Kato, Ryosuke; Wada, Yukako

    2005-01-01

    In this paper we treat a cavity QED quantum computation. Namely, we consider a model of quantum computation based on n atoms of laser-cooled and trapped linearly in a cavity and realize it as the n atoms Tavis-Cummings Hamiltonian interacting with n external (laser) fields. We solve the Schr{\\" o}dinger equation of the model in the weak coupling regime to construct the controlled NOT gate in the case of n=2, and to construct the controlled-controlled NOT gate in the case of n=3 by making use of several resonance conditions and rotating wave approximation associated to them. We also present an idea to construct general quantum circuits. The approach is more sophisticated than that of the paper [K. Fujii, Higashida, Kato and Wada, Cavity QED and Quantum Computation in the Weak Coupling Regime, J. Opt. B : Quantum Semiclass. Opt. {\\bf 6} (2004), 502]. Our method is not heuristic but completely mathematical, and the significant feature is based on a consistent use of Rabi oscillations.

  11. Single-mode surface-emitting distributed feedback quantum-cascade lasers based on hybrid waveguide structure

    Institute of Scientific and Technical Information of China (English)

    Wanhong Guo; Junqi Liu; Jianyan Chen; Lu Li; Lijun Wang; Fengqi Liu; Zhanguo Wang

    2011-01-01

    Surface-emitting distributed feedback quantum-cascade lasers operating at λ≈7.8 μm are demonstrated.The metal-covered second-order grating is shallow-etched into the surface of a thin InGaAs contact and cladding layer. This forms a hybrid waveguide and used to achieve relatively low waveguide losses and high coupling strengths. The devices exhibit stable single-mode operation from 90 to 130 K with a side mode suppression ratio above 20 dB. A slope efficiency of 194 mW/A is obtained at 90 K, which is twice higher than that of the Fabry-Perot counterpart.%@@ Surface-emitting distributed feedback quantum-cascade lasers operating at λ≈7.8 μm are demonstrated.The metal-covered second-order grating is shallow-etched into the surface of a thin InGaAs contact and cladding layer.This forms a hybrid waveguide and used to achieve relatively low waveguide losses and high coupling strengths.The devices exhibit stable single-mode operation from 90 to 130 K with a side mode suppression ratio above 20 dB.A slope efficiency of 194 mW/A is obtained at 90 K, which is twice higher than that of the Fabry-Perot counterpart.

  12. GaInAs/AlInAs quantum cascade laser design based on optimized second harmonic generation

    Science.gov (United States)

    Gajić, A.; Radovanović, J.; Milanović, V.; Indjin, D.; Ikonić, Z.

    2014-09-01

    In this work, we present an innovative procedure for the design and optimization of GaInAs/AlInAs quantum cascade laser (QCL) structures based on the use of the genetic algorithm. The purpose of the algorithm is to determine the set of design parameters that would enable the maximization of the second order nonlinear susceptibility, thus facilitating significant optical nonlinearities to take place. In our optimization model, we start from the existing design in which the active region consists of two coupled InGaAs quantum wells separated by an AlInAs barrier, and the active region levels form double resonant nonlinear cascades. Upon obtaining the optimized structure and evaluating its energies and wave functions, the output characteristics are calculated by applying the full self-consistent rate equation modeling of the electron transport in a periodic QCL structure. The results of the calculations predict a noticeable improvement of targeted properties of the optimized design, while at the same time the original design calculations show excellent agreement with experimental results. The described procedure is applicable to various active region designs and can be used for other wavelength ranges.

  13. Estimation of losses in a 300 m filter cavity and quantum noise reduction in the KAGRA gravitational-wave detector

    Science.gov (United States)

    Capocasa, Eleonora; Barsuglia, Matteo; Degallaix, Jérôme; Pinard, Laurent; Straniero, Nicolas; Schnabel, Roman; Somiya, Kentaro; Aso, Yoichi; Tatsumi, Daisuke; Flaminio, Raffaele

    2016-04-01

    The sensitivity of the gravitational-wave detector KAGRA, presently under construction, will be limited by quantum noise in a large fraction of its spectrum. The most promising technique to increase the detector sensitivity is the injection of squeezed states of light, where the squeezing angle is dynamically rotated by a Fabry-Pérot filter cavity. One of the main issues in the filter cavity design and realization is the optical losses due to the mirror surface imperfections. In this work we present a study of the specifications for the mirrors to be used in a 300 m filter cavity for the KAGRA detector. A prototype of the cavity will be constructed at the National Astronomical Observatory of Japan, inside the infrastructure of the former TAMA interferometer. We also discuss the potential improvement of the KAGRA sensitivity, based on a model of various realistic sources of losses and their influence on the squeezing amplitude.

  14. Cavity enhanced telecom heralded single photons for spin-wave solid state quantum memories

    Science.gov (United States)

    Rieländer, Daniel; Lenhard, Andreas; Mazzera, Margherita; de Riedmatten, Hugues

    2016-12-01

    We report on a source of heralded narrowband (≈ 3 MHz) single photons compatible with solid-state spin-wave quantum memories based on praseodymium doped crystals. Widely non-degenerate narrow-band photon pairs are generated using cavity enhanced down conversion. One photon from the pair is at telecom wavelengths and serves as heralding signal, while the heralded single photon is at 606 nm, resonant with an optical transition of Pr3+:Y2SiO5. The source offers a heralding efficiency of 28% and a generation rate exceeding 2000 pairs mW-1 in a single-mode. The single photon nature of the heralded field is confirmed by a direct antibunching measurement, with a measured antibunching parameter down to 0.010(4). Moreover, we investigate in detail photon cross- and autocorrelation functions proving non-classical correlations between the two photons. The results presented in this paper offer prospects for the demonstration of single photon spin-wave storage in an on-demand solid state quantum memory, heralded by a telecom photon.

  15. A cavity-Cooper pair transistor scheme for investigating quantum optomechanics in the ultra-strong coupling regime

    Science.gov (United States)

    Rimberg, A. J.; Blencowe, M. P.; Armour, A. D.; Nation, P. D.

    2014-05-01

    We propose a scheme involving a Cooper pair transistor (CPT) embedded in a superconducting microwave cavity, where the CPT serves as a charge tunable quantum inductor to facilitate ultra-strong coupling between photons in the cavity and a nano- to meso-scale mechanical resonator. The mechanical resonator is capacitively coupled to the CPT, such that mechanical displacements of the resonator cause a shift in the CPT inductance and hence the cavity's resonant frequency. The amplification provided by the CPT is sufficient for the zero point motion of the mechanical resonator alone to cause a significant change in the cavity resonance. Conversely, a single photon in the cavity causes a shift in the mechanical resonator position on the order of its zero point motion. As a result, the cavity-Cooper pair transistor coupled to a mechanical resonator will be able to access a regime in which single photons can affect single phonons and vice versa. Realizing this ultra-strong coupling regime will facilitate the creation of non-classical states of the mechanical resonator, as well as the means to accurately characterize such states by measuring the cavity photon field.

  16. A multi-atom and resonant interaction scheme for quantum state transfer and logical gates between two remote cavities via an optical fibre

    CERN Document Server

    Yin, Z; Yin, Zhang-qi; Li, Fu-li

    2007-01-01

    A system consisting of two single-mode cavities spatially separated and connected by an optical fibre and multi two-level atoms trapped in the cavities is considered. If the atoms resonantly and collectively interact with the local cavity fields but there is no direct interaction between the atoms, we show that an ideal quantum state transfer, and highly reliable quantum swap, entangling and controlled-Z gates can be deterministically realized between the distant cavities. We find that the operation of the state-transfer, and swap, entangling and controlled-Z gates can be greatly speeded up as number of the atoms in the cavities increases. We also notice that the effects of spontaneous emission of atoms and photon leakage out of cavity on the quantum processes can also be greatly diminished in the multi-atom case.

  17. Dawn of Cavity Spintronics

    OpenAIRE

    Hu, Can-Ming

    2015-01-01

    Merging the progress of spintronics with the advancement in cavity quantum electrodynamics and cavity polaritons, a new field of Cavity Spintronics is forming, which connects some of the most exciting modern physics, such as quantum information and quantum optics, with one of the oldest science on the earth, the magnetism.

  18. A comparison between experiment and theory on few-quantum-dot nanolasing in a photonic-crystal cavity

    DEFF Research Database (Denmark)

    Liu, Jin; Ates, Serkan; Lorke, Michael;

    2013-01-01

    We present an experimental and theoretical study on the gain mechanism in a photonic-crystal-cavity nanolaser with embedded quantum dots. From time-resolved measurements at low excitation power we find that four excitons are coupled to the cavity. At high excitation power we observe a smooth low-......-dot microcavity lasers and find that the number of excitons that must be included to fit the data largely exceeds the measured number, which shows that transitions involving the wetting layer can provide a surprisingly large contribution to the gain....

  19. Broadband tunable external cavity laser using a bent-waveguide quantum-dot superluminescent diode as gain device

    Institute of Scientific and Technical Information of China (English)

    Wu Jian; Lü Xue-Qin; Jin Peng; Meng Xian-Quan; Wang Zhan-Guo

    2011-01-01

    A broadband tunable grating-coupled external cavity laser is realized by employing a self-assembled InAs/GaAs quantum-dot (QD) superluminescent diode (SLD) as the gain device. The SLD device is processed with a bent-waveguide structure and facet antireflection (AR) coating. Tuning bandwidths of 106 nm and 117 nm are achieved under 3-A and 3.5-A injection currents, respectively. The large tuning range originates essentially from the broad gain spectrum of self-assembled QDs. The bent waveguide structure combined with the facet AR coating plays a role in suppressing the inner-cavity lasing under a large injection current.

  20. 腔光力学系统中的量子测量∗%Quantum measurement with cavity optomechanical systems

    Institute of Scientific and Technical Information of China (English)

    陈雪; 刘晓威; 张可烨; 袁春华; 张卫平

    2015-01-01

    Cavity optomechanics originates from the research of interferometric detection of gravitational waves, and later it has become a fast-growing area of techniques and approaches ranging from the fields of atomic, molecular, and optical physics to nano-science and condensed matter physics as well. Recently, it focused on the exploration of operating mechanical oscillators deep in the quantum regime, with an interest ranging from quantum-classical interface tests to high-precision quantum metrology. In this paper, recent theoretical work of our group in the field of quantum measurement with cavity optomechanical systems is reviewed. We explore the quantum measurement theory and its applications with several unconventional cavity optomechanical schemes working in the quantum regime. This review covers the basics of quantum noises in the cavity optomechanical setups and the resulting standard quantum limit of precision displacement and force measurement. Three novel quantum measurement proposals based on the hybrid optomechanical system are introduced. First, we describe a quantum back-action insulated weak force sensor. It is realized by forming a quantum-mechanics-free subsystem with two optomechanical oscillators of reversed effective mass. Then we introduce a role-reversed atomic optomechanical system which enables the preparation and the quantum tomography of a variety of non-classical states of atoms. In this system, the cavity field acts as a mechanical oscillator driven by the radiation pressure force from an ultracold atomic field. In the end, we recommend a multimode optomechanical transducer that can detect intensities significantly below the single-photon level via adiabatic transfer of the microwave signal to the optical frequency domain. These proposals demonstrate the possible applications of optomechanical devices in understanding of quantum-classical crossover and in achieving quantum measurement limit.%腔光力学系统近年来迅猛发展,在精

  1. Frequency Locking and Monitoring Based on Bi-directional Terahertz Radiation of a 3rd-Order Distributed Feedback Quantum Cascade Laser

    NARCIS (Netherlands)

    Van Marrewijk, N.; Mirzaei, B.; Hayton, D.; Gao, J.R.; Kao, T.Y.; Hu, Q.; Reno, J.L.

    2015-01-01

    We have performed frequency locking of a dual, forward reverse emitting third-order distributed feedback quantum cascade laser (QCL) at 3.5 THz. By using both directions of THz emission in combination with two gas cells and two power detectors, we can for the first time perform frequency stabilizati

  2. Saturated absorption in a rotational molecular transition at 2.5 THz using a quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Consolino, L., E-mail: luigi.consolino@ino.it; Campa, A.; Ravaro, M.; Mazzotti, D.; Bartalini, S.; De Natale, P. [INO, Istituto Nazionale di Ottica-CNR, Largo E. Fermi 6, Firenze I-50125 (Italy); LENS, European Laboratory for Non-Linear Spectroscopy, Via N. Carrara 1, Sesto Fiorentino, I-50019 (Italy); Vitiello, M. S. [NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa I-56127 (Italy)

    2015-01-12

    We report on the evidence of saturation effects in a rotational transition of CH{sub 3}OH around 2.5 THz, induced by a free-running continuous-wave quantum cascade laser (QCL). The QCL emission is used for direct-absorption spectroscopy experiments, allowing to study the dependence of the absorption coefficient on gas pressure and laser intensity. A saturation intensity of 25 μW/mm{sup 2}, for a gas pressure of 17 μbar, is measured. This result represents the initial step towards the implementation of a QCL-based high-resolution sub-Doppler THz spectroscopy, which is expected to improve by orders of magnitude the precision of THz spectrometers.

  3. V/III ratio effects on high quality InAlAs for quantum cascade laser structures

    Science.gov (United States)

    Demir, Ilkay; Elagoz, Sezai

    2017-04-01

    In this study we report the V/III ratio effects on growth, structural, optical and doping characteristics of low growth rate (∼1 Å/s) heteroepitaxial Metal Organic Chemical Vapor Deposition (MOCVD) grown InxAl1-xAs layers, a part of Quantum Cascade Laser (QCL) structures, on InP substrate. Especially photoluminescence (PL) properties of InAlAs-InP interface show strong dependence on AsH3 overpressure. We have shown that the V/III ratio with fixed metalorganic precursor flow is a crucial parameter on InxAl1-xAs layers to have a good material quality in terms of crystallinity, optical and electrical characteristics with and without doping.

  4. Quartz-enhanced photoacoustic detection of ethylene using a 10.5 μm quantum cascade laser.

    Science.gov (United States)

    Wang, Zhen; Li, Zhili; Ren, Wei

    2016-02-22

    A quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor has been developed for the sensitive detection of ethylene (C2H4) at 10.5 µm using a continuous-wave distributed-feedback quantum cascade laser. At this long-wavelength infrared, the key acoustic elements of quartz tuning fork and micro-resonators were optimized to improve the detection signal-to-noise ratio by a factor of >4. The sensor calibration demonstrated an excellent linear response (R2>0.999) to C2H4 concentration at the selected operating pressure of 500 and 760 Torr. With a minimum detection limit of 50 parts per billion (ppb) achieved at an averaging time of 70 s, the sensor has been deployed for measuring the C2H4 efflux during the respiration of biological samples in an agronomic environment.

  5. Recent Advances in Room Temperature, High-Power Terahertz Quantum Cascade Laser Sources Based on Difference-Frequency Generation

    Directory of Open Access Journals (Sweden)

    Quanyong Lu

    2016-07-01

    Full Text Available We present the current status of high-performance, compact, THz sources based on intracavity nonlinear frequency generation in mid-infrared quantum cascade lasers. Significant performance improvements of our THz sources in the power and wall plug efficiency are achieved by systematic optimizing the device’s active region, waveguide, and chip bonding strategy. High THz power up to 1.9 mW and 0.014 mW for pulsed mode and continuous wave operations at room temperature are demonstrated, respectively. Even higher power and efficiency are envisioned based on enhancements in outcoupling efficiency and mid-IR performance. Our compact THz device with high power and wide tuning range is highly suitable for imaging, sensing, spectroscopy, medical diagnosis, and many other applications.

  6. A calibration-free ammonia breath sensor using a quantum cascade laser with WMS 2f/1f

    KAUST Repository

    Owen, Kyle

    2013-12-22

    The amount of ammonia in exhaled breath has been linked to a variety of adverse medical conditions, including chronic kidney disease (CKD). The development of accurate, reliable breath sensors has the potential to improve medical care. Wavelength modulation spectroscopy with second harmonic normalized by the first harmonic (WMS 2f/1f) is a sensitive technique used in the development of calibration-free sensors. An ammonia gas sensor is designed and developed that uses a quantum cascade laser operating near 1,103.44 cm -1 and a multi-pass cell with an effective path length of 76.45 m. The sensor has a 7 ppbv detection limit and 5 % total uncertainty for breath measurements. The sensor was successfully used to detect ammonia in exhaled breath and compare healthy patients to patients diagnosed with CKD. © 2013 Springer-Verlag Berlin Heidelberg.

  7. Silver halide fiber-based evanescent-wave liquid droplet sensing with room temperature mid-infrared quantum cascade lasers

    Science.gov (United States)

    Chen, J. Z.; Liu, Z.; Gmachl, C. F.; Sivco, D. L.

    2005-08-01

    Quantum cascade lasers and unclad silver halide fibers were used to assemble mid-infrared fiber-optics evanescent-wave sensors suitable to measure the chemical composition of liquid droplets. The laser wavelengths were chosen to be in the regions which offer the largest absorption contrast between constituents inside the mixture droplets. A pseudo-Beer-Lambert law fits well with the experimental data. Using a 300μm diameter fiber with a 25 mm immersion length, the signal to noise ratios correspond to 1 vol.% for α-tocophenol in squalane and 2 vol.% for acetone in aqueous solution for laser wavenumbers of 1208 cm-1 and 1363 cm-1, respectively.

  8. Hydrogen peroxide detection with quartz-enhanced photoacoustic spectroscopy using a distributed-feedback quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Wei, E-mail: wr5@rice.edu; Jiang, Wenzhe; Tittel, Frank K. [Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, Texas 77005 (United States); Sanchez, Nancy P.; Griffin, Robert J. [Department of Civil and Environmental Engineering, Rice University, 6100 Main Street, Houston, Texas 77005 (United States); Patimisco, Pietro [Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, Texas 77005 (United States); Dipartimento Interateneo di Fisica, Università e Politecnico di Bari, Via Amendola 173, Bari 70126 (Italy); Spagnolo, Vincenzo [Dipartimento Interateneo di Fisica, Università e Politecnico di Bari, Via Amendola 173, Bari 70126 (Italy); Zah, Chung-en; Xie, Feng; Hughes, Lawrence C. [Corning Incorporated, Corning, New York 14831 (United States)

    2014-01-27

    A quartz-enhanced photoacoustic spectroscopy sensor system was developed for the sensitive detection of hydrogen peroxide (H{sub 2}O{sub 2}) using its absorption transitions in the v{sub 6} fundamental band at ∼7.73 μm. The recent availability of distributed-feedback quantum cascade lasers provides convenient access to a strong H{sub 2}O{sub 2} absorption line located at 1295.55 cm{sup −1}. Sensor calibration was performed by means of a water bubbler that generated titrated average H{sub 2}O{sub 2} vapor concentrations. A minimum detection limit of 12 parts per billion (ppb) corresponding to a normalized noise equivalent absorption coefficient of 4.6 × 10{sup −9} cm{sup −1}W/Hz{sup 1/2} was achieved with an averaging time of 100 s.

  9. Spectral research on an AlGaAs epitaxial material for a terahertz quantum-cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Zhi-Yong; Cao, Jun-Cheng [Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai (China)

    2012-04-15

    The spectral properties of a series of AlGaAs epitaxial films were studied by using a Fourier transform infrared spectrometer with an 80-degree grazing incidence reflection unit. The AlAs like transversal optical phonon was obviously observed in the spectra, but the longitudinal optical phonon was obscured in the transmission spectra. The variation curves for the transversal optical phonon energy were acquired from the two kinds of spectra and were compared with each other and with the early results. A comparison of the results show that the grazing incidence reflection spectrum is better in reflecting the AlAs-like phonon energy of an AlGaAs epitaxial film and could be a supplementary means in the characterization of the material for a terahertz quantum-cascade laser.

  10. Low-Power Cross-Phase Modulation in a Metastable Xenon-Filled Cavity for Quantum Information Applications

    CERN Document Server

    Hickman, G T; Franson, J D

    2015-01-01

    Weak single-photon nonlinearities have many potential applications in quantum computing and quantum information. Here we demonstrate a relatively simple system for producing low-power cross-phase modulation using metastable xenon inside a high finesse cavity. The use of a noble gas such as xenon eliminates the contamination of the high-finesse mirrors that can occur when using alkali metal vapors such as rubidium. Cross-phase shifts of 5 mrad with 4.5 fJ control pulses were demonstrated. Numerical solutions of the master equation are in good agreement with the experimental results, and they predict that cross-phase shifts greater than 1 mrad per control photon should be achievable by reducing the size of the cavity.

  11. Effects of magnetic field on photon-induced quantum transport in a single dot-cavity system

    Science.gov (United States)

    Abdullah, Nzar Rauf; Fatah, Aziz H.; Fatah, Jabar M. A.

    2016-11-01

    In this study, we show how a static magnetic field can control photon-induced electron transport through a quantum dot system coupled to a photon cavity. The quantum dot system is connected to two electron reservoirs and exposed to an external perpendicular static magnetic field. The propagation of electrons through the system is thus influenced by the static magnetic and the dynamic photon fields. It is observed that the photon cavity forms photon replica states controlling electron transport in the system. If the photon field has more energy than the cyclotron energy, then the photon field is dominant in the electron transport. Consequently, the electron transport is enhanced due to activation of photon replica states. By contrast, the electron transport is suppressed in the system when the photon energy is smaller than the cyclotron energy.

  12. Quantum limit of the laser linewidth in chaotic cavities and statistics of residues of scattering matrix poles

    CERN Document Server

    Schomerus, H; Patra, M; Beenakker, C W J

    1999-01-01

    The quantum-limited linewidth of a laser cavity is enhanced above the Schawlow-Townes value by the Petermann factor K, due to the non-orthogonality of the cavity modes. We derive the relation between the Petermann factor and the residues of poles of the scattering matrix and investigate the statistical properties of the Petermann factor for cavities in which the radiation is scattered chaotically. For a single scattering channel we determine the complete probability distribution of K and find that the average Petermann factor $$ depends non-analytically on the area of the opening, and greatly exceeds the most probable value. For an arbitrary number N of scattering channels we calculate $$ as a function of the decay rate $\\Gamma$ of the lasing mode. We find for $N\\gg 1$ that for typical values of $\\Gamma$ the average Petermann factor $\\propto \\sqrt{N}\\gg 1$ is parametrically larger than unity.

  13. Room temperature continuous wave InGaAsN quantum well vertical cavity lasers emitting at 1.3 um

    Energy Technology Data Exchange (ETDEWEB)

    CHOQUETTE,KENT D.; KLEM,JOHN F.; FISCHER,ARTHUR J.; SPAHN,OLGA B.; ALLERMAN,ANDREW A.; FRITZ,IAN J.; KURTZ,STEVEN R.; BREILAND,WILLIAM G.; SIEG,ROBERT M.; GEIB,KENT M.; SCOTT,J.W.; NAONE,R.L.

    2000-06-05

    Selectively oxidized vertical cavity lasers emitting at 1294 nm using InGaAsN quantum wells are reported for the first time which operate continuous wave at and above room temperature. The lasers employ two n-type Al{sub 0.94}Ga{sub 0.06}As/GaAs distributed Bragg reflectors each with a selectively oxidized current aperture adjacent to the optical cavity, and the top output mirror contains a tunnel junction to inject holes into the active region. Continuous wave single mode lasing is observed up to 55 C. These lasers exhibit the longest wavelength reported to date for vertical cavity surface emitting lasers grown on GaAs substrates.

  14. On statistical interpretation of quantum mechanics. Detection chambers and cascade measurements

    Energy Technology Data Exchange (ETDEWEB)

    Benzecri, J.-P.

    1986-01-01

    Using analysis of a concrete experimental system, and using a formal schema, we interpret this dictum due to Heisenberg: In quantum mechanics, the frontier between object and observer, can be arbitrarily moved in the direction of the latter.

  15. The Dicke model phase transition in the quantum motion of a Bose-Einstein condensate in an optical cavity

    CERN Document Server

    Nagy, D; Szirmai, G; Domokos, P

    2009-01-01

    We show that the motion of a laser-driven Bose-Einstein condensate in a high-finesse optical cavity realizes the spin-boson Dicke-model. The quantum phase transition of the Dicke-model from the normal to the superradiant phase corresponds to the self-organization of atoms from the homogeneous into a periodically patterned distribution above a critical driving strength. The fragility of the ground state due to photon measurement induced back action is calculated.

  16. High-Speed Widely-Tunable 90% Quantum-Efficiency Resonant Cavity Enhanced p-i-n Photodiodes

    Science.gov (United States)

    1998-12-01

    REPORT unclassified b . ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 8:45am - 9...00am WB2 High-Speed Widely-Tunable >90% Quantum-Efficiency Resonant Cavity Enhanced p-i-n Photodiodes Necmi Biyiklia. Ibrahim Kimukinb. Orhan ...Bilkent, Ankara 06533, Turkey. b Department of Physics, Bilkent University, Bilkent, Ankara 06533, Turkey. c Department of Electrical and Computer

  17. No-go theorem for superradiant quantum phase transitions in cavity QED and counter-example in circuit QED.

    Science.gov (United States)

    Nataf, Pierre; Ciuti, Cristiano

    2010-09-07

    In cavity quantum electrodynamics (QED), the interaction between an atomic transition and the cavity field is measured by the vacuum Rabi frequency Ω(0). The analogous term 'circuit QED' has been introduced for Josephson junctions, because superconducting circuits behave as artificial atoms coupled to the bosonic field of a resonator. In the regime with Ω(0) comparable with the two-level transition frequency, 'superradiant' quantum phase transitions for the cavity vacuum have been predicted, for example, within the Dicke model. In this study, we prove that if the time-independent light-matter Hamiltonian is considered, a superradiant quantum critical point is forbidden for electric dipole atomic transitions because of the oscillator strength sum rule. In circuit QED, the analogous of the electric dipole coupling is the capacitive coupling, and such no-go property can be circumvented by Cooper pair boxes capacitively coupled to a resonator, because of their peculiar Hilbert space topology and a violation of the corresponding sum rule.

  18. Dynamic Equations and Nonlinear Dynamics of Cascade Two-Photon Laser

    Institute of Scientific and Technical Information of China (English)

    XIE Xia; HUANG Hong-Bin; QIAN Feng; ZHANG Ya-Jun; YANG Peng; QI Guan-Xiao

    2006-01-01

    We derive equations and study nonlinear dynamics of cascade two-photon laser, in which the electromagnetic field in the cavity is driven by coherently prepared three-level atoms and classical field injected into the cavity. The dynamic equations of such a system are derived by using the technique of quantum Langevin operators, and then are studied numerically under different driving conditions. The results show thgt under certain conditions the cascade twophoton laser can generate chaotic, period doubling, periodic, stable and bistable states. Chaos can be inhibited by atomic populations, atomic coherences, and injected classical field. In addition, no chaos occurs in optical bistability.

  19. Scheme for Implementation of an Economic 1→3 Quantum Cloning Machine via Cavity-Assisted Atomic Collisions in Cavity-QED

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-Qiang; LIU Qi; LIANG Xian-Ting; ZHANG Wen-Hai; YE Liu

    2008-01-01

    A scheme to implement of 1→ 3 economic phase-covariant cloning machine for unknown equator state in cavity-QED is proposed. The scheme requires cavity-assisted collision processes between atoms, which cross through nonresonant cavity fields in the vacuum states. The cavity fields are only virtually excited so that the cavity quality factor can be loosened.

  20. Quantum information transfer and entanglement with SQUID qubits in cavity QED: a dark-state scheme with tolerance for nonuniform device parameter.

    Science.gov (United States)

    Yang, Chui-Ping; Chu, Shih-I; Han, Siyuan

    2004-03-19

    We investigate the experimental feasibility of realizing quantum information transfer (QIT) and entanglement with SQUID qubits in a microwave cavity via dark states. Realistic system parameters are presented. Our results show that QIT and entanglement with two-SQUID qubits can be achieved with a high fidelity. The present scheme is tolerant to device parameter nonuniformity. We also show that the strong coupling limit can be achieved with SQUID qubits in a microwave cavity. Thus, cavity-SQUID systems provide a new way for production of nonclassical microwave source and quantum communication.