Dynamic Behavior of Lambda-Type Three-Level Atoms and Two-Mode Cavity Field
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A system comprising of Lambda-type three-level atoms and the two-mode cavity field is considered in this paper. Under the adiabatical approximation and the large detuning condition, the effective Hamiltonian of the system in the interaction picture can be given out. If the two identical three-level atoms pass through the cavity in turn, the entangled state atoms can be generated. When the interaction time is taken to an appropriate value, the maximally entangled states are created. At the same time, the dynamic behaviors of the system are studied in detail.
Two-mode mazer injected with V-type three-level atoms
Institute of Scientific and Technical Information of China (English)
梁文青; 张智明; 谢绳武
2003-01-01
The properties of the two-mode mazer operating on V-type three-level atoms are studied. The effect of the oneatom pumping on the two modes of the cavity field in number-state is asymmetric, that is, the atom emits a photon into one mode with some probability and absorbs a photon from the other mode with some other probability. This effect makes the steady-state photon distribution and the steady-state photon statistics asymmetric for the two modes. The diagram of the probability currents for the photon distribution, given by the analysis of the master equation, reveals that there is no detailed balance solution for the master equation. The computations show that the photon statistics of one mode or both modes can be sub-Poissonian, that the two modes can have anticorrelation or correlation, that the photon statistics increases with the increase of thermal photons, and that the resonant position and strength of the photon statistics are influenced by the ratio of the two coupling strengths of the two modes. These properties are also discussed physically.
Institute of Scientific and Technical Information of China (English)
PING Yun-Xia; LIU Lie; ZHANG Chao-Min; CHENG Ze
2011-01-01
Violations of Bell inequality, Cauchy-Schwarz inequality and entanglement in a two-mode three-level atomic system are investigated. It is shown that there are some states, which are entangled but do not violate Bell inequality in this system. Moreover, the relations of violations of Bell inequality, Cauchy-Schwarz inequality, and entanglement are discussed in detail.
Nonclasssical Properties in Two-Mode Fields Resonantly Interacting with a Three-Level [Ⅰ]-Type Atom
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Some noclassical properties in electromagnetic Reid are investigated for the interaction of two-modes initially taken in coherent-state representation with the three-level [Ⅰ]-type atom, such as squeezing properties and violation of the Cauchy-Schwartz inequality. The enhancement of Geld squeezing is found by selective atomic measurement. The Cauchy-Schwartz inequality is violated by the application of the classical Geld followed by detection in excited state.
Institute of Scientific and Technical Information of China (English)
PING Yun-Xia; CHENG Ze
2007-01-01
Continuous variable entanglement and violation of Bell inequality for two modes are investigated in a three-level cascade atomic system. Entanglement of the system is demonstrated according to the entanglement criterion [Phys. Rev. Lett. 84 (2000) 2722]. Violation of Bell inequality is studied within the framework of a quantum theory of multiwave mixing. It is shown that there are some states that are entangled but do not violate the Bell inequality.
Poizat, J. Ph.; Collett, M. J.; Walls, D. F.
1992-04-01
We consider two modes of the electromagnetic field interacting via a three-level atom in a ladder configuration. We calculate the squeezing spectra of the sum and difference of the two output beams. The usefulness of this system as a quantum-nondemolition-measurement scheme is analyzed and a prediction is made using the parameters of a recent experiment by Grangier et al. [Phys. Rev. Lett. 66, 1418 (1991)]. We use a full three-level model in the most general case and in particular the influence of both the one-photon and the two-photon detunings are investigated.
Hassani Nadiki, M.; Tavassoly, M. K.
2016-12-01
In this paper the interaction of a three-level atom in V-configuration with a two-mode quantized field in cavity optomechanics is studied. To achieve the purpose, we first deduce the effective Hamiltonian and evaluate the explicit time-dependent form of the state vector of the whole system by choosing special initial conditions for atom, field and the oscillatory mirror. Interestingly, we can obtain the time evolution of atomic linear entropy, population inversion, quantum statistics and squeezing, both analytically and numerically. The results show that the entanglement between the atom and the subsystem of field and mirror, and all above-mentioned physical quantities can be appropriately controlled by the initial atom-field state condition, the parameters of cavity optomechanics as well as atom-field coupling strengths. In particular, the appearance of collapse-revival phenomenon in the entanglement and quantum photon statistics, also the full sub-Poissonian statistics in the two modes of field as well as in the mechanical mode of optomechanical system are noticeable features of the work.
Indian Academy of Sciences (India)
M Mohjoei; M M Golshan; H Safari
2013-05-01
In this paper the time evolution of von Neumann entropy, as a measure of entanglement between V-type three-level atoms and the union of a two-mode field, is studied. The atom–field interaction is assumed to occur in a Kerr-type medium with an intensity-dependent coupling. Introducing a Casmir operator whose eigenvalues, , give total excitations in the system and commutes with the governing Hamiltonian, it is concluded that the latter is block-diagonal with ever growing dimensions. As we shall show, however, each block consists of two 2 × 2 blocks while all the others, ( −1) in number, are 3 × 3. We then proceed to analytically calculate the time-evolution operator which is also block-diagonal, each block with the same properties as that of the Hamiltonian. Our calculations show that, as expected, the atom–field entanglement oscillates which, depending upon the initial state, exhibits the phenomenon of collapse revivals. It is further shown that collapse revivals occur whenever both 2 × 2 blocks are involved in the time evolution of the system. Properties of such behaviour in the entanglement are also discussed in detail.
Effect of Cavity Decay on Entanglement of Ladder-Type Three-Level Atoms and a Two-Mode Cavity Field
Institute of Scientific and Technical Information of China (English)
GAO Cheng-Yuan; LIU Jin-Ming; MA Lei
2008-01-01
Considering the adiabatical approximation and the large detuning condition, we give the effective Hamil-tonian of a ladder-type three levels atom interacting with a bimodal cavity field. If two identical three-level atoms are sent through the cavity one by one, a two-atom entangled state can be generated. With the choice of the appropriate interaction time, a maximally entangled state of two atoms can be obtained if decoherence effect is ignored. Moreover, we discuss the effect of cavity decay on four physical quantities including atomic population probability, residual entan-glement of the first atom and the cavity field, concurrence between the two atoms, and fidelity for generating atomic EPR state, all of which decrease with the increase of cavity decay when the other parameters are fixed.
Institute of Scientific and Technical Information of China (English)
胡明亮; 田东平; 柳海
2007-01-01
提出了一种利用V-型三能级原子与双模腔场的共振相互作用制备多原子及多腔场纠缠W态的新方案,并用共生纠缠度研究了该模型中的纠缠演化和热纠缠现象.%A new scheme for the preparation of multi-atom and nulti-cavity entangled W state via resonant interaction of V-type three-level atoms and two-mode cavity- field is proposed. Also the time evolution and the thermal entanglement of this model will be studied by the concept of concurrence in this paper.
Unconditional two-mode squeezing of separated atomic ensembles
Parkins, A S; Solano, E
2005-01-01
We propose schemes for the unconditional preparation of a two-mode squeezed state of effective bosonic modes realized in a pair of atomic ensembles interacting collectively with optical cavity and laser fields. The scheme uses Raman transitions between stable atomic ground states and under ideal conditions produces pure entangled states in the steady state. The scheme works both for ensembles confined within a single cavity and for ensembles confined in separate, cascaded cavities.
Transmission probability of the two-mode mazer with injected atomic coherence
Institute of Scientific and Technical Information of China (English)
袁春华; 张智明
2005-01-01
The transmission probability of the two-mode mazer injected with V-type three-level atoms is studied, and the effects of the atomic coherence on it are examined. It is shown that the atomic coherence can affect the transmission probability. In the plots of the atomic transmission probability versus the dimensionless centre-of-mass momentum, there are resonance peaks and non-resonance platforms. The heights of these resonance peaks and non-resonance platforms can be adjusted by the atomic coherence parameter and by the relative coupling strength of the two transition channels.
Analytic Solutions of Three-Level Dressed-Atom Model
Institute of Scientific and Technical Information of China (English)
WANG Zheng-Ling; YIN Jian-Ping
2004-01-01
On the basis of the dressed-atom model, the general analytic expressions for the eigenenergies, eigenstates and their optical potentials of the A-configuration three-level atom system are derived and analysed. From the calculation of dipole matrix element of different dressed states, we obtain the spontaneous-emission rates in the dressed-atom picture. We find that our general expressions of optical potentials for the three-level dressed atom can be reduced to the same as ones in previous references under the approximation of a small saturation parameter. We also analyse the dependences of the optical potentials of a three-level 85Rb atom on the laser detuning and the dependences of spontaneous-emission rates on the radial position in the dark hollow beam, and discuss the probability (population) evolutions of dressed-atomic eigenstates in three levels in the hollow beam.
Berry phases in the three-level atoms driven by quantized light fields
Indian Academy of Sciences (India)
Mai-Lin Liang; Zong-Cheng Xu; Bing Yuan
2008-03-01
A theoretical analysis of Berry's phases is given for the three-level atoms interacting with external one-mode and two-mode quantized light fields. Three main results are obtained: (i) There is a Berry phase which vanishes in the classical limit or this Berry phase is completely induced by the field quantization; (ii) Berry's phases for the one-mode field and the two-mode field can be equal so long as the photon numbers of the two-mode field are properly chosen; (iii) In the two-mode case, Berry phases of the atom interacting with one mode is affected by the other mode even if the photon number of the other mode is zero.
Tomography vs quantum control for a three-level atom
Energy Technology Data Exchange (ETDEWEB)
Aguilar, O. [Departamento de Fisica, Universidad de Guadalajara, Revolucion 1500, 44420 Guadalajara, Jalisco (Mexico)]. E-mail: caronte30@yahoo.com; Klimov, A.B. [Departamento de Fisica, Universidad de Guadalajara, Revolucion 1500, 44420 Guadalajara, Jalisco (Mexico); Guise, Hubert de [Department of Physics, Lakehead University, Thunder Bay, Ontario P7B 5E1 (Canada)
2006-12-04
We investigate the possibilities of controlling and reconstructing the state of a single three-level atom. We propose a physical scheme where information about the atomic state is extracted by measuring the total number of excitations after successive application of electromagnetic field pulses. We show that, in the non-degenerate case (different transition frequencies for different atomic transitions), a three-level atom is completely controllable and its state can be completely reconstructed. In the degenerate case (when both atomic transitions are identical), we consider two dynamically inequivalent configurations, {lambda} and {xi}. In this case, we show that the density matrix can always be completely reconstructed whereas their respective system cannot be completely controlled. We explain why this last incompatibility between control and tomography arises.
The Multiphoton Interaction of Lambda Model Atom and Two-Mode Fields
Liu, Tang-Kun
1996-01-01
The system of two-mode fields interacting with atom by means of multiphotons is addressed, and the non-classical statistic quality of two-mode fields with interaction is discussed. Through mathematical calculation, some new rules of non-classical effects of two-mode fields which evolue with time, are established.
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%.
Atomic Dipole Squeezing in the Correlated Two-Mode Two-Photon Jaynes-Cummings Model
Dong, Zhengchao; Zhao, Yonglin
1996-01-01
In this paper, we study the atomic dipole squeezing in the correlated two-mode two-photon JC model with the field initially in the correlated two-mode SU(1,1) coherent state. The effects of detuning, field intensity and number difference between the two field modes are investigated through numerical calculation.
Emission Probability of the Cascade Three-Level-Atom Mazer with Injected Atomic Coherence
Institute of Scientific and Technical Information of China (English)
熊锦; 张智明
2002-01-01
We investigate the effects of the injected atomic coherence on the atomic emission probability of the micromaser injected with ultracold cascade three-level atoms by considering that the atoms are initially in the coherent superposition states of the two upper levels. We show that there is no interference between the transitions from the two upper levels to the lowest level. In the large atom-field-detuning case, the atomic emission probability decreases as the coherent parameter increases. In the zero atom-field-detuning case, the atomic emission probability has three sets of resonance peaks. The reason for these results has been explained.
Some studies of the interaction between N-two level atoms and three level atom
Directory of Open Access Journals (Sweden)
D.A.M. Abo-Kahla
2016-07-01
Full Text Available In this paper, we present the analytical solution for the model that describes the interaction between a three level atom and two systems of N-two level atoms. The effect of the quantum numbers on the atomic inversion and the purity, for some special cases of the initial states, are investigated. We observe that the atomic inversion and the purity change remarkably by the change of the quantum numbers.
Information Entropy Squeezing of a Two-Level Atom Interacting with Two-Mode Coherent Fields
Institute of Scientific and Technical Information of China (English)
LIU Xiao-Juan; FANG Mao-Fa
2004-01-01
From a quantum information point of view we investigate the entropy squeezing properties for a two-level atom interacting with the two-mode coherent fields via the two-photon transition. We discuss the influences of the initial state of the system on the atomic information entropy squeezing. Our results show that the squeezed component number,squeezed direction, and time of the information entropy squeezing can be controlled by choosing atomic distribution angle,the relative phase between the atom and the two-mode field, and the difference of the average photon number of the two field modes, respectively. Quantum information entropy is a remarkable precision measure for the atomic squeezing.
Wang, Zhiping; Cao, Dewei; Yu, Benli
2016-05-01
We present a new scheme for three-dimensional (3D) atom localization in a three-level atomic system via measuring the absorption of a weak probe field. Owing to the space-dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the probe absorption. It is found that, by properly varying the parameters of the system, the probability of finding the atom in 3D space can be almost 100%. Our scheme opens a promising way to achieve high-precision and high-efficiency 3D atom localization, which provides some potential applications in laser cooling or atom nano-lithography via atom localization.
Resonance fluorescence of a trapped three-level atom
Bienert, M; Morigi, G; Bienert, Marc; Merkel, Wolfgang; Morigi, Giovanna
2003-01-01
We investigate theoretically the spectrum of resonance fluorescence of a harmonically trapped atom, whose internal transitions are $\\Lambda$--shaped and driven at two-photon resonance by a pair of lasers, which cool the center--of--mass motion. For this configuration, photons are scattered only due to the mechanical effects of the quantum interaction between light and atom. We study the spectrum of emission in the final stage of laser--cooling, when the atomic center-of-mass dynamics is quantum mechanical and the size of the wave packet is much smaller than the laser wavelength (Lamb--Dicke limit). We use the spectral decomposition of the Liouville operator of the master equation for the atomic density matrix and apply second order perturbation theory. We find that the spectrum of resonance fluorescence is composed by two narrow sidebands -- the Stokes and anti-Stokes components of the scattered light -- while all other signals are in general orders of magnitude smaller. For very low temperatures, however, th...
Radiation forces on a three-level atom in the high-order Bessel beams
Institute of Scientific and Technical Information of China (English)
Wang Zheng-Ling; Yin Jian-Ping
2008-01-01
The general expressions of the average dissipative and dipole forces acting on a A-configuration three-level atom in an arbitrary light field are derived by means of the optical Bloch equations based on the atomic density matrix elements, and the general properties of the average dissipative and dipole forces on a three-level atom in the linearly-polarized high-order Bessel beams (HBBs) are analysed. We find a resonant property (with two resonant peaks) of the dissipative force and a non-resonant property (with two pairs of non-resonant peaks) of the dipole force on the three-level atom, which are completely different from those on the two-level atom. Meanwhile we find a saturation effect of the average dissipative force in the HBB, which comes from the saturation of the upper-level population. Our study shows that the general expressions of the average dissipative and dipole forces on the three-level atom will be simplified to those of the two-level atom under the approximation of large detuning. Finally, we study the axial and azimuthal Doppler cooling of atoms in 1D optical molasses composed of two counter-propagating HBBs and discuss the azimuthal influence of the HBB on the Doppler cooling limit. We also find that the Doppler limit of atoms in the molasses HBB is slightly below the conventional Doppler limit of hг/(2кB) due to the orbital angular momentum lh of the HBB.
High-Speed Generation of Entangled States for Two Three-Level Atoms
Institute of Scientific and Technical Information of China (English)
ZHENG Shi-Biao
2007-01-01
A scheme is presented for generating entangled states for two three-level atoms in a cavity. In the scheme two atoms simultaneously interact with a cavity mode with a small detuning. Thus, the operation time is very short,which is important in view of decoherence.
Cavity quantum electrodynamics with quantum interference in a three-level atomic system
Joshi, Amitabh; Serna, Juan D.
2017-06-01
Spontaneously generated coherence and enhanced dispersion in a V-type, three-level atomic system interacting with a single mode field can considerably reduce the radiative and cavity decay rates. This may eliminate the use of high finesse, miniaturized cavities in optical cavity quantum electrodynamics experiments under strong atom-field coupling conditions.
Entanglement and coherence of a three-level atom in Λ configuration interacting with two fields
Institute of Scientific and Technical Information of China (English)
Zhang Jian-Song; Xu Jing-Bo
2009-01-01
We investigate the entanglement of a three-level atom in A configuration interacting with two quantized field modes by using logarithmic negativity. Then, we study the relationship of the atomic coherence and the entanglement between two fields which are initially prepared in vacuum or thermal states. We find that if the two fields are prepared in thermal states, the atomic coherence can induce the entanglement between two thermal fields. However, there is no coherence-induced entanglement between two vacuum fields.
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.
Observation of three-level rectified dipole forces acting on trapped atoms
Grove, T. T.; Duncan, B. C.; Sanchez-Villicana, V.; Gould, P. L.
1995-06-01
We have observed rectified dipole forces acting on three-level atoms in the cascade configuration. Laser cooled and trapped rubidium atoms are illuminated with an intense bichromatic standing wave (780 and 776 nm) tuned near resonance with the 5S1/2-->5P3/2-->5D5/2 transitions. The resulting rectified forces produce periodic potential wells (71-μm period), which localize the cold atoms. Experimental results are in reasonable agreement with theoretical predictions. These forces may be useful in atom optics and laser traps.
Entropy-Energy Inequality for a Qutrit on the Example of a Three-Level Atom
Man'ko, V. I.; Markovich, L. A.
2017-03-01
We consider the entropy-energy inequality for a three-level atom implemented on superconducting circuits with the Josephson junction. It is suggested to use the positivity of the relative entropy of the qutritquantum system for verification of tomography of quantum states of qudits. The relations obtained are considered in detail on the example of the temperature density matrix.
Teleporting N-qubit unknown atomic state by utilizing the Ⅴ-type three-level atom
Institute of Scientific and Technical Information of China (English)
ZHANG XinHua; YANG ZhiYong; XU PeiPei
2009-01-01
Realizing the teleportation of quantum state, especially the teleportation of N-qubit quantum state, is of great importance in quantum information. In this paper, Raman-interaction of the Ⅴ-type degenerate three-level atom and single-mode cavity field is studied by utilizing complete quantum theory. Then a new scheme for teleporting N-qubit unknown atomic state via Raman-interaction of the Ⅴ-type degen-erate three-level atom with a single-mode cavity field is proposed, which is based upon the complete quantum theory mentioned above.
Teleporting N-qubit unknown atomic state by utilizing the V-type three-level atom
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Realizing the teleportation of quantum state, especially the teleportation of N-qubit quantum state, is of great importance in quantum information. In this paper, Raman-interaction of the V-type degenerate three-level atom and single-mode cavity field is studied by utilizing complete quantum theory. Then a new scheme for teleporting N-qubit unknown atomic state via Raman-interaction of the V-type degenerate three-level atom with a single-mode cavity field is proposed, which is based upon the complete quantum theory mentioned above.
Cooling and trapping of three-level atoms in a bichromatic standing wave
Pu, H.; Cai, T.; Bigelow, N. P.; Grove, T. T.; Gould, P. L.
1995-02-01
We show that a three-level atom in the cascade configuration can be stably trapped and cooled in one dimension by an intense bichromatic standing wave. At the two-photon resonance, rectified dipole forces result in a deep potential well which can be used to localize the atoms in space. In the vicinity of the rectified potential minimum, the spatial dependence of the dressed state energies can lead to a velocity dependence of the force which produces damping of the atomic motion. Consideration of the heating effects of momentum diffusion indicates that cooling and stable trapping at low temperatures is possible in such a bichromatic field.
Absorption Spectra of a Three-Level Atom Embedded in a PBG Reservoir
Institute of Scientific and Technical Information of China (English)
ZHANG Ke; ZHANG Han-Zhuang
2007-01-01
We introduce the 'decay rate' terms into the density matrix equations of an atom embedded in a photonic band gap (PSG)reservoir successfully.By utilizing the master equations,the probe absorption spectra and the refractivity properties of a three-level atom in the PBG reservoir are obtained.The interaction between the atom and the PBG reservoir as well as the effects of the quantum interference on the absorption of the atom has also been taken into account.It is interesting that two different types of the anomalous dispersion relations of refractivity are exhibited in one dispersion line.The methodology used here can be applied to theoretical investigation of quantum interference effects of other atomic models embedded in a PBG reservoir.
Gavryusev, V.; Signoles, A.; Ferreira-Cao, M.; Zürn, G.; Hofmann, C. S.; Günter, G.; Schempp, H.; Robert-de-Saint-Vincent, M.; Whitlock, S.; Weidemüller, M.
2016-08-01
We present combined measurements of the spatially resolved optical spectrum and the total excited-atom number in an ultracold gas of three-level atoms under electromagnetically induced transparency conditions involving high-lying Rydberg states. The observed optical transmission of a weak probe laser at the center of the coupling region exhibits a double peaked spectrum as a function of detuning, while the Rydberg atom number shows a comparatively narrow single resonance. By imaging the transmitted light onto a charge-coupled-device camera, we record hundreds of spectra in parallel, which are used to map out the spatial profile of Rabi frequencies of the coupling laser. Using all the information available we can reconstruct the full one-body density matrix of the three-level system, which provides the optical susceptibility and the Rydberg density as a function of spatial position. These results help elucidate the connection between three-level interference phenomena, including the interplay of matter and light degrees of freedom and will facilitate new studies of many-body effects in optically driven Rydberg gases.
Gavryusev, V; Ferreira-Cao, M; Zürn, G; Hofmann, C S; Günter, G; Schempp, H; Robert-de-Saint-Vincent, M; Whitlock, S; Weidemüller, M
2016-01-01
We present combined measurements of the spatially-resolved optical spectrum and the total excited-atom number in an ultracold gas of three-level atoms under electromagnetically induced transparency conditions involving high-lying Rydberg states. The observed optical transmission of a weak probe laser at the center of the coupling region exhibits a double peaked spectrum as a function of detuning, whilst the Rydberg atom number shows a comparatively narrow single resonance. By imaging the transmitted light onto a charge-coupled-device camera, we record hundreds of spectra in parallel, which are used to map out the spatial profile of Rabi frequencies of the coupling laser. Using all the information available we can reconstruct the full one-body density matrix of the three-level system, which provides the optical susceptibility and the Rydberg density as a function of spatial position. These results help elucidate the connection between three-level interference phenomena, including the interplay of matter and li...
Zou, Xubo; Mathis, W.
2004-09-01
We propose an experimental scheme for one-step implementation of maximally entangled states of many three-level atoms in microwave cavity QED. In the scheme, many three-level atoms initially prepared in the same superposition states are simultaneously sent through one superconducting cavity, and maximally entangled states can be generated without requiring the measurement and individual addressing of the atoms.
Controlling Single-Photon Transport along an Optical Waveguide by using a Three-Level Atom
Institute of Scientific and Technical Information of China (English)
TIAN Wei; CHEN Bin; XU Wei-Dong
2012-01-01
We theoretically investigate the single-photon transport properties in an optical waveguide embedded with a V-type three-level atom (VTLA) based on symmetric and asymmetric couplings between the photon and the VTLA.Our numerical results show that the transmission spectrum of the incident photon can be well controlled by virtue of both symmetric and asymmetric coupling interactions.A multifrequency photon attenuator is realized by controlling the asymmetric coupling interactions.Furthermore,the influences of dissipation of the VTLA for the realistic physical system on single-photon transport properties are also analyzed.
Spontaneous emission spectrum of a three-level atom embedded in photonic crystal
Institute of Scientific and Technical Information of China (English)
刘国强; 王健; 张汉壮
2005-01-01
The two models of three-level (one upper level and two lower levels, or two upper levels and one lower level) atom embedded in a double-band photonic crystal are adopted. The atomic transitions from the upper levels to the lower levels are assumed to be coupled by the same reservoir which are respectively the isotropic photonic band gap (PBG)modes, the anisotropic PBG modes and the free vacuum modes. The effects of the fine structure of the atomic ground state levels in the model with one upper level and two lower levels, and the quantum interferences in the model with two upper levels and one lower level on the spontaneous emission spectrum of an atom are investigated in detail. Most interestingly, it is shown that new spontaneous emission lines are produced from the fine splitting of atomic ground state levels in the isotropic PBG case. The quantum interferences induce additional narrow spontaneous lines near the transition from the empty upper level to the lower level.
Average Dissipative and Dipole Forces on a Three-Level Atom in a Laguerre-Gaussian Beam
Institute of Scientific and Technical Information of China (English)
WANG Zheng-Ling; YIN Jian-Ping
2005-01-01
@@ By means of the optical Bloch equations based on the atomic density matrix elements, the general expressions of the average dissipative force, dipole force and the mechanical torque acting on a A-configuration three-level atom in a linearly-polarized Laguerre-Gaussian beam (LGB) with an angular momentum of lh are derived, and the general properties of the average dissipative and dipole force on the three-level atom in the linearly-polarized LGB are analysed. We find a resonant property (with two resonant peaks) of the dissipative force and a non-resonant property (with two pairs of non-resonant peaks) of the dipole force on the three-level atom, which are completely different from those on the two-level atom. Our study also shows that all of general expressions on the three-level atom will be simplified to those on the two-level atom in the approximation of large detuning.
Temperature limits in laser cooling of free atoms with three-level cascade transitions
Cruz, Flavio C; Magno, Wictor C
2013-01-01
We employ semiclassical theoretical analysis to study laser cooling of free atoms using three-level cascade transitions, where the upper transition is much weaker than the lower one. This represents an alternate cooling scheme, particularly useful for group II atoms. We find that temperatures below the Doppler limits associated with each of these transitions are expected. The lowest temperatures arise from a remarkable increase in damping and reduced diffusion compared to two-level cooling. They are reached at the two-photon resonance, where there is a crossing between the narrow and the partially-dark dressed states, and can be estimated simply by the usual Doppler limit considering the decay rate of the optical coherence between these states.
Negative and positive hysteresis in double-cavity optical bistability in three-level atom
Babu, H Aswath
2010-01-01
We present novel hysteretic behaviour of a three-level ladder atomic system exhibiting double-cavity optical bistability in the mean-field limit. The two fields coupling the atomic system experience feedback via two independent, unidirectional, single mode ring cavities and exhibit cooperative phenomena, simultaneously. The system displays a range of rich dynamical features varying from normal switching to self pulsing and a period-doubling route to chaos for both the fields. We focus our attention to a new hump like feature in the bistable curve arising purely due to cavity induced inversion, which eventually leads to negative hysteresis in the bistable response. This is probably the only all-optical bistable system that exhibits positive as well as negative bistable hysteresis in different input field intensity regimes. For both the fields, the switching times, the associated critical slowing down, the self-pulsing characteristics, and the chaotic behaviour can be controlled to a fair degree, moreover, all ...
Coupling of a nano mechanical oscillator and an atomic three-level medium
Sanz-Mora, A; Wüster, S; Rost, J -M
2015-01-01
We theoretically investigate the coupling of an ultracold three-level atomic gas and a nano-mechanical mirror via classical electromagnetic radiation. The radiation pressure on the mirror is modulated by absorption of a probe light field, caused by the atoms which are electromagnetically rendered nearly transparent, allowing the gas to affect the mirror. In turn, the mirror can affect the gas as its vibrations generate opto-mechanical sidebands in the control field. We show that the sidebands cause modulations of the probe intensity at the mirror frequency, which can be enhanced near atomic resonances. Through the radiation pressure from the probe beam onto the mirror, this results in resonant driving of the mirror. Controllable by the two photon detuning, the phase relation of the driving to the mirror motion decides upon amplification or damping of mirror vibrations. This permits direct phase locking of laser amplitude modulations to the motion of a nano-mechanical element opening a perspective for cavity-f...
Fully robust qubit in atomic and molecular three-level systems
Aharon, N.; Cohen, I.; Jelezko, F.; Retzker, A.
2016-12-01
We present a new method of constructing a fully robust qubit in a three-level system. By the application of continuous driving fields, robustness to both external and controller noise is achieved. Specifically, magnetic noise and power fluctuations do not operate within the robust qubit subspace. Whereas all the continuous driving based constructions of such a fully robust qubit considered so far have required at least four levels, we show that in fact only three levels are necessary. This paves the way for simple constructions of a fully robust qubit in many atomic and solid state systems that are controlled by either microwave or optical fields. We focus on the NV-center in diamond and analyze the implementation of the scheme, by utilizing the electronic spin sub-levels of its ground state. In current state-of-the-art experimental setups the scheme leads to improvement of more than two orders of magnitude in coherence time, pushing it towards the lifetime limit. We show how the fully robust qubit can be used to implement quantum sensing, and in particular, the sensing of high frequency signals.
Radiation pressure and laser cooling of a three-level atom in a ladder configuration
Institute of Scientific and Technical Information of China (English)
Tan Lei; Wang Zhi-Cheng; Gu Huai-Qiang
2004-01-01
Radiation pressure and laser cooling of a moving three-level ladder-type atom in bichromatic travelling fields are considered. The dependence of the force on parameters such as detunings, Rabi frequencies and spontaneous decay rates is calculated numerically and shown graphically, and analytical expressions for the force are obtained for some special parameter values. It is shown that the radiation pressure shows Doppler-shifted resonance peaks resulting respectively from one-photon and two-photon transitions. Using the present scheme, Doppler cooling of sodium exploiting the 3 2S1/2-3 2P3/2-3 2D5/2 cascade transitions is investigated. It is found that temperatures lower than the Doppler limit can be achieved.
Dynamics for a two-atom two-mode intensity-dependent Raman coupled model
Singh, S.; Gilhare, K.
2016-06-01
We study the quantum dynamics of a two-atom Raman coupled model interacting with a quantized bimodal field with intensity-dependent coupling terms in a lossless cavity. The unitary transformation method used to solve the time-dependent problem also gives the eigensolutions of the interaction Hamiltonian. We study the atomic-population dynamics and dynamics of the photon statistics in the two cavity modes, and present evidence of cooperative effects in the production of antibunching and anticorrelations between the modes. We also investigate the effect of detuning on the evolution of second-order correlation functions and observe that the oscillations become more rapid for large detuning.
Dynamics for a two-atom two-mode intensity-dependent Raman coupled model
Energy Technology Data Exchange (ETDEWEB)
Singh, S., E-mail: vasudha-rnc1@rediffmail.com, E-mail: sudhhasingh@gmail.com; Gilhare, K. [Ranchi University, Department of Physics (India)
2016-06-15
We study the quantum dynamics of a two-atom Raman coupled model interacting with a quantized bimodal field with intensity-dependent coupling terms in a lossless cavity. The unitary transformation method used to solve the time-dependent problem also gives the eigensolutions of the interaction Hamiltonian. We study the atomic-population dynamics and dynamics of the photon statistics in the two cavity modes, and present evidence of cooperative effects in the production of antibunching and anticorrelations between the modes. We also investigate the effect of detuning on the evolution of second-order correlation functions and observe that the oscillations become more rapid for large detuning.
Sehati, N.; Tavassoly, M. K.
2017-08-01
Inspiring from the scheme proposed in (Zheng in Phys Rev A 69:064,302 2004), our aim is to teleport an unknown qubit atomic state using the cavity QED method without using the explicit Bell-state measurement, and so the additional atom is not required. Two identical Λ-type three-level atoms are interacted separately and subsequently with a two-mode quantized cavity field where each mode is expressed with a single-photon field state. The interaction between atoms and field is well described via the Jaynes-Cummings model. It is then shown that how if the atomic detection results a particular state of atom 1, an unknown state can be appropriately teleported from atom 1 to atom 2. This teleportation procedure successfully leads to the high fidelity F (success probability P_g) in between 69%≲ F≲ 100% (0.14≲ P_g≲ 0.56). At last, we illustrated that our scheme considerably improves similar previous proposals.
Phase-controlled atom-photon entanglement in a three-level ∧-type closed-loop atomic system
Institute of Scientific and Technical Information of China (English)
Ali Mortezapour; Zeinab Kordi; Mohammad Mahmoudi
2013-01-01
We study the entanglement of dressed atom and its spontaneous emission in a three-level A-type closed-loop atomic system in a multi-photon resonance condition and beyond it.It is shown that the von Neumann entropy in such a system is phase-dependent,and it can be controlled by either the intensity or relative phase of applied fields.It is demonstrated that for the special case of the Rabi frequency of applied fields,the system is disentangled.In addition,we take into account the effect of Doppler broadening on the entanglement and it is found that a suitable choice of laser propagation direction allows us to obtain the steady state degree of entanglement (DEM) even in the presence of the Doppler effect.
Entropy squeezing for a two-level atom in two-mode Raman coupled model with intrinsic decoherence
Institute of Scientific and Technical Information of China (English)
Zhang Jian; Shao Bin; Zou Jian
2009-01-01
In this paper,we investigate the entropy squeezing for a two-level atom interacting with two quantized fields through Raman coupling.We obtain the dynamical evolution of the total system under the influence of intrinsic decoherence when the two quantized fields are prepared in a two-mode squeezing vacuum state initially.The effects of the field squeezing factor,the two-level atomic transition frequency,the second field frequency and the intrinsic decoherence on the entropy squeezing are discussed.Without intrinsic decoherence,the increase of field squeezing factor can break the entropy squeezing.The two-level atomic transition frequency changes only the period of oscillation but not the strength of entropy squeezing.The influence of the second field frequency is complicated.With the intrinsic decoherence taken into consideration,the results show that the stronger the intrinsic decoherence is,the more quickly the entropy squeezing will disappear.The increase of the atomic transition frequency can hasten the disappearance of entropy squeezing.
Mohamed, A.-B. A.; Eleuch, H.
2017-02-01
An analytical description of a three-level atom in an optical cavity coupled to the environment is obtained. The Husimi function and the Wehrl density are calculated to investigate the information loss dynamics of the phase space. The Wehrl entropy and the atomic information entropy are explored to study the coherence loss of the three-level system. We show that these measures, as non-classical indicators, are very sensitive not only to the coupling strength to the reservoir but also to the initial state.
Institute of Scientific and Technical Information of China (English)
Liu Xiao-Juan; Zhou Yuan-Jun; Fang Mao-Fa
2009-01-01
From the viewpoint of quantum information, this paper proposes a concept and a definition of the atomic optimal entropy squeezing sudden generation (AOESSG) for the system of an effective two-level moving atom which entangles with the two-mode coherent fields. It also researches the relationship between the AOESSG and entanglement sudden death of the atom-fields, and discusses the influences of atomic initial state on the AOESSG and obtains the system parameter which controls the AOESSG.
Li, Chuang; Yang, Sen; Song, Jie; Xia, Yan; Ding, Weiqiang
2017-05-15
In this paper, a scheme for the generation of long-living entanglement between two distant Λ-type three-level atoms separately trapped in two dissipative cavities is proposed. In this scheme, two dissipative cavities are coupled to their own non-Markovian environments and two three-level atoms are driven by the classical fields. The entangled state between the two atoms is produced by performing Bell state measurement (BSM) on photons leaving the dissipative cavities. Using the time-dependent Schördinger equation, we obtain the analytical results for the evolution of the entanglement. It is revealed that, by manipulating the detunings of classical field, the long-living stationary entanglement between two atoms can be generated in the presence of dissipation.
Institute of Scientific and Technical Information of China (English)
XU Jing-Bo; ZOU Xu-Bo; GAO Xiao-Chun; FU Jian
2004-01-01
With the help of an SU(3) dynamical algebraic structure, we find an exact solution of the Milburn equation for the system of a three-level atom in the Ξ configuration interacting with one quantized field mode with arbitrary detuning. The exact solution is then used to discuss the influence of the intrinsic decoherence on the nonclassical properties of the system, such as collapes and revivals of the atomic populations, oscillations of the photon number distribution, and squeezing of the radiation field.
Entropy squeezing of the field interacting with a nearly degenerate V-type three-level atom
Institute of Scientific and Technical Information of China (English)
Zhou Qing-Chun; Zhu Shi-Ning
2005-01-01
The position- and momentum-entopic squeezing properties of the optical field in the system of a nearly degenerate three-level atom interacting with a single-mode field are investigated. Calculation results indicate that when the field is initially in the vacuum state, it may lead to squeezing of the position entropy or the momentum entropy of the field if the atom is prepared properly. The effects of initial atomic state and the splitting of the excited levels of the atom on field entropies are discussed in this case. When the initial field is in a coherent state, we find that position-entropy squeezing of the field is present even if the atom is prepared in the ground state. By comparing the variance squeezing and entropy squeezing of the field we confirm that entropy is more sensitive than variance in measuring quantum fluctuations.
Measuring the Wigner Functions of Two-Mode Cavity Fields and Testing the Bell's Inequalities
Institute of Scientific and Technical Information of China (English)
张智明
2004-01-01
We propose a scheme for measuring the Wigner function of a two-mode cavity field. The scheme bases on the interaction between the two-mode cavity field and three-level atoms. We find a simple relation between the Wigner function and the atomic population. One can obtain the Wigner function by measuring the atomic population with a micromaser-like experiment and doing a numerical integral. By using the two-mode Wigner function one can obtain the Clauser-Horne combination and test the Bell's inequalities. We test our equations with a two-mode entanglement state and the results are rather good.
National Research Council Canada - National Science Library
Xiao-Li Song; Lei Wang; Rui-Zhu Lin; Zhi-Hui Kang; Xin Li; Yun Jiang; Jin-Yue Gao
2007-01-01
...) in a L-type configuration, and verify the theoretical predictions. Applying this technique, we are able to prepare the atoms with maximal coherence to enhance coherent anti-Stokes Raman scattering (CARS) signal...
Panchadhyayee, Pradipta
2013-11-01
We investigate the dynamical behaviour of atomic response in a closed three-level V-type atomic system with the variation of different relevant parameters to exhibit transient evolution of absorption, gain and transparency in the probe response. The oscillations in probe absorption and gain can be efficiently modulated by changing the values of the Rabi frequency, detuning and the collective phase involved in the system. The interesting outcome of the work is the generation of coherence controlled loop-structure with varying amplitudes in the oscillatory probe response of the probe field at various parameter conditions. The prominence of these structures is observed when the coherence induced in a one-photon excitation path is strongly modified by two-step excitations driven by the coherent fields operating in closed interaction contour. In contrast to purely resonant case, the time interval between two successive loops gets significantly reduced with the application of non-zero detuning in the coherent fields.
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.
Ma, Yun-Ming; Wang, Tie-Jun
2017-10-01
Higher-dimensional quantum system is of great interest owing to the outstanding features exhibited in the implementation of novel fundamental tests of nature and application in various quantum information tasks. High-dimensional quantum logic gate is a key element in scalable quantum computation and quantum communication. In this paper, we propose a scheme to implement a controlled-phase gate between a 2 N -dimensional photon and N three-level artificial atoms. This high-dimensional controlled-phase gate can serve as crucial components of the high-capacity, long-distance quantum communication. We use the high-dimensional Bell state analysis as an example to show the application of this device. Estimates on the system requirements indicate that our protocol is realizable with existing or near-further technologies. This scheme is ideally suited to solid-state integrated optical approaches to quantum information processing, and it can be applied to various system, such as superconducting qubits coupled to a resonator or nitrogen-vacancy centers coupled to a photonic-band-gap structures.
The mean first passage time of a three-level atomic optical bistable system subjected to noise
Institute of Scientific and Technical Information of China (English)
Wei Yong-Gang; Zeng Chun-Hua; Wang Hua; Li Kong-Zhai; Hu Jian-Hang
2013-01-01
The transient properties of a three-level atomic optical bistable system in the presence of multiplicative and additive noises are investigated.The explicit expressions of the mean first-passage time (MFPT) of the transition from the high intracavity intensity state to the low one are obtained by numerical computations.The impacts of the intensities of the multiplicative noise DM and the additive noise DA,the intensity of correlation between two noises λ,and the intensity of the incident light y on the MFPT are discussed,respectively.Our results show:(i) for the case of no correlation between two noises (λ =0.0),the increase in DM and DA can lead to an increase in the probability of the transition to the low intracavity intensity state,while the increase in y can lead to a retardation of the transition; and (ii) for the case of correlation between two noises (λ ≠ 0.0),the increase in λ can cause an increase in the probability of the transition,and the increase in DA can cause a retardation of the transition firstly and then an increase in the probability of the transition,i.e.,the noise-enhanced stability is observed for the case of correlation between two noises.
Institute of Scientific and Technical Information of China (English)
YANG Ya-Ping; Chen Hong; ZHU Shi-Yao
2000-01-01
The spontaneous emission from a V-type three-level atom embedded in a two-band photonic crystal is studied.Due to the quantum interference between the two transitions and existence of two bands, the populations in the upper levels display some novel behavior: anti-trapping, population oscillation, and population inversion.
Efficient three-wave mixing in a three-level atomic medium with an assisting microwave driven field
Institute of Scientific and Technical Information of China (English)
Li Jia-Hua; Luo Jin-Ming; Yang Wen-Xing; Zhan Zhi-Ming
2006-01-01
The potential for nonlinear conversion between two laser pulses in a three-level V-type medium with assistance of an auxiliary microwave resonant radiation is studied. The results show that microwave driven field can lead to the parametric generation of a new laser pulse with high conversion efficiency when a weak pump laser pulse is applied.
Kumar, Parvendra
2012-01-01
We report a study on the ultrafast coherent population oscillations (UCPO) in sodium atoms induced by the frequency modulated few-cycle optical pulse trains. The phenomenon of UCPO is investigated by numerically solving the appropriate density matrix equations beyond the rotating wave approximation. We demonstrate that the quantum state of the atoms and the frequency of UCPO may be controlled by controlling the number of pulses in the pulse trains and the pulse repetition time respectively. Moreover, the robustness of population transfer against the variation of laser pulse parameters is also investigated. The proposed scheme may be useful for the creation of atomic beam in selected quantum state for desired time duration and may have potential applications in ultrafast optical switching.
Institute of Scientific and Technical Information of China (English)
XUJing-Bo; ZOUXu-Bo; GAOXiao-Chun; FUJian
2004-01-01
With the help of an SU(3) dynamicalalgebraic structure, we ~nd an exact solutionof the Milburn equationfor the system of a three-levelatom in the [1] configuration interacting with one quantized field mode with arbitrary detuning ,The exact solution is then used to discuss the influence of the intrinsic decoherence on the nonclassical properties of the system,such as collapes and revivals of the atomic populations,oscillations of the photon number distribution,and squeezing of the radiation field.
Single-photon frequency conversion via interaction with a three-level atom coupled to a microdisk
Akbari, M.; Andrianov, S. N.; Kalachev, A. A.
2017-02-01
The frequency conversion of light has proved to be an important instrument for communication, spectroscopy, imaging and information processing. We theoretically study the frequency conversion of a single photon via its interaction with a Λ -type atom coupled to a microdisk. We show that the frequency conversion efficiency approaches unity even in the case of an interaction between clockwise and counterclockwise modes in the microdisk due to surface imperfections. By the use of the Schrieffer-Wolff transformation, we get an effective Hamiltonian that allows us to investigate the dynamics of the system and obtain time and probability of frequency conversion in different conditions.
Institute of Scientific and Technical Information of China (English)
ZHANG Hui-Hui; SHEN Hua-Jun; ZHOU Jing-Tao; LIU Xin-Yu
2009-01-01
The nonlinear theory of interaction between the q analogue of a single-mode field and a Ξ-type three-level atom has been established. And the formal solution of the Schrodinger equation in the representation and its average number are obtained. Then, the photon squeezing effects are studied through numerical calculation. The results show that the q deformation nonlinear action has a lot of influence on the quantum coherence and quantum properties. When q approaches 1, the theory reduces to the common linear theory.
Tavassoly, M. K.; Rastegarzadeh, M.
2016-10-01
In this paper based on a generalization of the Jaynes-Cummings model we solve the dynamical Hamiltonian describing the interaction between a (Λ or V-type) three-level atom and a single-mode field in the "full nonlinear regime" and then the analytical form of state vector of the system is explicitly obtained. In this manner, we encountered with "intensity-dependent detuning" as well as "intensity-dependent atom-field coupling" in our two models. Via choosing an appropriate deformation function (which imposes nonlinearity to the system) we consider the influence of Kerr-like medium from which the resonance condition for a selected number of quanta is achieved (selective transition is occurred). Furthermore, by these considerations, we may find the optimum values for atom-field coupling constants which provide a regular periodic behavior of probability amplitudes for the two considered atomic systems. Moreover, to show this periodic time behavior, the temporal evolution of the probability of the allowed atomic transitions as well as the Mandel parameter (as a non-classical sign) is depicted for various circumstances. As is observed, complete revivals may appear in some particular situations.
Dutta, Bibhas Kumar; Panchadhyayee, Pradipta
2016-09-01
It has been shown that coherence effects have a marked influence in the spontaneous emission spectrum of a three-level Λ -type atom driven by weak coherent and incoherent fields. Phase dependent evolution of interference effects leading to spectral narrowing, generation of spectral hole and dark line are exhibited in the present scheme when the atom does not interact with the incoherent fields. The basic mechanism underlying this scheme seems to be appropriate for a phaseonium. Apart from phase-coherence introduced in the system the phenomenon of line narrowing, in the presence of weak incoherent pumping, can be achieved in a different way as a consequence of two competitive resonant effects: sharp non-Lorentzian and symmetric Fano-like-resonance contributions to the line shape. In both the situations, the evolution of narrow structures in the line shape can be achieved even when the emission is influenced by the dephasing of Raman coherence.
Institute of Scientific and Technical Information of China (English)
Liu Su-Mei; He An-Zhi; Ji Yun-Jing
2008-01-01
In this paper the evolution characteristics of the fidelity of quantum information for the Ⅴ-type three-level atom interacting with number state light field in Kerr medium are investigated. It shows that the periodicity of the evolutions of fidelity of quantum information is influenced by the Kerr coefficient, the photon number of the initial field and intensity of light. The evolutions of the fidelity of quantum information are modulated by the initial number state field. The Rabi oscillation frequency and the modulation frequency of fidelity for the field and the system vary with the value of the Kerr coefficient. The evolutions of fidelity of quantum information obviously show the quantum collapse and revival behaviours in the system of atom interacting with light field.
Institute of Scientific and Technical Information of China (English)
焦志伟; 陈西园
2001-01-01
光子晶体中光子带隙的存在使得频率在带隙内的光无法通过光子晶体，镶嵌在光子晶体中的原子的自发辐射必然不同于在均匀介质中原子的自发辐射。关于二能级原子和V型三能级原子在光子晶体中的自发辐射已有文献报道，采用的方法是用拉普拉斯变换求解薛定鄂方程。用求系统本征值的方法讨论了光子晶体中单个三能级原子的自发辐射。讨论的模型为Ξ型三能级原子。由于光的局域化,两个上能级的粒子数布居取决于两个上能级之间跃迁频率相对于光子带隙边缘频率ωc的大小,当两个上能级之间跃迁频率位于带隙内时,两个上能级的粒子数布居出现了反转。这一性质区别于V型三能级原子在光子晶体中的自发辐射。%The band gap in the crystal for photons leads that the light with frequency in the band gap can not go through the photonic crystal. Spontaneous emission from atom in photonic crystal is different from that of atom in other medium. Spontaneous emission from a three-level atom embedded in the photonic crystal is studied with the solution for eigenvalue problem of atom-field trapped state. A model of Ξ type for three-level atom has been discussed. Because of the localization of light, the population of particles in the two upper levels depends on the transition frequency between the two upper levels. When the transition frequency between the two upper levels is within the forbidden band-gap, there is population inversion in the two upper levels, which differs from that of the two-level atom and other three-level atoms in a photonic crystal.
Institute of Scientific and Technical Information of China (English)
卢俊; 许毅; 董传华
2003-01-01
In this paper, evolution of the higher-order squeezing for atomic dipole of three-level atom in the Kerr-like medium is investigated. The atom discussed has two configurations and is driven by the single-mode coherent state field. Our results show that the squeezing effects are clearly influenced by nonlinear parameters, the initial atom state and the detuning.
Institute of Scientific and Technical Information of China (English)
WANG Yan-Hui; LIU Xiao-Shu; LONG Gui-Lu
2007-01-01
In this paper, we present decoupling bang-bang operations for the suppression of general decoherence, both amplitude and phase damping, in a three-level system in A-configuration. We give a program to design a sequence of periodic twinborn pulses to suppress the decoherence in such the system.
DEFF Research Database (Denmark)
Alrøe, Hugo Fjelsted
2016-01-01
This paper presents a second-order semiotic framework for ontological levels, which is based on the structure of semiosis in a more fundamental way than other existing approaches to semiotic levels. Building on the key semiotic concept of representation, three levels are posited: (1) non- or proto-semiotic...... processes, without representation, such as physical or causal processes, (2) semiotic processes, with representation, such as the processes of life and cognition, and (3) second-order semiotic processes, with representation of representation, such as self-conscious and self-reflexive communicative processes....... This semiotic framework for ontological levels is compared with recent discussions of different ontological kinds of kinds such as indifferent and interactive kinds. This leads to the distinction between not two, but three kinds of kinds: indifferent, adaptive and reflexive kinds, of which the last two hitherto...
Solutions of two-mode Jaynes-Cummings models
Indian Academy of Sciences (India)
Sudha Singh; Ashalata Sinha
2008-05-01
A simple procedure to solve two fully quantized non-linear Jaynes-Cummings models is presented, one in which an atom interacts with a two-mode radiation field in a Raman-type process and the other involving multiphoton interaction between the two-mode field and the atom. Effect of intensity-dependent coupling between the field and the atom in both the above-mentioned cases has also been investigated. The unitary transformation method presented here not only solves the time-dependent problem but also permits a determination of the eigensolutions of the interacting Hamiltonian at the same time. Graphical features of the time dependence of the population inversion have been analysed when one of the field modes is prepared initially in a coherent state while the other one in a vacuum state.
Study on three level system population transfer
Institute of Scientific and Technical Information of China (English)
Shan Yang(杨山); Ye Kuang(旷冶)
2003-01-01
Stimulated-Raman-adiabatic-passage (STIRAP) process provides an effective technique to transfer electronpopulation from an initial state (e.g. ground state) to excited final state for both atoms and molecules. Inthis paper, we present the results of the study on electron population transfer in three level system. Wehave analyzed the effects of various conditions on the transfer process, such as the time delay of the twolaser beams, two-photon off-resonance, one-photon off-resonance and the change of relative laser intensity.The numerical result is compared with experiment, and the reasons for the effects are also given.
Institute of Scientific and Technical Information of China (English)
李可; 董传华
2005-01-01
The Hamiltonian of coupled three-level atoms interacting with light field in the cavity filled with Kerr-like medium is derived.A simplified analytic solution to the Schrodinger equation of the system is obtained. The case of A type atom with degenerate lower levels is discussed in detail. It is shown that the coupling strength between atoms and Kerr coefficient affect the system's dynsmic behaviots, especially the modulation period and oscillation frequency of the squeezing parameters of the field and the collective dipole moment. Dynamic behaviors of the system are sensitive to the initial stateof atoms.
Arctic research at three levels.
McNabb, Steven
2004-01-01
This paper is a posthumous publication of a Steven McNabb's presentation to the 1993 annual meeting of the American Anthropological Association. In it he described how the Social Transitions in the North research project involved explicit cross-cultural contact or participation at three levels: between scientists and public agencies; between scientists and study populations; and between research teams themselves. He explored a few of the entanglements and opportunities that arise in those interactions. Dr. McNabb urged northern researchers to avoid embracing rigid standards, for they will result in more entanglements and fewer opportunities. On the otherhand, if researchers are open-minded, they will be able to treat each dilemma as an opportunity that will make for better science.
Reconstruction of the joint state of a two-mode Bose-Einstein condensate
Bolda, E L; Walls, D F; Bolda, Eric L.; Tan, Sze M.; Walls, Dan F.
1997-01-01
We propose a scheme to reconstruct the state of a two-mode Bose-Einstein condensate, with a given total number of atoms, using an atom interferometer that requires beam splitter, phase shift and non-ideal atom counting operations. The density matrix in the number-state basis can be computed directly from the probabilities of different counts for various phase shifts between the original modes, unless the beamsplitter is exactly balanced. Simulated noisy data from a two-mode coherent state is produced and the state is reconstructed, for 49 atoms. The error can be estimated from the singular values of the transformation matrix between state and probability data.
New theorem relating two-mode entangled tomography to two-mode Fresnel operator
Institute of Scientific and Technical Information of China (English)
Xie Chuan-Mei; Fan Hong-Yi
2012-01-01
Based on the Fan-Hu's formalism,i.e.,the tomogram of two-mode quantum states can be considered as the module square of the states' wave function in the intermediate representation,which is just the eigenvector of the Fresnel quadrature phase,we derive a new theorem for calculating the quantum tomogram of two-mode density operators,i.e.,the tomogram of a two-mode density operator is equal to the marginal integration of the classical Weyl correspondence function of F+2pF2,where F2 is the two-mode Fresnel operator. An application of the theorem in evaluating the tomogram of an optical chaotic field is also presented.
Engineering three-dimensional maximally entangled states for two modes in a bimodal cavity
Institute of Scientific and Technical Information of China (English)
Yang Zhen-Biao; Su Wan-Jun
2007-01-01
An alternative scheme is proposed for engineering three-dimensional maximally entangled states for two modes of a superconducting microwave cavity. In this scheme, an appropriately prepared four-level atom is sent through a bimodal cavity. During its passing through the cavity, the atom is coupled resonantly with two cavity modes simultaneously and addressed by a classical microwave pulse tuned to the required transition. Then the atomic states are detected to collapse two modes onto a three-dimensional maximally entangled state. The scheme is different from the previous one in which two nonlocal cavities are used. A comparison between them is also made.
SU(2) Coherent State Description of Two-Mode Bose-Einstein Condensates
Institute of Scientific and Technical Information of China (English)
WU Ying; YANG Xiao-Xue
2002-01-01
We show that the evolution equations for mean quantities such as atom numbers and the inter-modecorrelation for two-mode Bose-Einstein condensates form a closed set of equations in the SU(2) coherent state description,and they are identical in form to the two-mode mean-field model with only a slightly reduced two-body interactionstrength. The exact analytical solutions to the evolution equations are also presented.
Quantum memory for entangled two-mode squeezed states
Jensen, K; Krauter, H; Fernholz, T; Nielsen, B M; Serafini, A; Owari, M; Plenio, M B; Wolf, M M; Polzik, E S
2010-01-01
A quantum memory for light is a key element for the realization of future quantum information networks. Requirements for a good quantum memory are (i) versatility (allowing a wide range of inputs) and (ii) true quantum coherence (preserving quantum information). Here we demonstrate such a quantum memory for states possessing Einstein-Podolsky-Rosen (EPR) entanglement. These multi-photon states are two-mode squeezed by 6.0 dB with a variable orientation of squeezing and displaced by a few vacuum units. This range encompasses typical input alphabets for a continuous variable quantum information protocol. The memory consists of two cells, one for each mode, filled with cesium atoms at room temperature with a memory time of about 1msec. The preservation of quantum coherence is rigorously proven by showing that the experimental memory fidelity 0.52(2) significantly exceeds the benchmark of 0.45 for the best possible classical memory for a range of displacements.
Institute of Scientific and Technical Information of China (English)
Gao Yun-Feng; Feng Jian; Wang Ji-Suo
2005-01-01
The evolution of the entanglement degree of two-mode fields and atom with the intensity-dependent coupling is investigated using von Neumann entropy. The results for the initial fields in both coherent states and two-mode squeezed vacuum state are calculated. The influence of the field.intensity on the entropy is discussed. It is found that the field and atom are generally in maximum entanglement but subject to periodic pulsed disentanglement completely under the condition of strong initial field.
Equivalent classes of closed three-level systems
Plenio, M. B.
2001-01-01
In recent years a significant amount of research in quantum optics has been devoted to the analysis of atomic three-level systems and for many physical quantities the same effects have been predicted for different configurations. These configurations can be split into essentially two classes. One for which the system contains a metastable state and another where the system has two close-lying levels and coherence effects become important. We demonstrate when and why for a wide range of parame...
Global Optimization strategies for two-mode clustering
J.M. van Rosmalen (Joost); P.J.F. Groenen (Patrick); J. Trejos (Javier); W. Castilli
2005-01-01
textabstractTwo-mode clustering is a relatively new form of clustering that clusters both rows and columns of a data matrix. To do so, a criterion similar to k-means is optimized. However, it is still unclear which optimization method should be used to perform two-mode clustering, as various meth
Genetic algorithm based two-mode clustering of metabolomics data
Hageman, J.A.; Berg, R.A. van den; Westerhuis, J.A.; Werf, M.J. van der; Smilde, A.K.
2008-01-01
Metabolomics and other omics tools are generally characterized by large data sets with many variables obtained under different environmental conditions. Clustering methods and more specifically two-mode clustering methods are excellent tools for analyzing this type of data. Two-mode clustering metho
Modular interference characteristic of two-mode fiber
Institute of Scientific and Technical Information of China (English)
Helin Wang; Weihong Bi; Aijun Yang; Feng Liu
2006-01-01
The modular interference characteristics of circular-core and elliptical-core two-mode fibers are investigated in theory. The intensity distribution and figure of two-lobe mode patterns are evaluated and simulated quantitatively for different phase difference change between LP01 and LPeven11 mode. The interference mode patters of elliptical-core and circular-core two-mode fibers are compared, the result shows that the two-lobe interference patters of the two-mode fibers generate energy exchange and oscillation, and thedifference is that the interference mode patterns of circular-core two-mode fiber are almost elliptical, while the interference mode pattern of elliptical-core two-mode fiber is approximately circular on condition that proper selection of the ellipticity. Their two-dimensional (2D) profile determines the choice of the core shape of the information pick-up fiber.
Two-mode polarized traveling wave deflecting structure
Institute of Scientific and Technical Information of China (English)
谭建豪; 顾强; 方文程; 童德春; 赵振堂
2015-01-01
In this paper, we propose a two-mode polarizable deflecting structure, as a new concept for bunch measure-ment and beam control. With two modes of HEM11 and HEM12 operating in the same structure on horizontal and vertical directions, respectively, the operation status can be switched between the two polarization modes. They can be operated simultaneously with two independent input power sources. With two-mode deflecting structure, the bunch distortion caused by the geometric wake-fields in the accelerating structure can be mea-sured by one structure.
Institute of Scientific and Technical Information of China (English)
戴宏毅; 李承祖; 陈平形; 梁林梅
2003-01-01
介绍了单模压缩相干态及其基本性质,根据简并V型三能级原子与单模光场的改进型有效哈密顿量,通过矩阵方法推导出原子-光场系统的态矢量.提出利用简并V型三能级原子与单模光场的非共振相互作用制备压缩相干态的叠加态的一种新方案,讨论了怎样进行控制单模压缩相干态光场中的压缩方向问题.%The single-mode squeezed coherent states and their fundamental properties are discussed. Based on the modified effective Hamiltonian for the atom-field system, the state of the system is derived by means of matrix. A new scheme is presented to generate superposition of squeezed coherent states through non-resonant of degenerate V-type three-level atoms with single-mode cavity field. Controls of the squeezing direction of single-mode squeezed coherent states in the light field are also discussed.
Institute of Scientific and Technical Information of China (English)
HU Li-Yun; FAN Hong-Yi
2008-01-01
We find that the squeezed two-mode number state is just a two-variable Hermite polynomial excitation of the two-mode squeezed vacuum state (THPES). We find that the Wigner function of THPES and its marginal distributions are just related to two-variable Hermite polynomials (or Laguerre polynomials) and that the tomogram of THPES can be expressed by one-mode Hermite polynomial.
Dynamics of atom-field entanglement in a bimodal cavity
Deçordi, G L
2015-01-01
We investigate some aspects of the dynamics and entanglement of bipartite quantum system (atom-quantized field), coupled to a third ``external" subsystem (quantized field). We make use of the Raman coupled model; a three-level atom in a lambda configuration interacting with two modes of the quantized cavity field. We consider the far off resonance limit, which allows the derivation of an effective Hamiltonian of a two-level atom coupled to the fields. We also make a comparison with the situation in which one of the modes is treated classically rather than prepared in a quantum field (coherent state).
Modulation instabilities in randomly birefringent two-mode optical fibers
Li, Jin-Hua; Ren, Hai-Dong; Pei, Shi-Xin; Cao, Zhao-Lou; Xian, Feng-Lin
2016-12-01
Modulation instabilities in the randomly birefringent two-mode optical fibers (RB-TMFs) are analyzed in detail by accounting the effects of the differential mode group delay (DMGD) and group velocity dispersion (GVD) ratio between the two modes, both of which are absent in the randomly birefringent single-mode optical fibers (RB-SMFs). New MI characteristics are found in both normal and anomalous dispersion regimes. For the normal dispersion, without DMGD, no MI exists. With DMGD, a completely new MI band is generated as long as the total power is smaller than a critical total power value, named by Pcr, which increases significantly with the increment of DMGD, and reduces dramatically as GVD ratio and power ratio between the two modes increases. For the anomalous dispersion, there is one MI band without DMGD. In the presence of DMGD, the MI gain is reduced generally. On the other hand, there also exists a critical total power (Pcr), which increases (decreases) distinctly with the increment of DMGD (GVD ratio of the two modes) but varies complicatedly with the power ratio between the two modes. Two MI bands are present for total power smaller than Pcr, and the dominant band can be switched between the low and high frequency bands by adjusting the power ratio between the two modes. The MI analysis in this paper is verified by numerical simulation. Project supported by the Natural Science Foundation of Jiangsu Provincial Universities (Grant No. 14KJB140009), the National Natural Science Foundation of China (Grant No. 11447113), and the Startup Foundation for Introducing Talent of NUIST (Grant No. 2241131301064).
Institute of Scientific and Technical Information of China (English)
丛红璐; 唐多昌; 刘雪华; 成爽; 任学藻
2012-01-01
利用全量子理论,在非旋波近似下,对与级联型三能级原子相互作用的二项式光场的光场压缩效应和原子布居几率进行了精确求解.讨论了二项式光场参量η对光场压缩效应的影响,同时也讨论了二项式态光场的最大光子数M对原子布居几率的影响.数值计算结果表明:随着二项式光场参量η的增大,光场压缩效应的持续时间先增大后减小.在非旋波近似下,由于虚光子的影响,光场压缩效应的演化曲线出现了“小锯齿状”的振荡;随着二项式光场的最大光子数M的增大,原子布居几率回复塌缩周期逐渐增大,并且原子布居几率在塌缩区不能完全塌缩,而是出现了“小锯齿状”的振荡.另外文中也讨论了非旋波项对系统量子特性的影响.%The squeezing effect and atomic population of the binomial field interacting with a cascade three level atom are calculated accurately without rotating-wave approximation (without RWA) by using the complete quantum theory. The influences of the binomial state field parameter η on the field squeezing effect and the maximum photon number M of the binomial state field on the atomic population are considered. The results obtained from using the numerical method show that with increase of the binomial state field parameter η, the duration of the squeezing effect increases at first and then decreases. The little indentation oscillation appears in the evolution curves of the field squeezing effect, which is caused by virtual photon without RWA. The period of the revival-collapse increases with the increase of the maximum photon number M, and the atomic population can not collapse completely in the collapse regime, but displays little indentation oscillation. In addition the influence of the without-RWA terms on the quantum properties of the system are discussed.
Three-level cervical disc herniation
Directory of Open Access Journals (Sweden)
St. Iencean Andrei
2015-09-01
Full Text Available Multilevel cervical degenerative disc disease is well known in the cervical spine pathology, with radicular syndromes or cervical myelopathy. One or two level cervical herniated disc is common in adult and multilevel cervical degenerative disc herniation is common in the elderly, with spinal stenosis, and have the same cause: the gradual degeneration of the disc. We report the case of a patient with two level cervical disc herniation (C4 – C5 and C5 – C6 treated by anterior cervical microdiscectomy both levels and fusion at C5 – C6; after five years the patient returned with left C7 radiculopathy and MRI provided the image of a left C6 – C7 disc herniation, he underwent an anterior microsurgical discectomy with rapid relief of symptoms. Three-level cervical herniated disc are rare in adults, and the anterior microdiscectomy with or without fusion solve this pathology.
Quantum optical ABCD theorem in two-mode case
Institute of Scientific and Technical Information of China (English)
Fan Hong-Yi; Hu Li-Yun
2008-01-01
By introducing the entangled Fresnel operator (EFO) this paper demonstrates that there exists ABCD theorem for two-mode entangled case in quantum optics.The canonical operator method as mapping of ray-transfer ABCD matrix is explicitly shown by EFO's normally ordered expansion through the coherent state representation and the technique of integration within an ordered product of operators.
Periodically driven three-level systems
Kenmoe, M. B.; Fai, L. C.
2016-09-01
We study the dynamics of a three-level system (ThLS) sinusoidally driven in both longitudinal and transverse directions and in the presence of a uniaxial anisotropy D entering the generic Hamiltonian through the zero-energy splitting term D (Sz)2 where Sz is the projection of the spin vector along the quantization direction. As a consequence of the addition of this term, the order of the symmetry group of the Hamiltonian is increased by a unit and we observe a sequence of cascaded SU(3) Landau-Zener-Stückelberg-Majorana (LZSM) interferometers. The study is carried out by analytically and numerically calculating the probabilities of nonadiabatic and adiabatic evolutions. For nonadiabatic evolutions, two main approximations based on the weak and strong driving limits are discussed by comparing the characteristic frequency of the longitudinal drive with the amplitudes of driven fields. For each of the cases discussed, our analytical results quite well reproduce the gross temporal profile of the exact numerical probabilities. This allows us to check the range of validity of analytical results and confirm our assumptions. For adiabatic evolutions, a general theory is constructed allowing for the description of adiabatic passages in arbitrary ThLSs in which direct transitions between states with extremal spin projections are forbidden. A compact formula for adiabatic evolutions is derived and numerically tested for some illustrative cases. Interference patterns demonstrating multiple LZSM transitions are reported. Applications of our results to the nitrogen vacancy center in diamond are discussed.
Institute of Scientific and Technical Information of China (English)
刘洪毓
2007-01-01
Atoms(原子)are all around us.They are something like the bricks (砖块)of which everything is made. The size of an atom is very,very small.In just one grain of salt are held millions of atoms. Atoms are very important.The way one object acts depends on what
Distillation of the two-mode squeezed state.
Kurochkin, Yury; Prasad, Adarsh S; Lvovsky, A I
2014-02-21
We experimentally demonstrate entanglement distillation of the two-mode squeezed state obtained by parametric down-conversion. Applying the photon annihilation operator to both modes, we raise the fraction of the photon-pair component in the state, resulting in the increase of both squeezing and entanglement by about 50%. Because of the low amount of initial squeezing, the distilled state does not experience significant loss of Gaussian character.
A two-mode planetary nebula luminosity function
Rodríguez-González, A; Esquivel, A; Raga, A C; Stasińska, G; Peña, M; Mayya, D
2014-01-01
We propose a new Planetary Nebula Luminosity Function (PNLF) that includes two populations in the distribution. Our PNLF is a direct extension of the canonical function proposed by Jacoby et al. (1987), in order to avoid problems related with the histogram construction, it is cast in terms of cumulative functions. We are interested in recovering the shape of the faint part of the PNLF in a consistent manner, for galaxies with and without a dip in their PN luminosity functions. The parameters for the two mode PNLF are obtained with a genetic algorithm, which obtains a best fit to the PNLF varying all of the parameters simultaneously in a broad parameter space. We explore a sample of 9 galaxies with various Hubble types and construct their PNLF. All of the irregular galaxies, except one, are found to be consistent with a two-mode population, while the situation is less clear for ellipticals and spirals.For the case of NGC\\, 6822, we show that the two-mode PNLF is consistent with previous studies of the star for...
Institute of Scientific and Technical Information of China (English)
Lin Xiu; Li Hong-Cai; Yang Rong-Can; Huang Zhi-Ping
2007-01-01
This paper proposes a scheme for realizing entanglement swapping in cavity QED. The scheme is based on the resonant interaction of a two-mode cavity field with a A-type three-level atom. In contrast with the previously proposed schemes, the present scheme is ascendant, since the fidelity is 1.0 and the joint measurement isn't needed. And the scheme is experimentally feasible based on the current cavity QED technique.
Influence of Kerr-like medium on the dynamics of a two-mode Raman coupled model
Singh, Sudha; Gilhare, Karuna
2016-08-01
We study the quantum dynamics of an effective two-level atom interacting with two modes via Raman process inside an ideal cavity in the presence of Kerr non-linearity. The cavity modes interact both with the atom as well as the Kerr-like medium. The unitary transformation method presented here, not only solves the time-dependent problem, but also provides the eigensolutions of the interacting Hamiltonian at the same time. We study the atomic-population dynamics and the dynamics of the photon statistics in the two cavity modes. The influence of the Kerr-like medium on the statistics of the field is explored and it is observed that Kerr medium introduces antibunching in mode 1 and this effect is enhanced by a stronger interaction with the non-linear medium. In the high non-linear coupling regime anticorrelated beam become correlated. Kerr medium also introduces non-classical correlation between the two modes.
Electromagnetically induced absorption in a non-degenerate three-level ladder system
Whiting, Daniel J; Keaveney, James; Zentile, Mark A; Adams, Charles S; Hughes, Ifan G
2015-01-01
We investigate, theoretically and experimentally, the transmission of light through a thermal vapour of three-level ladder-type atoms, in the presence of 2 counter-propagating control fields. A simple theoretical model predicts the presence of electromagnetically induced absorption (EIA) in this pure three-level system when the control field is resonant. Experimentally, we use $^{87}$Rb in a large magnetic field of 0.62~T to reach the hyperfine Paschen-Back regime and realise a non-degenerate three-level system. Experimental observations verify the predictions over a wide range of detunings.
Semiclassical Wigner distribution for two-mode entangled state
Dechoum, K; Vallejos, R O; Khoury, A Z; 10.1103/PhysRevA.81.043834
2011-01-01
We derive the steady state solution of the Fokker-Planck equation that describes the dynamics of the nondegenerate optical parametric oscillator in the truncated Wigner representation of the density operator. We assume that the pump mode is strongly damped, which permits its adiabatic elimination. When the elimination is correctly executed, the resulting stochastic equations contain multiplicative noise terms, and do not admit a potential solution. However, we develop an heuristic scheme leading to a satisfactory steady-state solution. This provides a clear view of the intracavity two-mode entangled state valid in all operating regimes of the OPO. A nongaussian distribution is obtained for the above threshold solution.
Two modes of dipole events in tropical Indian Ocean
Institute of Scientific and Technical Information of China (English)
ZHAO YongPing; CHEN YongLi; WANG Fan; BAI XueZhi; WU AiMing
2009-01-01
By analyzing the distributions of subsurface temperature and the surface wind stress anomalies in the tropical Pacific and Indian Oceans during the Indian Ocean Dipole (IOD) events,two major modes of the IOD and their formation mechanisms are revealed.(1) The subsurface temperature anomaly (STA) in the tropical Indian Ocean during the IOD events can be described as a "＜" -shaped and west-east-oriented dipole pattern;in the east side of the "＜" pattern,a notable tongue-like STA extends westward along the equator in the tropical eastern Indian Ocean;while in the west side of the "＜" pattern,the STA has opposite sign with two centers (the southern one is stronger than the northern one in intensity) being of rough symmetry about the equator in the tropical mid-western Indian Ocean.(2) The IOD events are composed of two modes,which have similar spatial pattern but different temporal variabilities due to the large scale air-sea interactions within two independent systems.The first mode of the IOD event originates from the air-sea interaction on a scale of the tropical Pacific-Indian Ocean and coexists with ENSO.The second mode originates from the air-sea interaction on a scale of the tropical Indian Ocean and is closely associated with changes in the position and intensity of the Mascarene high pressure.The strong IOD event occurs when the two modes are in phase,and the IOD event weakens or disappears when the two modes are out of phase.Besides,the IOD events are normally strong when either of the two modes is strong.(3) The IOD event is caused by the abnormal wind stress forcing over the tropical Indian Ocean,which results in vertical transports,leading to the upwelling and pileup of seawater.This is the main dynamic processes resulting in the STA.When the anomalous easterly exists over the equatorial Indian Ocean,the cold waters upwell in the tropical eastern Indian Ocean while the warm waters pileup in the tropical western Indian Ocean,hence the thermocline in
Two-Mode Excited Entangled Coherent State: Nonclassicality and Entanglement
Zhang, Hao-Liang; Wu, Jia-Ni; Liu, Cun-Jin; Hu, Yin-Quan; Hu, Li-Yun
2017-03-01
Two-mode excited entangled coherent states (TME-ECSs) are introduced by operating repeatedly the photon-excited operator on the ECSs. It is shown that the normalization constant is related to the product of two Laguerre polynomials. The influence of the operation on nonclassical behaviour of the ECSs is investigated in terms of cross-correlation function, anti-bunching effect and the negativity of Wigner function, which show that nonclassical properties can be enhanced. In addition, inseparability properties of the TME-ECSs are discussed by using Bell inequality and concurrence. It is found that the degree of quantum entanglement of even ECSs increases with the increase of the total excited photon number, and the violation of Bell inequality can be present for both even and odd case only when the total excited photon numbers are even and odd, respectively.
Two-Mode Operation Engine Mount Design for Automotive Applications
Directory of Open Access Journals (Sweden)
Reza Tikani
2012-01-01
Full Text Available Hydraulic engine mounts are applied to the automotive applications to isolate the chassis from the high frequency noise and vibration generated by the engine as well as to limit the engine shake motions resulting at low frequencies. In this paper, a new hydraulic engine mount with a controllable inertia track profile is proposed and its dynamic behavior is investigated. The profile of the inertia track is varied by applying a controlled force to a cylindrical rubber disk, placed in the inertia track. This design provides a hydraulic engine mount design with an adjustable notch frequency location and also damping characteristics in shake motions. By using a simple control strategy, the efficiency of the proposed hydraulic engine mount in two-mode operation meaning isolating mode in the highway driving condition and damping mode in the shock motions, is investigated.
Two modes of dipole events in tropical Indian Ocean
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
By analyzing the distributions of subsurface temperature and the surface wind stress anomalies in the tropical Pacific and Indian Oceans during the Indian Ocean Dipole (IOD) events, two major modes of the IOD and their formation mechanisms are revealed. (1) The subsurface temperature anomaly (STA) in the tropical Indian Ocean during the IOD events can be described as a "<" -shaped and west-east-oriented dipole pattern; in the east side of the "<" pattern, a notable tongue-like STA extends westward along the equator in the tropical eastern Indian Ocean; while in the west side of the "<" pattern, the STA has op- posite sign with two centers (the southern one is stronger than the northern one in intensity) being of rough symmetry about the equator in the tropical mid-western Indian Ocean. (2) The IOD events are composed of two modes, which have similar spatial pattern but different temporal variabilities due to the large scale air-sea interactions within two independent systems. The first mode of the IOD event originates from the air-sea interaction on a scale of the tropical Pacific-Indian Ocean and coexists with ENSO. The second mode originates from the air-sea interaction on a scale of the tropical Indian Ocean and is closely associated with changes in the position and intensity of the Mascarene high pressure. The strong IOD event occurs when the two modes are in phase, and the IOD event weakens or disap- pears when the two modes are out of phase. Besides, the IOD events are normally strong when either of the two modes is strong. (3) The IOD event is caused by the abnormal wind stress forcing over the tropical Indian Ocean, which results in vertical transports, leading to the upwelling and pileup of sea- water. This is the main dynamic processes resulting in the STA. When the anomalous easterly exists over the equatorial Indian Ocean, the cold waters upwell in the tropical eastern Indian Ocean while the warm waters pileup in the tropical western Indian Ocean, hence
Two mode coupling in a single ion oscillator via parametric resonance
Gorman, Dylan J; Selvarajan, Sankaranarayanan; Daniilidis, Nikos; Häffner, Hartmut
2014-01-01
Atomic ions, confined in radio-frequency Paul ion traps, are a promising candidate to host a future quantum information processor. In this letter, we demonstrate a method to couple two motional modes of a single trapped ion, where the coupling mechanism is based on applying electric fields rather than coupling the ion's motion to a light field. This reduces the design constraints on the experimental apparatus considerably. As an application of this mechanism, we cool a motional mode close to its ground state without accessing it optically. As a next step, we apply this technique to measure the mode's heating rate, a crucial parameter determining the trap quality. In principle, this method can be used to realize a two-mode quantum parametric amplifier.
Modeling the interdependent network based on two-mode networks
An, Feng; Gao, Xiangyun; Guan, Jianhe; Huang, Shupei; Liu, Qian
2017-10-01
Among heterogeneous networks, there exist obviously and closely interdependent linkages. Unlike existing research primarily focus on the theoretical research of physical interdependent network model. We propose a two-layer interdependent network model based on two-mode networks to explore the interdependent features in the reality. Specifically, we construct a two-layer interdependent loan network and develop several dependent features indices. The model is verified to enable us to capture the loan dependent features of listed companies based on loan behaviors and shared shareholders. Taking Chinese debit and credit market as case study, the main conclusions are: (1) only few listed companies shoulder the main capital transmission (20% listed companies occupy almost 70% dependent degree). (2) The control of these key listed companies will be more effective of avoiding the spreading of financial risks. (3) Identifying the companies with high betweenness centrality and controlling them could be helpful to monitor the financial risk spreading. (4) The capital transmission channel among Chinese financial listed companies and Chinese non-financial listed companies are relatively strong. However, under greater pressure of demand of capital transmission (70% edges failed), the transmission channel, which constructed by debit and credit behavior, will eventually collapse.
Entanglement dynamics in two-mode Gaussian systems
Jami, S.; Labbafi, Z.
2017-04-01
The current study investigated the time evolution of entanglement in an open quantum system. This system includes two independent harmonic oscillators interacting with a general environment. This study reports the solution of the time evolution of the covariance matrix by using the Markovian master equation. It was found that the entanglement for a preferred Gaussian state, is a continuous variable system. This study examined the time evolution of the entanglement by using Simon's separability criterion for continuous variable systems and computing covariance matrix with considering environmental factors such as temperature for two initial state of system (separable and entangled) with drawing Simon's criterion and logarithmic negativity. The results demonstrated that for a certain value of dispersion and dissipation coefficient, the initial state of the system is saved over the time. But for other amounts of the above factors, entanglement birth, entanglement death and repeated entanglement birth and entanglement death happen in the system. Furthermore, the present study investigated the behavior of system's purity under the effects of environmental factors, such as temperature and environment parameter with regard to the relation between purity and covariance matrix for two-mode Gaussian state.
Vacuum-Induced Quantum Interference in a Trapped ∧-Configuration Three-Level System
Institute of Scientific and Technical Information of China (English)
WANG Zheng-Ling; YIN Jian-Ping
2005-01-01
@@ In consideration of quantization of centre-of-mass motion, we derive the second-order solution of the dynamic equation of a ∧-configuration three-level atom confined in an approximately harmonic trap by using the timedependent perturbation theory. It is found that there are a series of dark lines in the second-order probability spectrum with multi-peak structures, which is the result of the quantum interference from the same vacuum mode in the spontaneous decay process of the trapped atom from the upper level to the two nearby lower levels. Our study shows that the second-order spectrum may be modified by the oscillation frequency Ω of the trap and the frequency difference △ between two lower levels of the three-level atom, and the depth of the dark lines from the vacuum-induced quantum interference effect is strongly dependent on the above two parameters (Ω and △).
Fluoroquinolone-gyrase-DNA complexes: two modes of drug binding.
Mustaev, Arkady; Malik, Muhammad; Zhao, Xilin; Kurepina, Natalia; Luan, Gan; Oppegard, Lisa M; Hiasa, Hiroshi; Marks, Kevin R; Kerns, Robert J; Berger, James M; Drlica, Karl
2014-05-02
DNA gyrase and topoisomerase IV control bacterial DNA topology by breaking DNA, passing duplex DNA through the break, and then resealing the break. This process is subject to reversible corruption by fluoroquinolones, antibacterials that form drug-enzyme-DNA complexes in which the DNA is broken. The complexes, called cleaved complexes because of the presence of DNA breaks, have been crystallized and found to have the fluoroquinolone C-7 ring system facing the GyrB/ParE subunits. As expected from x-ray crystallography, a thiol-reactive, C-7-modified chloroacetyl derivative of ciprofloxacin (Cip-AcCl) formed cross-linked cleaved complexes with mutant GyrB-Cys(466) gyrase as evidenced by resistance to reversal by both EDTA and thermal treatments. Surprisingly, cross-linking was also readily seen with complexes formed by mutant GyrA-G81C gyrase, thereby revealing a novel drug-gyrase interaction not observed in crystal structures. The cross-link between fluoroquinolone and GyrA-G81C gyrase correlated with exceptional bacteriostatic activity for Cip-AcCl with a quinolone-resistant GyrA-G81C variant of Escherichia coli and its Mycobacterium smegmatis equivalent (GyrA-G89C). Cip-AcCl-mediated, irreversible inhibition of DNA replication provided further evidence for a GyrA-drug cross-link. Collectively these data establish the existence of interactions between the fluoroquinolone C-7 ring and both GyrA and GyrB. Because the GyrA-Gly(81) and GyrB-Glu(466) residues are far apart (17 Å) in the crystal structure of cleaved complexes, two modes of quinolone binding must exist. The presence of two binding modes raises the possibility that multiple quinolone-enzyme-DNA complexes can form, a discovery that opens new avenues for exploring and exploiting relationships between drug structure and activity with type II DNA topoisomerases.
Evolution of a two-mode squeezed vacuum in the amplitude dissipative channel
Institute of Scientific and Technical Information of China (English)
Jiang Nian-Quan; Fan Hong-Yi; Xi Liu-Sheng; Tang Long-Ying; Yuan Xian-Zhang
2011-01-01
For the first time we derive the dissipating result of an initial two-mode squeezed pure vacuum state passing through a two-mode amplitude dissipative channel described by the direct product of two independent single-mode master equations.Although these two master equations do not mix the two modes (there is no coupling between them),since the two-mode squeezed state is simultaneously an entangled state,the final state which emerges from passing this channel is a two-mode mixed density operator.The compact expression of the outcoming state is obtained,which manifestly shows that as time evolves,the squeezing effect decreases.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
We introduce the coordinate-dependent one- and two-mode squeezing transformations and discuss the properties of the corresponding one-and two-mode squeezed states. We show that the coordinate-dependent one-and two-mode squeezing transformations can be constructed by the combination of two transformations, a coordinate-dependent displacement followed by the standard squeezed transformation. Such a decomposition turns a nonlinear problem into a linear one because all the calculations involving the nonlinear one- and two-mode squeezed transformation have been shown to be able to reduce to those only concerning the standard one- and two-mode squeezed states.
experimental implementation of single-phase, three-level, sinusoidal ...
African Journals Online (AJOL)
To keep the power circuit component count to a minimum, the three-level topology simplifies the ... Assessment of the 3-level inverter is done by comparing its experimental voltage waveforms and the ..... mental switching functions were given.
Goos-Hanchen-like shift of three-level matter wave incident on Raman beams
Duan, Zhenglu; Hu, Liyun; Xu, XueXiang; Liu, Cunjin
2013-01-01
When a three-level atomic wavepacket is obliquely incident on a "edium slab" consisting of two far-detuned laser beams, there exists lateral shift between reflection and incident points at the surface of a "medium slab", analogous to optical Goos-Hanchen effect. We evaluate lateral shifts for reflected and transmitted waves via expansion of reflection and transmission coefficients, in contrast to the stationary phase method. Results show that lateral shifts can be either positive or negative ...
Detecting non-Abelian geometric phases with three-level {Lambda} systems
Energy Technology Data Exchange (ETDEWEB)
Du Yanxiong; Xue Zhengyuan; Zhang Xinding; Yan Hui [Laboratory of Quantum Information Technology, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China)
2011-09-15
We show that a non-Abelian gauge potential in two nearly degenerated dressed states may be induced by two laser beams interacting with a three-level {Lambda} atomic system. We demonstrate that the populations of the atomic states at the end of a composed path formed by two closed loops are dependent on the order of those two loops, showing an unambiguous signature of the non-Abelian geometric phase. Through numerical calculations, we show that the non-Abelian feature of the geometric phases can be tested under realistic conditions.
Goos-Hänchen-like shift of three-level matter wave incident on Raman beams
Duan, Zhenglu; Hu, Liyun; Xu, XueXiang; Liu, Cunjin
2014-07-01
When a three-level atomic wavepacket is obliquely incident on a "edium slab" consisting of two far-detuned laser beams, there exists lateral shift between reflection and incident points at the surface of a "medium slab", analogous to optical Goos-Hanchen effect. We evaluate lateral shifts for reflected and transmitted waves via expansion of reflection and transmission coefficients, in contrast to the stationary phase method. Results show that lateral shifts can be either positive or negative dependent on the incident angle and the atomic internal state. Interestingly, a giant lateral shift of transmitted wave with high transmission probability is observed, which is helpful to observe such lateral shifts experimentally. Different from the two-level atomic wave case, we find that quantum interference between different atomic states plays crucial role on the transmission intensity and corresponding lateral shifts.
Symplectic Group Representation of the Two-Mode Squeezing Operator in the Coherent State Basis
Institute of Scientific and Technical Information of China (English)
FAN Hong-Yi; CHEN Jun-Hua
2003-01-01
We find that the coherent state projection operator representation of the two-mode squeezing operator constitutes a loyal group representation of symplectic group, which is a remarkable property of the coherent state. As a consequence, the resultant effect of successively applying two-mode squeezing operators are equivalent to a single squeezing in the two-mode Fock space. Generalization of this property to the 2n-mode case is also discussed.
A new Zero Voltage Switching three-level NPC inverter
DEFF Research Database (Denmark)
He, Ning; Chen, Yenan; Xu, Dehong
2015-01-01
A novel Zero Voltage Switching (ZVS) three-level NPC inverter topology using a new ZVS Space Vector Modulation (SVM) scheme is proposed. A detailed operation analysis of ZVS three-level NPC inverter is given. The ZVS condition of the proposed ZVS inverter is derived and it can be achieved of all...... switches in the proposed inverter, which include both the main switches and the auxiliary switches. The design of resonant circuits parameters is also provided. Finally the proposed circuit and ZVS SVM scheme are verified by experimental results and demonstrate a superior performance....
Superradiant phase transitions with three-level systems
Baksic, Alexandre; Nataf, Pierre; Ciuti, Cristiano
2013-02-01
We determine the phase diagram of N identical three-level systems interacting with a single photonic mode in the thermodynamical limit (N→∞) by accounting for the so-called diamagnetic term and the inequalities imposed by the Thomas-Reich-Kuhn (TRK) oscillator strength sum rule. The key role of transitions between excited levels and the occurrence of first-order phase transitions is discussed. We show that, in contrast to two-level systems, in the three-level case the TRK inequalities do not always prevent a superradiant phase transition in the presence of a diamagnetic term.
Superradiant phase transitions with three-level systems
Baksic, Alexandre; Ciuti, Cristiano
2013-01-01
We determine the phase diagram of $N$ identical three-level systems interacting with a single photonic mode in the thermodynamical limit ($N \\to \\infty$) by accounting for the so-called diamagnetic term and the inequalities imposed by the Thomas-Reich-Kuhn (TRK) oscillator strength sum rule. The key role of transitions between excited levels and the occurrence of first-order phase transitions is discussed. We show that, in contrast to two-level systems, in the three-level case the TRK inequalities do not always prevent a superradiant phase transition in presence of a diamagnetic term.
A Three-level 4 x 3 Conventinal Matrix Converter
DEFF Research Database (Denmark)
Rong, Runjie; Loh, Poh Chiang; Wang, Peter;
2007-01-01
This paper proposes a topology of a three-level 4 × 3 conventional matrix converter with 12 bi-directional switches. PWM control and modulation index compensation have been investigated. Operation theory has been verified by the simulation results using Matlab. The simulation results show that th...
On three-level problem of competitive pricing
Plyasunov, A.; Panin, A.
2016-10-01
We propose a new pricing model that are designed for the study of competitive pricing. As pricing strategies we use the uniform and discriminatory pricing. We formulate the model as a three-level quadratic programming problem with integer and boolean variables. To solve few cooperative formulations of this model we develop polynomial-time algorithms.
Exploration and Planning in a Three-Level Cognitive Architecture
DEFF Research Database (Denmark)
Kraft, Dirk; Baseski, Emre; Popovic, Mila;
2008-01-01
We describe an embodied cognitive system based on a three-level architecture that includes a sensorimotor layer, a mid-level layer that stores and reasons about object-action episodes, and a high-level symbolic planner that creates abstract action plans to be realised and possibly further specifi...
40 CFR 761.346 - Three levels of sampling.
2010-07-01
... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Three levels of sampling. 761.346... PROHIBITIONS Sampling Non-Liquid, Non-Metal PCB Bulk Product Waste for Purposes of Characterization for PCB Disposal in Accordance With Â§ 761.62, and Sampling PCB Remediation Waste Destined for Off-Site...
Optical Generation of Single- or Two-Mode Excited Entangled Coherent States
Institute of Scientific and Technical Information of China (English)
REN Zhen-Zhong; JING Hui; ZHANG Xian-Zhou
2008-01-01
With nonlinear Mach-Zehnder interferometer (NLMZI) and a type-Ⅰ beta-barium borate (BBO) crystal, we optically generate single-mode excited entangled coherent states. This scheme can be easily generalized to generate two-mode excited entangled coherent states. We simply analyse different influences of single- and two-mode photon excitations on entangled coherent states.
Two-mode clustering of genotype by trait and genotype by environment data
Hageman, J.A.; Malosetti, M.; Eeuwijk, van F.A.
2012-01-01
In this paper, we demonstrate the use of two-mode clustering for genotype by trait and genotype by environment data. In contrast to two separate (one mode) clusterings on genotypes or traits/environments, two-mode clustering simultaneously produces homogeneous groups of genotypes and traits/environm
Dynamics of cascade three-level system interacting with the classical and quantized ﬁeld
Indian Academy of Sciences (India)
Mihir Ranjan Nath; Surajit Sen; Gautam Gangopadhyay
2003-12-01
We study the exact solutions of the cascade three-level atom interacting with a single mode classical and quantized ﬁeld with different initial conditions ofthe atom. For the semiclassical model, it is found that if the atom is initially in the middle level, the time-dependent populations of the upper and lower levels are always equal. This dynamical symmetry exhibited by the classical ﬁeld is spoiled on quantization of the ﬁeld mode. To reveal this non-classical effect, a Euler matrix formalism is developed to solve the dressed states of the cascade Jaynes–Cummings model (JCM). Possible modiﬁcation of such an effect on the collapse and revival phenomenon is also discussed by taking the quantized ﬁeld in a coherent state.
Ge, Wenchao; Bhattacharya, M.
2016-10-01
Nonclassical states of macroscopic objects are promising for ultrasensitive metrology as well as testing quantum mechanics. In this work, we investigate dissipative mechanical quantum state engineering in an optically levitated nanodiamond. First, we study single-mode mechanical squeezed states by magnetically coupling the mechanical motion to a dressed three-level system provided by a nitrogen-vacancy center in the nanoparticle. Quantum coherence between the dressed levels is created via microwave fields to induce a two-phonon transition, which results in mechanical squeezing. Remarkably, we find that in ultrahigh vacuum quantum squeezing is achievable at room temperature with feedback cooling. For moderate vacuum, quantum squeezing is possible with cryogenic temperature. Second, we present a setup for two mechanical modes coupled to the dressed three levels, which results in two-mode squeezing analogous to the mechanism of the single-mode case. In contrast to previous works, our study provides a deterministic method for engineering macroscopic squeezed states without the requirement for a cavity.
Vulnerability of complex networks under three-level-tree attacks
Hao, Yao-hui; Han, Ji-hong; Lin, Yi; Liu, Lin
2016-11-01
We investigate vulnerability of complex networks including model networks and real world networks subject to three-level-tree attack. Specifically, we remove three different three-level-tree structures: RRN (Random Root Node), MaxDRN (Max Degree Root Node) and MinDRN (Min Degree Root Node) from a network iteratively until there is no three-level-tree left. Results demonstrate that random network is more robust than scale-free network against three tree attacks, and the robustness of random network decreases as the increases. And scale-free network shows different characteristics in different tree attack modes. The robustness of scale-free is not affected by the parameters for RRN, but increases as the increases for MinDRN. The important thing is that MaxDRN is the most effective in the three tree attack modes, especially for scale-free network. These findings supplement and extend the previous attack results on nodes and edges, and can thus help us better explain the vulnerability of different networks, and provide an insight into more tolerant real complex systems design.
A Three-level BDDC algorithm for saddle point problems
Energy Technology Data Exchange (ETDEWEB)
Tu, X.
2008-12-10
BDDC algorithms have previously been extended to the saddle point problems arising from mixed formulations of elliptic and incompressible Stokes problems. In these two-level BDDC algorithms, all iterates are required to be in a benign space, a subspace in which the preconditioned operators are positive definite. This requirement can lead to large coarse problems, which have to be generated and factored by a direct solver at the beginning of the computation and they can ultimately become a bottleneck. An additional level is introduced in this paper to solve the coarse problem approximately and to remove this difficulty. This three-level BDDC algorithm keeps all iterates in the benign space and the conjugate gradient methods can therefore be used to accelerate the convergence. This work is an extension of the three-level BDDC methods for standard finite element discretization of elliptic problems and the same rate of convergence is obtained for the mixed formulation of the same problems. Estimate of the condition number for this three-level BDDC methods is provided and numerical experiments are discussed.
Phase Properties of Two-Mode Squeezing-Rotating Entangled Representation
Institute of Scientific and Technical Information of China (English)
YUAN Hong-Chun; LI Heng-Mei; QI Kai-Guo
2006-01-01
By virtue of the squeezing-rotating entangled representation, we mainly establish thc new two-mode phase operator and phase angle operator, which is a general form including the foregoing formalist in two-mode Fock space.In addition, the corresponding phase distribution function is given in the entangled representation. In terms of this definition, we also analyze the phase behavior of some simple two-mode states such as squeezing-rotating coherent state,squeezing-rotating vacuum state, and so on. It is found that the results exactly agree with the foregoing phase theory.
Two-mode elliptical-core weighted fiber sensors for vibration analysis
Vengsarkar, Ashish M.; Murphy, Kent A.; Fogg, Brian R.; Miller, William V.; Greene, Jonathan A.; Claus, Richard O.
1992-01-01
Two-mode, elliptical-core optical fibers are demonstrated in weighted, distributed and selective vibration-mode-filtering applications. We show how appropriate placement of optical fibers on a vibrating structure can lead to vibration mode filtering. Selective vibration-mode suppression on the order of 10 dB has been obtained using tapered two-mode, circular-core fibers with tapering functions that match the second derivatives of the modes of vibration to be enhanced. We also demonstrate the use of chirped, two-mode gratings in fibers as spatial modal sensors that are equivalents of shaped piezoelectric sensors.
Realization of a holonomic quantum computer in a chain of three-level systems
Energy Technology Data Exchange (ETDEWEB)
Gürkan, Zeynep Nilhan, E-mail: nilhan.gurkan@gediz.edu.tr [Department of Industrial Engineering, Gediz University, Seyrek, 35665 Menemen, Izmir (Turkey); Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore (Singapore); Sjöqvist, Erik, E-mail: erik.sjoqvist@kemi.uu.se [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Department of Quantum Chemistry, Uppsala University, Box 518, SE-751 20 Uppsala (Sweden)
2015-12-18
Holonomic quantum computation is the idea to use non-Abelian geometric phases to implement universal quantum gates that are robust to fluctuations in control parameters. Here, we propose a compact design for a holonomic quantum computer based on coupled three-level systems. The scheme does not require adiabatic evolution and can be implemented in arrays of atoms or ions trapped in tailored standing wave potentials. - Highlights: • We develop a novel scheme for universal holonomic quantum computation. • The scheme involves non-Abelian geometric phases in a spin-chain. • The resources scale linearly with the number of logical qubits. • The scheme does not require adiabatic evolution.
Exact solution to laser rate equations: three-level laser as a Morse-like oscillator
León-Montiel, R. de J.; Moya-Cessa, Héctor M.
2016-08-01
It is shown how the rate equations that model a three-level laser can be cast into a single second-order differential equation, whose form describes a time-dependent harmonic oscillator. Using this result, we demonstrate that the resulting equation can be identified as a Schrödinger equation for a Morse-like potential, thus allowing us to derive exact closed-form expressions for the dynamics of the number of photons inside the laser cavity, as well as the atomic population inversion.
Irby, Stefan M.; Phu, Andy L.; Borda, Emily J.; Haskell, Todd R.; Steed, Nicole; Meyer, Zachary
2016-01-01
There is much agreement among chemical education researchers that expertise in chemistry depends in part on the ability to coordinate understanding of phenomena on three levels: macroscopic (observable), sub-microscopic (atoms, molecules, and ions) and symbolic (chemical equations, graphs, etc.). We hypothesize this "level-coordination…
Indian Academy of Sciences (India)
JAGHOURI HAKIMEH; SARBISHAEI MOHSEN; JAVIDAN KUROSH
2016-05-01
We solve the Nakajima–Zwanzig (NZ) non-Markovian master equation to study the dynamics of different types of three-level atomic systems interacting with bosonic Lorentzian reservoirs at zero temperature. Von Neumann entropy (S) is used to show the evolution of the degree of entanglement of the subsystems. The results presented are also compared with some recently published reports.
Institute of Scientific and Technical Information of China (English)
Jun Qian; Chengpu Liu; Shangqing Gong
2005-01-01
The effects of vacuum-induced coherence (VIC) on the properties of the absorption and gain of the probe field in an equispaced three-level ladder atomic system are investigated. It is found that lasing without inversion (LWI) is remarkably enhanced due to the effect of VIC in the case of the small incoherent pump rate.
Statistical Properties of Photon-Added Two-Mode Squeezed Coherent States
Wang, Zhen; Li, Heng-Mei; Yuan, Hong-Chun; Wan, Zhi-Long; Meng, Xiang-Guo
2016-12-01
The nonclassical and non-Gaussian quantum states—photon-added two-mode squeezed coherent states have been theoretically introduced by adding multiple photons to each mode of the two-mode squeezed coherent states. Starting from the new expression of two-mode squeezing operator in entangled states representation, the normalization factor is obtained, which is directly related to bivariate Hermite polynomials. The sub-Poissonian photon statistics, cross-correlation between two modes, partial negative Wigner function are observed, which fully reflect the nonclassicality of the target states. The negative Wigner function often display non-Gaussian distribution meanwhile. The investigations may provide experimentalists with some better references in quantum engineering.
Two-Mode Wave Solutions to the Degasperis-Procesi Equation
Institute of Scientific and Technical Information of China (English)
ZHANG Zheng-Di; BI Qin-Sheng
2008-01-01
@@ By introducing a new type of solutions, called the multiple-mode wave solutions which can be expressed in nonlinear superposition of single-mode waves with different speeds, we investigate the two-mode wave solutions in Degasperis-Procesi equation and two cases are derived.The explicit expressions for the two-mode waves as well as the existence conditions are presented.It is shown that the two-mode waves may be the nonlinear combinations of many types of single-mode waves, such as periodic waves, solitons, compactons, etc., and more complicated multiple-mode waves can be obtained if higher order or more single-mode waves are taken into consideration.It is pointed out that the two-mode wave solutions can be employed to display the typical mechanism of the interactions between different single-mode waves.
An Extra Phase for Two-Mode Coherent States Displaced in Noncommutative Phase Space
Institute of Scientific and Technical Information of China (English)
YAN Long; FENG Xun-Li; ZHANG Zhi-Ming; LIU Song-Hao
2012-01-01
Using deformed boson algebra,we study the property of two-mode coherent states in noncommutative phase space.When a two-mode field evolves in the noncommutative phase space,it can acquire an extra θ-dependent phase compared to the case of commutative space.This phase is detectable and may be used to test noncommutativity.%Using deformed boson algebra, we study the property of two-mode coherent states in noncommutative phase space. When a two-mode field evolves in the noncommutative phase space, it can acquire an extra 9-dependent phase compared to the case of commutative space. This phase is detectable and may be used to test noncommutativity.
Analysis of MPN, MHN and Phase Noise of a Two-Mode Semiconductor Laser
Institute of Scientific and Technical Information of China (English)
Ebrahim Mortazy; Vahid Ahmadi; Mohammad Kazem Moravvej-Farshi; Abbas Zarifkar
2003-01-01
Intensity noise including Mode Partition Noise (MPN) and Mode Hopping Noise (MHN), and Phase/Frequency Noise Spectrum (FNS) are calculated for a two-mode semiconductor laser. RIN is derived considering of MPN and MHN effect.
An EMTDC Model of a Three Level four MVAR Compensator
DEFF Research Database (Denmark)
Rasmussen, Tonny Wederberg
1997-01-01
The paper discusses the dynamic characteristics of a three level ±4mvar solid state var compensator which is built and will be used for dynamic reactive power compensation in a wind farm. An investigation has been carried out of the influence of the compensator reactor, the DC intermediate voltage...... capacitor and the losses of the compensator for its speed of control, specially its response to fast phase shift in the grid. Furthermore the need for DC midpoint control will be compared with the inherent stabilisation. The harmonics made by the midpoint control will be compared with the harmonics without...
Institute of Scientific and Technical Information of China (English)
HOU Bang-Pin; WANG Shun-Jin; YU Wan-Lun; SUN Wei-Li; WANG Gang
2004-01-01
@@ We obtain the analytical solution to the master equation in the photon number representation by using algebraic dynamical method in the nonautonomous case. Based on the solution we find that a two-mode coherent sate can be produced within dissipative background, and the averaged photon number for each mode is related to the damping constant, external field amplitude and coupling constant between two modes.
Institute of Scientific and Technical Information of China (English)
He Guang-Qiang; Zhu Si-Wei; Guo Hong-Bin; Zeng Gui-Hua
2008-01-01
For the beam splitter attack strategy against quantum key distribution using two-mode squeezed states, the analytical expression of the optimal beam splitter parameter is provided in this paper by applying the Shannon information theory. The theoretical secret information rate after error correction and privacy amplification is given in terms of the squeezed parameter and channel parameters. The results show that the two-mode squeezed state quantum key distribution is secure against an optimal beam splitter attack.
Probabilistic teleportation scheme of two-mode entangled photon states by using linear optic element
Institute of Scientific and Technical Information of China (English)
XIANG Shao-hua
2003-01-01
A scheme for teleporting two-mode entangled photon states with the successful probability 33.3% is proposed. In the scheme, the teleporte d qubit is two-mode photon entangled states, and two pairs of EPR pair are used as quantum channel between a sender and a receiver. This procedure is achieved by using two 50/50 symmetric beam splitters and four photon number detectors wit h the help of classical information.
Zhou, L; Sun, C P; Lu, Jing; Zhou, Lan
2006-01-01
In the first paper of our series of articles on photon transmission in the coupled resonator optical waveguide (CROW), we used the two time Green function approach to study the physical mechanism for the coherent control by doping two-level atoms. In present paper, we propose and study a hybrid mechanism for photon transmission in the CROW by incorporating the electromagnetically induced transparency (EIT) effect in the doping artificial atoms and the band structure of the CROW. Here, the configuration setup of system, similar to that in the first paper, consists of a CROW with homogeneous couplings and the artificial atoms with $\\Lambda$-type three levels doped in each cavity. Unlike the stimulated Raman process used in the first paper to reduce the three level systems into the two level ones, the roles of three levels are completely considered based on a kind of mean field approach where the collection of three-level atoms collectively behave as two-mode spin waves. Then the total system is reduced into an ...
CONSTRUCTING UNIFORM DESIGNS WITH TWO- OR THREE-LEVEL
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
When the number of runs is large, to search for uniform designs in the sense of low-discrepancy is an NP hard problem. The number of runs of most of the available uniform designs is small (≤ 50). In this article, the authors employ a kind of the so-called Hamming distance method to construct uniform designs with two- or three-level such that some resulting uniform designs have a large number of runs. Several infinite classes for the existence of uniform designs with the same Hamming distances between any distinct rows are also obtained simultaneously. Two measures of uniformity, the centered L2-discrepancy (CD, for short) and wrap-around L2-discrepancy (WD, for short), are employed.
Three-level description of the domino cellular automaton
Czechowski, Zbigniew
2010-01-01
Inspired by the approach of kinetic theory of gases, a three-level description (microscopic, mesoscopic and macroscopic) of cellular automaton is presented. To provide an analytical treatment a simple domino cellular automaton with avalanches was constructed. Formulas concerning exact relations for density, clusters, avalanches and other parameters in an equilibrium state were derived. It appears that some relations are approximately valid for deviations from the equilibrium, so the adequate Ito equation could be constructed. The equation provides the time evolution description of some variable on the macroscopic level. The results also suggest a motive for applying of the procedure of construction of the Ito equation (from time series data) to natural time series.
Matched Pulse Propagation in a Three-Level System
Park, Q H
1997-01-01
The Bãcklund transformation for the three-level Maxwell-Bloch equation is presented in the matrix potential formalism. By applying the Bãcklund transformation to a constant electric field background, we obtain a general solution for matched pulses (a pair of solitary waves) which can emit or absorb a light velocity solitary pulse but otherwise propagate with their shapes invariant. In the special case, this solution describes a steady state pulse without emission or absorption, and becomes the matched pulse solution recently obtained by Hioe and Grobe. A nonlinear superposition rule is derived from the solitons as well as nonabelian breathers. Various new features of these solutions are addressed. In particular, we analyze in detail the scattering of "invertons", a specific pair of different wavelength solitons one of which moving with the velocity of light. Unlike the usual case of soliton scattering, the broader inverton changes its sign through the scattering. Surprisingly, the light velocity inverton re...
Superadiabatic driving of a three-level quantum system
Theisen, M.; Petiziol, F.; Carretta, S.; Santini, P.; Wimberger, S.
2017-07-01
We study superadiabatic quantum control of a three-level quantum system whose energy spectrum exhibits multiple avoided crossings. In particular, we investigate the possibility of treating the full control task in terms of independent two-level Landau-Zener problems. We first show that the time profiles of the elements of the full control Hamiltonian are characterized by peaks centered around the crossing times. These peaks decay algebraically for large times. In principle, such a power-law scaling invalidates the hypothesis of perfect separability. Nonetheless, we address the problem from a pragmatic point of view by studying the fidelity obtained through separate control as a function of the intercrossing separation. This procedure may be a good approach to achieve approximate adiabatic driving of a specific instantaneous eigenstate in realistic implementations.
Consciousness, Mind, and Spirit: Three Levels of Human Cognition
Directory of Open Access Journals (Sweden)
Andrej Ule
2015-10-01
Full Text Available The article elucidates three important concepts and realities that refer to cognitive phenomena and are often (mistakenly used as synonyms: consciousness (slo. zavest, mind (slo. um, and spirit (slo. duh. They present three levels of human cognition: individual-experiential, individual-mental, and trans-individual-mental. Simply put: the concept of consciousness pertains to the waking mental life of a human being, while the concept of mind pertains to the ability and activity to consciously comprehend and understand contents and objects of human activity. I delineate three “types” of spirit: personal spirit, objective spirit, and the objectification of spirit in productions of human culture; I have doubts, however, about the existence of cosmic or super-cosmic dimensions of spirit, although some interpretations of quantum physics and modern cosmology suggest that such dimensions are possible.
Arkhipov, Ievgen I.; Peřina, Jan; Peřina, Jan; Miranowicz, Adam
2016-07-01
The behavior of general nonclassical two-mode Gaussian states at a beam splitter is investigated. Single-mode nonclassicality as well as two-mode entanglement of both input and output states are analyzed suggesting their suitable quantifiers. These quantifiers are derived from local and global invariants of linear unitary two-mode transformations such that the sum of input (or output) local nonclassicality measures and entanglement measure gives a global invariant. This invariant quantifies the global nonclassicality resource. Mutual transformations of local nonclassicalities and entanglement induced by the beam splitter are analyzed considering incident noisy twin beams, single-mode noisy squeezed vacuum states, and states encompassing both squeezed states and twin beams. A rich tapestry of interesting nonclassical output states is predicted.
Classical Stückelberg interferometry of a nanomechanical two-mode system
Seitner, Maximilian J.; Ribeiro, Hugo; Kölbl, Johannes; Faust, Thomas; Kotthaus, Jörg P.; Weig, Eva M.
2016-12-01
Stückelberg interferometry is a phenomenon that has been well established for quantum-mechanical two-level systems. Here, we present classical two-mode interference of a nanomechanical two-mode system, realizing a classical analog of Stückelberg interferometry. Our experiment relies on the coherent energy exchange between two strongly coupled, high-quality factor nanomechanical resonator modes. Furthermore, we discuss an exact theoretical solution for the double-passage Stückelberg problem by expanding the established finite-time Landau-Zener single-passage solution. For the parameter regime explored in the experiment, we find that the Stückelberg return probability in the classical version of the problem formally coincides with the quantum case, which reveals the analogy of the return probabilities in the quantum-mechanical and the classical version of the problem. This result qualifies classical two-mode systems at large to simulate quantum-mechanical interferometry.
Gaussian measures of entanglement versus negativities and the ordering of two-mode Gaussian states
Adesso, G; Adesso, Gerardo; Illuminati, Fabrizio
2005-01-01
In this work we focus on entanglement of two--mode Gaussian states of continuous variable systems. We introduce the formalism of Gaussian entanglement measures, adopting the framework developed in [M. M. Wolf {\\em et al.}, Phys. Rev. A {\\bf 69}, 052320 (2004)], where the Gaussian entanglement of formation was defined. We compute Gaussian measures explicitely for two important families of nonsymmetric two--mode Gaussian states, namely the states of extremal (maximal and minimal) negativities at fixed global and local purities, introduced in [G. Adesso {\\em et al.}, Phys. Rev. Lett. {\\bf 92}, 087901 (2004)]. This allows us to compare the {\\em orderings} induced on the set of entangled two--mode Gaussian states by the negativities and by the Gaussian entanglement measures. We find that in a certain range of global and local purities (characterizing the covariance matrix of the corresponding extremal states), states of minimum negativity can have more Gaussian entanglement than states of maximum negativity. Thus ...
Degeneration of Four Wave Mixing in 500 m Step Index Two Mode Fiber
Directory of Open Access Journals (Sweden)
J. Jamaludin
2016-12-01
Full Text Available Four wave mixing (FWM in two-mode fiber was experimentally demonstrated at 24.7 dBm of output Erbium doped fiber amplifier (EDFA. The 0.5 km two mode fiber in laser cavity enhances the performance of four wave mixing by suppressing the homogenous broadening effect in erbium-doped fiber and perform a stable oscillation. At output EDFA approaches to 24.7 dBm, FWM is generated and the increasing of output EDFA induced the optical signal to noise ratio (OSNR of all laser peaks.
Nonlinear Bethe-Heitler Pair Creation in an Intense Two-Mode Laser Field
Augustin, Sven
2013-01-01
We investigate electron-positron pair creation in the interaction of a nuclear Coulomb field and a highly intense two-mode laser field. For bichromatic laser fields, we examine the differences arising for commensurable and incommensurable frequencies in a continuous variation of the laser frequency ratio and the quantum interference effects, which may occur in the commensurable case. We show that the interference manifests in the angular distributions and the total pair-production rates of the created particles. Additionally, by varying the amplitudes of the two modes we study pair creation in a monochromatic laser wave of arbitrarily elliptical polarization.
Terahertz beat freuquency generation from two-mode lasing operation of coupled microdisk laser
Ryu, Jung-Wan; Kim, Chil-Min; Shinohara, Susumu; Kim, Sang Wook
2012-01-01
We propose a coupled microdisk laser as a compact and tunable laser source for the generation of a coherent continuous wave THz radiation by photomixing. Using the Schr\\"odinger-Bloch model including the nonlinear effect of active medium, we find single mode and two mode lasings depending on the pumping strength. We explain the transitions of lasing modes in terms of resonant modes which are the solutions of the Schr\\"odinger-Bloch model without active medium and nonlinear interaction. In particular, a two mode lasing is shown to generate THz oscillating frequency originating from the light beating of two nearly degenerated resonant modes with different symmetries.
A Two-Mode Mean-Field Optimal Switching Problem for the Full Balance Sheet
Directory of Open Access Journals (Sweden)
Boualem Djehiche
2014-01-01
a two-mode optimal switching problem of mean-field type, which can be described by a system of Snell envelopes where the obstacles are interconnected and nonlinear. The main result of the paper is a proof of a continuous minimal solution to the system of Snell envelopes, as well as the full characterization of the optimal switching strategy.
Computation of expectation values from vibrational coupled-cluster at the two-mode coupling level
DEFF Research Database (Denmark)
Zoccante, Alberto; Seidler, Peter; Christiansen, Ove
2011-01-01
In this work we show how the vibrational coupled-cluster method at the two-mode coupling level can be used to calculate zero-point vibrational averages of properties. A technique is presented, where any expectation value can be calculated using a single set of Lagrangian multipliers computed...
Computation of expectation values from vibrational coupled-cluster at the two-mode coupling level
DEFF Research Database (Denmark)
Zoccante, Alberto; Seidler, Peter; Christiansen, Ove
2011-01-01
In this work we show how the vibrational coupled-cluster method at the two-mode coupling level can be used to calculate zero-point vibrational averages of properties. A technique is presented, where any expectation value can be calculated using a single set of Lagrangian multipliers computed...
An Exact Solution and the Pancharatnam Phase for the Generalized Two-Mode Optical System
Institute of Scientific and Technical Information of China (English)
侯邦品; 王顺金; 余万伦
2002-01-01
Using the algebraic dynamical method, we obtain the exact solution for the generalized two-mode optical system. From the solution, the Pancharatnam phase and the mean values of the number operators of the system are calculated. It is emphasized that the system can be used as a quantum memory.
Analytical Study of Two-Mode Thermal Squeezed States and Black Holes
Venkataratnam, K. K.
2017-02-01
We study the two-mode thermal squeezed states formalism to examine the particle creation by black holes.We also study the entropy generation and derive an equation for Hawking temperature in terms of squeezed parameter and an associated temperature dependent parameters.
Bounds for entanglement of formation of two mode squeezed thermal states
Chen, X Y; Chen, Xiao-Yu; Qiu, Pei-liang
2003-01-01
The upper and lower bounds of entanglement of formation are given for two mode squeezed thermal state. The bounds are compared with other entanglement measure or bounds. The entanglement distillation and the relative entropy of entanglement of infinitive squeezed state are obtained at the postulation of hashing inequality.
Cognition from life: the two modes of cognition that underlie moral behavior
Andringa, Tjeerd; van den Bosch, Kirsten; Wijermans, Nanda
2015-01-01
We argue that the capacity to live life to the benefit of self and others originates in the defining properties of life. These lead to two modes of cognition; the coping mode that is preoccupied with the satisfaction of pressing needs and the co-creation mode that aims at the realization of a world
Spatial Four Wave Mixing, Probe Images, and Fluorescence Signals in Dressed Three-Level System
Lan, Huayan; Sun, Jia; Wu, Zhenkun; Zhang, Dan; Zhang, Yiqi; Zheng, Huaibin; Zhang, Yanpeng
2013-10-01
We investigate the spatial images of the probe, generated four wave mixing (FWM) signal and the accompanying fluorescence spectrum signal simultaneously in FWM process in a cascade three-level atomic system for the first time. We experimentally observe and theoretically investigate the three spectrum signals versus the probe field as well as the dressing field frequency detunings. Utilizing the experimental results of spectrum signals, the cross phase modulation and the relative position between the weak and strong beams, we analyze the characteristics indicated in the spatial images of probe transmission and FWM, such as focusing or defocusing, shift and splitting in detail. Such studies can be used in all-optical controlled spatial signal transmission.
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
By using the method of eigenvectors, the atomic populations and emission spectrum are investigated in a system that consists of a cascade three-level atom resonantly interacting with a single-mode field in a Kerr-like medium.The atom and the field are assumed to be initially in the upper atomic state and the Fock state, respectively. Results for models with intensity-dependent coupling and with intensity-independent coupling are compared. It is found that both population dynamics and emission spectrum show no indications of atom-field decoupling in the strong field limit if the intensity-dependent coupling is taken into account.
A Three Level Autonomous Software System for Increased Science Return
Robinson, P. I.; Mancinelli, R. L.; Landheim, R.
2005-12-01
The development of smart science instruments for autonomous operation (on Earth or in space) has the potential to increase science return and reduce the risk of experiment failure. When researchers are confronted with unexpected data/results of the experimental test system, they must determine whether the experimental setup has failed, or scientific discovery is being made. These two classes of events could have the same time series signature. To directly address this issue, we have developed a three-level software system referred to as E3, which consists of an engineering level, an experiment level, and an executive level. Each level of the software system is designed in a modular fashion using model based feedback controllers. The same feedback control mechanism is used for each level; the model itself determines the level. To determine if failure of the experimental setup can explain the data/results, researchers run calibration tests for hardware (e.g., sensors and actuators) as well as verify that the software (e.g., controls and analog to digital conversion routines) is running as planned. If anomalies are found, then modifications are made to the experimental setup, or the anomaly is accepted as the new baseline state of the instrument. The engineering level of the E3 software system is responsible for this process. To determine if scientific discovery, as opposed to failure, can explain the data/results, a researcher tries to explain the difference between the observed and expected results. These explanations are terms of the basic processes of nature to determine the rate limiting step(s) of a complex set of processes, where the flux could be due to heat transfer, mass transfer, momentum transfer, or chemical reaction processes. Once the differences are understood, modifications are made to the software control of the experiment, as well as to the model the researcher is building over the course of repeated experiments. The experiment level of the E3
Two-mode excited entangled coherent states and their entanglement properties
Institute of Scientific and Technical Information of China (English)
Zhou Dong-Lin; Kuang Le-Man
2009-01-01
This paper introduces two types of two-mode excited entangled coherent states(TMEECSs)|Ψ±(α,m,n)>,studies their entanglement characteristics,and investigates the influence of photon excitations on quantum entanglement.It shows that for the state|Ψ+(α,m,m)>the two-mode photon excitations affect seriously entanglement character while the state |Ψ-(α,m,m)>is always a maximally entangled state,and shows how such states can be produced by using cavity quantum electrodynamics and quantum measurements.It finds that the entanglement amount of the TMEECSs is larger than that of the single-mode excited entangled coherent states with the same photon excitation number.
Entanglement concentration for two-mode Gaussian states in non-inertial frames
Di Noia, Maurizio; Giraldi, Filippo; Petruccione, Francesco
2017-04-01
Entanglement creation and concentration by means of a beam splitter (BS) is analysed for a generic two-mode bipartite Gaussian state in a relativistic framework. The total correlations, the purity and the entanglement in terms of logarithmic negativity are analytically studied for observers in an inertial state and in a non-inertial state of uniform acceleration. The dependence of entanglement on the BS transmissivity due to the Unruh effect is analysed in the case when one or both observers undergo uniform acceleration. Due to the Unruh effect, depending on the initial Gaussian state parameters and observed accelerations, the best condition for entanglement generation limited to the two modes of the observers in their regions is not always a balanced beam splitter, as it is for the inertial case.
TWO-MODE GALERKIN APPROACH IN DYNAMIC STABILITY ANALYSIS OF VISCOELASTIC PLATES
Institute of Scientific and Technical Information of China (English)
张能辉; 程昌钧
2003-01-01
The dynamic stability of viscoelastic thin plates with large deflections was investigated by using the largest Liapunov exponent analysis and other numerical and analytical dynamic methods. The material behavior was described in terms of the Boltzmann superposition principle. The Galerkin method was used to simplify the original integropartial-differential model into a two-mode approximate integral model, which further reduced to an ordinary differential model by introducing new variables. The dynamic properties of one-mode and two-mode truncated systems were numerically compared. The influence of viscoelastic properties of the material, the loading amplitude and the initial values on the dynamic behavior of the plate under in-plane periodic excitations was discussed.
Energy Technology Data Exchange (ETDEWEB)
Laurat, Julien [Laboratoire Kastler Brossel, Case 74, Universite Pierre et Marie curie, 4 Place Jussieu, 75252 Paris cedex 05 (France); Keller, Gaelle [Laboratoire Kastler Brossel, Case 74, Universite Pierre et Marie curie, 4 Place Jussieu, 75252 Paris cedex 05 (France); Oliveira-Huguenin, Jose Augusto [Laboratoire Kastler Brossel, Case 74, Universite Pierre et Marie curie, 4 Place Jussieu, 75252 Paris cedex 05 (France); Fabre, Claude [Laboratoire Kastler Brossel, Case 74, Universite Pierre et Marie curie, 4 Place Jussieu, 75252 Paris cedex 05 (France); Coudreau, Thomas [Laboratoire Kastler Brossel, Case 74, Universite Pierre et Marie curie, 4 Place Jussieu, 75252 Paris cedex 05 (France); Laboratoire Materiaux et Phenomenes Quantiques, Case 7021, Universite Denis Diderot, 2 Place Jussieu, 75251 Paris cedex 05 (France); Serafini, Alessio [Dipartimento di Fisica ' E R Caianiello' , Universita di Salerno (Italy); CNR-Coherentia, Gruppo di Salerno (Italy); and INFN Sezione di Napoli-Gruppo Collegato di Salerno, Via S Allende, 84081 Baronissi (Saudi Arabia) (Italy); Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Adesso, Gerardo [Dipartimento di Fisica ' E R Caianiello' , Universita di Salerno (Italy); CNR-Coherentia, Gruppo di Salerno (Italy); and INFN Sezione di Napoli-Gruppo Collegato di Salerno, Via S Allende, 84081 Baronissi (Saudi Arabia) (Italy); Illuminati, Fabrizio [Dipartimento di Fisica ' E R Caianiello' , Universita di Salerno (Italy) and CNR-Coherentia, Gruppo di Salerno (Italy) and INFN Sezione di Napoli-Gruppo Collegato di Salerno, Via S Allende, 84081 Baronissi (SA) (Italy)
2005-12-01
A powerful theoretical structure has emerged in recent years on the characterization and quantification of entanglement in continuous-variable systems. After reviewing this framework, we will illustrate it with an original set-up based on a type-II OPO (optical parametric oscillator) with adjustable mode coupling. Experimental results allow a direct verification of many theoretical predictions and provide a sharp insight into the general properties of two-mode Gaussian states and entanglement resource manipulation.
Laurat, J; Oliveira-Huguenin, J A; Fabre, C; Coudreau, T; Serafini, A; Adesso, G; Illuminati, F; Laurat, Julien; Keller, Ga\\"{e}lle; Oliveira-Huguenin, Jose-Augusto; Fabre, Claude; Coudreau, Thomas; Serafini, Alessio; Adesso, Gerardo; Illuminati, Fabrizio
2005-01-01
A powerful theoretical structure has emerged in recent years on the characterization and quantification of entanglement in continuous-variable systems. After reviewing this framework, we will illustrate it with an original set-up based on a type-II OPO with adjustable mode coupling. Experimental results allow a direct verification of many theoretical predictions and provide a sharp insight into the general properties of two-mode Gaussian states and entanglement resource manipulation.
Entanglement and purity of two-mode Gaussian states in noisy channels
Serafini, A; Paris, M G A; De Siena, S; Serafini, Alessio; Illuminati, Fabrizio; Paris, Matteo G. A.; Siena, Silvio De
2004-01-01
We study the evolution of purity, entanglement and total correlations of general two--mode Gaussian states of continuous variable systems in arbitrary uncorrelated Gaussian environments. The time evolution of purity, Von Neumann entropy, logarithmic negativity and mutual information is analyzed for a wide range of initial conditions. In general, we find that a local squeezing of the bath leads to a faster degradation of purity and entanglement, while it can help to preserve the mutual information between the modes.
Engineering of Two Quantum States via Conditional Measurement on Two-Mode Squeezed State
Institute of Scientific and Technical Information of China (English)
LIAN Yi-Min; ZHANG Jun-Xiang; XIE Chang-De; PENG Kun-Chi
2008-01-01
@@ We propose a scheme for the simultaneously preparation radiation-field modes of a single photon and a superposition of zero-and one-photon states,based on the coherent quantum state displacement and photon subtraction from two-mode squeezed state.It is shown that the single-photon and the superposition states can be obtained by only choosing the suitable parameter of displacements.The experimental feasibility to accomplish this scheme is also discussed.
Institute of Scientific and Technical Information of China (English)
FAN Hong-Yi; LI Chao
2004-01-01
We extend the approach of solving master equations for density matrices by projecting it onto the thermal entangled state representation (Hong-Yi Fan and Jun-Hua Chen, J. Phys. A35 (2002) 6873) to two-mode case. In this approach the two-photon master equations can be directly and conveniently converted into c-number partial differential equations. As an example, we solve the typical master equation for two-photon process in some limiting cases.
Comment on ''Teleportation of two-mode squeezed states''
Energy Technology Data Exchange (ETDEWEB)
He Guangqiang; Zhang Jingtao [State Key Lab of Advanced Optical Communication Systems and Networks Department of Electronic Engineering, Shanghai Jiaotong University, Shanghai 200030 (China)
2011-10-15
We investigate the teleportation scheme of two-mode squeezed states proposed by Adhikari et al.[S. Adhikari et al., Phys. Rev. A 77, 012337 (2008)]. It uses four-mode entangled states to teleport two-mode squeezed states. The fidelity between the original two-mode squeezed states and teleported ones is calculated. The maximal fidelity value of Adhikari's protocol is 0.38, which is incompatible with the fidelity definition with the maximal value 1. In our opinion, one reason is that they calculate the fidelity for multimodes Gaussian states using the fidelity formula for single-mode ones. Another reason is that the covariance matrix of output states should be what is obtained after applying the linear unitary Bogoliubov operations (two cascaded Fourier transformations) on the covariance matrix given in Eq. (12) in their paper. These two reasons result in the incomparable results. In addition, Adhikari's protocol can be simplified to be easily implemented.
Directory of Open Access Journals (Sweden)
D.V. Slobodianiuk
2014-03-01
Full Text Available Two-mode model of spin-torque nano-oscillator (STNO under the action of thermal noise is considered. Langevin equations for mode amplitudes were derived starting from general nonlinear oscillator model. Stationary probability distribution function describing mean mode generation powers was obtained using Fokker-Planck equation. It was shown that thermal noise can lead to two-mode generation in STNO. An increase of thermal noise power leads to excitation of the second mode in a system and to a two-mode generation regime through intermediate state when two modes coexist only in some range of the applied currents.
Noise squeezing of fields that bichromatically excite atoms in a cavity.
Li, Lingchao; Hu, Xiangming; Rao, Shi; Xu, Jun
2016-11-14
It is well known that bichromatic excitation on one common transition can tune the emission or absorption spectra of atoms due to the modulation frequency dependent non-linearities. However little attention has been focused on the quantum dynamics of fields under bichromatic excitation. Here we present dissipative effects on noise correlations of fields in bichromatic interactions with atoms in cavities. We first consider an ensemble of two-level atoms that interacts with the two cavity fields of different frequencies and considerable amplitudes. By transferring the atom-field nonlinearities to the dressed atoms we separate out the dissipative interactions of Bogoliubov modes with the dressed atoms. The Bogoliubov mode dissipation establishes stable two-photon processes of two involved fields and therefore leads to two-mode squeezing. As a generalization, we then consider an ensemble of three-level Λ atoms for cascade bichromatic interactions. We extract the Bogoliubov-like four-mode interactions, which establish a quadrilateral of the two-photon processes of four involved fields and thus result in four-mode squeezing.
Heisenberg-Limited Qubit Read-Out with Two-Mode Squeezed Light.
Didier, Nicolas; Kamal, Archana; Oliver, William D; Blais, Alexandre; Clerk, Aashish A
2015-08-28
We show how to use two-mode squeezed light to exponentially enhance cavity-based dispersive qubit measurement. Our scheme enables true Heisenberg-limited scaling of the measurement, and crucially, it is not restricted to small dispersive couplings or unrealistically long measurement times. It involves coupling a qubit dispersively to two cavities and making use of a symmetry in the dynamics of joint cavity quadratures (a so-called quantum-mechanics-free subsystem). We discuss the basic scaling of the scheme and its robustness against imperfections, as well as a realistic implementation in circuit quantum electrodynamics.
Characterization of Rayleigh backscattering arising in various two-mode fibers.
Yu, Dawei; Fu, Songnian; Cao, Zizheng; Tang, Ming; Deng, Lei; Liu, Deming; Giles, Ian; Koonen, Ton; Okonkwo, Chigo
2016-05-30
We experimentally characterize the mode dependent characteristics of Rayleigh backscattering (RB) arising in various two-mode fibers (TMFs). With the help of an all-fiber photonic lantern, we are able to measure the RB power at individual modes. Consequently, mode dependent power distribution of RB light caused by arbitrary forward propagation mode superposition can be obtained. The total RB power of the TMFs under test is higher than that of single mode fiber by at least 2 dB over the C band. Meanwhile, the RB light occurs among all guided modes in the TMFs with specific power ratios. The experimental characterization agrees well with the theoretical calculations.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The generalized continuous variable two-mode entangled state |〉 is proposed by using the tech-nique of integration within an ordered product (IWOP) of operators. The characteristics of this new entangled representation and its application in quantum teleportation are analyzed in detail. These results indicate that such real parameters |〉 indeed make up a new entangled representation owing to its completeness and orthogonal relation. By employing the |〉 as quantum transmission channel,the teleportation of any single-mode quantum state |ψ〉 3 can be realized by a unitary transformation.
Assessing Two-Mode Semantic Network Story Representations Using a False Memory Paradigm
Corman, Steven R.; Ball, B. Hunter; Talboom, Kimberly M.; GENE A. BREWER
2013-01-01
This paper describes a novel method of representing semantic networks of stories (and other text) as a two-mode graph. This method has some advantages over traditional one-mode semantic networks, but has the potential drawback (shared with n-gram text networks) that it contains paths that are not present in the text. An empirical study was devised using a false memory paradigm to determine whether these induced paths are remembered as being true of a set of stories. Results indicate that part...
Generalized two-mode coherent-entangled state with real parameters
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The coherent-entangled state |α, x; λ> with real parameters λ is proposed in the two-mode Fock space, which exhibits the properties of both the coherent and entangled states. The completeness relation of |α, x; λ> is proved by virtue of the technique of integral within an ordered product of operators. The corresponding squeezing operator is derived, with its own squeezing properties. Furthermore, generalized P-representation in the coherent-entangled state is constructed. Finally, it is revealed that superposition of the coherent-entangled states may produce the EPR entangled state.
EFFECTS OF COLOURED NOISE IN A TWO-MODE LASER SYSTEM
Institute of Scientific and Technical Information of China (English)
罗晓琴; 朱士群; 高伟建
2001-01-01
A homogeneously broadened two-mode laser system with multiplicative coloured noise is investigated when the mode coupling constant ξ=2. An analytical result is obtained when two-dimensional decoupling theory is applied to the system. The intensity auto-correlation function and effective eigenvalue of the laser system are calculated when the difference of pump parameters, multiplicative noise strength and noise correlation time are varied. It is shown that the multiplicative noise can enhance the fluctuations while the noise colour can reduce the fluctuations in the laser system.
A robust and simple two-mode digital calibration technique for pipelined ADC
Institute of Scientific and Technical Information of China (English)
Yin Xiumei; Zhao Nan; Sekedi Bomeh Kobenge; Yang Huazhong
2011-01-01
This paper presents a two-mode digital calibration technique for pipelined analog-to-digital converters (ADC).The proposed calibration eliminates the errors of residual difference voltage induced by capacitor mismatch of pseudorandom (PN) sequence injection capacitors at the ADC initialization,while applies digital background calibration to continuously compensate the interstage gain errors in ADC normal operation.The presented technique not only reduces the complexity of analog circuit by eliminating the implementation of PN sequence with accurate amplitude in analog domain,but also improves the performance of digital background calibration by minimizing the sensitivity of calibration accuracy to sub-ADC errors.The use ofopamps with low DC gains in normal operation makes the proposed design more compatible with future nanometer CMOS technology.The prototype of a 12-bit 40-MS/s pipelined ADC with the two-mode digital calibration is implemented in 0.18-μm CMOS process.Adopting a simple telescopic opamp with a DC gain of 58-dB in the first stage,the measured SFDR and SNDR within the first Nyquist zone reach 80-dB and 66-dB,respectively.With the calibration,the maximum integral nonlinearity (INL) of the ADC reduces from 4.75-LSB to 0.65-LSB,while the ADC core consumes 82-mW at 3.3-V power supply.
A robust and simple two-mode digital calibration technique for pipelined ADC
Energy Technology Data Exchange (ETDEWEB)
Yin Xiumei; Zhao Nan; Sekedi Bomeh Kobenge; Yang Huazhong, E-mail: yxm@mails.tsinghua.edu.cn [Department of Electronic Engineering, Tsinghua University, Beijing 100084 (China)
2011-03-15
This paper presents a two-mode digital calibration technique for pipelined analog-to-digital converters (ADC). The proposed calibration eliminates the errors of residual difference voltage induced by capacitor mismatch of pseudorandom (PN) sequence injection capacitors at the ADC initialization, while applies digital background calibration to continuously compensate the interstage gain errors in ADC normal operation. The presented technique not only reduces the complexity of analog circuit by eliminating the implementation of PN sequence with accurate amplitude in analog domain, but also improves the performance of digital background calibration by minimizing the sensitivity of calibration accuracy to sub-ADC errors. The use of opamps with low DC gains in normal operation makes the proposed design more compatible with future nanometer CMOS technology. The prototype of a 12-bit 40-MS/s pipelined ADC with the two-mode digital calibration is implemented in 0.18-{mu}m CMOS process. Adopting a simple telescopic opamp with a DC gain of 58-dB in the first stage, the measured SFDR and SNDR within the first Nyquist zone reach 80-dB and 66-dB, respectively. With the calibration, the maximum integral nonlinearity (INL) of the ADC reduces from 4.75-LSB to 0.65-LSB, while the ADC core consumes 82-mW at 3.3-V power supply. (semiconductor integrated circuits)
A robust and simple two-mode digital calibration technique for pipelined ADC
Xiumei, Yin; Nan, Zhao; Bomeh Kobenge, Sekedi; Huazhong, Yang
2011-03-01
This paper presents a two-mode digital calibration technique for pipelined analog-to-digital converters (ADC). The proposed calibration eliminates the errors of residual difference voltage induced by capacitor mismatch of pseudorandom (PN) sequence injection capacitors at the ADC initialization, while applies digital background calibration to continuously compensate the interstage gain errors in ADC normal operation. The presented technique not only reduces the complexity of analog circuit by eliminating the implementation of PN sequence with accurate amplitude in analog domain, but also improves the performance of digital background calibration by minimizing the sensitivity of calibration accuracy to sub-ADC errors. The use of opamps with low DC gains in normal operation makes the proposed design more compatible with future nanometer CMOS technology. The prototype of a 12-bit 40-MS/s pipelined ADC with the two-mode digital calibration is implemented in 0.18-μm CMOS process. Adopting a simple telescopic opamp with a DC gain of 58-dB in the first stage, the measured SFDR and SNDR within the first Nyquist zone reach 80-dB and 66-dB, respectively. With the calibration, the maximum integral nonlinearity (INL) of the ADC reduces from 4.75-LSB to 0.65-LSB, while the ADC core consumes 82-mW at 3.3-V power supply.
Cognition from life: the two modes of cognition that underlie moral behavior
Directory of Open Access Journals (Sweden)
Tjeerd C Andringa
2015-04-01
Full Text Available We argue that the capacity to live life to the benefit of self and others originates in the defining properties of life. These lead to two modes of cognition; the coping mode that is preoccupied with the satisfaction of pressing needs and the co-creation mode that aims at the realization of a world where pressing needs occur less frequently. We have used the Rule of Conservative Changes – stating that new functions can only scaffold on evolutionary older, yet highly stable functions – to predict that the interplay of these two modes define a number of core functions in psychology associated with moral behavior. We explore this prediction with five examples reflecting different theoretical approaches to human cognition and action selection. We conclude the paper with the observation that science is currently dominated by the coping mode and that the benefits of the co-creation mode may be necessary to generate realistic prospects for a modern synthesis in the sciences of the mind.
Narrowband Biphoton Generation with Four-Wave Mixing in a Far-Detuning Three-Level System
Institute of Scientific and Technical Information of China (English)
CHEN Peng; ZHOU Shu-Yu; XU Zhen; DUAN Ya-Fan; CUI Guo-Dong; HONG Tao; WANG Yu-Zhu
2011-01-01
Non-classical paired photons are generated by a four-wave mixing process in a far-detuning three-level system with cold atoms.A violation of the Cauchy-Schwartz inequality of a factor of 310 is observed.This phenomenon shows that paired photons have a non-classical correlation. The experimental results are compared with theoretical results obtained using perturbation theory.The oscillation frequencies of the two-photon intensity correlation functions are in reasonable agreement with the effective Rabi frequencies of the coupling laser.However,we find that the dephasing rates (or decay rates) observed are far larger than the theoretical values.
The q-analogues of two-mode squeezed states constructed by virtue of the IWOP technique
Institute of Scientific and Technical Information of China (English)
Meng Xiang-Guo; Wang Ji-Suo; Li Hong-Qi
2008-01-01
The q-analogues of two-mode squeezed states are introduced by virtue of deformation quantization methods and the technique of integration within an ordered product (IWOP) of operators. Some new completeness relations about these squeezed states composed of the bra and ket which are not mutually Hermitian conjugates are obtained. Furthermore,the antibunching effects of the two-mode squeezed vacuum state S'2(r) |00> are investigated. It is found that, in different ranges of the squeezed parameter r, both modes of the state exhibit the antibunching effects and the two modes of the state are always nonclassical correlation.
Indian Academy of Sciences (India)
Mihir Ranjan Nath; Surajit Sen; Asoke Kumar Sen; Gautam Gangopadhyay
2008-07-01
We develop a scheme to construct the Hamiltonians of the lambda-, vee- and cascade-type three-level configurations using the generators of (3) group. It turns out that this approach provides a well-defined selection rule to give different Hamiltonians for each configuration. The lambda- and vee-type configurations are exactly solved with different initial conditions while taking the two-mode classical and quantized fields. For the classical field, it is shown that the Rabi oscillation of the lambda model is similar to that of the vee model and the dynamics of the vee model can be recovered from lambda model and vice versa simply by inversion. We then proceed to solve the quantized version of both models by introducing a novel Euler matrix formalism. It is shown that this dynamical symmetry exhibited in the Rabi oscillation of two configurations for the semiclassical models is completely destroyed on quantization of the field modes. The symmetry can be restored within the quantized models when both field modes are in the coherent states with large average photon number which is depicted through the collapse and revival of the Rabi oscillations.
Superradiant phase transition in a model of three-level-Λ systems interacting with two bosonic modes
Hayn, Mathias; Emary, Clive; Brandes, Tobias
2012-12-01
We consider an ensemble of three-level particles in Lambda configuration interacting with two bosonic modes. The Hamiltonian has the form of a generalized Dicke model. We show that in the thermodynamic limit this model supports a superradiant quantum phase transition. Remarkably, this can be both a first- and a second-order phase transition. A connection of the phase diagram to the symmetries of the Hamiltonian is also given. In addition, we show that this model can describe atoms interacting with an electromagnetic field in which the microscopic Hamiltonian includes a diamagnetic contribution. Even though the parameters of the atomic system respect the Thomas-Reiche-Kuhn sum rule, the system still shows a superradiant phase transition.
Electromagnetically induced transparency and slow light in two-mode optomechanics
Jiang, Cheng; Cui, Yuanshun; Li, Xiaowei
2013-01-01
We theoretically demonstrate the mechanically mediated electromagnetically induced transparency in a two-mode cavity optomechanical system, where two cavity modes are coupled to a common mechanical resonator. When the two cavity modes are driven on their respective red sidebands by two pump beams, a transparency window appears in the probe transmission spectrum due to destructive interference. Under this situation the transmitted probe beam can be delayed as much as 4 us, which can be easily controlled by the power of the pump beams. In addition, we also investigate the amplification of the transmitted probe beam owing to constructive interference when one cavity is driven on its blue sideband while another one is driven on its red sideband.
Two modes of change in Southern Ocean productivity over the past million years.
Jaccard, S L; Hayes, C T; Martínez-García, A; Hodell, D A; Anderson, R F; Sigman, D M; Haug, G H
2013-03-22
Export of organic carbon from surface waters of the Antarctic Zone of the Southern Ocean decreased during the last ice age, coinciding with declining atmospheric carbon dioxide (CO(2)) concentrations, signaling reduced exchange of CO(2) between the ocean interior and the atmosphere. In contrast, in the Subantarctic Zone, export production increased into ice ages coinciding with rising dust fluxes, thus suggesting iron fertilization of subantarctic phytoplankton. Here, a new high-resolution productivity record from the Antarctic Zone is compiled with parallel subantarctic data over the past million years. Together, they fit the view that the combination of these two modes of Southern Ocean change determines the temporal structure of the glacial-interglacial atmospheric CO(2) record, including during the interval of "lukewarm" interglacials between 450 and 800 thousand years ago.
Quantum metrology with two-mode squeezed thermal state: Parity detection and phase sensitivity
Li, Heng-Mei; Xu, Xue-Xiang; Yuan, Hong-Chun; Wang, Zhen
2016-10-01
Based on the Wigner-function method, we investigate the parity detection and phase sensitivity in a Mach-Zehnder interferometer (MZI) with two-mode squeezed thermal state (TMSTS). Using the classical transformation relation of the MZI, we derive the input-output Wigner functions and then obtain the explicit expressions of parity and phase sensitivity. The results from the numerical calculation show that supersensitivity can be reached only if the input TMSTS have a large number photons. Project supported by the National Natural Science Foundation of China (Grant No. 11447002), the Research Foundation of the Education Department of Jiangxi Province of China (Grant No. GJJ150338), and the Research Foundation for Changzhou Institute of Modern Optoelectronic Technology (Grant No. CZGY15).
Sensor applications of two-mode fiber in the Michelson interferometer configuration
Hlubina, Petr; Prochazka, Pavel
1994-11-01
The classical coherence formalism and guided-mode field representation is used to discuss the operation of few-mode fiber waveguide excited by a low-coherence, cross-spectrally pure, spatially coherent source in Michelson interferometer configuration as a sensor, even if a suppressed interference pattern at its exit face exists. In the case of a low- coherence excitation of few-mode fiber waveguide the principle of coherence modulation can be used, that is, the optical path difference between guided modes that exceeds the source coherence length can be compensated in Michelson interferometer configuration. The analysis of temporal coherence in a particular case of two-mode, weakly-guiding, step-index fiber waveguide takes also into consideration the effect of second-order modal dispersion; the potential applications to low- coherence source based interferometric sensors are discussed.
Inter-modal four-wave mixing study in a two-mode fiber.
Friis, S M M; Begleris, I; Jung, Y; Rottwitt, K; Petropoulos, P; Richardson, D J; Horak, P; Parmigiani, F
2016-12-26
We demonstrate efficient four-wave mixing among different spatial modes in a 1-km long two-mode fiber at telecommunication wavelengths. Two pumps excite the LP01 and LP11 modes, respectively, while the probe signal excites the LP01 mode, and the phase conjugation (PC) and Bragg scattering (BS) idlers are generated in the LP11 mode. For these processes we experimentally characterize their phase matching efficiency and bandwidth and find that they depend critically on the wavelength separation of the two pumps, in good agreement with the numerical study we carried out. We also confirm experimentally that BS has a larger bandwidth than PC for the optimum choice of the pump wavelength separation.
Wavelength Dependence of the Polarization Singularities in a Two-Mode Optical Fiber
Directory of Open Access Journals (Sweden)
V. V. G. Krishna Inavalli
2012-01-01
Full Text Available We present here an experimental demonstration of the wavelength dependence of the polarization singularities due to linear combination of the vector modes excited directly in a two-mode optical fiber. The coherent superposition of the vector modes excited by linearly polarized Gaussian beam as offset skew rays propagated in a helical path inside the fiber results in the generation of phase singular beams with edge dislocation in the fiber output. The polarization character of these beams is found to change dramatically with wavelength—from left-handed elliptically polarized edge dislocation to right-handed elliptically polarized edge-dislocation through disclinations. The measured behaviour is understood as being due to intermodal dispersion of the polarization corrections to the propagating vector modes, as the wavelength of the input beam is scanned.
EPR-Steering measure for two-mode continuous variable states
Kogias, Ioannis
2014-01-01
Steering is a manifestation of quantum correlations that embodies the Einstein-Podolsky-Rosen (EPR) paradox. While there have been recent attempts to quantify steering, continuous variable systems remained elusive. We introduce a steering measure for two-mode continuous variable systems that is valid for arbitrary states. The measure is based on the violation of an optimized variance test for the EPR paradox, and admits a computable and experimentally friendly lower bound only depending on the second moments of the state, which reduces to a recently proposed quantifier of steerability by Gaussian measurements. We further show that Gaussian states are extremal with respect to our measure, minimizing it among all continuous variable states with fixed second moments. As a byproduct of our analysis, we generalize and relate well-known EPR-steering criteria. Finally an operational interpretation is provided, as the proposed measure is shown to quantify the optimal guaranteed key rate in semi-device independent qua...
Two-mode model for metal-dielectric guided-mode resonance filters.
Tuambilangana, Christelle; Pardo, Fabrice; Sakat, Emilie; Bouchon, Patrick; Pelouard, Jean-Luc; Haïdar, Riad
2015-12-14
Symmetric metal-dielectric guided-mode resonators (GMR) can operate as infrared band-pass filters, thanks to high-transmission resonant peaks and good rejection ratio. Starting from matrix formalism, we show that the behavior of the system can be described by a two-mode model. This model reduces to a scalar formula and the GMR is described as the combination of two independent Fabry-Perot resonators. The formalism has then been applied to the case of asymmetric GMR, in order to restore the properties of the symmetric system. This result allows designing GMR-on-substrate as efficient as free-standing systems, the same high transmission maximum value and high quality factor being conserved.
Relaxation Process of Interacting Two-mode System Influenced by Markovian Thermal Reservoirs
Ban, Masashi
2016-11-01
Two different models of a relaxation process are considered for a linearly interacting two-mode system under the influence of independent Markovian thermal reservoirs. One is to describe the relaxation process of bare particles and the other is to describe the one of quasi particles which are derived from bare particles by the Bogoliubov transformation. The difference is that the former does not includes the effect of the inter-mode interaction on the damping operator while the latter does. The equations of motion are solved algebraically by making use of non-equilibrium thermo field dynamics. The relaxation processes in the two models are investigated in detail. The results are applied for investigating a non-ideal beam splitter with photon loss and noise addition.
Crosstalk analysis in homogeneous multi-core two-mode fiber under bent condition.
Chang, J H; Choi, H G; Bae, S H; Sim, D H; Kim, Hoon; Chung, Y C
2015-04-20
We analyze the inter-core crosstalk in homogeneous multi-core two-mode fibers (MC-TMFs) under bent condition by using the coupled-mode equations. In particular, we investigate the effects of the intra-core mode coupling on the inter-core crosstalk for two different types of MC-TMFs at various bending radii. The results show that the inter-core homo-mode crosstalk of LP(11) mode is dominant under the gentle fiber bending condition due to its large effective area. However, as the fiber bending becomes tight, the intra-core mode coupling is significantly enhanced and consequently makes all the inter-core crosstalk levels comparable to each other regardless of the mode. A similar tendency is observed at a reduced bending radius when the difference in the propagation constants between modes is large and core pitch is small.
Institute of Scientific and Technical Information of China (English)
XIANG Shao-Hua; SONG Ke-Hui; WEN Wei; SHI Zhen-Gang
2011-01-01
We study a system consisting of two identical non-interacting single-mode cavity fields coupled to a common vacuum environment and provide general, explicit, and exact solutions to its master equation by means of the characteristic function method. We analyze the entanglement dynamics of two-mode squeezed thermal state in this model and show that its entanglement dynamics is strongly determined by the two-mode squeezing parameter and the purity. In particular, we find that two-mode squeezed thermal state with the squeezing parameter r ≤ -(1/2) In (V)u is extremely fragile and almost does not survive in a common vacuum environment. We investigate the time evolution of nonlocality for two-mode squeezed thermal state in such an environment. It is found that the evolved state loses its nonlocality in the beginning of the evolution, but after a time, the revival of nonlocality can occur.
Wang, Zhen; Li, Heng-Mei; Yuan, Hong-Chun
2016-10-01
We theoretically introduce a kind of non-Gaussian entangled states, i.e., photon-subtracted two-mode squeezed coherent states (PSTMSCS), by successively subtracting photons from each mode of the two-mode squeezed coherent states. The normalization factor which is related to bivariate Hermite polynomials is obtained by virtue of the two-mode squeezing operator in entangled-states representation. The sub-Poissonian photon statistics, antibunching effects, and partial negative Wigner function, respectively, are observed numerically, which fully reflect the nonclassicality of the resultant states. Finally, employing the SV criteria and the EPR correlation, respectively, the entangled property of PSTMSCS is analyzed. It is shown that the photon subtraction operation can effectively enhance the inseparability between the two modes.
Modeling of SVM Diode Clamping Three-Level Inverter Connected to Grid
DEFF Research Database (Denmark)
Guo, Yougui; Zeng, Ping; Zhu, Jieqiong
2011-01-01
PLECS is used to model the diode clamping three-level inverter connected to grid and good results are obtained. First the output voltage SVM is described for diode clamping three-level inverter with loads connected to Y. Then the output voltage SVM of diode clamping three-level inverter is simply...... is very powerful tool to real power circuits and it is very easy to simulate them. They have also verified that SVM control strategy is feasible to control the diode clamping three-level inverter....
Institute of Scientific and Technical Information of China (English)
DAIHong-Yi; KUANGLe-Man; LICheng-Zu
2005-01-01
We propose a scheme to probabilistically teleport an unknown arbitrary three-level two-particle state by using two partial entangled two-particle states of three-level as the quantum channel. The classical communication cost required in the ideal probabilistic teleportation process is also calculated. This scheme can be directly generalized to teleport an unknown and arbitrary three-level K-particle state by using K partial entangled two-particle states of three-level as the quantum channel.
Teleportation of Atomic States for Atoms in a Lambda Configuration
Guerra, E S
2004-01-01
In this article we discuss a scheme of teleportation of atomic states making use of three-level lambda atoms. The experimental realization proposed makes use of cavity QED involving the interaction of Rydberg atoms with a micromaser cavity prepared in a coherent state. We start presenting a scheme to prepare atomic EPR states involving two-level atoms via the interaction of these atoms with a cavity. In our scheme the cavity and some atoms play the role of auxiliary systems used to achieve the teleportation.
Institute of Scientific and Technical Information of China (English)
CHENG Mu-Tian; SONG Yan-Yan; LUO Ya-Qin; ZHAO Guang-xing
2011-01-01
We investigate theoretically the single-photon scattering by a A-type three-level system interacting with a whispering-gallery-type resonator which is coupled to a one-dimensional waveguide by full quantum-mechanical approach,The single-photon transmission amplitude and reflection amplitude are obtained exactly via real-space approach. The single-photon transport properties controlling by classic optical field are discussed. The critical coupling condition in the coupled waveguide-whispering-gallery resonator-atom with three-level system is also analyzed.
Control and Modeling of Push-Pull Forward Three-Level Converter for Microgrid
DEFF Research Database (Denmark)
Yao, Zhilei; Xu, Jing; Guerrero, Josep M.
2015-01-01
Renewable energy sources are widely used in microgrid. Output voltage of them is often low and varies widely. Because diodes in three-level legs in traditional three-level (TL) converter are substituted by MOSFETs, the push-pull forward (PPF) TL converter is very suitable for wide and low...
Atomic Coherent Trapping and Properties of Trapped Atom
Institute of Scientific and Technical Information of China (English)
YANG Guo-Jian; XIA Li-Xin; XIE Min
2006-01-01
Based on the theory of velocity-selective coherent population trapping, we investigate an atom-laser system where a pair of counterpropagating laser fields interact with a three-level atom. The influence of the parametric condition on the properties of the system such as velocity at which the atom is selected to be trapped, time needed for finishing the coherent trapping process, and possible electromagnetically induced transparency of an altrocold atomic medium,etc., is studied.
Feasibility of two modes of treatment delivery for child anxiety in primary care.
Chavira, Denise A; Drahota, Amy; Garland, Ann F; Roesch, Scott; Garcia, Maritza; Stein, Murray B
2014-09-01
In this study, we examine the feasibility of cognitive behavior therapy (CBT) for children with anxiety in primary care, using two modes of treatment delivery. A total of 48 parents and youth (8-13) with anxiety disorders were randomly assigned to receive 10-sessions of CBT either delivered by a child anxiety specialist in the primary care clinic or implemented by the parent with therapist support by telephone (i.e., face-to-face or therapist-supported bibliotherapy). Feasibility outcomes including satisfaction, barriers to treatment participation, safety, and dropout were assessed. Independent evaluators, blind to treatment condition, administered the Anxiety Disorders Interview Schedule for Children (ADIS) and the Clinical Global Impression of Improvement (CGI-I) at baseline, post-treatment and 3-month follow-up; clinical self-report questionnaires were also administered. Findings revealed high satisfaction, low endorsement of barriers, low drop out rates, and no adverse events across the two modalities. According to the CGI-I, 58.3%-75% of participants were considered responders (i.e., much or very much improved) at the various time points. Similar patterns were found for remission from "primary anxiety disorder" and "all anxiety disorders" as defined by the ADIS. Clinically significant improvement was seen on the various parent and child self-report measures of anxiety. Findings suggest that both therapy modalities are feasible and associated with significant treatment gains in the primary care setting. (clinicaltrials.gov unique identifier: NCT00769925).
Keiderling, Michael C.; Kojima, Harry
2009-03-01
We have extended our studies on the non-classical behavior of solid ^4He contained in compound torsional oscillator (TO) cell below 1 K. Our unique TO design allows observations on the identical sample at two distinct frequencies(f1=493 and f2=1165 Hz). The sample was grown by blocked capillary method in an annular cell(id = 8.0 mm, od = 10.0 mm, height = 9.0 mm). We focus here on experiments in which the two modes are excited simultaneously. While keeping the drive of f2 mode at a very low level, the drive of f1 mode was varied from high to low levels to produce substantial variations in the non-classical rotation inertia fraction (NCRIf). When the NCRIf seen by f1 mode is reduced by 89, 91 and 94 % at 9.7, 23.5 and 56.5 mK, respectively, the NCRIf seen by f2 mode (driven at low level) is reduced by 62, 68 and 80 %. The discrepancies and their temperature dependence in the observed reductions in NCRIf are not yet understood. Similar Measurements with the roles of the drive levels of the modes reversed as well as the changes in the dissipation of the torsional oscillator during the simultaneous drive will be reported.
Postprandial lipoprotein profile in two modes of high-intensity intermittent exercise
Panissa, Valéria Leme Gonçalves; Julio, Ursula Ferreira; Diniz, Tiego Aparecido; de Moura Mello Antunes, Barbara; Lira, Fabio Santos; Takito, Monica Yuri; Franchini, Emerson
2016-01-01
The aim of present study was to compare blood lipid postprandial profile response in two modes of high-intensity intermittent exercise. Twelve individuals (6 men and 6 women) were submitted to a maximal incremental test (to determine maximal aerobic power [MAP] and V. O2peak [peak oxygen uptake]), high-intensity intermittent all-out exercise (60×8-sec bouts interspersed by 12-sec passive recovery) and fixed high-intensity intermittent exercise (100% maximal aerobic speed, consisted of 1-min repetitions at MAP [70 rpm] separated by 1-min of passive recovery). Blood samples were collected pre, immediately, 45 and 90-min postexercise. Serum was analyzed for total cholesterol and its ratio, high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), very low-density lipoprotein (VLDL) cholesterol, and triacylglycerol (TAG). For TAG there was a main effect of moment with higher values immediately postexercise compared to 45-min postexercise. For VLDL there was a main effect to moment with higher values immediately post exercise than pre and 45-min postexercise; higher values 90-min postexercise than 45-min postexercise. There was no effect for HDL-c, LDL-c, and cholesterol. For area under the curve there was no difference for any variable. Our results indicated that both kinds of acute exercise session lead to no improvement in the acute response of serum lipid profile of healthy young. PMID:27807528
Chen, Tsun-Hsu; Wang, Hsin-Hu; Hsu, Yu-Hsiang; Lee, Chih-Kung
2016-03-01
In comparison to more developed optical method for microparticle manipulation like optical tweezers, an optopiezoelectric actuating system could provide force output that is several orders higher. Taking advantages of photoconductive materials, the concept of integrating a virtual electrode in a distributed opto-piezoelectric actuators was developed for real-time in-situ spatial tailoring for vast varieties of applications in biochips, smart structures, etc. In this study, photoconductive material titanium oxide phthalocyanine (TiOPc) was used as the active ingredient to enable the virtual electrode in an opto-piezoelectric material based distributed actuator. By illuminating light of proper wavelength and enough intensity onto TiOPc photoconductive material, the effective impedance of the illuminated portion of TiOPc could drop significantly. The contributions of using additives in the TiOPc photoconductive electrode to adjust the electrical properties was investigated for optimization. Further, the two-mode excited linear ultrasonic motor was also studied and the feasibility to integrate the TiOPc photoconductive electrode was discussed. The flexibility provided by this newly developed system could potential deliver versatile performance in biochip applications.
Two modes of release shape the postsynaptic response at the inner hair cell ribbon synapse.
Grant, Lisa; Yi, Eunyoung; Glowatzki, Elisabeth
2010-03-24
Cochlear inner hair cells (IHCs) convert sounds into receptor potentials and via their ribbon synapses into firing rates in auditory nerve fibers. Multivesicular release at individual IHC ribbon synapses activates AMPA-mediated EPSCs with widely ranging amplitudes. The underlying mechanisms and specific role for multivesicular release in encoding sound are not well understood. Here we characterize the waveforms of individual EPSCs recorded from afferent boutons contacting IHCs and compare their characteristics in immature rats (postnatal days 8-11) and hearing rats (postnatal days 19-21). Two types of EPSC waveforms were found in every recording: monophasic EPSCs, with sharp rising phases and monoexponential decays, and multiphasic EPSCs, exhibiting inflections on rising and decaying phases. Multiphasic EPSCs exhibited slower rise times and smaller amplitudes than monophasic EPSCs. Both types of EPSCs had comparable charge transfers, suggesting that they were activated by the release of similar numbers of vesicles, which for multiphasic EPSCs occurred in a less coordinated manner. On average, a higher proportion of larger, monophasic EPSCs was found in hearing compared to immature rats. In addition, EPSCs became significantly faster with age. The developmental increase in size and speed could improve auditory signaling acuity. Multiphasic EPSCs persisted in hearing animals, in some fibers constituting half of the EPSCs. The proportion of monophasic versus multiphasic EPSCs varied widely across fibers, resulting in marked heterogeneity of amplitude distributions. We propose that the relative contribution of two modes of multivesicular release, generating monophasic and multiphasic EPSCs, may underlie fundamental characteristics of auditory nerve fibers.
Schemes for Probabilistic Teleportation of an Unknown Three-Particle Three-Level Entangled State
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
In this paper, two schemes for teleporting an unknown three-particle three-level entangled state are proposed. In the first scheme, two partial three-particle three-level entangled states are used as the quantum channels, while in the second scheme, three two-particle three-level non-maximally entangled states are employed as quantum channels.It is shown that the teleportation can be successfully realized with certain probability, for both two schemes, if a receiver adopts some appropriate unitary transformations. It is shown also that the successful probabilities of these two schemes are different.
Two modes of cell death caused by exposure to nanosecond pulsed electric field.
Directory of Open Access Journals (Sweden)
Olga N Pakhomova
Full Text Available High-amplitude electric pulses of nanosecond duration, also known as nanosecond pulsed electric field (nsPEF, are a novel modality with promising applications for cell stimulation and tissue ablation. However, key mechanisms responsible for the cytotoxicity of nsPEF have not been established. We show that the principal cause of cell death induced by 60- or 300-ns pulses in U937 cells is the loss of the plasma membrane integrity ("nanoelectroporation", leading to water uptake, cell swelling, and eventual membrane rupture. Most of this early necrotic death occurs within 1-2 hr after nsPEF exposure. The uptake of water is driven by the presence of pore-impermeable solutes inside the cell, and can be counterbalanced by the presence of a pore-impermeable solute such as sucrose in the medium. Sucrose blocks swelling and prevents the early necrotic death; however the long-term cell survival (24 and 48 hr does not significantly change. Cells protected with sucrose demonstrate higher incidence of the delayed death (6-24 hr post nsPEF. These cells are more often positive for the uptake of an early apoptotic marker dye YO-PRO-1 while remaining impermeable to propidium iodide. Instead of swelling, these cells often develop apoptotic fragmentation of the cytoplasm. Caspase 3/7 activity increases already in 1 hr after nsPEF and poly-ADP ribose polymerase (PARP cleavage is detected in 2 hr. Staurosporin-treated positive control cells develop these apoptotic signs only in 3 and 4 hr, respectively. We conclude that nsPEF exposure triggers both necrotic and apoptotic pathways. The early necrotic death prevails under standard cell culture conditions, but cells rescued from the necrosis nonetheless die later on by apoptosis. The balance between the two modes of cell death can be controlled by enabling or blocking cell swelling.
Two modes of cell death caused by exposure to nanosecond pulsed electric field.
Pakhomova, Olga N; Gregory, Betsy W; Semenov, Iurii; Pakhomov, Andrei G
2013-01-01
High-amplitude electric pulses of nanosecond duration, also known as nanosecond pulsed electric field (nsPEF), are a novel modality with promising applications for cell stimulation and tissue ablation. However, key mechanisms responsible for the cytotoxicity of nsPEF have not been established. We show that the principal cause of cell death induced by 60- or 300-ns pulses in U937 cells is the loss of the plasma membrane integrity ("nanoelectroporation"), leading to water uptake, cell swelling, and eventual membrane rupture. Most of this early necrotic death occurs within 1-2 hr after nsPEF exposure. The uptake of water is driven by the presence of pore-impermeable solutes inside the cell, and can be counterbalanced by the presence of a pore-impermeable solute such as sucrose in the medium. Sucrose blocks swelling and prevents the early necrotic death; however the long-term cell survival (24 and 48 hr) does not significantly change. Cells protected with sucrose demonstrate higher incidence of the delayed death (6-24 hr post nsPEF). These cells are more often positive for the uptake of an early apoptotic marker dye YO-PRO-1 while remaining impermeable to propidium iodide. Instead of swelling, these cells often develop apoptotic fragmentation of the cytoplasm. Caspase 3/7 activity increases already in 1 hr after nsPEF and poly-ADP ribose polymerase (PARP) cleavage is detected in 2 hr. Staurosporin-treated positive control cells develop these apoptotic signs only in 3 and 4 hr, respectively. We conclude that nsPEF exposure triggers both necrotic and apoptotic pathways. The early necrotic death prevails under standard cell culture conditions, but cells rescued from the necrosis nonetheless die later on by apoptosis. The balance between the two modes of cell death can be controlled by enabling or blocking cell swelling.
Teacher argumentation in the secondary science classroom: Images of two modes of scientific inquiry
Gray, Ron E.
The purpose of this exploratory study was to examine scientific arguments constructed by secondary science teachers during instruction. The analysis focused on how arguments constructed by teachers differed based on the mode of inquiry underlying the topic. Specifically, how did the structure and content of arguments differ between experimentally and historically based topics? In addition, what factors mediate these differences? Four highly experienced high school science teachers were observed daily during instructional units for both experimental and historical science topics. Data sources include classroom observations, field notes, reflective memos, classroom artifacts, a nature of science survey, and teacher interviews. The arguments were analyzed for structure and content using Toulmin's argumentation pattern and Walton's schemes for presumptive reasoning revealing specific patterns of use between the two modes of inquiry. Interview data was analyzed to determine possible factors mediating these patterns. The results of this study reveal that highly experienced teachers present arguments to their students that, while simple in structure, reveal authentic images of science based on experimental and historical modes of inquiry. Structural analysis of the data revealed a common trend toward a greater amount of scientific data used to evidence knowledge claims in the historical science units. The presumptive reasoning analysis revealed that, while some presumptive reasoning schemes remained stable across the two units (e.g. 'causal inferences' and 'sign' schemes), others revealed different patterns of use including the 'analogy', 'evidence to hypothesis', 'example', and 'expert opinion' schemes. Finally, examination of the interview and survey data revealed five specific factors mediating the arguments constructed by the teachers: view of the nature of science, nature of the topic, teacher personal factors, view of students, and pedagogical decisions. These
Li, Xi-Zeng; Su, Bao-Xia
1994-01-01
It is found that two-mode output quantum electromagnetic field in two-mode squeezed states exhibits higher-order squeezing to all even orders. And the generalized uncertainty relations are also presented for the first time. The concept of higher-order squeezing of the single-mode quantum electromagnetic field was first introduced and applied to several processes by Hong and Mandel in 1985. Lately Li Xizeng and Shan Ying have calculated the higher-order squeezing in the process of degenerate four-wave mixing and presented the higher-order uncertainty relations of the fields in single-mode squeezed states. In this paper we generalize the above work to the higher-order squeezing in two-mode squeezed states. The generalized uncertainty relations are also presented for the first time.
Performance Evaluation of Three-Level Z-Source Inverters Under Semiconductor-Failure Conditions
DEFF Research Database (Denmark)
Gao, Feng; Loh, Poh Chiang; Blaabjerg, Frede
2009-01-01
, the proposed methods for three-level Z-source inverters simply reconfigure their relevant gating signals so as to ride-through the failed semiconductor conditions smoothly without any significant decrease in their ac-output quality and amplitude. These features are partly attributed to the inherent boost...... characteristics of a Z-source inverter, in addition to its usual voltage-buck operation. By focusing on specific types of three-level Z-source inverters, it can also be shown that, for the dual Z-source inverters, a unique feature accompanying it is its extra ability to force common-mode voltage to zero even......This paper evaluates and proposes various compensation methods for three-level Z-source inverters under semiconductor-failure conditions. Unlike the fault-tolerant techniques used in traditional three-level inverters, where either an extra phase-leg or collective switching states are used...
Common voltage eliminating of SVM diode clamping three-level inverter connected to grid
DEFF Research Database (Denmark)
Guo, Yougui; Zeng, Ping; Zhu, Jieqiong
2011-01-01
A novel method of common voltage eliminating is put forward for SVM diode clamping three-level inverter connected to grid by calculation of common voltage of its various switching states. PLECS is used to model this three-level inverter connected to grid and good results are obtained. First...... analysis of common mode voltage for switching states of diode clamping 3-level inverter is given in detail. Second the common mode voltage eliminating control strategy of SVM is described for diode clamping three-level inverter. Third, PLECS is briefly introduced. Fourth, the modeling of diode clamping...... three-level inverter is presented with PLECS. Finally, a series of simulations are carried out. The simulation results tell us PLECS is a very powerful tool to real power circuits modeling. They have also verified that proposed common mode voltage eliminating control strategy of SVM is feasible...
Reverse engineering of a Hamiltonian for a three-level system via the Rodrigues’ rotation formula
Kang, Yi-Hao; Huang, Bi-Hua; Lu, Pei-Min; Xia, Yan
2017-02-01
We propose a scheme to reversely construct a three-level Hamiltonian via the Rodrigues’ rotation formula and an auxiliary unitary transformation. The main goal of the scheme is designing feasible pulses to drive a three-level system to evolve rapidly from an arbitrary initial state to a desired final state. Numerical simulations demonstrate that the scheme is not only fast but also robust against the decoherence caused by fluctuations of control parameters and some dissipation factors. Besides, we apply the idea to implement a Hadamard gate in a three-level system, and the results show the present scheme is much faster compared with stimulated Raman adiabatic passage (STIRAP). Therefore, the scheme may be useful to find out an effective shortcut to the adiabatic passage in a three-level system.
Three-Level Z-Source Inverters Using a Single LC Impedance Network
DEFF Research Database (Denmark)
Loh, Poh Chiang; Lim, Sok Wei; Gao, Feng
2007-01-01
Three-level Z-source inverters are recent single-stage topological solutions proposed for buck-boost energy conversion with all favorable advantages of three-level switching retained. Despite their effectiveness in achieving voltage buck-boost conversion, existing three-level Z-source inverters use...... three-level Z-source inverters, whose output voltage can be stepped down or up using only a single LC impedance network connected between the dc input source and either a neutral-point-clamped (NPC) or dc-link cascaded inverter circuitry. Through careful design of their modulation scheme, both inverters...... can conveniently be implemented using a generic "alternative phase opposition disposition" carrier-based modulator with the appropriate triplen offset and time advance/delay added. The designed inverters, having a reduced passive component count, are lastly tested in simulation and experimentally...
Two-Mode Multiplexing at 2×10.7 Gbps over 7-Cell Hollow- Core Photonic Band Gap Fiber
DEFF Research Database (Denmark)
Xu, Jing; Peucheret, Christophe
2011-01-01
We demonstrate two-mode multiplexing at 2×10.7 Gbps over 7-cell hollow-core photonic band gap fiber. BER performances below FEC threshold limit (3.3×10-3) are shown for both data channels.......We demonstrate two-mode multiplexing at 2×10.7 Gbps over 7-cell hollow-core photonic band gap fiber. BER performances below FEC threshold limit (3.3×10-3) are shown for both data channels....
Buica, Gabriela
2014-01-01
We investigate the dynamics of a pair of short laser pulse trains propagating in a medium consisting of three-level $\\Lambda$-type atoms by numerically solving the Maxwell-Schr\\"odinger equations for atoms and fields. By performing propagation calculations with different parameters, under conditions of electromagnetically induced transparency, we compare the propagation dynamics by a single pair of probe and coupling laser pulses and by probe and coupling laser pulse trains. We discuss the influence of the coupling pulse area, number of pulses, and detunings on the probe laser propagation and realization of electromagnetically induced transparency conditions, as well on the formation of a dark state.
A tale of two modes: neutrino free-streaming in the early universe
Lancaster, Lachlan; Cyr-Racine, Francis-Yan; Knox, Lloyd; Pan, Zhen
2017-07-01
We present updated constraints on the free-streaming nature of cosmological neutrinos from cosmic microwave background (CMB) temperature and polarization power spectra, baryonic acoustic oscillation data, and distance ladder measurements of the Hubble constant. Specifically, we consider a Fermi-like four-fermion interaction between massless neutrinos, characterized by an effective coupling constant Geff, and resulting in a neutrino opacity dot tauνpropto Geff2 Tν5. Using a conservative flat prior on the parameter log10( Geff MeV2), we find a bimodal posterior distribution with two clearly separated regions of high probability. The first of these modes is consistent with the standard ΛCDM cosmology and corresponds to neutrinos decoupling at redshift zν,dec > 1.3×105, that is before the Fourier modes probed by the CMB damping tail enter the causal horizon. The other mode of the posterior, dubbed the "interacting neutrino mode", corresponds to neutrino decoupling occurring within a narrow redshift window centered around zν,dec~8300. This mode is characterized by a high value of the effective neutrino coupling constant, log10( Geff MeV2) = -1.72 ± 0.10 (68% C.L.), together with a lower value of the scalar spectral index and amplitude of fluctuations, and a higher value of the Hubble parameter. Using both a maximum likelihood analysis and the ratio of the two mode's Bayesian evidence, we find the interacting neutrino mode to be statistically disfavored compared to the standard ΛCDM cosmology, and determine this result to be largely driven by the low-l CMB temperature data. Interestingly, the addition of CMB polarization and direct Hubble constant measurements significantly raises the statistical significance of this secondary mode, indicating that new physics in the neutrino sector could help explain the difference between local measurements of H0, and those inferred from CMB data. A robust consequence of our results is that neutrinos must be free streaming long
Hlubina, Petr
1999-12-01
Intermodal dispersion in a two-mode optical fiber can be measured in the spectral domain when the spectral interference between modes at the output of the optical fiber shows up as a periodic modulation of the source spectrum that can be processed. However, this technique cannot be used to measure intermodal dispersion in the two- mode optical fiber when the period of modulation is too small to be resolved by a spectrometer. Consequently, we proposed a new measuring technique utilizing a tandem configuration of a dispersive Michelson interferometer and the two-mode optical fiber in which the spectral interference can be resolved even if a low-resolution spectrometer is used. In the tandem configuration of the Michelson interferometer and the two-mode optical fiber, the optical path difference (OPD) in the Michelson interferometer is adjusted close to the group OPD between modes of the optical fiber so that the low-frequency spectral modulation that can be processed is produced. Using the Fourier transform method in processing the measured spectral modulations and subtracting the effect of the dispersive Michelson interferometer, the feasibility of this technique has successfully been demonstrated in obtaining the intermodal dispersion in the two-model optical fiber.
Exact Solution of the Milburn Equation for the Two-Mode Two-Photon Jaynes-Cummings Model
Institute of Scientific and Technical Information of China (English)
ZOU Xu-Bo; YU Ji-Hua; XU Jing-Bo
2001-01-01
We adopt an algebraic method to study the two-mode two-photon Jaynes Cummings model governed by the Milburn equation and find an exact solution of Milburn equation of the system. The influence of the intrinsic decoherence on the nonclassical effects of the system is also discussed.``
Modelling and Simulation of Three Level Inverters for Main Drive of the Plate Mill Rolling Stand
Directory of Open Access Journals (Sweden)
Gasiyarov Vadim R.
2016-01-01
Full Text Available This paper addresses a modelling and a simulation of three level inverters for main drive of the plate mill rolling stand. The main purpose of the article is to develop of a mathematical description of the three level voltage source inverter based on a space vector pulse width modulation and to simulate a consumption current by the main electric drive based on 18-pulse rectification circuit. A twelve-megawatt synchronous motor as a load has been used. The modelling results were simulated at the Matlab/Simulink program. It can allow us to estimate an electromagnetic compatibility of the main electric drive based on transients of the consumption current. The research results can be used to assess the electromagnetic compatibility of powerful three level natural point clamped converters with different types of the space vector pulse width modulation on a load or a grid.
Modulation Schemes of Multi-phase Three-Level Z-Source Inverters
DEFF Research Database (Denmark)
Gao, F.; Loh, P.C.; Blaabjerg, Frede;
2007-01-01
This paper investigates the modulation schemes of three-level multiphase Z-source inverters with either two Z-source networks or single Z-source network connected between the dc sources and inverter circuitry. With the proper offset added for achieving both desired four-leg operation and optimized...... harmonic performance, the proposed modulation schemes of four-leg three-level Z-source inverters can satisfy the expected buck-boost operation under unbalanced modulation conditions. Except of the modulation complexity hidden in the four-leg inverters, five-phase three-level Z-source inverters show totally...... different modulation requirement and output performance. For clearly illustrating the detailed modulation process, time domain analysis instead of the traditional multi-dimensional space vector demonstration is assumed which reveals the right way to insert shoot-through durations in the switching sequence...
Grid Integration of Single Stage Solar PV System using Three-level Voltage Source Converter
Hussain, Ikhlaq; Kandpal, Maulik; Singh, Bhim
2016-08-01
This paper presents a single stage solar PV (photovoltaic) grid integrated power generating system using a three level voltage source converter (VSC) operating at low switching frequency of 900 Hz with robust synchronizing phase locked loop (RS-PLL) based control algorithm. To track the maximum power from solar PV array, an incremental conductance algorithm is used and this maximum power is fed to the grid via three-level VSC. The use of single stage system with three level VSC offers the advantage of low switching losses and the operation at high voltages and high power which results in enhancement of power quality in the proposed system. Simulated results validate the design and control algorithm under steady state and dynamic conditions.
Energy Technology Data Exchange (ETDEWEB)
Tesfa, Sintayehu, E-mail: sint_tesfa@yahoo.co [Department of Physics, Dilla University, PO Box 419, Dilla (Ethiopia)
2009-11-14
A detailed comparison among the exhibited nature of entanglement of the cavity radiation of the nondegenerate three-level cascade laser when different inseparability criteria are employed is presented. Although the achievable degree of entanglement is generally found to vary with the applied inseparability criteria, there are cases for which more than two of the applied criteria lead to a significant degree of entanglement for certain parameters. Particularly, the procedures following from the criterion of Duan-Geidke-Cirac-Zoller and logarithmic negativity predict a similar pattern of entanglement except when the atoms are initially prepared in a maximum atomic coherent superposition. In the same manner, in relation to the absence of interatomic interaction, the Hillery-Zubairy and Cauchy-Schwarz inequalities virtually lead to a similar degree of entanglement. Since an appreciably large degree of entanglement is shown to be realizable using various criteria, there is no doubt that this quantum system can be utilized as a viable source of entangled light.
A Comparative analysis of three level VSC based multi-pulse STATCOM
Directory of Open Access Journals (Sweden)
Smruti Ranjan Barik
2014-07-01
Full Text Available This paper presents a comparative analysis among different models of three level NPC (Neutral point clamped VSC (Voltage source converter based STATCOMs. Here separate models of 12- pulse, 24-pulse, 36-pulse, 48-pulse VSC based STATCOMs are configured in MATLAB environment. These individual models are synthesized using appropriate number of three level converters which are switched at fundamental frequency and their gate pulse pattern are properly phase shifted to get desired number of pulses. The simulation results of each individual model are analyzed in three different modes: inductive, capacitive and floating mode. Harmonic content of the proposed higher pulse models are limited as per IEEE 519 standards.
Performance Evaluation of Three-Level Z-Source Inverters Under Semiconductor Failure Conditions
DEFF Research Database (Denmark)
Gao, Feng; Loh, P.C.; Vilathgamuwa, D.M.
2007-01-01
reconfigure the gating signals in order to tolerate the failed semiconductor devices without significantly decreasing the ac output quality and amplitude by properly using the inherent boost characteristic of Z-source network. In addition, the Z-source dual inverters can maintain the zero common mode voltage......This paper proposes various compensation methods for three-level Z-source inverters under semiconductor failure conditions. Unlike the traditional fault tolerant techniques in three-level inverter by using either an additional phase-leg or collective switching states, the proposed methods simply...
A Component-Reduced Zero-Voltage Switching Three-Level DC-DC Converter
DEFF Research Database (Denmark)
Qin, Zian; Pang, Ying; Wang, Huai;
2016-01-01
The basic Zero-Voltage Switching (ZVS) three-level DC-DC converter has one clamping capacitor to realize the ZVS of the switches, and two clamping diodes to clamp the voltage of the clamping capacitor. In order to reduce the reverse recovery loss of the diode as well as its cost, this paper...... proposes to remove one of the clamping diodes in basic ZVS three-level DC-DC converter. With less components, the proposed converter can still have a stable clamping capacitor voltage, which is clamped at half of the dc link voltage. Moreover, the ZVS performance will be influenced by removing the clamping...
A linear atomic quantum coupler
Energy Technology Data Exchange (ETDEWEB)
El-Orany, Faisal A A [Department of Mathematics and computer Science, Faculty of Science, Suez Canal University 41522, Ismailia (Egypt); Wahiddin, M R B, E-mail: el_orany@hotmail.co, E-mail: faisal.orany@mimos.m, E-mail: mridza@mimos.m [Cyberspace Security Laboratory, MIMOS Berhad, Technology Park Malaysia, 57000 Kuala Lumpur (Malaysia)
2010-04-28
In this paper we develop the notion of the linear atomic quantum coupler. This device consists of two modes propagating into two waveguides, each of which includes a localized atom. These waveguides are placed close enough to allow exchange of energy between them via evanescent waves. Each mode interacts with the atom in the same waveguide in the standard way as the Jaynes-Cummings model (JCM) and with the atom-mode system in the second waveguide via the evanescent wave. We present the Hamiltonian for this system and deduce its wavefunction. We investigate the atomic inversions and the second-order correlation function. In contrast to the conventional coupler the atomic quantum coupler is able to generate nonclassical effects. The atomic inversions can exhibit a long revival-collapse phenomenon as well as subsidiary revivals based on the competition among the switching mechanisms in the system. Finally, under certain conditions the system can yield the results of the two-mode JCM.
El-Orany, Faisal A A
2009-01-01
In this paper, we develop the notion of the linear atomic quantum coupler. This device consists of two modes propagating into two waveguides, each of them includes a localized and/or a trapped atom. These waveguides are placed close enough to allow exchanging energy between them via evanescent waves. Each mode interacts with the atom in the same waveguide in the standard way, i.e. as the Jaynes-Cummings model (JCM), and with the atom-mode in the second waveguide via evanescent wave. We present the Hamiltonian for the system and deduce the exact form for the wavefunction. We investigate the atomic inversions and the second-order correlation function. In contrast to the conventional linear coupler, the atomic quantum coupler is able to generate nonclassical effects. The atomic inversions can exhibit long revival-collapse phenomenon as well as subsidiary revivals based on the competition among the switching mechanisms in the system. Finally, under certain conditions, the system can yield the results of the two-m...
Topological Design and Modulation Strategy for Buck-Boost Three-Level Inverters
DEFF Research Database (Denmark)
Teodorescu, Remus; Gao, F.; Blaabjerg, Frede;
2007-01-01
To date, designed topologies for dc-ac inversion with both voltage-buck and boost capabilities are mainly focused on two-level circuitries with extensions to three-level possibilities left nearly unexplored. Contributing to this area of research, this paper presents the design of a number of viable...
Design and comparison of three-level three-phase T-source inverters
DEFF Research Database (Denmark)
Shults, T.; Husev, Oleksandr; Blaabjerg, Frede
2015-01-01
This paper presents guidelines for component design of recently proposed topologies of the three-level three-phase T-source inverters. Two different topologies are considered: T-source inverters with discontinuous input current and T-source inverters with continuous input current. Steady state...
Topological Design and Modulation Strategy for Buck-Boost Three-Level Inverters
DEFF Research Database (Denmark)
Gao, Feng; Loh, Poh Chiang; Teodorescu, Remus
2009-01-01
can perform distinct five-level line voltage and three-level phase voltage switching by simply controlling the active switches located in the designed voltage boost section of the circuits. As a cost saving option, one active switch can further be removed from the voltage boost section of the circuits...
Kramers-Kronig relation in a Doppler-broadenedΛ-type three-level system
Institute of Scientific and Technical Information of China (English)
王梦; 庞兆广; 王如泉; 左战春; 芦小刚; 白金海; 裴丽娅; 缪兴绪; 高艳磊; 吴令安; 傅盘铭; 杨世平
2015-01-01
We measure the absorption and dispersion in a Doppler-broadenedΛ-type three level system by resonant stimulated Raman spectroscopy with homodyne detection. Through studying the dressed state energies of the system, it is found that the absorption and dispersion satisfy the Kramers–Kronig relation. The absorption and dispersion spectra calculated by employing this relation agree well with our experimental observations.
Integrated Differential Three-Level High-Voltage Pulser Output Stage for CMUTs
DEFF Research Database (Denmark)
Llimos Muntal, Pere; Larsen, Dennis Øland; Jørgensen, Ivan Harald Holger;
2015-01-01
A new integrated differential three-level highvoltage pulser output stage to drive capacitive micromachined ultrasonic transducers (CMUTs) is proposed in this paper. A topology comparison between the new differential output stage and the most commonly used single-ended topology is performed...
Neutral-point voltage dynamic model of three-level NPC inverter for reactive load
DEFF Research Database (Denmark)
Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, Sergio
2012-01-01
A three-level neutral-point-clamped inverter needs a controller for the neutral-point voltage. Typically, the controller design is based on a dynamic model. The dynamic model of the neutral-point voltage depends on the pulse width modulation technique used for the inverter. A pulse width modulati...
Simulation of a Diode Pumped Alkali Laser; a Three Level Numerical Approach
2010-03-01
further iteration of the three level numerical model should include this effect as it is a persistent issue for DPAL systems and without its effects a...1 26.24 * 10-9 H*Lewis Hz*L; A32@85D = 0; A32@87D = 0; III. Parameters Printed by Mathematica for Students 65 III. Parameters A. Enviromental
Carrier-based modulation schemes for various three-level matrix converters
DEFF Research Database (Denmark)
Blaabjerg, Frede; Loh, P.C.; Rong, R.C.;
2008-01-01
Matrix converters with three-level phase switching and five-level line switching characteristics have recently been proposed as improved ldquoall semiconductorrdquo ac-ac power processors. For their control, different modulation schemes have also been developed with different researchers claiming...... be implemented on a single common hardware platform....
Enhanced Buck-Boost Three-Level Neutral-Point-Clamped Inverters
DEFF Research Database (Denmark)
Tan, K. K.; Gao, F.; Chiang Loh, Poh
2009-01-01
In traditional three-level neutral-point-clamped (NPC) inverters, a major issue is capacitor voltage imbalance, which results in low order harmonics. The compensation of the capacitor voltages often require additional control complexity, which cannot be conveniently implemented. The "alternative ...
Three-level systems as amplifiers and attenuators: a thermodynamic analysis.
Boukobza, E; Tannor, D J
2007-06-15
Thermodynamics of a three-level maser was studied in the pioneering work of Scovil-Schulz-DuBois [Phys. Rev. Lett. 2, 262 (1959)10.1103/PhysRevLett.2.262]. In this Letter we consider the same three-level model, but we give a full thermodynamic analysis based on Hamiltonian and dissipative Lindblad superoperators. The first law of thermodynamics is obtained using a recently developed alternative [Phys. Rev. A 74, 063823 (2006)10.1103/PhysRevA.74.063823] to Alicki's definitions for heat flux and power [J. Phys. A 12, L103 (1979)10.1088/0305-4470/12/5/007]. Using a novel variation on Spohn's entropy production function [J. Math. Phys. (N.Y.) 19, 1227 (1978)10.1063/1.523789], we obtain Carnot's efficiency inequality and the Scovil-Schulz-DuBois maser efficiency formula when the three-level system is operated as a heat engine (amplifier). Finally, we show that the three-level system has two other modes of operation--a refrigerator mode and a squanderer mode--both of which attenuate the electric field.
Intensity correlations and anticorrelations in a three-level cascade system
Indian Academy of Sciences (India)
SHAIK AHMED; PREETHI N WASNIK; SUNEEL SINGH; P ANANTHA LAKSHMI
2016-12-01
We study the intensity–intensity correlations of the radiation emitted on probe transition in a three level cascade electromagnetically-induced transparency (EIT) scheme. Further, we show that by applying even a very weak incoherent pump, the nature of the emitted radiation can be switched from classical to non-classicalwithout significantly affecting the probe transparency
蔵谷, 樹; 高須, 晃; カビール, エムデイ ファズレー
2015-01-01
Garnet epidote amphibolite from the central part of the Tonaru metagabbro mass consists mainly of garnet, epidote and amphibole (ferro-hornblende), with small amounts of quartz, plagioclase (albite and oligoclase) and paragonite. Rutile, apatite, hematite, calcite and chlorite occur occasionally. Garnets in the garnet epidote amphibolites exhibit two modes of occurrence. Garnet 1 (Grt 1) occurs as porphyroblast, and garnet 2 (Grt 2) is found as fine grain in the matrix. Porphyroblastic garnet...
Armstrong, Cameron R; David, John A; Thompson, John R
2015-07-13
We present a simple numerical model that is used in conjunction with a systematic algorithm for parameter optimization to understand the three-dimensional stochastic intensity dynamics of stimulated Brillouin scattering in a two-mode optical fiber. The primary factors driving the complex dynamics appear to be thermal density fluctuations, transverse pump fluctuations, and asymmetric transverse mode fractions over the beam cross-section.
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.
DEFF Research Database (Denmark)
Chiang Loh, Poh; Gao, Feng; Blaabjerg, Frede
2009-01-01
Three-level Z-source inverters are recent single-stage topological solutions proposed for buck-boost energy conversion with all favorable advantages of three-level switching retained. Despite their proven buck-boost capability, existing three-level Zsource inverters are either too costly...
Testing strong factorial invariance using three-level structural equation modeling
Directory of Open Access Journals (Sweden)
Suzanne eJak
2014-07-01
Full Text Available Within structural equation modeling, the most prevalent model to investigate measurement bias is the multigroup model. Equal factor loadings and intercepts across groups in a multigroup model represent strong factorial invariance (absence of measurement bias across groups. Although this approach is possible in principle, it is hardly practical when the number of groups is large or when the group size is relatively small. Jak, Oort and Dolan (2013 showed how strong factorial invariance across large numbers of groups can be tested in a multilevel structural equation modeling framework, by treating group as a random instead of a fixed variable. In the present study, this model is extended for use with three-level data. The proposed method is illustrated with an investigation of strong factorial invariance across 156 school classes and 50 schools in a Dutch dyscalculia test, using three-level structural equation modeling.
Three-Level Z-Source Inverters Using a Single LC Impedance Network
DEFF Research Database (Denmark)
Loh, Poh Chiang; Lim, Sok Wei; Gao, Feng
2007-01-01
two LC impedance networks and two isolated dc sources, which can significantly increase the overall system cost and require a more complex modulator for balancing the network inductive voltage boosting. Offering a number of less costly alternatives, this letter presents the design and control of two...... three-level Z-source inverters, whose output voltage can be stepped down or up using only a single LC impedance network connected between the dc input source and either a neutral-point-clamped (NPC) or dc-link cascaded inverter circuitry. Through careful design of their modulation scheme, both inverters...... can function with the minimum of six device commutations per half carrier cycle (similar to that needed by a traditional buck three-level NPC inverter), while producing the correct volt-sec average and inductive voltage boosting at their ac output terminals. Physically, the designed modulation scheme...
Three-Level AC-DC-AC Z-Source Converter Using Reduced Passive Component Count
DEFF Research Database (Denmark)
Loh, Poh Chiang; Gao, Feng; Tan, Pee-Chin;
2007-01-01
This paper presents a three-level ac-dc-ac Z-source converter with output voltage buck-boost capability. The converter is implemented by connecting a low cost front-end diode rectifier to a neutral-point-clamped inverter through a single X-shaped LC impedance network. The inverter is controlled...... to switch with a three-level output voltage, where the middle neutral potential is uniquely tapped from the star-point of a wye-connected capacitive filter placed before the front-end diode rectifier for input current filtering. Through careful control, the resulting converter can accurately produce...... the correct volt-sec average at its output, while simultaneously achieving inductive voltage boosting. More interestingly, these performance features are achieved with no increase in the number of semiconductor commutations, and hence no increase in switching losses. The proposed converter therefore offers...
Why do we need three levels to understand the molecular optical response?
Perez-Moreno, Javier; Clays, Koen; Kuzyk, Mark G.
2011-10-01
Traditionally, the nonlinear optical response at the molecular level has been modeled using the two-level approximation, under the assumption that the behavior of the exact sum-over-states (SOS) expressions for the molecular polarizabilities is well represented by the contribution of only two levels. We show how, a rigorous application of the Thomas-Kuhn sum-rules over the SOS expression for the diagonal component of the first-hyperpolarziability proves that the two-level approximation is unphysical. In addition, we indicate how the contributions of potentially infinite number of states to the SOS expressions for the first-hyperpolarizability are well represented by the contributions of a generic three-level system. This explains why the analysis of the three-level model in conjugation with the sum rules has lead to successful paradigms for the optimization of organic chromophores.
Testing strong factorial invariance using three-level structural equation modeling.
Jak, Suzanne
2014-01-01
Within structural equation modeling, the most prevalent model to investigate measurement bias is the multigroup model. Equal factor loadings and intercepts across groups in a multigroup model represent strong factorial invariance (absence of measurement bias) across groups. Although this approach is possible in principle, it is hardly practical when the number of groups is large or when the group size is relatively small. Jak et al. (2013) showed how strong factorial invariance across large numbers of groups can be tested in a multilevel structural equation modeling framework, by treating group as a random instead of a fixed variable. In the present study, this model is extended for use with three-level data. The proposed method is illustrated with an investigation of strong factorial invariance across 156 school classes and 50 schools in a Dutch dyscalculia test, using three-level structural equation modeling.
A three-level framework for performance-based railway timetabling
DEFF Research Database (Denmark)
Goverde, Rob M P; Bešinović, Nikola; Binder, Anne
2016-01-01
The performance of railway operations depends highly on the quality of the railway timetable. In particular for dense railway networks it can be challenging to obtain a stable robust conflict-free and energy-efficient timetable with acceptable infrastructure occupation and short journey times....... This paper presents a performance-based railway timetabling framework integrating timetable construction and evaluation on three levels: microscopic, macroscopic, and a corridor fine-tuning level, where each performance indicator is optimized or evaluated at the appropriate level. A modular implementation...... of the three-level framework is presented and demonstrated on a case study on the Dutch railway network illustrating the feasibility of this approach to achieve the highest timetabling design level....
Control and design of full-bridge three-level converter for renewable energy sources
DEFF Research Database (Denmark)
Yao, Zhilei; Xu, Jing; Guerrero, Josep M.
2015-01-01
Output voltage of renewable energy sources, such as fuel cell and PV cell, is often low and varies widely with load and environmental conditions. Therefore, the high step-up DC-DC converter is needed between renewable energy sources and the grid-connected inverter. However, voltage stress...... of rectifier diodes is high and filter is large in traditional voltage-source converters in a wide input-voltage range. In order to solve the aforementioned problems, a full-bridge (FB) three-level (TL) converter is proposed. It can operate at both two-level and three-level modes, so it is suitable for wide...... input-voltage range application. Compared with FB converter, voltage stress of rectifier diodes and the filter can be reduced. Operating principle and control strategy of the proposed converter are illustrated. Design guidelines and example are given. Simulation results of a 1-kW FB TL converter verify...
Institute of Scientific and Technical Information of China (English)
无
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.
A study of electron transfer using a three-level system coupled to an ohmic bath
Takasu, Masako; Chandler, David
1993-01-01
Electron transfer is studied using a multi-level system coupled to a bosonic bath. Two body correlation functions are obtained using both exact enumeration of spin paths and Monte Carlo simulation. It was found that the phase boundary for the coherent-incoherent transition lies at a smaller friction in the asymmetric two-level model than in the symmetric two-level model. A similar coherent-incoherent transition is observed for three-level system.
Nonlinear Theory of Light Speed Reduction in a Three-Level A System
Institute of Scientific and Technical Information of China (English)
王德重; 李代军; 刘夏姬; 李师群; 王育竹
2001-01-01
We present a nonlinear theory of light velocity reduction in a three-level A system based on electromagneticllyinduced transparency. Analysis shows that the probe field propagates with a velocity that is quite strongly dependent on its intensity instead of being merely approximately dependent on the coupling intensity. Moreover,the minimum group velocity of the probe field is analytically given for a given input power.
Chi, Liping
2013-04-01
Although the intergenerational transmission of educational attainment has been confirmed by many researchers, its mechanism still remains controversial. Parent-child communication has been regarded as one of the important mediators. The present study primarily aimed to examine the potentially mediating role of parent-child communication in the transmission of educational attainment, based on a sample of 366 Chinese fifth and sixth graders. Parent-child communication was measured against the three levels of the parents' communication ability, the quality of the father-child and mother-child communications, and the relation between the two dyadic communications. The results duplicated the positive effect of parents' educational attainment on children's academic achievement. Moreover, it was found that parents' communication ability alone played a mediating role, and that the three levels of parent-child communication constructed a "mediator chain" between the parents' educational attainment and the children's academic achievement. Finally, the intergenerational transmission of educational attainment in China and the mediating role of the three levels of parent-child communication were discussed. © 2012 The Institute of Psychology, Chinese Academy of Sciences and Blackwell Publishing Asia Pty Ltd.
Control of Grid Connected Photovoltaic System Using Three-Level T-Type Inverter
Zorig, Abdelmalik; Belkeiri, Mohammed; Barkat, Said; Rabhi, Abdelhamid
2016-08-01
Three-level T-Type inverter (3LT2I) topology has numerous advantageous compared to three-level neutral-point-clamped (NPC) inverter. The main benefits of 3LT2I inverter are the efficiency, inverter cost, switching losses, and the quality of output voltage waveforms. In this paper, a photovoltaic distributed generation system based on dual-stage topology of DC-DC boost converter and 3LT2I is introduced. To that end, a decoupling control strategy of 3LT2I is proposed to control the current injected into the grid, reactive power compensation, and DC-link voltage. The resulting system is able to extract the maximum power from photovoltaic generator, to achieve sinusoidal grid currents, and to ensure reactive power compensation. The voltage-balancing control of two split DC capacitors of the 3LT2I is achieved using three-level space vector modulation with balancing strategy based on the effective use of the redundant switching states of the inverter voltage vectors. The proposed system performance is investigated at different operating conditions.
Transmission Probability of an Ultracold Atom in the Presence of Atomic Coherence
Institute of Scientific and Technical Information of China (English)
熊锦; 储开芹; 张智明
2002-01-01
We investigate the transmission probability of an ultracold V-type three-level atom passing through a micromaser cavity, in the presence of atomic coherence which is established by a coherent driving field. We show that the transmissibility of this micromaser system with the atomic coherence is better than that of the ordinary micromaser system without atomic coherence. When the driving field is strong enough, for any cavity length the ultracold atom can pass through the micromaser cavity freely.
Snijders, Tom A. B.; Lomi, Alessandro; Torlo, Vanina Jasmine
2013-01-01
We propose a new stochastic actor-oriented model for the co-evolution of two-mode and one-mode networks. The model posits that activities of a set of actors, represented in the two-mode network, co-evolve with exchanges and interactions between the actors, as represented in the one-mode network. The
Institute of Scientific and Technical Information of China (English)
WU Ying; YANG Xiao-Xue
2002-01-01
We present the analytical solutions to the two-mode mean-field model for a split Bose Einstein condensate.These explicit solutions completely determine the system's dynamics under the two-mode mean-field approximation for all possible initial conditions.
A coordination theoretic model for three level supply chains using contracts
Indian Academy of Sciences (India)
Arshinder; Arun Kanda; S G Deshmukh
2009-10-01
Typically, supply chain members are dependent on each other to manage various resources and information. The conﬂicting objectives and lack of coordination between supply chain members may often cause uncertainties in supply and demand. The basic elements of coordination theory like interdependency, coherency and mutuality may help in effective ﬂow of information and material between the dependent supply chain members. Supply chain contract can be an effective coordination mechanism to motivate all the members to be a part of the entire supply chain. There are different types of supply chain contracts such as buy back and quantity ﬂexibility contracts. Supply chain performance may be substantially improved by properly designing the contracts to share risks and rewards. The objective of this paper is to explore the applicability of coordination elements through an analytical model in three-level (Manufacturer–distributor–retailer) serial supply chains using contracts. The model evaluates the impact of supply chain contracts on various performance measures. The impact of some contract may be on some speciﬁc performance measure only, which helps managers to choose the type of contract if there is an objective of improving certain performance measure before hand. In three-level supply chains, the contracts are designed at two distinct interfaces: Manufacturer–distributor and distributor–retailer. The model demonstrates the complexity in evaluating the decision variables of three level supply chains. The proposed model is a novel approach to apply coordination theory at various levels of supply chain. The model also presents how the coordination elements are related to each other in various coordination cases.
Coherent Phase Control of Multiphoton Ionization in Three-Level Ladder-Type System
Institute of Scientific and Technical Information of China (English)
ZHANG Shi-An; CHEN Yu-Ting; WANG Zu-Geng; SUN Zhen-Rong
2009-01-01
We present the theoretical investigation of photoelectron spectroscopy resulting from the strong field induced multiphoton ionization in a typical three-level ladder-style system.Our theoretical results show that the photoelectron spectral structure can be alternatively steered by spectral phase modulation.This physical mechanism for strong field quantum control is explicitly exploited by the time-dependent dressed state population.It is concluded that the phase-shaped laser pulses can be used to selectively manipulate the multiphoton ionization process in complicated quantum systems.
Coherent control of a V-type three-level system in a single quantum dot.
Wang, Q Q; Muller, A; Cheng, M T; Zhou, H J; Bianucci, P; Shih, C K
2005-10-28
In a semiconductor quantum dot, the IIx and IIy transitions to the polarization eigenstates, |x> and |y>, naturally form a three-level V-type system. Using low-temperature polarized photoluminescence spectroscopy, we have investigated the exciton dynamics arising under strong laser excitation. We also explicitly solved the density matrix equations for comparison with the experimental data. The polarization of the exciting field controls the coupling between the otherwise orthogonal states. In particular, when the system is initialized into \\Y>, a polarization-tailored pulse can swap the population into |x>, and vice versa, effectively operating on the exciton spin.
Single molecule photon emission statistics of driven three-level systems.
Peng, Yonggang; Zheng, Yujun; Brown, Frank L H
2007-03-14
We study the statistics of photon emission from three-level single molecule systems. The generating function method [Y. Zheng and F. L. H. Brown, Phys. Rev. Lett. 90, 238305 (2003)] is used to calculate steady state absorption line shapes and Mandel's Q parameter as a function of excitation frequency, as well as the time dependence associated with approach to the steady state. The line shape calculations confirm known results derived via other methods, while the Q parameter results display complex frequency dependences not amenable to simple interpretation. This study confirms the applicability of the generating function formalism to multilevel quantum systems, including the proper modeling of quantum coherence effects.
THE CONSTRUCTIONS OF ALMOST BINARY SEQUENCE PAIRS WITH THREE-LEVEL CORRELATION BASED ON CYCLOTOMY
Institute of Scientific and Technical Information of China (English)
Peng Xiuping; Xu Chengqian
2012-01-01
In this paper,a new class of almost binary sequence pair with a single zero element is presented.The almost binary sequence pairs with three-level correlation are constructed based on cyclotomic numbers of order 2,4,and 6.Most of them have good correlation and balance property,whose maximum nontrivial correlation magnitudes are 2 and the difference between the numbers of occurrence of +1's and -1's are 0 or 1.In addition,the corresponding binary sequence pairs are investigated as well and we can also get some kinds of binary sequence pairs with optimum balance and good correlation.
Modeling of Busbars in High Power Neutral Point Clamped Three-Level Inverters
Institute of Scientific and Technical Information of China (English)
YI Rung; ZHAO Zhengming; ZHONG Yulin
2008-01-01
The busbars in high power neutral point clamped three-level inverters are modeled using the Maxwell Q3D Extractor software, which is based on the partial element equivalent circuits method. The equivalent circuits of the busbars and devices model are simulated in the electric simulator PSIM to analyze the effects of the parasitic inductance on the switching characteristics of the integrated gate commutatedthyristor (IGCT) in different topology positions. The simulation results agree well with the measured imped-ance analyzer results and the IGCT test results, which proves the effectiveness of the modeling method for the large, complex busbars.
Coherent Phase Control of Ultrafast Polarization Beats in Reverse V-Type Three-Level System
Institute of Scientific and Technical Information of China (English)
LI Ling; NIE Zhi-Qiang; JIANG Tong; ZHANG Yan-Peng; LI Pei-Zhe; GAN Chen-Li; SONG Jian-Ping; LI Yuan-Yuan
2007-01-01
We investigate the third-order nonlinear absorption and dispersion of femto- and atto-second polarization beats between the one-photon degenerate four-wave mixing process and the two-photon nondegenerate four-wave mixing process in the pure homogeneously-broadened reverse V-three-level using twin noisy Gelds. The third-order nonlinear response can be controlled and modified by the colour-locked correlation of twin noisy fields. Most importantly, the coherent phase control in optical heterodyne detection for studying the phase dispersion of the third-order susceptibility is demonstrated. The radiation-matter detuning oscillation is also considered in the frequency domain.
Path-Controlled Time Reordering of Paired Photons in a Dressed Three-Level Cascade
Bounouar, Samir; Strauß, Max; Carmele, Alexander; Schnauber, Peter; Thoma, Alexander; Gschrey, Manuel; Schulze, Jan-Hindrik; Strittmatter, André; Rodt, Sven; Knorr, Andreas; Reitzenstein, Stephan
2017-06-01
The two-photon dressing of a "three-level ladder" system, here the ground state, the exciton, and the biexciton of a semiconductor quantum dot, leads to new eigenstates and allows one to manipulate the time ordering of the paired photons without unitary postprocessing. We show that, after spectral postselection of the single dressed states, the time ordering of the cascaded photons can be removed or conserved. Our joint experimental and theoretical study demonstrates the high potential of a "ladder" system to be a versatile source of orthogonally polarized, bunched or antibunched pairs of photons.
Kramers-Kronig relation in a Doppler-broadened Λ-type three-level system
Wang, Meng; Lu, Xiao-Gang; Bai, Jin-Hai; Pei, Li-Ya; Miao, Xing-Xu; Gao, Yan-Lei; Wu, Ling-An; Fu, Pan-Ming; Yang, Shi-Ping; Pang, Zhao-Guang; Wang, Ru-Quan; Zuo, Zhan-Chun
2015-11-01
We measure the absorption and dispersion in a Doppler-broadened Λ-type three level system by resonant stimulated Raman spectroscopy with homodyne detection. Through studying the dressed state energies of the system, it is found that the absorption and dispersion satisfy the Kramers-Kronig relation. The absorption and dispersion spectra calculated by employing this relation agree well with our experimental observations. Project supported by the National Basic Research Program of China (Grant Nos. 2013CB922002 and 2010CB922904), the National Natural Science Foundation of China (Grant Nos. 11274376 and 61308011), and the Natural Science Foundation of Hebei Province, China (Grant No. A2015205161).
Three-Level AC-DC-AC Z-Source Converter Using Reduced Passive Component Count
DEFF Research Database (Denmark)
Loh, Poh Chiang; Gao, Feng; Tan, Pee-Chin;
2009-01-01
to switch with a three-level output voltage, where the middle neutral potential is uniquely tapped from the star-point of a wye-connected capacitive filter placed before the front-end diode rectifier for input current filtering. Through careful control, the resulting converter can produce the correct volt......-second average at its output, while simultaneously achieving inductive voltage boosting by shooting through either an appropriately selected inverter phase-leg or two phase-legs being commanded simultaneously. More interestingly, these performance features are achieved with no increase in the number...
Elimination of zero sequence circulating current between parallel operating three-level inverters
DEFF Research Database (Denmark)
Li, Kai; Wang, Xiaodong; Dong, Zhenhua
2016-01-01
In order to suppress the zero sequence circulating currents (ZSCCs) between parallel operating three level voltage source inverters with common AC and DC buses, a common mode voltage reduction PWM (CMVR-PWM) technique and neural point potentials (NPPs) control based method is proposed in this paper...... strategies, ZSCCs between parallel inverters can be eliminated effectively. This strategy has the advantage of without carrier synchronization and can be utilized to parallel operating inverters with different types of filter. Simulation result validate the proposed ZSCC elimination schemes....
Space vector modulation strategy for neutral-point voltage balancing in three-level inverter systems
DEFF Research Database (Denmark)
Choi, Uimin; Lee, Kyo Beum
2013-01-01
This study proposes a space vector modulation (SVM) strategy to balance the neutral-point voltage of three-level inverter systems. The proposed method is implemented by combining conventional symmetric SVM with nearest three-vector (NTV) modulation. The conventional SVM is converted to NTV...... modulation by properly adding or subtracting a minimum gate-on time. In addition, using this method, the switching frequency is reduced and a decrease of switching loss would be yielded. The neutral-point voltage is balanced by the proposed SVM strategy without additional hardware or complex calculations...
A new interleaved double-input three-level boost converter
DEFF Research Database (Denmark)
Chen, Jianfei; Hou, Shiying; Sun, Tao
2016-01-01
. The operating principle of the DITLB converter under the individual supplying power (ISP) and simultaneous supplying power (SSP) mode is analyzed. In addition, closed-loop control strategies composed of a voltage-current loop and a voltage-balance loop, have been researched to make the converter operate......This paper proposes a new interleaved double-input three-level Boost (DITLB) converter, which is composed of two boost converters indirectly in series. Thus, a high voltage gain, together with a low component stress and a small input current ripple due to the interleaved control scheme, is achieved...
Truong, Cao Dung; Trinh, M. Tuan; Dang, Hoai Bac; Nguyen, Van Tho
2017-02-01
We propose a polarization insensitive two-mode division (de)multiplexer based on a silicon-on-insulator platform operating with a broadband, low insertion and scattering loss, and small crosstalk. By using an asymmetric directional coupler, two-mode (de)multiplexing functions for both polarization TE and TM states can be realized by the numerical simulation. Simulated results using a three dimensional beam propagation method (3D-BPM) incorporated with an effective index method (EIM) show high performance of the device with an operation efficiency above 81.2% (i.e., insertion loss is less than 0.9 dB) in the range of ±5 nm around the central wavelength of 1550 nm. Fabrication tolerances also have proved suitability to current manufacture technologies for the planar waveguides. Besides a low scattering loss of the sidewall roughness and a little influence of dispersion, a small footprint can bring the device to applications of high bitrate and compact on-chip silicon photonic integrated circuits.
Direct Torque Control for Three-Level Neutral Point Clamped Inverter-Fed Induction Motor Drive
Directory of Open Access Journals (Sweden)
M. K. Sahu
2012-04-01
Full Text Available Direct torque control (DTC is a control technique in AC drive systems to obtain high performance torque control. The classical DTC drive contains a pair of hysteresis comparators and suffers from variable switching frequency and high torque ripple. These problems can be solved by using space vector depending on the reference torque and flux. In this paper the space vector modulation technique is applied to the three-level Neutral Point Clamped (NPC inverter control in the proposed DTC-based induction motor drive system, resulting to a significant reduce of torque ripple. Three-level neutral point clamped inverters have been widely used in medium voltage applications. This type of inverters have several advantages over standard two-level VSI, such as greater number of levels in the output voltage waveforms, less harmonic distortion in voltage and current waveforms and lower switching frequencies. This paper emphasizes the derivation of switching states using the Space Vector Pulse Width Modulation (SVPWM technique. The control scheme is implemented using Matlab/Simulink. Experimental results using dSPACE validate the steady-state and the dynamic performance of the proposed control strategy.
B-MIC: An Ultrafast Three-Level Parallel Sequence Aligner Using MIC.
Cui, Yingbo; Liao, Xiangke; Zhu, Xiaoqian; Wang, Bingqiang; Peng, Shaoliang
2016-03-01
Sequence alignment is the central process for sequence analysis, where mapping raw sequencing data to reference genome. The large amount of data generated by NGS is far beyond the process capabilities of existing alignment tools. Consequently, sequence alignment becomes the bottleneck of sequence analysis. Intensive computing power is required to address this challenge. Intel recently announced the MIC coprocessor, which can provide massive computing power. The Tianhe-2 is the world's fastest supercomputer now equipped with three MIC coprocessors each compute node. A key feature of sequence alignment is that different reads are independent. Considering this property, we proposed a MIC-oriented three-level parallelization strategy to speed up BWA, a widely used sequence alignment tool, and developed our ultrafast parallel sequence aligner: B-MIC. B-MIC contains three levels of parallelization: firstly, parallelization of data IO and reads alignment by a three-stage parallel pipeline; secondly, parallelization enabled by MIC coprocessor technology; thirdly, inter-node parallelization implemented by MPI. In this paper, we demonstrate that B-MIC outperforms BWA by a combination of those techniques using Inspur NF5280M server and the Tianhe-2 supercomputer. To the best of our knowledge, B-MIC is the first sequence alignment tool to run on Intel MIC and it can achieve more than fivefold speedup over the original BWA while maintaining the alignment precision.
Directory of Open Access Journals (Sweden)
S. Sengottaian
2015-08-01
Full Text Available This study deals with a five phase three level Neutral Point Clamped (NPC inverter fed PMSM drive application. The motor performances depend upon mathematical model so the parameters vary are: noise, common mode voltage, flux variation and harmonic levels of the inverter or motor. Voltage saturation is one of the major problems of a motor which occurs due to speed oscillations, more current fluctuations. This problem can be solved by using PWM technique depends on the reference motor torque and flux. In this study Indirect Field Oriented Control (IFOC NPC inverter is suggested to reduce the voltage saturation. The three level neutral point clamped inverter is widely used for medium and high level applications. Compared with standard two level inverter, this type of NPC inverters have more merits. It generates greater number of levels output waveform in lower harmonic content at the same switching frequency and less voltage stress across the semiconductor switches; finally motor performance and control schemes are verified by using MATLAB/SIMULINK.
Characterization of interface traps on MOS transistor submicronic by the three level charge pumping
Sellami, M.; Bouchemat, M.; Kahouadji, M.; Djahli, F.
2005-05-01
Because of its efficiency, its high precision and its easy use regarding to classical techniques of Si-Sio2 (C-V, DLTS, Conductanceldots), interface characterization, the charge pumping technique has seen a large evolution these years. Many improvements have been made other, derivation techniques have been developed (at three-level charge pumping, spectroscopic charge pumping ldots) This technique is particularly used for very slight geometry MOS transistors damaging, where other techniques have no utility. This damaging often leads to the creation of a fixed trapped charge in the oxide coat and active electronically defaults in the oxide Semi-conductor interface after the application of ageing constraint (ionizing radiation, injection carrier). This ageing is so pronounced when the dimensions are slight this represents the main obstacle that the microelectronics must face. In this article we simulate the three-level charge pumping technique with SPICE3F4 simulator. This simulation will permit the obtaining of spatial and energetic spread of defaults at the interface.
Three Level Diode Clamped Inverter Fed Induction Motor with Dtc-Svm
Directory of Open Access Journals (Sweden)
V. Ranjith Kumar
2013-09-01
Full Text Available This project presents a three-level diode-clamped inverter feeding an asynchronous motor drive with direct torque control (DTC. The control method is based on DTC operating principles. The stator voltage vector reference is computed from the stator flux and torque errors imposed by the flux and torque controllers. This voltage reference is then generated using a diode-clamped inverter, where each phase of the inverter can be implemented using a dc source, which would be available from fuel cells, batteries, or ultra capacitors. This inverter provides nearly sinusoidal voltages with very low distortion, even without filtering, using fewer switching devices. In addition, the multilevel inverter can generate a high and fixed switching frequency output voltage with fewer switching losses, since only the small power cells of the inverter operate at a high switching rate. Therefore, a high performance and also efficient torque and flux controllers are obtained, enabling a DTC solution for multilevel-inverter-powered motor drives. The Pulse Width modulation technique for an inverter permits to obtain three phase system voltages, which can be applied to the controlled output. Space Vector Modulation (SVPWM principle differs from other PWM processes in the fact that all three drive signals for the inverter will be created simultaneously. The implementation of SVPWM process in digital systems necessitates less operation time and also less program memory. This project uses SVPWM technique for generation of pulses for three-level diode clamped inverter. Simulation is carried out on MATLAB-Simulink software.
Directory of Open Access Journals (Sweden)
Amado González Moga
Full Text Available ABSTRACT Objective: To present the results of treatment of patients with cervical discopathy by anterior cervical approach, discectomy and placement of a PEEK interbody cage without anterior plate fixation. Methods: Retrospective, cross-sectional study from March 2013 to March 2015. Sixteen patients with radiculopathy or clinical signs of myelopathy were included; all patients underwent cervical surgery through anterior approach, discectomy, and placement of PEEK cages on three levels. Decompression levels were determined according to the correlation between preoperative radiological and clinical findings. Results: Sixteen patients predominantly male were included, with mean age of 50 years at the onset of the condition. Ten patients had involvement of C4-C5, C5-C6, C6-C7 levels, and six patients C3-C4, C4-C5 and C5-C6. Fourteen patients had cervicobrachialgia and two myelopathy. The preoperative visual analog scale average was 8/10 and the average postoperative value at 6 months was 3/10. At 6 months, there was no radiological evidence of recurrence. One patient had non-fatal complications. Conclusions: The treatment of cervical discopathy by anterior approach with interbody fusion with PEEK cage on three levels, with no plate fixation seemed to be safe and effective with better long-term results in terms of pain and myelopathy. The clinical results compare favorably with other similar series and, most importantly, the complications associated with anterior fixation plate are avoided.
Frequency Up- and Down-conversions in Two-mode Cavity%两模腔中的参量上转换和下转换
Institute of Scientific and Technical Information of China (English)
李斌; 冯勋立; 张智明
2011-01-01
提出了一种通过建立双线性二次哈密顿量在量子腔中实现参量上转换和下转换的方案.通常在非线性过程中,介质本身不参与能量的净交换,但光波频率可以发生转换的作用称为参量转换作用.此方案建立在一个四能级原子同时与两经典场和两量子场相互作用的基础上,理论属于非线性光学四波混频范畴.将原子制备在合适的能级上,经典光场与相应的能级发生共振,而同时量子光场与相应的能级产生大失谐相互作用,在强相互作用区域内,原子和腔场失耦合,进而实现腔模的参量转换.根据所制备初始能级的不同以及光场激发能级的差异,分别实现了参量上转换和参量下转换.在利用参量下转换制备压缩算符后,对实验的可行性进行了讨论,并且给出了理论值.结果表明:在级联三能原子中采用一个级联双光子过程代替了原来的两个偶极禁戒跃迁间的经典驱动,可以保证高的不同频率之间的转换效率,并且用于光的量子操控和量子信息处理.%A scheme was proposed to construct bilinear and quadratic Hamiltonians for frequency up-and down-conversions in cavity quantum electrodynamics (QED).Generally,in nonlinear optics,the interaction that the energe swaps between different optic modes without atomic transition is named frequency conversion.The proposed scheme was based on the interactions of a single four-level atom simultaneously with two classical driving fields and a two-mode cavity field,which is in the domain of four-wave mixing.By initially preparing the atom in a suitable state,each pump light was resonant with its transition,and two quantum modes were large tune to the other two transition,respectively,In the strong laser regime,the atomic degrees of freedom could be decoupled from the cavity degrees of freedom and the frequency conversion could be realized for the cavity modes.Due to the different initial states and
High-power free-electron maser operated in a two-mode frequency-multiplying regime
Directory of Open Access Journals (Sweden)
N. Yu. Peskov
2016-06-01
Full Text Available The frequency multiplication effects in high-power free-electron masers (FEM with Bragg cavities were studied to provide the advance of the oscillators into short-wavelength bands. Theoretical analysis of frequency-multiplying FEMs was carried out within the framework of the averaged coupled-wave approach. Proof-of-principle experiments were performed based on a moderately relativistic induction linac LIU-3000 (JINR. As a result, an FEM multiplier operated with a megawatt power level in the 6-mm and 4-mm wavelength bands at the second and third harmonics, respectively, was realized. The possibility of using two-mode bichromatic FEMs for powering a double-frequency accelerating structure was discussed.
Diamantopoulos, N. P.; Nakazawa, M.; Yoshida, Y.; Maruta, A.; Maruyama, R.; Kuwaki, N.; Matsuo, S.; Kitayama, K.
2015-11-01
Mode-division multiplexing (MDM) over wavelength division multiplexed (WDM) networks is studied, particularly for the deployment of metro area networks (MAN) using two-mode fibers (TMF). Full C-band differential mode group delay (DMGD)-compensated TMF links are adopted for decreasing the computational complexity of real-time multiple-input multiple-output (MIMO) signal processing. The effect of modal crosstalk to the maximum delay spread of the channel is validated through numerical simulations. Finally, the 2×2 MIMO channel state information (CSI) of a 102.6-km DMGD-compensated TMF link is experimentally estimated for mode path provisioning based upon routing and mode assignment (RMA) in MDM networks. The results confirm close-to-zero total DMGD value over the entire C-band.
An ultra-low crosstalk and broadband two-mode (de)multiplexer based on adiabatic couplers
Sun, Chunlei; Yu, Yu; Ye, Mengyuan; Chen, Guanyu; Zhang, Xinliang
2016-12-01
A novel adiabatic couplers (ACs) based broadband and fabrication-tolerant two-mode multiplexer (MUX) is designed using silicon-on-insulator (SOI) platform. Being different from the previously reported ACs-based scheme, the converted and multiplexed signals are on conventional modes, rather than supermodes. The experimental results are in good agreement with the simulations. Over a wavelength range of 75 nm measured, the crosstalk is lower than ‑20 dB, and the insertion loss is ~1 dB. The eye diagram and bit error rate measurements validate the good performance of the proposed mode MUX. The investigation on fabrication tolerance indicates reasonable performance degradation for a large gap deviation from ‑30 to 30 nm and etching depth deviation from ‑50 to 50 nm.
Photon scattering by a three-level emitter in a one-dimensional waveguide
Witthaut, D
2010-01-01
We discuss the scattering of photons from a three-level emitter in a one-dimensional waveguide, where the transport is governed by the interference of spontaneously emitted and directly transmitted waves. The scattering problem is solved in closed form for different level structures. Several possible applications are discussed: The state of the emitter can be switched deterministically by Raman scattering, thus enabling applications in quantum computing such as a single photon transistor. An array of emitters gives rise to a photonic band gap structure, which can be tuned by a classical driving laser. A disordered array leads to Anderson localization of photons, where the localization length can again be controlled by an external driving.
A Novel Neutral Point Voltage Control Strategy for Three-Level NPC APF Based on SVPWM
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Yao Xiaolong
2015-01-01
Full Text Available The unbalance of the neutral point voltage is an inherent problem of three-level neutral-point-clamped (NPC Active Power Filter (APF; this paper analyzes the causes of unbalanced neutral point voltage and studies the reason of the unbalance of the neutral point voltage. A novel neutral point voltage control strategy using Space Vector Pulse Width Modulation (SVPWM is proposed. The proposed strategy is based on the traditional SVPWM, by controlling the effect time of small vector, which can change the state of the midpoint voltage fluctuation, and the neutral point voltage can be maintained balance. The influence of the vector on neutral point balance is investigated in depth. Simulation results show the neutral point voltage balancing control strategy based on SPWM is effective.
Directory of Open Access Journals (Sweden)
Sreedhar Madichetty
2014-02-01
Full Text Available In this paper it proposes a high efficient soft-switching scheme based on zero-voltage-switching (ZVS and zero-current-switching(ZCS principle operated with a simple auxiliary circuit extended range for the front-end isolated DC-AC-DC-AC high power converter with an three phase three level diode clamped multi level inverter by using Minority Charge Carrier inspired optimization technique (MCI with Total Harmonic Distortion(THD,Switching losses, Selective harmonic elimination maintaining with its fundamental as an objective function. Input to the inverter is obtained by the photo voltaic cells and with battery bank. The switching scheme is optimized by MCI technique, analyzed and executed in Matlab and implemented with a digital signal processor (DSP .Experimental results with different loads have observed and shows its effectives, robustness of the applied technique.
A high-resolution time-to-digital converter using a three-level resolution
Dehghani, Asma; Saneei, Mohsen; Mahani, Ali
2016-08-01
In this article, a three-level resolution Vernier delay line time-to-digital converter (TDC) was proposed. The proposed TDC core was based on the pseudo-differential digital architecture that made it insensitive to nMOS and pMOS transistor mismatches. It also employed a Vernier delay line (VDL) in conjunction with an asynchronous read-out circuitry. The time interval resolution was equal to the difference of delay between buffers of upper and lower chains. Then, via the extra chain included in the lower delay line, resolution was controlled and power consumption was reduced. This method led to high resolution and low power consumption. The measurement results of TDC showed a resolution of 4.5 ps, 12-bit output dynamic range, and integral nonlinearity of 1.5 least significant bits. This TDC achieved the consumption of 68.43 µW from 1.1-V supply.
Current Sensorless Control Algorithm for Single-Phase Three-Level NPC Inverter
Directory of Open Access Journals (Sweden)
Suzdalenko Alexander
2014-12-01
Full Text Available The current measurement is becoming a challenging task in power converters operating at high switching frequencies, moreover traditional control system requires two control loops - first (slow regulates DC-link voltage, second (fast controls the shape of current, that all together results in complicated transfer function and long transition periods. The current sensorless control (CSC allows neglecting the mentioned problems. This research for the first time presents the solution of CSC implementation in single-phase three-level neutral point clamped inverter. Mathematical equations were defined for inductor current peaks and transistor conduction time during discontinuous and continuous conduction modes, as well as major problem of current fitting between different voltage levels (consequently with different current peak-to-peak values was solved, providing two solutions - pre-fitting and post-fitting trajectories. The verification of our theoretical assumptions and analytical equations was confirmed by the simulation analysis. Challenges of real experiments are discussed in the conclusion.
Optimal Control of Population Transfer in Three-Level A System with Genetic Algorithms
Institute of Scientific and Technical Information of China (English)
ZHANG Xiang-Yun; SUN Zhen-Rong; CHEN Guo-Liang; WANG Zu-Geng; XU Zhi-Zhan; LI Ru-Xin
2004-01-01
Population transfer in a three-level A system is simulated numerically and optimized. Almost complete population transfer from |1〉 to |3〉 is achieved by a genetic algorithm while the population in state |2〉 reached minimum over the entire evolution at the same time. The result shows that the optimal pulse sequence is the well-known stimulated Raman adiabatic passage (STIRAP) scheme. The detuning of pump pulse and Stokes pulse △p and △s with the opposite sign and the chirps χp and χs with the same sign are in favour of the complete and robust population transfer for few-cycle laser pulse. Rabi frequencies Ωp and Ωs have insensitive effects on the complete population transfer during a large scope of their ratio when they are large enough.
Sliding mode control of solid state transformer using a three-level hysteresis function
Institute of Scientific and Technical Information of China (English)
刘宝龙; 査亚兵; 张涛
2016-01-01
The solid state transformer (SST) can be viewed as an energy router in energy internet. This work presents sliding mode control (SMC) to improve dynamic state and steady state performance of a three-stage (rectifier stage, isolated stage and inverter stage) SST for energy internet. SMC with three-level hysteresis sliding functions is presented to control the input current of rectifier stage and output voltage of inverter stage to improve the robustness under external disturbance and parametric uncertainties and reduce the switching frequency. A modified feedback linearization technique using isolated stage simplified model is presented to achieve satisfactory regulation of output voltage of the isolated stage. The system is tested for steady state operation, reactive power control, dynamic load change and voltage sag simulations, respectively. The switching model of SST is implemented in Matlab/ Simulink to verify the SST control algorithms.
Statistics of scattered photons from a driven three-level emitter in 1D open space
Energy Technology Data Exchange (ETDEWEB)
Roy, Dibyendu [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Div. and Center for Nonlinear Studies; Bondyopadhaya, Nilanjan [Visva-Bharati University, Santiniketan (India). Integrated Science Education and Research Centre
2014-01-07
We derive the statistics of scattered photons from a Λ- or ladder-type three-level emitter (3LE) embedded in a 1D open waveguide. The weak probe photons in the waveguide are coupled to one of the two allowed transitions of the 3LE, and the other transition is driven by a control beam. This system shows electromagnetically induced transparency (EIT) which is accompanied with the Autler-Townes splitting (ATS) at a strong driving by the control beam, and some of these effects have been observed recently. We show that the nature of second-order coherence of the transmitted probe photons near two-photon resonance changes from bunching to antibunching to constant as strength of the control beam is ramped up from zero to a higher value where the ATS appears.
Dual Z-Source Inverter With Three-Level Reduced Common-Mode Switching
DEFF Research Database (Denmark)
Gao, Feng; Loh, Poh Chiang; Blaabjerg, Frede
2007-01-01
This paper presents the design of a dual Z-source inverter that can be used with either a single dc source or two isolated dc sources. Unlike traditional inverters, the integration of a properly designed Z-source network and semiconductor switches to the proposed dual inverter allows buck......-boost power conversion to be performed over a wide modulation range, with three-level output waveforms generated. The connection of an additional transformer to the inverter ac output also allows all generic wye-or delta-connected loads with three-wire or four-wire configuration to be supplied by the inverter....... Modulationwise, the dual inverter can be controlled using a carefully designed carrier-based pulsewidth-modulation (PWM) scheme that will always ensure balanced voltage boosting of the Z-source network while simultaneously achieving reduced common-mode switching. Because of the omission of dead-time delays...
Social Influence Study in Online Networks：A Three-Level Review
Institute of Scientific and Technical Information of China (English)
李辉; 崔江涛; 马建峰
2015-01-01
Social network analysis (SNA) views social relationships in terms of network theory consisting of nodes and ties. Nodes are the individual actors within the networks; ties are the relationships between the actors. In the sequel, we will use the term node and individual interchangeably. The relationship could be friendship, communication, trust, etc. These reason is that these relationships and ties are driven by social influence, which is the most important phenomenon that distinguishes social network from other networks. In this paper, we present an overview of the representative research work in social influence study. Those studies can be classified into three levels, namely individual, community, and network levels. Throughout the study, we are able to unveil a series of research directions in future and possible applications based on the state-of-the-art study.
Jerger, Markus; Macha, Pascal; Hamann, Andrés Rosario; Reshitnyk, Yarema; Juliusson, Kristinn; Fedorov, Arkady
2016-07-01
Binary-outcome measurements allow one to determine whether a multilevel quantum system is in a certain state while preserving quantum coherence between all orthogonal states. In this paper, we explore different regimes of the dispersive readout of a three-level superconducting quantum system coupled to a microwave cavity in order to implement binary-outcome measurements. By designing identical cavity-frequency shifts for the first and second excited states of the system, we realize strong projective binary-outcome measurements onto its ground state with a fidelity of 94.3%. Complemented with standard microwave control and low-noise parametric amplification, this scheme enables the quantum nondemolition detection of leakage errors and can be used to create sets of compatible measurements to reveal the contextual nature of superconducting circuits.
Directory of Open Access Journals (Sweden)
Hui Peng
Full Text Available BACKGROUND: Multidrug resistance (MDR is a major problem in successful treatment of cancers. Human ABCG2, a member of the ATP-binding cassette transporter superfamily, plays a key role in MDR and an important role in protecting cancer stem cells. Knockout of ABCG2 had no apparent adverse effect on the mice. Thus, ABCG2 is an ideal target for development of chemo-sensitizing agents for better treatment of drug resistant cancers and helping eradicate cancer stem cells. METHODS/PRELIMINARY FINDINGS: Using rational screening of representatives from a chemical compound library, we found a novel inhibitor of ABCG2, PZ-39 (N-(4-chlorophenyl-2-[(6-{[4,6-di(4-morpholinyl-1,3,5-triazin-2-yl]amino}-1,3-benzothiazol-2-ylsulfanyl]acetamide, that has two modes of actions by inhibiting ABCG2 activity and by accelerating its lysosome-dependent degradation. PZ-39 has no effect on ABCB1 and ABCC1-mediated drug efflux, resistance, and their expression, indicating that it may be specific to ABCG2. Analyses of its analogue compounds showed that the pharmacophore of PZ-39 is benzothiazole linked to a triazine ring backbone. CONCLUSION/SIGNIFICANCE: Unlike any previously known ABCG2 transporter inhibitors, PZ-39 has a novel two-mode action by inhibiting ABCG2 activity, an acute effect, and by accelerating lysosome-dependent degradation, a chronic effect. PZ-39 is potentially a valuable probe for structure-function studies of ABCG2 and a lead compound for developing therapeutics targeting ABCG2-mediated MDR in combinational cancer chemotherapy.
Directory of Open Access Journals (Sweden)
Ahmad Jaafarnehad
2015-09-01
Full Text Available The role and importance of supply chain management, has faced with many challenges and problems. Although a comprehensive model of supply chain issues, has not been explained, we have to indicate that issues such as reviewing the theoretical foundations of information systems, marketing, financial management, logistical and organizational relations have been considered by many researchers. The objective of supply chain management is to improve various activities and components to increase overall supply chain system benefits. In order to achieve the overall objectives, many contradictions may occur between the components and different levels of supply chain and the contradictions that these disorders over time, result in decreased strength and competitiveness of the supply chain. Such conflicts, like marketing costs (advertising, pricing and inventory can occur during the supply chain life cycle. A Game Theory approach with respect to property is the appropriate tool for collaboration in the supply chain. This tool is used for collaborative making in any kind of supply chain such as cooperative supply chain and non-cooperative supply chain. In the present study and assuming a lack of cooperation between different levels of a supply chain, a dynamic game with complete information has been generated. In addition identifying appropriate leaders of various levels of the supply chain is considered. Non-Cooperative dynamic game mode (Stackelberg Game, for each of the three levels of supply chain including retailers, suppliers and manufacturers are modeled. Depending on the bargaining power and its position in the market, any level of supply chain can make a leader of the following rule. In the present study, the equilibrium model to play Stackelberg game may be led by a leader or leading players and ultimately identifying and modeling the appropriate unlimited three level supply chain are determined.
Comparative Analysis of PWM Techniques for Three Level Diode Clamped Voltage Source Inverter
Directory of Open Access Journals (Sweden)
Zulkifilie Bin Ibrahim
2014-07-01
Full Text Available Multilevel inverters are increasingly being used in high-power medium voltage industrial drive applications due to their superior performance compared to conventional two-level inverters. Thre are a number of Pulse width modulation (PWM techniques applied in recent years. The most widely applied PWM techniques are Sine Pulse Width Modulation (SPWM and Space Vector Pulse Width Modulation (SVPWM. SPWM is the most simple modulation technique that can realize easily in analog circuit. However, it has some drawbacks such as higher total harmonic distortion (THD, lower effective DC utilization and lower switching frequency. Space vector pulse width modulation (SVPWM is widely used because of their easier digital realization and better DC bus utilization and lower THD. The complexity is due to the difficulty in determining the reference vector location, on times calculation, and switching states selection. This paper presents a simple SVPWM algorithm for diode clamped three level inverters based on standard two-level SVPWM which can easily determine the location of reference vector, calculate the on-times, the selection of switching states. Three level diode clamped inverter (3LDCI using space vector modulation technique has been modeled and simulated using MATLAB/SIMULINK and Origin 6.1 with a passive R-L load that can be extended to any level. Simulation results are presented to verify the proposed SVPWM control in terms of THD. The results are compared with conventional sinusoidal pulse width modulation (SPWM where SVPWM shows better performance than SPWM in terms of THD.
Analysis and identification of two reconstituted tobacco sheets by three-level infrared spectroscopy
Wu, Xian-xue; Xu, Chang-hua; Li, Ming; Sun, Su-qin; Li, Jin-ming; Dong, Wei
2014-07-01
Two kinds of reconstituted tobacco (RT) from France (RTF) and China (RTC) were analyzed and identified by a three-level infrared spectroscopy method (Fourier-transform infrared spectroscopy (FT-IR) coupled with second derivative infrared spectroscopy (SD-IR) and two-dimensional infrared correlation spectroscopy (2D-IR)). The conventional IR spectra of RTF parallel samples were more consistent than those of RTC according to their overlapped parallel spectra and IR spectra correlation coefficients. FT-IR spectra of both two RTs were similar in holistic spectral profile except for small differences around 1430 cm-1, indicating that they have similar chemical constituents. By analysis of SD-IR spectra of RTFs and RTCs, more distinct fingerprint features, especially peaks at 1106 (1110), 1054 (1059) and 877 (874) cm-1, were disclosed. Even better reproducibility of five SD-IR spectra of RTF in 1750-1400 cm-1 could be seen intuitively from their stacked spectra and could be confirmed by further similarity evaluation of SD-IR spectra. Existence of calcium carbonate and calcium oxalate could be easily observed in two RTs by comparing their spectra with references. Furthermore, the 2D-IR spectra provided obvious, vivid and intuitive differences of RTF and RTC. Both two RTs had a pair of strong positive auto-peaks in 1600-1400 cm-1. Specifically, the autopeak at 1586 cm-1 in RTF was stronger than the one around 1421 cm-1, whereas the one at 1587 cm-1 in RTC was weaker than that at 1458 cm-1. Consequently, the RTs of two different brands were analyzed and identified thoroughly and RTF had better homogeneity than RTC. As a result, three-level infrared spectroscopy method has proved to be a simple, convenient and efficient method for rapid discrimination and homogeneousness estimation of RT.
Ran, Du; Hu, Chang-Sheng; Yang, Zhen-Biao
2016-08-24
We study the entanglement transfer from a two-mode continuous variable system (initially in the two-mode SU(2) cat states) to a couple of discrete two-state systems (initially in an arbitrary mixed state), by use of the resonant Jaynes-Cummings (JC) interaction. We first quantitatively connect the entanglement transfer to non-Gaussianity of the two-mode SU(2) cat states and find a positive correlation between them. We then investigate the behaviors of the entanglement transfer and find that it is dependent on the initial state of the discrete systems. We also find that the largest possible value of the transferred entanglement exhibits a variety of behaviors for different photon number as well as for the phase angle of the two-mode SU(2) cat states. We finally consider the influences of the noise on the transferred entanglement.
DEFF Research Database (Denmark)
Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.
2011-01-01
In this paper, a circuit-level decoupling modulation strategy is proposed for the three-level (TL) neutral-point-clamped (NPC) inverters. With the proposed modulation scheme, the TL-NPC inverter can be decoupled into two three-level Buck converters in each defined operating section, which makes...... without any feedback control. The simulation results show the validity of theoretical analysis....
DEFF Research Database (Denmark)
Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.
2011-01-01
In this paper, a circuit-level decoupling modulation strategy is proposed for the three-level (TL) neutral-point-clamped (NPC) inverters. With the proposed modulation scheme, the TL-NPC inverter can be decoupled into two three-level Buck converters in each defined operating section, which makes...
Passive synchronized Q-switching between a quasi-three-level and a four-level laser
DEFF Research Database (Denmark)
Cheng, Haynes Pak Hay; Tidemand-Lichtenberg, Peter; Jensen, Ole Bjarlin;
2011-01-01
Synchronized Q-switching between quasi-three-level and four-level lasers is interesting for sum-frequency generation into the blue and ultraviolet. We report, for the first time, stable synchronized Q-switching between a quasi-three-level laser at 946 nm and a four-level laser at 1064 nm in an al...
Snijders, Tom A. B.; Lomi, Alessandro; Torló, Vanina Jasmine
2013-01-01
We propose a new stochastic actor-oriented model for the co-evolution of two-mode and one-mode networks. The model posits that activities of a set of actors, represented in the two-mode network, co-evolve with exchanges and interactions between the actors, as represented in the one-mode network. The model assumes that the actors, not the activities, have agency.
Advances in quantum control of three-level superconducting circuit architectures
Energy Technology Data Exchange (ETDEWEB)
Falci, G.; Paladino, E. [Dipartimento di Fisica e Astronomia, Universita di Catania (Italy); CNR-IMM UOS Universita (MATIS), Consiglio Nazionale delle Ricerche, Catania (Italy); INFN, Sezione di Catania (Italy); Di Stefano, P.G. [Dipartimento di Fisica e Astronomia, Universita di Catania (Italy); Centre for Theoretical Atomic, Molecular and Optical Physics, School of Mathematics and Physics, Queen' s University Belfast(United Kingdom); Ridolfo, A.; D' Arrigo, A. [Dipartimento di Fisica e Astronomia, Universita di Catania (Italy); Paraoanu, G.S. [Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science (Finland)
2017-06-15
Advanced control in Lambda (Λ) scheme of a solid state architecture of artificial atoms and quantized modes would allow the translation to the solid-state realm of a whole class of phenomena from quantum optics, thus exploiting new physics emerging in larger integrated quantum networks and for stronger couplings. However control solid-state devices has constraints coming from selection rules, due to symmetries which on the other hand yield protection from decoherence, and from design issues, for instance that coupling to microwave cavities is not directly switchable. We present two new schemes for the Λ-STIRAP control problem with the constraint of one or two classical driving fields being always-on. We show how these protocols are converted to apply to circuit-QED architectures. We finally illustrate an application to coherent spectroscopy of the so called ultrastrong atom-cavity coupling regime. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Zhang, Yichen; Li, Zhengyu; Zhao, Yijia; Yu, Song; Guo, Hong
2017-02-01
We analyze the security of the two-way continuous-variable quantum key distribution protocol in reverse reconciliation against general two-mode attacks, which represent all accessible attacks at fixed channel parameters. Rather than against one specific attack model, the expression of secret key rates of the two-way protocol are derived against all accessible attack models. It is found that there is an optimal two-mode attack to minimize the performance of the protocol in terms of both secret key rates and maximal transmission distances. We identify the optimal two-mode attack, give the specific attack model of the optimal two-mode attack and show the performance of the two-way protocol against the optimal two-mode attack. Even under the optimal two-mode attack, the performances of two-way protocol are still better than the corresponding one-way protocol, which shows the advantage of making double use of the quantum channel and the potential of long-distance secure communication using a two-way protocol.
Randomized, controlled trial of three levels of critical incident stress intervention.
Macnab, Andrew; Sun, Charles; Lowe, John
2003-01-01
Stress debriefing following exposure to a critical incident is becoming more prevalent. Its aim is to prevent or minimize the development of excessive stress response symptoms that lead to loss of productivity or effectiveness in the workplace or at home. There is little evidence that any form of psychological debriefing is effective. This study evaluated the effectiveness of three intervention strategies, and attempted to correlate the symptoms with the severity of the incident and level of intervention. A randomized, controlled trial of three levels of critical stress intervention was conducted in the British Columbia Ambulance Service (BCAS), in British Columbia, Canada, among paramedics and emergency medical technicians (EMTs), reporting critical incident stress. Outcomes were measured at one week (Stanford Acute Stress Reaction Questionnaire (SASRQ), the Life Impact Score (LIS), and Schedule of Recent Events (SRE)), and at three months and six months following the intervention (Impact of Events (IE), Coping Mechanisms, LIS, and SRE). Fifty calls were received during the 26-month study period (incident and scores on the SASRQ, IE, or LIS, or between any of these scores. There was no consistent pattern in the stress scores over time. Requests for critical incident stress intervention were uncommon. The need for intervention may not be as great as generally is assumed. Further randomized trials, ideally multicenter studies, are indicated.
A Novel Space Vector Technique for the Direct Three-level Matrix Converter
Directory of Open Access Journals (Sweden)
C. Agees Kumar
2014-10-01
Full Text Available This study proposes a novel Direct Torque Control (DTC method for the Direct Three level Matrix Converter (DTMC, which uses both the input phase voltage vectors (short vectors and the input line voltage vectors (long vectors. The problem of voltage imbalance at the input filter capacitance due to the use of the short vectors is addressed with an additional voltage hysteresis comparator. With the errors of torque, flux, sin Ψ and the neutral point voltage, an Optimum Switching Table (OST is designed for the DTMC. The OST generates the necessary switching signals for the DTC of the DTMC. The DTMC topology with the modified ISVM technique reduces the THD at the output. The proposed DTMC Indirect Space Vector pulse width Modulation (ISVM technique uses the idea of multilevel inverter SVM technique along with the proposed neutral current balancing strategy for generating the firing pulses. The switching loss model for the DTMC is developed and the performance of the DTMC is compared with that of the Conventional Matrix Converter (CMC. The performance of the proposed DTC technique for the DTMC is evaluated through simulation to explain the reduced torque ripple characteristics. To validate the proposed DTMC ISVM technique, a 3 kVA direct multilevel matrix converter prototype was developed.
Analysis of three level supply chain of inventory with deterioration for multi-items
Directory of Open Access Journals (Sweden)
Narayan Singh
2014-05-01
Full Text Available The objective of this work is to generalize the three echelon supply chain model proposed by Jaber and Goyal (2008 [Jaber, M. Y., & Goyal, S. K. (2008. Coordinating a three-level supply chain with multiple suppliers, a vendor and multiple buyers. International Journal Production Economics, 116, 95-103.] for multi-items where single item was considered in production and distribution. This paper develops the coordination amongst different parties in a three-echelon supply chain with a centralized decision process. Producer, suppliers and retailers are the parties of the supply chain where multiple suppliers deliver various types of raw materials to a producer; producer produces different types of items, multi-items, in different units of the factory and supplies the items to multiple retailers. Different deterioration rates for finished items and raw materials are also considered. The model developed of this paper guarantees that the local costs for the members either remain the same as before coordination, or decrease as a result of coordination. A numerical example along with graphical illustrations is considered and the sensitivity analysis is provided to test the feasibility of the proposed model.
Kobesova, Alena; Kolar, Pavel
2014-01-01
Three levels of sensorimotor control within the central nervous system (CNS) can be distinguished. During the neonatal stage, general movements and primitive reflexes are controlled at the spinal and brain stem levels. Analysis of the newborn's spontaneous general movements and the assessment of primitive reflexes is crucial in the screening and early recognition of a risk for abnormal development. Following the newborn period, the subcortical level of the CNS motor control emerges and matures mainly during the first year of life. This allows for basic trunk stabilization, a prerequisite for any phasic movement and for the locomotor function of the extremities. At the subcortical level, orofacial muscles and afferent information are automatically integrated within postural-locomotor patterns. Finally, the cortical (the highest) level of motor control increasingly becomes activated. Cortical control is important for the individual qualities and characteristics of movement. It also allows for isolated segmental movement and relaxation. A child with impaired cortical motor control may be diagnosed with developmental dyspraxia or developmental coordination disorder. Human ontogenetic models, i.e., developmental motor patterns, can be used in both the diagnosis and treatment of locomotor system dysfunction. Copyright © 2013 Elsevier Ltd. All rights reserved.
Rectified optical force on dark-state atoms
Korsunsky, E. A.; Kosachiov, D. V.
1997-12-01
We show that an imperfection of velocity-selective coherent population trapping (VSCPT) in three-level atoms excited by standing light waves causes a rectified force on cooled atoms. The rectified force as well as the cooling force are calculated both analytically and numerically for 0953-4075/30/24/010/img5 and cascade three-level systems. Combination of these forces with the VSCPT mechanism can lead to localization of very cold atoms in potential wells created by the rectified force. This effect should be taken into account in experiments with VSCPT in standing waves, and can be used for realizing superlattices of cold atoms, in particular, cold Rydberg atoms.
Entanglement Swapping: Entangling Atoms That Never Interacted
Guerra, E S
2005-01-01
In this paper we discuss four different proposals of entangling atomic states of particles which have never interacted. The experimental realization proposed makes use of the interaction of Rydberg atoms with a micromaser cavity prepared in either a coherent state or in a superposition of the zero and one field Fock states. We consider atoms in either a three-level cascade or lambda configuration
Atomic dynamics in the mode-mode competition system
Institute of Scientific and Technical Information of China (English)
Wu Qin; Fang Mao-Fa
2004-01-01
The atomic dynamical properties in the system with competing k-photon and l-photon transitions are studied fully by means of quantum theory. We discuss the influences of the mode-mode competition, the relative competing strengths of the atom and the two-mode field, and the initial state of the system on the atomic dynamics. We show that the presence of the mode-mode competition can result in quite a periodical collapses-revivals of the atomic inversion and the increase of the initial photons of the system can lead to the collapse-revival phenomenon and prolong the revival time of the atomic inversion.
Yoshioka, T.; Bensamaïa, S. J.; Craig, J. C.; Hsiao, S. S.
2007-01-01
Considerable information about the texture of objects can be perceived remotely through a probe. It is not clear, however, how texture perception with a probe compares with texture perception with the bare finger. Here we investigate the perception of a variety of textured surfaces encountered daily (e.g., corduroy, paper, and rubber) using the two scanning modes—direct touch through the finger and indirect touch through a probe held in the hand—in two tasks. In the first task, subjects rated the overall pair-wise dissimilarity of the textures. In the second task, subjects rated each texture along three continua, namely, perceived roughness, hardness, and stickiness of the surfaces, shown previously as the primary dimensions of texture perception in direct touch. From the dissimilarity judgment experiment, we found that the texture percept is similar though not identical in the two scanning modes. From the adjective rating experiments, we found that while roughness ratings are similar, hardness and stickiness ratings tend to differ between scanning conditions. These differences between the two modes of scanning are apparent in perceptual space for tactile textures based on multidimensional scaling (MDS) analysis. Finally, we demonstrate that three physical quantities, vibratory power, compliance, and friction carry roughness, hardness, and stickiness information, predicting perceived dissimilarity of texture pairs with indirect touch. Given that different types of texture information are processed by separate groups of neurons across direct and indirect touch, we propose that the neural mechanisms underlying texture perception differ between scanning modes. PMID:17558923
Haghshenasfard, Zahra; Cottam, Michael G
2017-03-20
A microscopic (Hamiltonian-based) method for the quantum statistics of bosonic excitations in a two-mode magnon system is developed. Both the exchange and the dipole-dipole interactions, as well as the Zeeman term for an external applied field, are included in the spin Hamiltonian, and the model also contains the nonlinear effects due to parallel pumping and four-magnon interactions. The quantization of spin operators is achieved through the Holstein-Primakoff formalism, and then a coherent magnon state representation is used to study the occupation magnon number and the quantum statistical behaviour of the system. Particular attention is given to the cross correlation between the two coupled magnon modes in a ferromagnetic nanowire geometry formed by two lines of spins. Manipulation of the collapse-and-revival phenomena for the temporal evolution of the magnon number as well as the control of the cross correlation between the two magnon modes is demonstrated by tuning the parallel pumping field amplitude. The role of the four-magnon interactions is particularly interesting and leads to anti-correlation in some cases with coherent states.
Dynamical properties of total intensity fluctuation spectrum in two-mode Nd:YVO4 microchip laser
Zhang, Shao-Hui; Shu-Lian, Zhang; Tan, Yi-Dong; Sun, Li-Qun
2015-12-01
We investigate the total intensity fluctuation spectrum of the two-longitudinal- mode Nd:YVO4 microchip laser (ML). We find that low-frequency relaxation oscillation (RO) peaks still appear in the total intensity fluctuation spectrum, which is different from a previous research result that the low-frequency RO peaks exist in the spectrum of the individual mode but compensate for each other totally in the total intensity fluctuation spectrum. Taking the spatial hole-burning effect into account, one and two-mode rate equations for Nd:YVO4 ML laser are established and studied. Based on the theoretical model, we find that when the gains and losses for two longitudinal models are different, a low-frequency RO peak will appear in the total intensity fluctuation spectrum, while when they share the same gain and loss, the total spectrum will behave like that of a single mode laser. Theoretical simulation results coincide with experimental results very well. Project supported by the Beijing Higher Education Young Elite Teacher Project, China (Grant No. YETP0086), the Tsinghua University Initiative Scientific Research Programme, China (Grant No. 2012Z02166), and the Special-funded Programme on National Key Scientific Instruments and Equipment Development of China (Grant No. 2011YQ04013603).
Exact diagonalization of non-Hermitian so(3,2) models: Generalized two-mode boson systems
Zhang, Hong-Biao; Wang, Gangcheng
2016-12-01
We propose a unified approach to exactly diagonalize generalized non-Hermitian so(3,2) models. This approach is a series of similarity transformations, which is constructed by some similarity transformation operators associated with su(1,1) and su(2) subalgebras of so(3,2) Lie algebra. During this diagonalization, it is worth noting that a key step is to get rid of the terms E ˆ ± and F ˆ ± together via the proper similarity transformations first. In this way, exact solutions of the non-Hermitian so(3,2) models are obtained. Meanwhile we give the corresponding eigenstates, which are regarded as Lie algebra so(3,2) coherent-like number states. The results can cover the generic form of the eigenvalues and eigenstates to the generalized non-Hermitian two-mode boson systems with the discrete spectrum, including 2D PT-symmetric and non-PT-symmetric oscillators as the special cases. Also they are true for the Hermitian case.
Lutz, D; Rafferty, D; Shao, L; Hasinger, G; Weiss, A; Walter, F; Smail, I; Alexander, D M; Brandt, W N; Chapman, S; Coppin, K; Schreiber, N M Forster; Gawiser, E; Genzel, R; Greve, T R; Ivison, R J; Koekemoer, A M; Kurczynski, P; Menten, K M; Nordon, R; Popesso, P; Schinnerer, E; Silverman, J D; Wardlow, J; Xue, Y Q
2010-01-01
We study the co-existence of star formation and AGN activity in X-ray selected AGN by analyzing stacked 870um submm emission from a deep and wide map of the Extended Chandra Deep Field South, obtained with LABOCA at the APEX telescope. The total X-ray sample of 895 sources with median redshift z~1 is detected at a mean submm flux of 0.49+-0.04mJy, corresponding to a typical star formation rate around 30Msun/yr for a T=35K, beta=1.5 greybody far-infrared SED. The good S/N permits stacking analyses for subgroups. We observe a trend of star formation rate increasing with redshift. An increase of star formation rate with AGN luminosity is indicated at the highest L_2-10>~1E44erg/s luminosities only. Increasing trends with X-ray obscuration as expected in some AGN evolutionary scenarios are not observed for the bulk of the X-ray AGN sample but may be present for the highest intrinsic luminosity objects. This suggests a transition between two modes in the coexistence of AGN activity and star formation. For the bulk...
Sala, Matthieu; Egorova, Dassia
2016-12-01
The multi-dimensional electronic spectroscopy of ultrafast nuclear dynamics at conical intersections (CI) is an emerging field of investigation, which profits also from the recent extension of the techniques to the UV domain. We present a detailed computational study of oscillatory signatures in two-dimensional (2D) photon-echo spectroscopy (also known as 2D electronic spectroscopy, 2DES) for the two-mode pyrazine model with dissipation. Conventional 2D signals as well as the resulting beating maps are considered. Although of a reduced character, the model captures quite well all the main signatures of the excited-state dynamics of the molecule. Due to the ultrafast relaxation via the CI and no excited-state absorption from the low-lying dark state, the oscillatory components of the signal are found to be predominantly determined by the ground state bleach contribution. They reflect, therefore, the ground-state vibrational coherence induced in the Raman active mode. Beating maps provide a way to experimentally differentiate between ground state bleach and stimulated emission oscillatory components. The ultrafast decay of the latter constitutes a clear indirect signature of the CI. In the considered model, because of the sign properties of the involved transition dipole moments, the dominance of the ground-state coherence leads to anti-correlated oscillations of cross peaks located at symmetric positions with respect to the main diagonal.
Influence of subcutaneous fat on mechanomyographic signals at three levels of voluntary effort
Directory of Open Access Journals (Sweden)
Eduardo Mendonça Scheeren
Full Text Available Abstract Introduction This study aims to assess the influence of different skinfold thicknesses (ST and their relation to the attenuation of the mechanomyographic (MMG signal at different force levels (maximal voluntary contraction – MVC, 40% of MVC and 70% of MVC of the rectus femoris muscle. Methods Fifteen volunteers were divided in two groups: ST lower than 10mm (G35 (7 participants. Student t tests were employed to investigate differences between G35 regarding MMG analysis parameters (acceleration root mean square – aRMS, zero crossing – ZC, and median frequency – MDF, for the X, Y and Z axes, as well as for the modulus of these three axes. Results We found that thicker layers of body fat act as attenuator filters for the MMG signal [MDFMVC: X (p = 0.005, Z (p = 0.003; MDF70%MVC: X (p = 0.034; ZCMVC: Z (p = 0.037, modulus (p = 0.005; ZC70%MVC: Z (p = 0.047]. We found significant correlation between ST values and aRMS in three levels, in the Yaxis (p = 0.591, for the group G35 in 40%MVC (R2 = 0.610, and 70%MVC (R2 = 0.592. The MDF parameter showed correlation with ST values only in the Yaxis in 70%MVC (R2 = 0.700 for G>35. Conclusions We observed MMG signal attenuation in at least one of the parameters analyzed for each level of the rectus femoris muscle force, indicating that MMG signals are significantly attenuated with increasing thickness of the subcutaneous fat layer.
Directory of Open Access Journals (Sweden)
Ivan Enrici
Full Text Available Parkinson's disease (PD is characterised by well-known motor symptoms, whereas the presence of cognitive non-motor symptoms, such as emotional disturbances, is still underestimated. One of the major problems in studying emotion deficits in PD is an atomising approach that does not take into account different levels of emotion elaboration. Our study addressed the question of whether people with PD exhibit difficulties in one or more specific dimensions of emotion processing, investigating three different levels of analyses, that is, recognition, representation, and regulation.Thirty-two consecutive medicated patients with PD and 25 healthy controls were enrolled in the study. Participants performed a three-level analysis assessment of emotional processing using quantitative standardised emotional tasks: the Ekman 60-Faces for emotion recognition, the full 36-item version of the Reading the Mind in the Eyes (RME for emotion representation, and the 20-item Toronto Alexithymia Scale (TAS-20 for emotion regulation.Regarding emotion recognition, patients obtained significantly worse scores than controls in the total score of Ekman 60-Faces but not in any other basic emotions. For emotion representation, patients obtained significantly worse scores than controls in the RME experimental score but no in the RME gender control task. Finally, on emotion regulation, PD and controls did not perform differently at TAS-20 and no specific differences were found on TAS-20 subscales. The PD impairments on emotion recognition and representation do not correlate with dopamine therapy, disease severity, or with the duration of illness. These results are independent from other cognitive processes, such as global cognitive status and executive function, or from psychiatric status, such as depression, anxiety or apathy.These results may contribute to better understanding of the emotional problems that are often seen in patients with PD and the measures used to test
Enrici, Ivan; Adenzato, Mauro; Ardito, Rita B; Mitkova, Antonia; Cavallo, Marco; Zibetti, Maurizio; Lopiano, Leonardo; Castelli, Lorys
2015-01-01
Parkinson's disease (PD) is characterised by well-known motor symptoms, whereas the presence of cognitive non-motor symptoms, such as emotional disturbances, is still underestimated. One of the major problems in studying emotion deficits in PD is an atomising approach that does not take into account different levels of emotion elaboration. Our study addressed the question of whether people with PD exhibit difficulties in one or more specific dimensions of emotion processing, investigating three different levels of analyses, that is, recognition, representation, and regulation. Thirty-two consecutive medicated patients with PD and 25 healthy controls were enrolled in the study. Participants performed a three-level analysis assessment of emotional processing using quantitative standardised emotional tasks: the Ekman 60-Faces for emotion recognition, the full 36-item version of the Reading the Mind in the Eyes (RME) for emotion representation, and the 20-item Toronto Alexithymia Scale (TAS-20) for emotion regulation. Regarding emotion recognition, patients obtained significantly worse scores than controls in the total score of Ekman 60-Faces but not in any other basic emotions. For emotion representation, patients obtained significantly worse scores than controls in the RME experimental score but no in the RME gender control task. Finally, on emotion regulation, PD and controls did not perform differently at TAS-20 and no specific differences were found on TAS-20 subscales. The PD impairments on emotion recognition and representation do not correlate with dopamine therapy, disease severity, or with the duration of illness. These results are independent from other cognitive processes, such as global cognitive status and executive function, or from psychiatric status, such as depression, anxiety or apathy. These results may contribute to better understanding of the emotional problems that are often seen in patients with PD and the measures used to test these problems
Institute of Scientific and Technical Information of China (English)
2011-01-01
A single phase three-level converter （shown in Fig. 1） has been widely applied in high-speed railway electrical traction drive systems. But the main technical drawback of the three-level converter is DC-link neutral point voltage drift. In order to solve this problem, it is important to understand the cause of DC-link neutral point voltage drift.
Coherence generation and population transfer in a three-level ladder system
Institute of Scientific and Technical Information of China (English)
Zhang Bing; Jiang Yun; Wang Gang; Zhang Li-Da; Wu Jin-Hui; Gao Jin-Yue
2011-01-01
This work explores the effect of spontaneous emission on coherence generation and population transfer in a threelevel ladder atomic system driven by two pulses in counterintuitive order. With adiabatic evolution and the weakdephasing approximation, we find that a large coherence and population transfer can be achieved even with spontaneous decay rate. The maximum coherence and population transfer decrease with the increase of spontaneous decay rate from the highest state to intermediate state. But this effect can be compensated by shortening the pulse width and enlarging the delay time. Results show that the coherence generation and population transfer never depend on the spontaneous decay rate from the intermediate state to ground state. The validity of the analytic solution is examined by numerical calculation.
Institute of Scientific and Technical Information of China (English)
Jianping Song; Xiangchen Zhang; Yanpeng Zhang; Keqing Lu; Yu Feng; Chenli Gan; Long Li; Yuanyuan Li; Xiaojun Yu; Hao Ge; Ruiqiong Ma; Chuangshe Li
2005-01-01
Fifth-order attosecond sum-frequency polarization beat (FASPB) is studied in a cascade three level system with the phase-conjugation fourth-order coherence function theory. An improved schematic diagram of geometry, which is different from that inducing fifth-order femtosecond different-frequency polarization beat(FFDPB), is used to obtain FASPB. By analyzing the cases that pump beams have either narrow or broad bandwidth, it is found that the temporal behavior of the sum-frequency polarization beat signal depends on the properties of the lasers and transverse relaxation rate of the atomic energy-level system. Finally,the cascaded four-wave mixing (FWM) processes and the difference between attosecond and femtosecond polarization beats have been discussed, it is found that cascaded or sequential lower processes can often obscure the direct fifth-order polarization beat processes.
Tajik, Mohammad; Yamini, Yadollah; Esrafili, Ali; Ebrahimpour, Behnam
2015-02-01
Two different modes of three-phase hollow fiber liquid-phase microextraction were studied for the extraction of two herbicides, bensulfuron-methyl and linuron. In these two modes, the acceptor phases in the lumen of the hollow fiber were aqueous and organic solvents. The extraction and determination were performed using an automated hollow fiber microextraction instrument followed by high-performance liquid chromatography. For both three-phase hollow fiber liquid-phase microextraction modes, the effect of the main parameters on the extraction efficiency were investigated and optimized by central composite design. Under optimal conditions, both modes showed good linearity and repeatability, but the three-phase hollow fiber liquid-phase microextraction based on two immiscible organic solvents has a better extraction efficiency and figures of merit. The calibration curves for three-phase hollow fiber liquid-phase microextraction with an organic acceptor phase were linear in the range of 0.3-200 and 0.1-150 μg/L and the limits of detection were 0.1 and 0.06 μg/L for bensulfuron-methyl and linuron, respectively. For the conventional three-phase hollow fiber liquid-phase microextraction, the calibration curves were linear in the range of 3.0-250 and 15-400 μg/L and LODs were 1.0 and 5.0 μg/L for bensulfuron-methyl and linuron, respectively. The real sample analysis was carried out by three-phase hollow fiber liquid phase microextraction based on two immiscible organic solvents because of its more favorable characteristics.
Quantum Collapse and Revival of Atom in Mode-Mode Competing System
Institute of Scientific and Technical Information of China (English)
WU Qin; FANG Mao-Fa
2005-01-01
The atomic inversion dynamics in the mode-mode competing system is studied by means of fully quantum theory. A general solution to the Schrodinger equation of this system is obtained. The influence of the relative competing strength between the atom and the two-mode field on the atomic inversion is disccussed. We show that the presence of the mode-mode competition can result in periodical collapses-revivals of the atomic inversion.
Sliding Mode Control of Three Levels Back-To-Back VSC-HVDC System Using Space Vector Modulation
Directory of Open Access Journals (Sweden)
Bouafia Saber
2014-03-01
Full Text Available In this study, a sliding mode strategy proposed to control a three levels Back-to-Back High Voltage Direct Current (HVDC system based on the three-level voltage source converter (VSC. The voltage-balancing control of two split DC capacitors of the VSC-HVDC system is achieved using three-level space vector modulation with balancing strategy based on the effective use of the redundant switching states of the inverter voltage vectors. Finally, a complete simulation of the VSC-HVDC system validates the efficiency of the proposed strategy law. Compared to the conventional control, Sliding Mode Control scheme for the VSC-HVDC system shows the attractive advantages such as offering high tracking accuracy, fast dynamic response and good robustness.
Directory of Open Access Journals (Sweden)
S. Radha Krishna Reddy
2012-06-01
Full Text Available Multilevel inverters are increasingly being used in high-power medium voltage applications due to their superior performance compared to two-level inverters. Among various modulation techniques for a multilevel inverter, the space vector pulse width modulation (SVPWM is widely used. This paper deals with the three-phase three-level inverter fed induction motor drive. The proposed scheme deals with the development and implementation of three phase three level inverter to improve the efficiency and reliability of the inverter. Simulation tests have been carried out to examine the operating characteristics of the completed three-phase three-level inverter driving induction motor and an RL load with different switching devices and are compared
Carver, Charles S.; Johnson, Sheri L.; Joormann, Jutta
2008-01-01
Evidence from diverse literatures supports the viewpoint that two modes of self-regulation exist, a lower-order system that responds quickly to associative cues of the moment and a higher-order system that responds more reflectively and planfully; that low serotonergic function is linked to relative dominance of the lower-order system; that how…
Two-mode multiplexing at 2 × 10.7 Gbps over a 7-cell hollow-core photonic bandgap fiber
DEFF Research Database (Denmark)
Xu, Jing; Peucheret, Christophe; Lyngsø, Jens Kristian
2012-01-01
mode division multiplexing (MDM). In this work, we demonstrate MDM over a HC-PBGF for the first time. Two 10.7 Gbps channels are simultaneously transmitted over two modes of a 30-m long 7-cell HC-PBGF. Bit error ratio (BER) performances below the FEC threshold limit (3.3 × 10−3) are shown for both data...
Probabilistic teleportation of an arbitrary pure state of two atoms
Institute of Scientific and Technical Information of China (English)
Yang Zhen-Biao; Wu Huai-Zhi; Su Wan-Jun
2007-01-01
In the context of microwave cavity QED, this paper proposes a new scheme for teleportation of an arbitrary pure state of two atoms. The scheme is very different from the previous ones which achieve the integrated state measurement,it deals in a probabilistic but simplified way. In the scheme, no additional atoms are involved and thus only two atoms are required to be detected. The scheme can also be used for the teleportation of arbitrary pure states of many atoms or two-mode cavities.
Soliton Atom Laser with Quantum State Transfer Property
Institute of Scientific and Technical Information of China (English)
LIU Xiong-Jun; JING Hui; GE Mo-Lin
2006-01-01
@@ We study the nonlinear effects in the quantum states transfer technique from photons to matter waves in the three-level case, which may provide the formation of a soliton atom laser with nonclassical atoms. The validity of quantum transfer mechanism is confirmed in the presence of the intrinsic nonlinear atomic interactions. The accompanied frequency chirp effect is shown to have no influence on the grey solitons formed by the output atom laser and the possible quantum depletion effect is also briefly discussed.
1996-01-01
Interviews following the 1991 co-operation Agreement between the Department of Atomic Energy (DAE) of the Government of India and the European Organization for Nuclear Research (CERN) concerning the participation in the Large Hadron Collider Project (LHC) . With Chidambaram, R, Chairman, Atomic Energy Commission and Secretary, Department of Atomic Energy, Department of Atomic Energy (DAE) of the Government of India and Professor Llewellyn-Smith, Christopher H, Director-General, CERN.
Reichel, Jakob
2010-01-01
This book provides a stimulating and multifaceted picture of a rapidly developing field. The first part reviews fundamentals of atom chip research in tutorial style, while subsequent parts focus on the topics of atom-surface interaction, coherence on atom chips, and possible future directions of atom chip research. The articles are written by leading researchers in the field in their characteristic and individual styles.
Chen, Jun Mian
2017-01-01
The extant literature on student migration flows generally focus on the traditional push-pull factors of migration at the individual level. Such a tendency excludes the broader levels affecting international student mobility. This paper proposes a hybrid of three levels of push-pull dynamics (micro-individual decision-making, meso-academic…
Long-lived entangled qudits in a trapped three-level ion beyond the Lamb-Dicke limit
Energy Technology Data Exchange (ETDEWEB)
Dermez, Rasim [Department of Physics, Afyon Kocatepe University, Afyonkarahisar 03200 (Turkey); Muestecaplioglu, Oezguer E [Department of Physics, Koc University, Sariyer, Istanbul 34450 (Turkey)], E-mail: dermez@aku.edu.tr
2009-01-15
Higher dimensional quantum entanglement in a trapped three-level ion interacting with two laser beams in {lambda} scheme is investigated beyond the Lamb-Dicke limit. It is shown that higher dimensional entanglement can be established in a single step, with a tunable dimensionality and duration via the Lamb-Dicke parameter.
DEFF Research Database (Denmark)
Ma, Ke; Blaabjerg, Frede
2016-01-01
This letter investigates the loss and thermal behaviors of a three-level neutral-point-clamped (3L-NPC) inverter undergoing moderate modulation index, which is typically presented during minor voltage sags of the power grid or speed changes of the electric machines. A series of new space vector m...
Dong, Nianbo; Spybrook, Jessaca; Kelcey, Ben
2016-01-01
The purpose of this study is to propose a general framework for power analyses to detect the moderator effects in two- and three-level cluster randomized trials (CRTs). The study specifically aims to: (1) develop the statistical formulations for calculating statistical power, minimum detectable effect size (MDES) and its confidence interval to…
DEFF Research Database (Denmark)
Lee, Kyo-Beum; Huh, Sung-Hoe; Yoo, Ji-Yoon
2005-01-01
A stable sensorless controller for DTC of induction motor fed by three-level inverter using the Radial Basis Function Network (RBFN) is presented in this paper. The torque ripple can be drastically reduced and low speed performance can be obtained in the DTC system for high performance induction ...
Design of Three-Phase Three-Level CIC T-Source Inverter with Maximum Boost Control
DEFF Research Database (Denmark)
Shults, Tatiana; Husev, Oleksandr; Roncero-Clemente, Carlos
2015-01-01
This paper presents guidelines for component design of the three-level three-phase T-source inverter with continuous input current under maximum boost control proposed recently. Steady state analysis under low-frequency current and voltage ripples in the dc side was made. Component sizes for both...
Medium voltage three-level converters for the grid connection of a multi-MW wind turbine
DEFF Research Database (Denmark)
Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig;
2009-01-01
Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter topo...
van Veldhoven, M; de Jonge, J; Broersen, S; Kompier, M; Meijman, T
2002-01-01
This cross-sectional questionnaire study presents a multi-level analysis on 2565 workers in 188 departments in 36 organizations in the Netherlands. A three-level model is used in which individual workers are nested within departments, which in turn are nested within organizations. Research questions
Real-Time Estimation of Power System Frequency Using a Three-Level Discrete Fourier Transform Method
Directory of Open Access Journals (Sweden)
Soon-Ryul Nam
2014-12-01
Full Text Available This paper proposes a three-level discrete Fourier transform (DFT method to provide an accurate estimate of power system frequency in real time. The first level decomposes a power system signal into two orthogonal cosine- and sine-filtered signals. The second and third levels are used to determine the amplitude ratio of the cosine- and sine-filtered signals without encountering the zero-crossing problem and with an increase in ability to suppress harmonics and inter-harmonics. The performance of the three-level DFT method is evaluated using computer-simulated signals with harmonics and inter-harmonics. The three-level DFT method is also implemented on a digital signal processor (DSP-based hardware prototype, and its performance in the hardware implementation is evaluated using a real-time digital simulator (RTDS. The evaluation results show that the three-level DFT method can achieve real-time estimation of power system frequency with satisfactory performance.
Quezada, L. F.; Nahmad-Achar, E.
2017-01-01
We show how the use of variational states to approximate the ground state of a system can be employed to study a multimode Dicke model. One of the main contributions of this work is the introduction of a not very commonly used quantity, the cooperation number, and the study of its influence on the behavior of the system, paying particular attention to the quantum phase transitions and the accuracy of the used approximations. We also show how these phase transitions affect the dependence of the expectation values of some of the observables relevant to the system and the entropy of entanglement with respect to the energy difference between atomic states and the coupling strength between matter and radiation, thus characterizing the transitions in different ways.
Energy Technology Data Exchange (ETDEWEB)
Safronova, M. S. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Clark, Charles W. [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899-8410 (United States); Kozlov, M. G. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation)
2015-01-22
The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.
Two-Photon Collective Atomic Recoil Lasing
Directory of Open Access Journals (Sweden)
James A. McKelvie
2015-11-01
Full Text Available We present a theoretical study of the interaction between light and a cold gasof three-level, ladder conﬁguration atoms close to two-photon resonance. In particular, weinvestigate the existence of collective atomic recoil lasing (CARL instabilities in differentregimes of internal atomic excitation and compare to previous studies of the CARL instabilityinvolving two-level atoms. In the case of two-level atoms, the CARL instability is quenchedat high pump rates with signiﬁcant atomic excitation by saturation of the (one-photoncoherence, which produces the optical forces responsible for the instability and rapid heatingdue to high spontaneous emission rates. We show that in the two-photon CARL schemestudied here involving three-level atoms, CARL instabilities can survive at high pump rateswhen the atoms have signiﬁcant excitation, due to the contributions to the optical forces frommultiple coherences and the reduction of spontaneous emission due to transitions betweenthe populated states being dipole forbidden. This two-photon CARL scheme may form thebasis of methods to increase the effective nonlinear optical response of cold atomic gases.
DEFF Research Database (Denmark)
Krüger, Peter; Hofferberth, S.; Haller, E.
2005-01-01
Miniaturized potentials near the surface of atom chips can be used as flexible and versatile tools for the manipulation of ultracold atoms on a microscale. The full scope of possibilities is only accessible if atom-surface distances can be reduced to microns. We discuss experiments in this regime...
Guerra, E S
2004-01-01
In this article we discuss two schemes of teleportation of atomic states. In the first scheme we consider atoms in a three-level cascade configuration and in the second scheme we consider atoms in a three-level lambda configuration. The experimental realization proposed makes use of cavity Quatum Electrodynamics involving the interaction of Rydberg atoms with a micromaser cavity prepared in a state $|\\psi >_{C}=(|0> +|1>)/\\sqrt{2}$
Institute of Scientific and Technical Information of China (English)
FAN Hong-Yi; LU Hai-Liang
2006-01-01
We show that the time-dependent two-mode Fresnel operator is just the time-evolutional unitary operator governed by the Hamiltonian composed of quadratic combination of canonical operators in the way of exhibiting SU(1,1)algebra. This is an approach for obtaining the time-dependent Hamiltonian from the preassigned time evolution in classical phase space, an approach which is in contrast to Lewis-Riesenfeld's invariant operator theory of treating time-dependent harmonic oscillators.
Directory of Open Access Journals (Sweden)
Boucher Yann G.
2017-01-01
Full Text Available In terms of Linear Algebra, a directional coupler between a single-mode waveguide and a two-mode waveguide can be thought of as formally equivalent to a set of three mutually coupled single-mode waveguides. Its responses, easily derived in the frame of ternary Coupled-Mode Theory, are used to establish analytically the scattering parameters of a hybrid ring-based modal multiplexer.
Boucher, Yann G.; Parini, Alberto; Féron, Patrice
2017-03-01
In terms of Linear Algebra, a directional coupler between a single-mode waveguide and a two-mode waveguide can be thought of as formally equivalent to a set of three mutually coupled single-mode waveguides. Its responses, easily derived in the frame of ternary Coupled-Mode Theory, are used to establish analytically the scattering parameters of a hybrid ring-based modal multiplexer.
Snijders, Tom A B; Lomi, Alessandro; Torló, Vanina Jasmine
2013-05-01
We propose a new stochastic actor-oriented model for the co-evolution of two-mode and one-mode networks. The model posits that activities of a set of actors, represented in the two-mode network, co-evolve with exchanges and interactions between the actors, as represented in the one-mode network. The model assumes that the actors, not the activities, have agency. The empirical value of the model is demonstrated by examining how employment preferences co-evolve with friendship and advice relations in a group of seventy-five MBA students. The analysis shows that activity in the two-mode network, as expressed by number of employment preferences, is related to activity in the friendship network, as expressed by outdegrees. Further, advice ties between students lead to agreement with respect to employment preferences. In addition, considering the multiplexity of advice and friendship ties yields a better understanding of the dynamics of the advice relation: tendencies to reciprocation and homophily in advice relations are mediated to an important extent by friendship relations. The discussion pays attention to the implications of this study in the broader context of current efforts to model the co-evolutionary dynamics of social networks and individual behavior.
Space Vector Pulse Width Modulation Strategy for Single-Phase Three-Level CIC T-source Inverter
DEFF Research Database (Denmark)
Shults, Tatiana E.; Husev, Oleksandr O.; Blaabjerg, Frede
2016-01-01
This paper presents a novel space vector pulse-width modulation strategy for a single-phase three-level buck-boost inverter based on an impedance-source network. The case study system is based on T-source inverter with continuous input current. To demonstrate the improved performance of the inver......This paper presents a novel space vector pulse-width modulation strategy for a single-phase three-level buck-boost inverter based on an impedance-source network. The case study system is based on T-source inverter with continuous input current. To demonstrate the improved performance...... of the inverter, the strategy was compared the traditional pulse-width modulation. It is shown that the approach proposed has fewer switching states and does not suffer from neutral point misbalance....
Achalhi, A.; Bezza, M.; Belbounaguia, N.; Boujoudi, B.
2017-03-01
The performances of Direct Torque Control (DTC) of Induction machine are highly related to the inverter used therewith. The purpose of this paper is to highlight the efficiency of the space vector modulation (SVM) control of three level inverter associated with the direct torque control. The first part of this work is devoted to present the mathematical models of the DTC associated with 2-levels inverter then 3-levels inverter. Simulations on Matlab/Simulink will allow a comparative study to highlight advantages of the use of three levels inverter. The second part is devoted to the improvement of the DTC associated with a 3-levels inverter by application of the space vector modulation strategy (SVM) in order to manage the switching frequency and reduce harmonics. The efficiency of this solution will be attested by simulation on Matlab/Simulink.
Energy Technology Data Exchange (ETDEWEB)
Agamy, Mohammed; Harfman-Todorovic, Maja; Elasser, Ahmed; Essakiappan, Somasundaram
2013-03-01
Photovoltaic architectures with distributed power electronics provide many advantages in terms of energy yield as well as system level optimization. As the power level of the solar farm increases it becomes more beneficial to increase the dc collection network voltage, which requires the use of power devices with higher voltage ratings, and thus making the design of efficient, low cost, distributed power converters more challenging. In this paper a simple partial power converter topology is proposed. The topology is implemented using a three-level switching cell, which allows the use of semiconductor devices with lower voltage rating; thus improving design and performance and reducing converter cost. This makes the converters suitable for use for medium to high power applications where dc-link voltages of 600V~1kV may be needed without the need for high voltage devices. Converter operation and experimental results are presented for two partial power circuit variants using three-level switching cells.
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.
Pseudo information entropy of a three-level atom interaction with two-laser ﬁelds in -conﬁguration
Indian Academy of Sciences (India)
A-S F Obada; T M El-Shahat; M Abdel-Aty
2003-10-01
In this report we investigate some aspects of the pseudo entropy of multi-level system in the language of quantum information theory. The inﬂuence of the non-linear interaction and detuning parameter on the properties of the pseudo information entropy is examined.
Photon counting statistics of V-type three-level systems:Effects of the field fluctuations
Institute of Scientific and Technical Information of China (English)
彭勇刚; 郑雨军
2015-01-01
We investigate the infl uence of the filed fl uctuations to the emission photons of V three-level systems. The emission intensity I and Mandel’s Q parameter show stochastic resonance with respect to the pure dephasing constant γp. The amplitude fl uctuation of the field causes the systems lose their coherence, on the other way, the amplitude fl uctuation provides a new interference way for the systems. The quantum beats are shown in the orthogonal system.
DEFF Research Database (Denmark)
Pouresmaeil, Edris; Montesinos-Miracle, Daniel; Gomis-Bellmunt, Oriol
2011-01-01
This paper presents a control strategy of multilevel converters for integration of renewable energy resources into power grid. The proposed technique provides compensation for active, reactive, and harmonic current components of grid-connected loads. A three-level H-bridge converter is proposed a...... (THD) of grid current through Matlab/Simulink under proposed operating conditions. © 2011 EPE Association - European Power Electr....
Institute of Scientific and Technical Information of China (English)
HU Wen-Hui; YUAN Kai-Jun; HAN Yong-Chang; Shu Chuang-Cun; CONG Shu-Lin
2007-01-01
The Autler-Townes (AT) splitting in femtosecond photoelectron spectrum of three-level Lii molecules is theoretically investigated using time-dependent quantum wave packet method. With proper femtosecond laser pulses, three peaks of the AT splitting can be observed in the photoelectron spectrum. The AT splitting stems from rapid Rabi oscillation caused by intense ultrashort laser pluses. The effects of laser parameters on the molecular ionization dynamics are also discussed.
Directory of Open Access Journals (Sweden)
Stefan Seuring
2011-04-01
Full Text Available Supply chain management and closed-loop supply chain management (CLSCM have developed into established concepts in recent years. The related material cycles and product returns form an important part of all related processes with high potential for reducing environmental burden. The paper proposes a framework for (environmentally triggered closed-loop supply chain management, spanning three different levels: the societal or governance, the chain and the actor level. Within each level, a set of activities or processes can be identified. Taken together, the levels allow a comprehensive analysis of a closed-loop supply chain system. This is illustrated building on two case studies in the textile and apparel industry, where closed-loop supply chains have been designed to take specific apparel products back. The case studies are analyzed against all three levels and allow exemplification of related challenges and interrelations among the three levels. The three levels contribute to the further comprehension of the multiple issues having to be taken into account for successfully implementing closed-loop supply chains.
Atomic-position Localization Via Dual Measurement
Nha, H; Chang, J S; An, K; Nha, Hyunchul; Lee, Jai-Hyung; Chang, Joon-Sung; An, Kyungwon
2002-01-01
We study localization of atomic position when a three-level atom interacts with a quantized standing-wave field in the Ramsey interferometer setup. Both the field quadrature amplitude and the atomic internal state are measured to obtain the atomic position information. It is found that this dual measurement scheme produces an interference pattern superimposed on a diffraction-like pattern in the atomic position distribution, where the former pattern originates from the state-selective measurement and the latter from the field measurement. The present scheme results in a better resolution in the position localization than the field-alone measurement schemes. We also discuss the measurement-correlated mechanical action of the standing-wave field on the atom in the light of Popper's test.
Chebabhi, Ali; Fellah, Mohammed Karim; Kessal, Abdelhalim; Benkhoris, Mohamed F
2016-07-01
In this paper is proposed a new balancing three-level three dimensional space vector modulation (B3L-3DSVM) strategy which uses a redundant voltage vectors to realize precise control and high-performance for a three phase three-level four-leg neutral point clamped (NPC) inverter based Shunt Active Power Filter (SAPF) for eliminate the source currents harmonics, reduce the magnitude of neutral wire current (eliminate the zero-sequence current produced by single-phase nonlinear loads), and to compensate the reactive power in the three-phase four-wire electrical networks. This strategy is proposed in order to gate switching pulses generation, dc bus voltage capacitors balancing (conserve equal voltage of the two dc bus capacitors), and to switching frequency reduced and fixed of inverter switches in same times. A Nonlinear Back Stepping Controllers (NBSC) are used for regulated the dc bus voltage capacitors and the SAPF injected currents to robustness, stabilizing the system and to improve the response and to eliminate the overshoot and undershoot of traditional PI (Proportional-Integral). Conventional three-level three dimensional space vector modulation (C3L-3DSVM) and B3L-3DSVM are calculated and compared in terms of error between the two dc bus voltage capacitors, SAPF output voltages and THDv, THDi of source currents, magnitude of source neutral wire current, and the reactive power compensation under unbalanced single phase nonlinear loads. The success, robustness, and the effectiveness of the proposed control strategies are demonstrated through simulation using Sim Power Systems and S-Function of MATLAB/SIMULINK.
Born, Max
1989-01-01
The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.
Imboden, Matthias; Pardo, Flavio; Bolle, Cristian; Han, Han; Tareen, Ammar; Chang, Jackson; Christopher, Jason; Corman, Benjamin; Bishop, David
2013-03-01
Here we present a MEMS based method to fabricate devices with a small number of atoms. In standard semiconductor fabrication, a large amount of material is deposited, after which etching removes what is not wanted. This technique breaks down for structures that approach the single atom limit, as it is inconceivable to etch away all but one atom. What is needed is a bottom up method with single or near single atom precision. We demonstrate a MEMS device that enables nanometer position controlled deposition of gold atoms. A digitally driven plate is swept as a flux of gold atoms passes through an aperture. Appling voltages on four comb capacitors connected to the central plate by tethers enable nanometer lateral precision in the xy plane over 15x15 sq. microns. Typical MEMS structures have manufacturing resolutions on the order of a micron. Using a FIB it is possible to mill apertures as small as 10 nm in diameter. Assuming a low incident atomic flux, as well as an integrated MEMS based shutter with microsecond response time, it becomes possible to deposit single atoms. Due to their small size and low power consumption, such nano-printers can be mounted directly in a cryogenic system at ultrahigh vacuum to deposit clean quench condensed metallic structures.
Atom-field entanglement in two-atom Jaynes-Cummings model with intensity-dependent coupling
Bashkirov, E. K.
2014-01-01
An exact solution of the problem of two-atom one- and two-mode Jaynes-Cummings model with intensity-dependent coupling is presented. Asymptotic solutions for system state vectors are obtained in the approximation of large initial coherent fields. The atom-field entanglement is investigated on the basis of the reduced atomic entropy dynamics. The possibility of the system being initially in a pure disentangled state to revive into this state during the evolution process for both models is show...
Light Propagation in Ultracold Atomic Gases
Bariani, Francesco
2009-01-01
The propagation of light through an ultracold atomic gas is the main topic of the present work. The thesis consists of two parts. In Part I (Chapters 1,2,3), we give a complete description of the 1D photonic bands of a MI of two-level atoms paying attention to both band diagrams and reflectivity spectra. The role of regular periodicity of the system is addressed within a polariton formalism. The scattering on defects inside lattices of three-level atoms is also studied in view of optica...
Three-level three-phase neutral-point-clamped back-to-back converter applied to a wind emulator
Calle Prado, Alejandro; Rocabert Delgado, Joan; Busquets Monge, Sergio; Bordonau Farrerons, José; Alepuz Menéndez, Salvador; Peracaula Roura, Joan
2009-01-01
This paper presents a three-level three-phase neutral-point-clamped back-to-back converter applied to a wind emulator, where a wind power generator is connected to the grid through the back-to-back converter. The converter regulates the power extracted from the generator and controls how this power is injected to the grid with the desired power factor. Two phase locked loops are in charge of synchronizing the generator-side and the grid-side converters, regardless of the rotor speed of the...
DEFF Research Database (Denmark)
Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.
2013-01-01
A new pulse width modulation (PWM) strategy which is an alternative approach of discontinuous PWM (DPWM) for a three-level neutral point clamped (NPC) inverter is developed and presented in this paper. The proposed PWM scheme not only takes advantage of the special properties available in NPC...... can be simplified. The salient features of the proposed scheme, as compared with the existing carrier-based DPWM strategies, are: 1) its reduced computational processing time, 2) its capability to balance the DC-link voltage without any additional control and 3) its reduced complexity e.g. only one...
Medium Voltage Three-level Converters for the Grid Connection of aMulti-MW Wind Turbine
DEFF Research Database (Denmark)
Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig
2009-01-01
Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter...... connection circuit (without capacitive switching ripple filters), the 3L-HB-VSC is expected to be superior with respect to power density and reliability over the 3L-NPC- and -FC-VSCs....
DEFF Research Database (Denmark)
Pouresmaeil, Edris; Montesinos-Miracle, Daniel; Gomis-Bellmunt, Oriol
2011-01-01
This paper presents a control strategy of multilevel converters for integration of renewable energy resources into power grid. The proposed technique provides compensation for active, reactive, and harmonic current components of grid-connected loads. A three-level H-bridge converter is proposed...... as the interfacing system between renewable energy resources and utility grid. High performance of the proposed technique is indicated with injection of maximum available power from renewable energy resources to the power grid, increases power factor of the utility grid, and reduces the total harmonic distortion...
Institute of Scientific and Technical Information of China (English)
SONG Wen-xiang; YAO Gang; CHEN Chen; CHEN Guo-cheng
2008-01-01
A new modulation approach was presented for the control of neutral-point (NP) voltage variation in the three-level NP-clamped voltage source inverter, and the average NP current model was established based on vector diagram partition. Thus, theory base was built for balancing control of NP potential. Theoretical analysis and experimental results indicate that the proposed method for NP balancing control vector synthesizing concept based can make the average NP current zero, and do not influence NP potential within every sample period. The effectiveness of proposed research approach was verified by simulative and experimental results.
DEFF Research Database (Denmark)
Kejian, Song; Konstantinou, Georgios; Jing, Li
2017-01-01
Operational data from Chinese railways indicate a number of challenges for traction four-quadrant converter (4QC) control including low-order voltage and current harmonics and reference tracking. A control strategy for a single-phase three-level neutral-point-clamped 4QC employed in the electric...... multiple unit traction system is proposed in this study. The strategy is based on a multiple frequency tuned quasi-proportional resonant controller in the ac-side current loop and a multiple frequency tuned notch filter in the dc-link voltage loop. Under the typical supply voltage distortion present...
Directory of Open Access Journals (Sweden)
Jiraporn Janwised
2014-01-01
Full Text Available We introduce a new technique, a three-level average linear-implicit finite difference method, for solving the Rosenau-Burgers equation. A second-order accuracy on both space and time numerical solution of the Rosenau-Burgers equation is obtained using a five-point stencil. We prove the existence and uniqueness of the numerical solution. Moreover, the convergence and stability of the numerical solution are also shown. The numerical results show that our method improves the accuracy of the solution significantly.
Entanglement swapping between atom and cavity and generation of entangled state of cavity fields
Institute of Scientific and Technical Information of China (English)
Chen Ai-Xi; Deng Li
2007-01-01
This paper proposes a scheme where entanglement swapping between atom and cavity can be realized. A-type three-level atoms interacting resonantly with cavity field are considered. By detecting atom and cavity field, it realizes entanglement swapping between atom and cavity. It uses the technique of entanglement swapping to generate an entangled state of two cavity fields by measuring on atoms. It discusses the experimental feasibility of the proposed scheme and application of entangled state of cavity fields.
Directory of Open Access Journals (Sweden)
K.Mohan Krishna
2015-12-01
Full Text Available Multilevel inverter topology has developed recently as a very important alternative in the area of high power medium voltage energy control. In multilevel inverter, thethree basic types of topologies used are diode clamped inverter (neutral point clamped, capacitorclamped (flying capacitor and cascaded multi cell with separate dc sources. Multilevel inverters are used in medium voltage and high power applications with less harmonic contents. This paper proposes a software implementation of neutral point clamped (NPC three level voltage source inverter using space vector pulse width modulation (SVPWM techniques. The inverter feeds an electrical system which is controlled by field oriented control (FOC.The improvement of the control technique is achieved using intelligence techniques. The operation of the electrical system is verified in steady state and transient state responses. This software implementation is performed by using matlab/Simulink software. This paper gives comparison between SVPWM three phase three level with neutral point clamped and without neutral point clamped. Finally, the comparative study of different techniques was implemented.
Information entropy of a time-dependent three-level trapped ion interacting with a laser field
Abdel-Aty, Mahmoud
2005-10-01
Trapped and laser-cooled ions are increasingly used for a variety of modern high-precision experiments, frequency standard applications and quantum information processing. Therefore, in this communication we present a comprehensive analysis of the pattern of information entropy arising in the time evolution of an ion interacting with a laser field. A general analytic approach is proposed for a three-level trapped-ion system in the presence of the time-dependent couplings. By working out an exact analytic solution, we conclusively analyse the general properties of the von Neumann entropy and quantum information entropy. It is shown that the information entropy is affected strongly by the time-dependent coupling and exhibits long time periodic oscillations. This feature attributed to the fact that in the time-dependent region Rabi oscillation is time dependent. Using parameters corresponding to a specific three-level ionic system, a single beryllium ion in a RF-(Paul) trap, we obtain illustrative examples of some novel aspects of this system in the dynamical evolution. Our results establish an explicit relation between the exact information entropy and the entanglement between the multi-level ion and the laser field. We show that different nonclassical effects arise in the dynamics of the ionic population inversion, depending on the initial states of the vibrational motion/field and on the values of Lamb-Dicke parameter η.
Moeyaert, Mariola; Ugille, Maaike; Ferron, John M; Beretvas, S Natasha; Van den Noortgate, Wim
2013-06-01
In this study, we focus on a three-level meta-analysis for combining data from studies using multiple-baseline across-participants designs. A complicating factor in such designs is that results might be biased if the dependent variable is affected by not explicitly modeled external events, such as the illness of a teacher, an exciting class activity, or the presence of a foreign observer. In multiple-baseline designs, external effects can become apparent if they simultaneously have an effect on the outcome score(s) of the participants within a study. This study presents a method for adjusting the three-level model to external events and evaluates the appropriateness of the modified model. Therefore, we use a simulation study, and we illustrate the new approach with real data sets. The results indicate that ignoring an external event effect results in biased estimates of the treatment effects, especially when there is only a small number of studies and measurement occasions involved. The mean squared error, as well as the standard error and coverage proportion of the effect estimates, is improved with the modified model. Moreover, the adjusted model results in less biased variance estimates. If there is no external event effect, we find no differences in results between the modified and unmodified models.
Directory of Open Access Journals (Sweden)
Ming-Hung Chen
2015-06-01
Full Text Available This paper describes the design and implementation of three-level power converters for wind-driven permanent-magnet synchronous generators with unbalanced loads. To increase voltage stress and reduce current harmonics in the electrical power generated by a wind generator, a three-phase, three-level rectifier is used. Because a synchronous rotating frame is used on the AC-input side, the use of a neutral-point-clamped controller is proposed to increase the power factor to unity and reduce current harmonics. Furthermore, a novel six-leg inverter is proposed for transferring energy from the DC voltage to a three-phase, four-wire AC source with a constant voltage and a constant frequency. The power converters also contain output transformers and filters for power buffering and filtering, respectively. All three output phase voltages are fed back to control the inverter output during load variations. A digital signal processor is used as the core control device for implementing a 1.5 kV, 75 kW drive system. Experimental data show that the power factor is successfully increased to unity and the total current harmonic distortion is 3.2% on the AC-input side. The entire system can attain an efficiency of 91%, and the voltage error between the upper and lower capacitors is approximately zero. Experimental results that confirm the high performance of the proposed system are presented.
Wilson, David B.
1981-01-01
Surveys the research of scientists like Joule, Kelvin, Maxwell, Clausius, and Boltzmann as it comments on the basic conceptual issues involved in the development of a more precise kinetic theory and the idea of a kinetic atom. (Author/SK)
Li, Huajiao; Fang, Wei; An, Haizhong; Gao, Xiangyun; Yan, Lili
2016-05-01
Economic networks in the real world are not homogeneous; therefore, it is important to study economic networks with heterogeneous nodes and edges to simulate a real network more precisely. In this paper, we present an empirical study of the one-mode derivative holding-based network constructed by the two-mode affiliation network of two sets of actors using the data of worldwide listed energy companies and their shareholders. First, we identify the primitive relationship in the two-mode affiliation network of the two sets of actors. Then, we present the method used to construct the derivative network based on the shareholding relationship between two sets of actors and the affiliation relationship between actors and events. After constructing the derivative network, we analyze different topological features on the node level, edge level and entire network level and explain the meanings of the different values of the topological features combining the empirical data. This study is helpful for expanding the usage of complex networks to heterogeneous economic networks. For empirical research on the worldwide listed energy stock market, this study is useful for discovering the inner relationships between the nations and regions from a new perspective.
Song, Kyung Jin; Kim, Gyu Hyung; Choi, Byeong Yeol
2011-03-01
To evaluate the clinical efficacy of three-level anterior cervical arthrodesis with polyethyletherketone (PEEK) cages and plate fixation for aged and osteoporotic patients with degenerative cervical spinal disorders. Twenty one patients, who had undergone three-level anterior cervical arthrodesis with a cage and plate construct for degenerative cervical spinal disorder from November 2001 to April 2007 and were followed up for at least two years, were enrolled in this study. The mean age was 71.7 years and the mean T-score using the bone mineral density was -2.8 SD. The fusion rate, change in cervical lordosis, adjacent segment degeneration were analyzed by plain radiographs and computed tomography, and the complications were assessed by the medical records. The clinical outcomes were analyzed using the SF-36 physical composite score (PCS) and neck disability index (NDI). Radiological fusion was observed at a mean of 12.3 weeks (range, 10 to 15 weeks) after surgery. The average angle of cervical lordosis was 5° preoperatively, 17.6° postoperatively and 16.5° at the last follow-up. Degenerative changes in the adjacent segments occurred in 3 patients (14.3%), but revision surgery was unnecessary. In terms of instrument-related complications, there was cage subsidence in 5 patients (23.8%) with an average of 2.8 mm, and loosening of the plate and screw occurred in 3 patients (14.3%) but there were no clinical problems. The SF-36 PCS before surgery, second postoperative week and at the last follow-up was 29.5, 43.1, and 66.2, respectively. The respective NDI was 55.3, 24.6, and 15.9. For aged and osteoporotic patients with degenerative cervical spinal disorders, three-level anterior cervical arthrodesis with PEEK cages and plate fixation reduced the pseudarthrosis and adjacent segment degeneration and improved the clinical outcomes. This method is considered to be a relatively safe and effective treatment modality.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Objective: The functional relationship between calculated alpha band spectral power and inter-/intra-hemispheric coherence during a three-level working memory task of patients with mild cognitive impairment (MCI) was investigated. Methods:Subjects included 35 MCI patients according to the DSM-Ⅳ criteria (mean age: 62.3, SD: 6.5) and 34 healthy controls (mean age:57.4, SD: 4.0) were selected from the community at large. All subjects performed a simple calculation and recall task with three levels of working memory load while electroencephalograph (EEG) signal was recorded. The spectral EEG power was computed over alphal (8.0～10.0 Hz) and alpha2 (10.5～13.0 Hz) frequency bands and was compared between rest stage and working memory processing stage by two-way ANOVA. Post hoc testing analyzed the differences between each two levels of working memory load during task processing. The inter-hemisphere EEG coherence of frontal (F3-F4), central (C3-C4), parietal (P3-P4), temporal (T5-T6) as well as occipital (O1-O2) was compared between MCI patients and normal controls. The EEG signals from F3-C3,F4-C4, C3-P3, C4-P4, P3-O1, P4-O2, T5-C3, T6-C4, T5-P3 and T6-P4 electrode pairs resulted from the intra-hemispheric action for alphal and alpha2 frequency bands. Result: There was significantly higher EEG power from MCI patients than from normal controls both at rest and during working memory processing. Significant differences existed between rest condition and three-level working memory tasks (P＜0.001). The inter- and intra-hemispheric coherence during working memory tasks showed a "drop to rise" tendency compared to that at rest condition. There was significantly higher coherence in MCI patients than in the controls.When task difficulties increased, the cortical connectivity of intra-hemispheric diminished while the inter-hemispheric connectivity dominantly maintained the cognitive processing in MCI patients. Conclusion: The results of the present study indicate that the
DEFF Research Database (Denmark)
Liu, Dong; Deng, Fujin; Chen, Zhe
2017-01-01
The capacitor current would be imbalanced under the conventional control strategy in the half-bridge three-level (HBTL) DC/DC converter due to the effect of the output inductance of the power supply and the input line inductance, which would affect the converter's reliability. This paper proposes...... a pulse-wide modulation (PWM) strategy composed of two operation modes for the HBTL DC/DC converter, which can realize the zero-voltage switching (ZVS) for the efficiency improvement. In addition, a capacitor current balancing control is proposed by alternating the two operation modes of the proposed ZVS...... PWM strategy, which can eliminate the current imbalance among the two input capacitors. Therefore, the proposed control strategy can improve the converter's performance and reliability in: 1) reducing the switching losses and noises of the power switches; 2) balancing the thermal stresses...
DEFF Research Database (Denmark)
Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, S.
2013-01-01
A Neutral-Point-Clamped (NPC) three-level inverter with small dc-link capacitors is presented in this paper. The inverter requires zero average neutral-point current for stable neutral-point voltage. The small dc-link capacitors may not maintain capacitor voltage balance, even with zero neutral-point...... current. This may happen due to nonlinearities present in the circuit. This requires a fast control of the neutral-point voltage. A simple carrier based modulation strategy which allows modeling of the neutral-point voltage dynamics as a continuous function of power drawn from the inverter is proposed....... This continuous model shows that the neutral-point current is proportional to the power drawn from the inverter, and it enables the use of well established classical control theory for the neutral-point voltage controller design. A simple PI (proportional integral) controller is designed for the neutral-point...
Diagnosis and Tolerant Strategy of an Open-Switch Fault for T-type Three-Level Inverter Systems
DEFF Research Database (Denmark)
Choi, Uimin; Lee, Kyo Beum; Blaabjerg, Frede
2014-01-01
This paper proposes a new diagnosis method of an open-switch fault and fault-tolerant control strategy for T-type three-level inverter systems. The location of faulty switch can be identified by the average of normalized phase current and the change of the neutral-point voltage. The proposed fault......-tolerant strategy is explained by dividing into two cases: the faulty condition of half-bridge switches and the neutral-point switches. The performance of the T-type inverter system improves considerably by the proposed fault tolerant algorithm when a switch fails. The roposed method does not require additional...... components and complex calculations. Simulation and experimental results verify the feasibility of the proposed fault diagnosis and fault-tolerant control strategy....
Institute of Scientific and Technical Information of China (English)
Jie ZHANG; Ryuichi YOKOYAMA; Jinhua SHE; Win WU
2013-01-01
One problem with a single source three-level inverter is the drafting of its neutral-point voltage. This may occur during transition or when unbalanced loads are connected to the inverter system. Variation of neutral-point voltage may greatly deteriorate the power quality. In this paper, we employ an equivalent-input-disturbance approach to deal with this problem. By adding an extra neutral leg, the control problem of neutral-point voltage is converted to a disturbance rejection problem. This method suppresses the variation of the neutral-point voltage to a low level and reduces the capacity of DC-link capacitors. Simulation results show the effectiveness of the method.
DEFF Research Database (Denmark)
Ma, Ke; Blaabjerg, Frede; Liserre, Marco
2012-01-01
In order to fulfill the continuous growing grid-side demands, the full-scale power converters are becoming more and more popular in the wind power application. Nevertheless, the more severe loading of the power semiconductor devices in the full-scale power converters, especially during Low Voltag...... devices is highlighted. It has been found that the thermal loading of the phases of the power converter may be uneven and dependent on the different types and severities of grid voltage dips as well as on the chosen control algorithms....... Ride Through (LVRT) operation under grid faults, may compromise the reliability of the system and consequently further increase its cost. In this paper, the impact of various grid faults on a three-level Neutral-Point-Clamped (3L-NPC) grid-converter in terms of thermal loading of power semiconductor...
Reliability Improvement of a T-Type Three-Level Inverter With Fault-Tolerant Control Strategy
DEFF Research Database (Denmark)
Choi, Uimin; Blaabjerg, Frede; Lee, Kyo-Beum
2015-01-01
in a neutral-point switch, two methods will be proposed and compared based on thermal analysis and neutral-point voltage oscillation. The reliability of T-type inverter systems is improved considerably by the proposed algorithm when a switch fails. The proposed method does not require any additional components......This paper proposes a fault-tolerant control strategy for a T-type three-level inverter when an open-circuit fault occurs. The proposed method is explained by dividing fault into two cases: the faulty condition of half-bridge switches and neutral-point switches. In case of the open-circuit fault....... Simulation and experimental results verify the validity and feasibility of the proposed fault-tolerant control strategy....
Ernst, Stephan
2004-01-01
In the debate on the ethical evaluation of the stem cell research three levels can be differentiated. The first level of argumentation is that of weighing up goods: The possible therapeutical success for thousands of humans seems to justify the consumption of a few embryos. It is show, that this, however, already presupposes - on a second argumentation level - a judgement on the moral status of the embryo. Different moments of time, when human dignity and life protection are ascribe to the embryo, have already been discussed, but in spite of all rationality of the arguments a consensus has not been reached. On this third level of argumentation two fundamental meanings of reality can be differentiated. The empirical-observing and the communicative-participating view. These lead to a different moral evaluation of the embryo. This contribution votes for the priority of the communicative-participating view. It receives addition support by theology and Christian faith.
DEFF Research Database (Denmark)
Choi, Uimin; Lee, June-Seok; Lee, Kyo-Beum
2014-01-01
This paper proposes a new modulation strategy that balances the neutral-point voltage for three-level neutral-clamped inverter systems. The proposed modulation replaces the P-type or N-type small switching states with other switching states that do not affect the neutral-point voltage. The zero...... and medium switching states are employed to help the neutral-point voltage balancing. This method little bit increases the switching events and output total harmonic distortion. However, this method has a strong balancing ability at all regions. Further, it is very simple to implement in both space vector...... modulation and carrier-based PWM methods. Simulation and experimental results verify the validity and feasibility of the proposed new modulation strategy....
Institute of Scientific and Technical Information of China (English)
He Qiong-Yi; Wang Tie-Jun; Gao Jin-Yue
2006-01-01
A simple three-level system is proposed to produce high index of refraction with zero absorption in an Er3+-doped yttrium aluminium garnet (YAG) crystal, which is achieved for a probe field between the excited state 4Ⅰ13/2 and ground state 4Ⅰ15/2 by adjusting a strong coherent driving field between the upper excited state 4Ⅰ11/2 and 4Ⅰ15/2· It is found that the changes of the frequency of the coherent driving field and the concentration of Er3+ ions in the YAG crystal can maximize the index of refraction accompanied by vanishing absorption. This result could be useful for the dispersion compensation in fibre communication, laser particle acceleration, high precision magnetometry and so on.
Institute of Scientific and Technical Information of China (English)
Liu Ji-Cai; Wang Chun-Xin; Gel'mukhanov Faris; Wang Chuan-Kui
2008-01-01
This paper investigates the dynamics of cooperative emissions in a cascade three-level system driven by an ultrashort laser pulse by solving numerically the full-wave Maxwell-Bloeh equations.The 4,4'-bis(dimethylamino) stilbene molecule is used as the model molecule because of its strong two-photon absorption property.The two-colour cooperative emissions are studied as functions of molecular number density and dephasing rate of the dipole coherence.The propagation effects on the evolution of the cooperative radiations are also taken into account.The cooperative radiations are enhanced for large number density of the molecule,while the fast dephasing of the dipole coherence reduces the intensity of the cooperative radiations and delays the emission times or even inhibits the formation of the emissions.The delay time of the radiation decreases with the increase of the molecular number density and the propagation distance.
Directory of Open Access Journals (Sweden)
S.Saravanan
2014-04-01
Full Text Available In this paper, the analysis of a three-level LLC series resonant converter (TL LLC SRC for high- and wide input-voltage applications is presented. It consists of two half-bridge LLC SRCs in series, sharing a resonant inductor and a transformer. Its main advantages are that the voltage across each switch is clamped at half of the input voltage and that voltage balance is achieved and simple driving signals . Thus it is suitable for high-inputvoltage applications. Based on the results of these analyses, a design example is provided and its validity is confirmed by an experiment involving a prototype converter with an input of 600V and an output of 48 V/20 A.
DEFF Research Database (Denmark)
Ma, Ke; Liserre, Marco; Blaabjerg, Frede
2014-01-01
In order to fulfill the growing demands from the grid side, full-scale power converters are becoming popular in the wind turbine system. The low-voltage ride-through (LVRT) requirements may not only cause control problems but also result in overstressed components for the power converter. However......, the thermal loading of the wind power converter under various grid faults is still not yet clarified, particularly at megawatt power level. In this paper, the impacts by three types of grid faults to a three-level neutral-point-clamped (3L-NPC) wind power converter in terms of operating and loading conditions...... are analytically solved and simulated. It has been found that the operating and loading conditions of the converter under LVRT strongly depend on the types/severity values of grid voltage dips and also the chosen control algorithms. The thermal distribution among the three phases of the converter may be quite...
Control of improved full-bridge three-level DC/DC converter for wind turbines in a DC grid
DEFF Research Database (Denmark)
Deng, Fujin; Chen, Zhe
2013-01-01
transformer in the IFBTL dc/dc converter. A modulation strategy, including two operation modes, is proposed for the IFBTL dc/dc converter. Then, a voltage balancing control strategy is proposed for the IFBTL dc/dc converter. Furthermore, the control of the wind turbine based on the IFBTL dc/dc converter......This paper presents an improved full-bridge three-level (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency...... in a dc-grid system is presented. Finally, a small-scale IFBTL dc/dc converter prototype was built and tested in the laboratory, and the results verify the theoretical analysis....
Two modes for dune orientation
Courrech Du Pont, Sylvain; Narteau, Clément; Gao, Xin
2015-11-01
Earth sand seas experience winds that blow with different strengths and from different directions in line with the seasons. In response, dune fields show a rich variety of shapes from small crescentic barchans to big star and linear dunes. Linear dunes often exhibit complex and compound patterns with different length scales and orientations, which seem difficult to relate to a single wind cycle. We present results of underwater experiments and numerical simulations where a single wind regime can lead to two different dunes orientation depending on sediment availability. Sediment availability selects the overriding mechanism for the formation of dunes: increasing in height from the destabilization of a sand bed or elongating in a finger on a non-erodible ground from a localized sand source. These mechanisms drive the dunes orientation. Therefore, dunes alignment maximizes dunes orthogonality to sand fluxes in the bed instability mode, while dunes are aligned with the sand transport direction in the fingering mode. Then, we derive a model for dunes orientation, which explains the coexistence of bedforms with different alignments and quantitatively predicts the orientation of dunes in Earth deserts. Finally, we explore the phase diagram and the stability of the fingering mode.
Loring, FH
2014-01-01
Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec
Nano Goes to School: A Teaching Model of the Atomic Force Microscope
Planinsic, Gorazd; Kovac, Janez
2008-01-01
The paper describes a teaching model of the atomic force microscope (AFM), which proved to be successful in the role of an introduction to nanoscience in high school. The model can demonstrate the two modes of operation of the AFM (contact mode and oscillating mode) as well as some basic principles that limit the resolution of the method. It can…
Nano Goes to School: A Teaching Model of the Atomic Force Microscope
Planinsic, Gorazd; Kovac, Janez
2008-01-01
The paper describes a teaching model of the atomic force microscope (AFM), which proved to be successful in the role of an introduction to nanoscience in high school. The model can demonstrate the two modes of operation of the AFM (contact mode and oscillating mode) as well as some basic principles that limit the resolution of the method. It can…
DEFF Research Database (Denmark)
Hesselbo, Stephen P.; Korte, Christoph
2010-01-01
-isotope signature), but also some significant contrasts (oxygen-isotope based paleotemperatures which provide no evidence for warming). Significant contrast in oxygen- and carbon-isotope co-variation also occurs on a long timescale. There appear to be two modes in the co-variation of carbon and oxygen isotopes...... environmental changes were global has been strongly debated. Nevertheless, partly as a result of the international effort to define Global Stratotype Sections and Points (GSSPs), much more is now being discovered about environmental changes taking place at and around the other Jurassic Age (Stage) boundaries...... that both long-term and short-term carbon-isotope shifts from the UK Early Jurassic represent global changes in carbon cycle balances. The Sinemurian-Pliensbachian boundary event is an event of global significance and shows several similarities to the Toarcian OAE (relative sea-level change, carbon...
Joshi, Nidhi; Mathew, Sylvia; George, John V.; Hegde, Swaroop; Bhandi, Shilpa; Madhu, K. S.
2016-01-01
Background: Alleviating pain is of utmost importance when treating patients with endodontic pain. Aim: To compare and evaluate the efficacy of two modes of delivery of pretreatment Piroxicam (Dolonex®, Pfizer) for the management of postendodontic pain. Materials and Methods: Sixty-six patients with symptomatic irreversible pulpitis were randomly divided into three groups of 22 subjects Group I - control group, no pharmacological intervention, Group II - patients received pretreatment oral Piroxicam (40 mg), Group III - patients received pretreatment intraligamentary injections totaling 0.4 mL of Piroxicam. Single visit endodontic therapy was performed by a single endodontist. Visual analogue scale was used to record pain before treatment and 4, 8, 12, 24, and 48 h postoperatively. Mann–Whitney U-test and Kruskal–Wallis tests were used to analyze the data. Results: The patients in Groups II and III perceived less postendodontic pain as compared to Group I (P Piroxicam was more efficacious. PMID:27563175
An, Pengli; Li, Huajiao; Zhou, Jinsheng; Chen, Fan
2017-10-01
Complex network theory is a widely used tool in the empirical research of financial markets. Two-mode and multi-mode networks are new trends and represent new directions in that they can more accurately simulate relationships between entities. In this paper, we use data for Chinese listed companies holding non-listed financial companies over a ten-year period to construct two networks: a two-mode primitive network in which listed companies and non-listed financial companies are considered actors and events, respectively, and a one-mode network that is constructed based on the decreasing-mode method in which listed companies are considered nodes. We analyze the evolution of the listed company co-holding network from several perspectives, including that of the whole network, of information control ability, of implicit relationships, of community division and of small-world characteristics. The results of the analysis indicate that (1) China's developing stock market affects the share-holding condition of listed companies holding non-listed financial companies; (2) the information control ability of co-holding networks is focused on a few listed companies and the implicit relationship of investment preference between listed companies is determined by the co-holding behavior; (3) the community division of the co-holding network is increasingly obvious, as determined by the investment preferences among listed companies; and (4) the small-world characteristics of the co-holding network are increasingly obvious, resulting in reduced communication costs. In this paper, we conduct an evolution analysis and develop an understanding of the factors that influence the listed companies co-holding network. This study will help illuminate research on evolution analysis.
Indian Academy of Sciences (India)
E K Bashkirov; M S Mastyugin
2015-01-01
Considering two artificial identical atoms interacting with two-mode thermal field through non-degenerate two-photon transitions, this paper studies the influence of atomic coherence and dipole–dipole interaction on the entanglement of two qubits. It is found that the entanglement is greatly enhanced by these mechanisms.
Directory of Open Access Journals (Sweden)
CORRYANTI
2007-07-01
Full Text Available To examine the phosphatase alkaline activity of VA mycorrhizal fungi in the rizhosphere and in root, teak seedlings inoculated spores of VA mycorrhizal fungi were grown in sterilized soils. Teak seedlings were fertilized with NPK fertilizer consisting three levels, i.e. 0; 0.0625; 0.125 g per seedling. Phosphatase alkaline in rizhosphere was measured in terms of pNP on soil dry weight basis, meanwhile alkaline phosphatase activity in roots were quantified in using method developed by Tisserant. The results showed that alkaline phosphatase activity increased on inoculated seedlings compare to with uninoculated. NPK fertilization of 0.0625 g per seedling and inoculation on teak seedlings showed alkaline phosphatase activity in range 90-201 EU, and in roots indicated in range 14-72%. Gigaspora sp inoculation on teak seedlings was showing the highest of alkaline phosphatase activity. Increasing phosphatase alkaline activity relevant to hyphae growth, and increasing of root infection decreased alkaline phosphatase activity. Arbuscular mycorrhizal inoculation increased seedling dry weight.
Non-Hermitian shortcut to adiabaticity of two- and three-level systems with gain and loss
Li, Guan-Qiang; Chen, Guang-De; Peng, Ping; Qi, Wei
2017-01-01
Achieving effectively adiabatic dynamics in finite time is a ubiquitous goal in virtually all fields of modern physics. So-called shortcuts to adiabaticity refer to a set of methods and techniques that allow us to obtain in a short time the same final state that would result from an adiabatic, infinitely slow process. In this paper we generalized the non-Hermitian shortcut method to the situation of the unbalanced gain and loss. We found that the ratio between the gain and loss can control the transfer time and may become a new freedom to speed up the adiabatic transfer process. By using two-level Landau-Zener model and Allen-Eberly model and three-level stimulated Raman adiabatic passage, we investigated the transfer processes and obtained the analytical results about the final transfer time, which are related with the parameters of the corresponding systems. It is pointed out that these processes can be implemented in many systems experimentally such as coupled optical waveguides.
Etxeberria, A.; Vechiu, I.; Baudoin, S.; Camblong, H.; Kreckelbergh, S.
2014-02-01
The increasing use of distributed generators, which are mainly based on renewable sources, can create several issues in the operation of the electric grid. The microgrid is being analysed as a solution to the integration in the grid of the renewable sources at a high penetration level in a controlled way. The storage systems play a vital role in order to keep the energy and power balance of the microgrid. Due to the technical limitations of the currently available storage systems, it is necessary to use more than one storage technology to satisfy the requirements of the microgrid application. This work validates in simulations and experimentally the use of a Three-Level Neutral Point Clamped converter to control the power flow of a hybrid storage system formed by a SuperCapacitor and a Vanadium Redox Battery. The operation of the system is validated in two case studies in the experimental platform installed in ESTIA. The experimental results prove the validity of the proposed system as well as the designed control algorithm. The good agreement among experimental and simulation results also validates the simulation model, that can therefore be used to analyse the operation of the system in different case studies.
A location-inventory model for distribution centers in a three-level supply chain under uncertainty
Directory of Open Access Journals (Sweden)
Ali Bozorgi-Amiri
2013-01-01
Full Text Available We study a location-inventory problem in a three level supply chain network under uncertainty, which leads to risk. The (r,Q inventory control policy is applied for this problem. Besides, uncertainty exists in different parameters such as procurement, transportation costs, supply, demand and the capacity of different facilities (due to disaster, man-made events and etc. We present a robust optimization model, which concurrently specifies: locations of distribution centers to be opened, inventory control parameters (r,Q, and allocation of supply chain components. The model is formulated as a multi-objective mixed-integer nonlinear programming in order to minimize the expected total cost of such a supply chain network comprising location, procurement, transportation, holding, ordering, and shortage costs. Moreover, we develop an effective solution approach on the basis of multi-objective particle swarm optimization for solving the proposed model. Eventually, computational results of different examples of the problem and sensitivity analysis are exhibited to show the model and algorithm's feasibility and efficiency.
Electromagnetically induced transparency with degenerate atomic levels
Reshetov, V A
2013-01-01
For the coherently driven \\Lambda-type three-level systems the general ready-to-calculate expression for the susceptibility tensor at the frequency of the weak probe field is obtained for the arbitrary polarization of the strong coupling laser field and arbitrary values of the angular momenta of resonant atomic levels. The dependence of the relative difference in the group velocities of the two polarization components of the probe field on the polarization of the coupling field is studied.
Storage of Quantum Variables in Atomic Media
DEFF Research Database (Denmark)
Cviklinski, J.; Ortalo, J.; Josse, V.
2007-01-01
Storage and read-out of non classical states of light is a critical element for quantum information networks. Simultaneous storage of two non-commuting variables carried by light and subsequent read-out is shown to be possible in atomic ensembles. Interaction of light fields with three-level syst......Storage and read-out of non classical states of light is a critical element for quantum information networks. Simultaneous storage of two non-commuting variables carried by light and subsequent read-out is shown to be possible in atomic ensembles. Interaction of light fields with three...
Atomic and efficient e-cash transaction protocol
Institute of Scientific and Technical Information of China (English)
王茜; 杨德礼
2004-01-01
Atomicity is necessary for reliable and secure electronic commerce transaction and to guarantee the participants'interests. An atomic and efficient e-cash (electronic cash) transaction protocol based on the classical e-cash scheme is presented. The delivery of digital goods is incorporated into the process of payment in the protocol. Apart from ensuring all three levels of atomicity, the novel protocol features high efficiency and practicability with unfavorable strong assumption removed. Furthermore, the proposed protocol provides non-repudiation proofs for any future disputes. At last, analysis of the atomicity and efficiency is illustrated.
Energy Technology Data Exchange (ETDEWEB)
Goldschmidt, B.
1990-01-01
This book is a memoir of rivalries among the Allies over the bomb, by a participant and observer. Nuclear proliferation began in the uneasy wartime collaboration of the United States, England, Canada, and Free France to produce the atom bomb. Through the changes of history, a young French chemist had a role in almost every act of this international drama. This memoir is based on Goldschmidt's own recollections, interviews with other leading figures, and 3,000 pages of newly declassified documents in Allied archives. From his own start as Marie Curie's lab assistant, Goldschmidt's career was closely intertwined with Frances complicated rise to membership in the nuclear club. As a refugee from the Nazis, he became part of the wartime nuclear energy project in Canada and found himself the only French scientist to work (although briefly) on the American atom bomb project.
Energy Technology Data Exchange (ETDEWEB)
Livingston, A.E.; Kukla, K.; Cheng, S. [Univ. of Toledo, OH (United States)] [and others
1995-08-01
In a collaboration with the Atomic Physics group at Argonne and the University of Toledo, the Atomic Physics group at the University of Notre Dame is measuring the fine structure transition energies in highly-charged lithium-like and helium-like ions using beam-foil spectroscopy. Precise measurements of 2s-2p transition energies in simple (few-electron) atomic systems provide stringent tests of several classes of current atomic- structure calculations. Analyses of measurements in helium-like Ar{sup 16+} have been completed, and the results submitted for publication. A current goal is to measure the 1s2s{sup 3}S{sub 1} - 1s2p{sup 3}P{sub 0} transition wavelength in helium-like Ni{sup 26+}. Measurements of the 1s2s{sup 2}S{sub 1/2} - 1s2p{sup 2}P{sub 1/2,3/2} transition wavelengths in lithium-like Kr{sup 33+} is planned. Wavelength and lifetime measurements in copper-like U{sup 63+} are also expected to be initiated. The group is also participating in measurements of forbidden transitions in helium-like ions. A measurement of the lifetime of the 1s2s{sup 3}S{sub 1} state in Kr{sup 34+} was published recently. In a collaboration including P. Mokler of GSI, Darmstadt, measurements have been made of the spectral distribution of the 2E1 decay continuum in helium-like Kr{sup 34+}. Initial results have been reported and further measurements are planned.
Energy Technology Data Exchange (ETDEWEB)
Musil, Stanislav, E-mail: stanomusil@biomed.cas.cz; Matoušek, Tomáš; Dědina, Jiří
2015-06-01
Sapphire is presented as a high temperature and corrosion resistant material of an optical tube of an atomizer for volatile species of Ag generated by the reaction with NaBH{sub 4}. The modular atomizer design was employed which allowed to carry out the measurements in two modes: (i) on-line atomization and (ii) in situ collection (directly in the optical tube) by means of excess of O{sub 2} over H{sub 2} in the carrier gas during the trapping step and vice versa in the volatilization step. In comparison with quartz atomizers, the sapphire tube atomizer provides a significantly increased atomizer lifetime as well as substantially improved repeatability of the Ag in situ collection signals shapes. In situ collection of Ag in the sapphire tube atomizer was highly efficient (> 90%). Limit of detection in the on-line atomization mode and in situ collection mode, respectively, was 1.2 ng ml{sup −1} and 0.15 ng ml{sup −1}. - Highlights: • Sapphire was tested as a new material of an atomizer tube for Ag volatile species. • Two measurement modes were investigated: on-line atomization and in situ collection. • In situ collection of Ag was highly efficient (> 90%) with LOD of 0.15 ng ml{sup −1}. • No devitrification of the sapphire tube observed in the course of several months.
Directory of Open Access Journals (Sweden)
José Luis Moletta
2014-02-01
Full Text Available The objective of this experiment was to evaluate quantitative and qualitative characters of carcass and meat from bulls and steers finished in feedlot during a 116 day period, in individual stalls and fed with a diet of corn silage and three levels of concentrate (0.70; 0.97 and 1.23% of body weight. The concentrate was formulated with 25% soybean meal, 73% of ground corn grain 1% of a mineral mix and 1% of limestone. A total of 169 composite Purunã animals, being 94 bulls and 75 steers with average age of 20 months. The interaction between physiological condition and level of concentrate was not significant (P>0.05 for any of the studied variables. Likewise, no effect of level of concentrate was detected upon the same traits. The bulls presented heavier slaughter weight (493.1 kg in comparison with the steers (450.0 kg as well as higher carcass yield (55.2 vs. 53.5%, resulting in a hot carcass weight 12.1% heavier than bulls animals, though with a lower degree of carcass finishing (3.6 vs. 4.2 mm, respectively. Bulls produced carcasses with better conformation and higher area of Longissimus dorsi (68.6 vs. 63.3 cm2, and higher percentage of muscle in comparison with castrated (66.5 vs. 62.8%. The meat from bulls was darker and with lower degree of marbling in relation to steers. Nevertheless, no differences were observed for tenderness nor for juiciness, though steers had more palatable meat.
Guerrero, J A; Macías-Díaz, J E
2014-02-01
In the present work, we develop a computational technique to approximate the changes of phase in temporal series associated to electric signals of muscles which perform activities at three different levels of intensity. We suppose that the temporal series are samples of independent, normally distributed random variables with mean equal to zero, and variance equal to one of three possible values, each of them associated to a certain degree of electric intensity. For example, these intensity levels may represent a leg muscle at rest, or active during a light activity (walking), or active during a highly demanding performance (jogging). The model is presented as a maximum likelihood problem involving discrete variables. In turn, this problem is transformed into a continuous one via the introduction of continuous variables with penalization parameters, and it is solved recursively through an iterative numerical method. An a posteriori treatment of the results is used in order to avoid the detection of relatively short periods of silence or activity. We perform simulations with synthetic data in order to assess the validity of our technique. Our computational results show that the method approximates well the occurrence of the change points in synthetic temporal series, even in the presence of autocorrelated sequences. In the way, we show that a generalization of a computational technique for the change-point detection of electric signals with two phases of activity (Esquivel-Frausto et al., 2010 [40]), may be inapplicable in cases of temporal series with three levels of intensity. In this sense, the method proposed in the present manuscript improves previous efforts of the authors.
Enrici, Ivan; Adenzato, Mauro; Ardito, Rita B.; Mitkova, Antonia; Cavallo, Marco; Zibetti, Maurizio; Lopiano, Leonardo; Castelli, Lorys
2015-01-01
Background Parkinson’s disease (PD) is characterised by well-known motor symptoms, whereas the presence of cognitive non-motor symptoms, such as emotional disturbances, is still underestimated. One of the major problems in studying emotion deficits in PD is an atomising approach that does not take into account different levels of emotion elaboration. Our study addressed the question of whether people with PD exhibit difficulties in one or more specific dimensions of emotion processing, investigating three different levels of analyses, that is, recognition, representation, and regulation. Methodology Thirty-two consecutive medicated patients with PD and 25 healthy controls were enrolled in the study. Participants performed a three-level analysis assessment of emotional processing using quantitative standardised emotional tasks: the Ekman 60-Faces for emotion recognition, the full 36-item version of the Reading the Mind in the Eyes (RME) for emotion representation, and the 20-item Toronto Alexithymia Scale (TAS-20) for emotion regulation. Principal Findings Regarding emotion recognition, patients obtained significantly worse scores than controls in the total score of Ekman 60-Faces but not in any other basic emotions. For emotion representation, patients obtained significantly worse scores than controls in the RME experimental score but no in the RME gender control task. Finally, on emotion regulation, PD and controls did not perform differently at TAS-20 and no specific differences were found on TAS-20 subscales. The PD impairments on emotion recognition and representation do not correlate with dopamine therapy, disease severity, or with the duration of illness. These results are independent from other cognitive processes, such as global cognitive status and executive function, or from psychiatric status, such as depression, anxiety or apathy. Conclusions These results may contribute to better understanding of the emotional problems that are often seen in patients
DEFF Research Database (Denmark)
Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, S.
2012-01-01
The size of passive components in an adjustable speed drive can be reduced by using small dc-link capacitors. The EMI filter in the drive also consists of passive components. The size of the filter can be reduced by using a three-level inverter, which can have low output voltage distortion. However......, the three-level inverter based on small dc-link capacitors requires a PWM strategy to maintain neutral-point voltage balance. In this paper, the common mode voltage, which is the determining factor for the EMI filter size, is analyzed for a virtual-vector-based PWM strategy. The common mode voltage....... Results show that the conducted emission from the three-level inverter is lower than that of the two-level inverter. Thus, a three-level inverter requires a smaller EMI filter in motor drives with small dc-link capacitors....
The Atomic orbitals of the topological atom
Ramos-Cordoba, Eloy; Salvador Sedano, Pedro
2013-01-01
The effective atomic orbitals have been realized in the framework of Bader's atoms in molecules theory for a general wavefunction. This formalism can be used to retrieve from any type of calculation a proper set of orthonormalized numerical atomic orbitals, with occupation numbers that sum up to the respective Quantum Theory of Atoms in Molecules (QTAIM) atomic populations. Experience shows that only a limited number of effective atomic orbitals exhibit significant occupation numbers. These c...
新型级联式交流斩波器%Cascade Mode Three-Level AC Chopper
Institute of Scientific and Technical Information of China (English)
李磊; 唐栋材
2012-01-01
Three-level(TL) AC switch unit is produced by two-level AC switch unit connected together in series manner.TL AC converter is produced by applying TL AC switch unit in basic converter.By combining Buck mode TL and Boost mode AC converters,a novel cascade mode AC chopper was proposed.The AC chopper can chopper unsteady high AC voltage with distortion into regulated sinusoidal voltage with low THD.The AC chopper,which is suit for high input voltage fields,has such following fetures as less power stages,bi-directional power flow,lower voltage stress in the front stage,low THD of output voltage,Buck and Boost mode conversion,unchanged voltage stress in the back stage.The operation principle was also investigated.For cascade mode TL AC chopper,control strategy of flying capacitor voltage was also presented.The AC chopper and the control strategy are fully proved by experimental results.%两电平交流开关单元串联后可得到三电平交流开关单元,将其应用到基本变换器中,可以获得三电平交流变换器。本文将Buck型三电平和Boost型两电平交流变换器进行组合,提出了一种新颖的级联式交流斩波器,并研究了其工作原理。该交流斩波器能够将不稳定、畸变的高压交流电变换成稳定或可调的优质正弦交流电,具有功率变换级数少,双向功率流,前级开关管的电压应力可降低,输出电压波形质量好,可实现升降压变换,后级电压应力未降低等特点,适用于高输入电压的交流变换场合。针对浮动电容电压控制问题,本文还提出了相应的控制策略。实验结果充分证实了本文所提出的级联式交流斩波器及其控制策略的可行性和正确性。
Liu, Lei; Tian, Bo; Xie, Xi-Yang; Guan, Yue-Yang
2017-01-01
Studied in this paper are the vector bright solitons of the coupled higher-order nonlinear Schrödinger system, which describes the simultaneous propagation of two ultrashort pulses in the birefringent or two-mode fiber. With the help of auxiliary functions, we obtain the bilinear forms and construct the vector bright one- and two-soliton solutions via the Hirota method and symbolic computation. Two types of vector solitons are derived. Single-hump, double-hump, and flat-top solitons are displayed. Elastic and inelastic interactions between the Type-I solitons, between the Type-II solitons, and between the two combined types of the solitons are revealed, respectively. Especially, from the interaction between a Type-I soliton and a Type-II soliton, we see that the Type-II soliton exhibits the oscillation periodically before such an interaction and becomes the double-hump soliton after the interaction, which is different from the previously reported.
Atom Skimmers and Atom Lasers Utilizing Them
Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.
2005-01-01
Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.
Information Entropy Squeezing for a Atom in Mode-Mode Competition System
Institute of Scientific and Technical Information of China (English)
WU Qin; FANG Mao-Fa; LI Shao-Xin; LI Ying; HU Yao-Hua
2008-01-01
The entropy squeezing properties for a two-level atom interacting with a two-mode field via two different competing transitions are investigated from a quantum information point of view. The influences of the initial state of the system and the relative coupling strength between the atom and the field on the atomic information entropy squeezing are discussed. Our results show that the squeezed direction and the frequency of the information entropy squeezing can be controlled by choosing the phase of the atom dipole and the relative competing strength of atom-field, respectively. We find that, under the same condition, no atomic variance squeezing is predicted from the HUR while optimal entropy squeezing is obtained from the EUR, so the quantum information entropy is a remarkable precision measure for the atomic squeezing in the considered system.
Atom-light interactions in quasi-one-dimensional nanostructures: A Green's-function perspective
Asenjo-Garcia, A.; Hood, J. D.; Chang, D. E.; Kimble, H. J.
2017-03-01
Based on a formalism that describes atom-light interactions in terms of the classical electromagnetic Green's function, we study the optical response of atoms and other quantum emitters coupled to one-dimensional photonic structures, such as cavities, waveguides, and photonic crystals. We demonstrate a clear mapping between the transmission spectra and the local Green's function, identifying signatures of dispersive and dissipative interactions between atoms. We also demonstrate the applicability of our analysis to problems involving three-level atoms, such as electromagnetically induced transparency. Finally we examine recent experiments, and anticipate future observations of atom-atom interactions in photonic band gaps.
Schwindt, Peter [Albuquerque, NM; Johnson, Cort N [Albuquerque, NM
2012-07-03
An atomic magnetometer is disclosed which uses a pump light beam at a D1 or D2 transition of an alkali metal vapor to magnetically polarize the vapor in a heated cell, and a probe light beam at a different D2 or D1 transition to sense the magnetic field via a polarization rotation of the probe light beam. The pump and probe light beams are both directed along substantially the same optical path through an optical waveplate and through the heated cell to an optical filter which blocks the pump light beam while transmitting the probe light beam to one or more photodetectors which generate electrical signals to sense the magnetic field. The optical waveplate functions as a quarter waveplate to circularly polarize the pump light beam, and as a half waveplate to maintain the probe light beam linearly polarized.
High Atom Number in Microsized Atom Traps
2015-12-14
Final Performance Report on ONR Grant N00014-12-1-0608 High atom number in microsized atom traps for the period 15 May 2012 through 14 September...TYPE Final Technical Report 3. DATES COVERED (From - To) 05/15/2012-09/14/2012 4. TITLE AND SUBTITLE High atom number in microsized atom traps...forces for implementing a small-footprint, large-number atom -chip instrument. Bichromatic forces rely on absorption and stimulated emission to produce
Detecting Neutral Atoms on an Atom Chip
Wilzbach, M.; Haase, A.; Schwarz, M; Heine, D.; Wicker, K.; Liu, X; Brenner, K. -H.; Groth, S.; Fernholz, Th.; Hessmo, B.; Schmiedmayer, J.
2006-01-01
Detecting single atoms (qubits) is a key requirement for implementing quantum information processing on an atom chip. The detector should ideally be integrated on the chip. Here we present and compare different methods capable of detecting neutral atoms on an atom chip. After a short introduction to fluorescence and absorption detection we discuss cavity enhanced detection of single atoms. In particular we concentrate on optical fiber based detectors such as fiber cavities and tapered fiber d...
Atom-membrane cooling and entanglement using cavity electromagnetically induced transparency
DEFF Research Database (Denmark)
Genes, Claudiu; Ritsch, Helmut; Drewsen, Michael;
2011-01-01
We investigate a hybrid optomechanical system composed of a micromechanical oscillator as a movable membrane and an atomic three-level ensemble within an optical cavity. We show that a suitably tailored cavity field response via electromagnetically induced transparency (EIT) in the atomic medium...
Institute of Scientific and Technical Information of China (English)
张俊香; 董瑞芳; 常宏; 谢常德; 彭忻墀; 肖敏
2001-01-01
The effects of the electromagnetically induced transparency and dispersion of a A-type three-level atomic system are experimentally measured with a vapour cell of Cs atoms. The steep dispersion at low absorption is observed. Thus a small group velocity for the probe beam is inferred from the measured dispersion curve.
Ghosh, Sharmistha
2010-04-06
The DNA polymerase encoded by bacteriophage T7 has low processivity. Escherichia coli thioredoxin binds to a segment of 76 residues in the thumb subdomain of the polymerase and increases the processivity. The binding of thioredoxin leads to the formation of two basic loops, loops A and B, located within the thioredoxin-binding domain (TBD). Both loops interact with the acidic C terminus of the T7 helicase. A relatively weak electrostatic mode involves the C-terminal tail of the helicase and the TBD, whereas a high affinity interaction that does not involve the C-terminal tail occurs when the polymerase is in a polymerization mode. T7 gene 2.5 single-stranded DNA-binding protein (gp2.5) also has an acidic C-terminal tail. gp2.5 also has two modes of interaction with the polymerase, but both involve the C-terminal tail of gp2.5. An electrostatic interaction requires the basic residues in loops A and B, and gp2.5 binds to both loops with similar affinity as measured by surface plasmon resonance. When the polymerase is in a polymerization mode, the C terminus of gene 2.5 protein interacts with the polymerase in regions outside the TBD.gp2.5 increases the processivity of the polymerase-helicase complex during leading strand synthesis. When loop B of the TBD is altered, abortive DNA products are observed during leading strand synthesis. Loop B appears to play an important role in communication with the helicase and gp2.5, whereas loop A plays a stabilizing role in these interactions. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.
Li, Huajiao; An, Haizhong; Wang, Yue; Huang, Jiachen; Gao, Xiangyun
2016-05-01
Keeping abreast of trends in the articles and rapidly grasping a body of article's key points and relationship from a holistic perspective is a new challenge in both literature research and text mining. As the important component, keywords can present the core idea of the academic article. Usually, articles on a single theme or area could share one or some same keywords, and we can analyze topological features and evolution of the articles co-keyword networks and keywords co-occurrence networks to realize the in-depth analysis of the articles. This paper seeks to integrate statistics, text mining, complex networks and visualization to analyze all of the academic articles on one given theme, complex network(s). All 5944 "complex networks" articles that were published between 1990 and 2013 and are available on the Web of Science are extracted. Based on the two-mode affiliation network theory, a new frontier of complex networks, we constructed two different networks, one taking the articles as nodes, the co-keyword relationships as edges and the quantity of co-keywords as the weight to construct articles co-keyword network, and another taking the articles' keywords as nodes, the co-occurrence relationships as edges and the quantity of simultaneous co-occurrences as the weight to construct keyword co-occurrence network. An integrated method for analyzing the topological features and evolution of the articles co-keyword network and keywords co-occurrence networks is proposed, and we also defined a new function to measure the innovation coefficient of the articles in annual level. This paper provides a useful tool and process for successfully achieving in-depth analysis and rapid understanding of the trends and relationships of articles in a holistic perspective.
Directory of Open Access Journals (Sweden)
Tatsuro Naganuma
Full Text Available Fatty acids (FAs are diverse molecules, and such diversity is important for lipids to exert their functions under several environmental conditions. FA elongation occurs at the endoplasmic reticulum and produces a variety of FA species; the FA elongation cycle consists of four distinct enzyme reactions. For this cycle to be driven efficiently, there must exist coordinated regulation of protein components of the FA elongation machinery. However, such regulation is poorly understood. In the present study, we performed biochemical analyses using the FA elongase ELOVL6 and the 3-ketoacyl-CoA reductase KAR, which catalyze the first and second steps of the FA elongation cycle, respectively. In vitro FA elongation assays using membrane fractions demonstrated that ELOVL6 activity was enhanced ∼10-fold in the presence of NADPH, although ELOVL6 itself did not require NADPH for its catalysis. On the other hand, KAR does use NADPH as a reductant in its enzyme reaction. Activity of purified ELOVL6 was enhanced by ∼3-fold in the presence of KAR. This effect was KAR enzyme activity-independent, since it was observed in the absence of NADPH and in the KAR mutant. However, ELOVL6 enzyme activity was further enhanced in a KAR enzyme activity-dependent manner. Therefore, KAR regulates ELOVL6 via two modes. In the first mode, KAR may induce conformational changes in ELOVL6 to become structure that can undergo catalysis. In the second mode, conversion of 3-ketoacyl-CoA to 3-hydroxyacyl-CoA by KAR may facilitate release of the product from the presumed ELOVL6-KAR complex.
Grinberg, Horacio
2008-12-18
The interaction of a two-level cyclic XY n-spin model with a two-mode cavity field involving two-photon transitions is investigated through a generalized Jaynes-Cummings model in the rotating-wave approximation. The two-photon interacting Hamiltonian becomes from the replacement of each single-mode field in the one-photon interacting Hamiltonian with the second-harmonic generation. It was assumed that initially the correlated field modes are in disentangled coherent states having the same photon distribution and that the spin system is in an excited state. At any time t > 0, the spin system and the field are in an entangled state, in this case, via a unitary time evolution operator. Thus, the spontaneous decay of a spin level was treated by considering the interaction of the two-level spin system with the modes of the universe in the vacuum state. The different cases of interest, characterized in terms of a detuning parameter for each mode, which emerge from nonvanishing commutation relations, were analytically implemented and numerically discussed for various values of the initial mean photon number and spin-photon coupling constants. Photon distribution, time evolution of the spin population inversion, as well as the statistical properties of the field leading to the possible production of nonclassical states, such as antibunched light, violations of the Cauchy-Schwartz inequality, and second- and fourth-order squeezing, are examined. The case of zero detuning of both modes was treated in terms of a linearization of the expansion of the time evolution operator, while in other three cases, the computations were conducted via second- and third-order Dyson perturbation expansion of the time evolution operator matrix elements for the excited and ground states of the spin system, respectively.
Institute of Scientific and Technical Information of China (English)
SONG Fengfei; ZHOU Tianjun; WANG Lu
2013-01-01
In this study,two modes of the Silk Road pattern were investigated using NCEP2 reanalysis data and the simulation produced by Spectral Atmospheric Circulation Model of IAP LASG,Version 2 (SAMIL2.0) that was forced by SST observation data.The horizontal distribution of both modes were reasonably reproduced by the simulation,with a pattern correlation coefficient of 0.63 for the first mode and 0.62 for the second mode.The wave train was maintained by barotropic energy conversion (denoted as CK) and baroclinic energy conversion (denoted as CP) from the mean flow.The distribution of CK was dominated by its meridional component (CKy) in both modes.When integrated spatially,CKy was more efficient than its zonal component (CKx) in the first mode but less in the second mode.The distribution and efficiency of CK were not captured well by SAMIL2.0.However,the model performed reasonably well at reproducing the distribution and efficiency of CP in both modes.Because CP is more efficient than CK,the spatial patterns of the Silk Road pattern were well reproduced.Interestingly,the temporal phase of the second mode was well captured by a single-member simulation.However,further analysis of other ensemble runs demonstrated that the successful reproduction of the temporal phase was a result of internal variability rather than a signal of SST forcing.The analysis shows that the observed temporal variations of both CP and CK were poorly reproduced,leading to the low accuracy of the temporal phase of the Silk Road pattern in the simulation.
Dang, Juntao; Yi, Xingwen; Zhang, Jing; Ye, Taiping; Xu, Bo; Qiu, Kun
2016-07-25
While optical OFDM has been demonstrated for superior transmission performance, its analogue waveform in the time domain challenges many conventional all-optical wavelength converters (AOWC) that are needed for future flexible optical networks. There only exist a few reports on AOWC of OFDM signals, which are mainly based on the low-efficient four-wave mixing. In this paper, we propose an AOWC for OFDM signals by using two-mode injection-locking in a low-cost Fabry-Pérot laser. The control signal and the probe signal at a milliwatt power level are combined and injected into the FP laser. By a proper control, they can be injection-locked to two longitudinal modes in the FP laser and subsequently, the transmission of the probe signal is conditioned by the control signal. We conduct an experimental study on various aspects of this AOWC. Despite a vendor-specified electrical-to-optical (E/O) modulation bandwidth of 2.5 GHz, we find that the optical-to-optical (O/O) modulation bandwidth of AOWC is free from this limit and can be much wider. We examine the linear transfer curve of the AOWC by simply using the OFDM waveforms as the stimulus. The performance tolerance to the wavelength detuning and injected power ratio is also measured. The proposed AOWC can provide a linear transfer function from the control signal to the probe signal to support the random-fluctuated OFDM waveform. We also investigate the maximum capacity of the AOWC by using the adaptive bit-loading OFDM. Finally, we measure the power penalty after the AOWC at two different bit rates to show the tradeoff between the penalty and capacity.
Song, Fengfei; Zhou, Tianjun; Wang, Lu
2013-05-01
In this study, two modes of the Silk Road pattern were investigated using NCEP2 reanalysis data and the simulation produced by Spectral Atmospheric Circulation Model of IAP LASG, Version 2 (SAMIL2.0) that was forced by SST observation data. The horizontal distribution of both modes were reasonably reproduced by the simulation, with a pattern correlation coefficient of 0.63 for the first mode and 0.62 for the second mode. The wave train was maintained by barotropic energy conversion (denoted as CK) and baroclinic energy conversion (denoted as CP) from the mean flow. The distribution of CK was dominated by its meridional component (CK y ) in both modes. When integrated spatially, CK y was more efficient than its zonal component (CK x ) in the first mode but less in the second mode. The distribution and efficiency of CK were not captured well by SAMIL2.0. However, the model performed reasonably well at reproducing the distribution and efficiency of CP in both modes. Because CP is more efficient than CK, the spatial patterns of the Silk Road pattern were well reproduced. Interestingly, the temporal phase of the second mode was well captured by a single-member simulation. However, further analysis of other ensemble runs demonstrated that the successful reproduction of the temporal phase was a result of internal variability rather than a signal of SST forcing. The analysis shows that the observed temporal variations of both CP and CK were poorly reproduced, leading to the low accuracy of the temporal phase of the Silk Road pattern in the simulation.
Electromagnetically induced grating with Rydberg atoms
Asghar, Sobia; Ziauddin, Qamar, Shahid; Qamar, Sajid
2016-09-01
We present a scheme to realize electromagnetically induced grating in an ensemble of strongly interacting Rydberg atoms, which act as superatoms due to the dipole blockade mechanism. The ensemble of three-level cold Rydberg-dressed (87Rb) atoms follows a cascade configuration where a strong standing-wave control field and a weak probe pulse are employed. The diffraction intensity is influenced by the strength of the probe intensity, the control field strength, and the van der Waals (vdW) interaction. It is noticed that relatively large first-order diffraction can be obtained for low-input intensity with a small vdW shift and a strong control field. The scheme can be considered as an amicable solution to realize the atomic grating at the microscopic level, which can provide background- and dark-current-free diffraction.
Mutual coherence and spin squeezing in double-well atomic condensates
Energy Technology Data Exchange (ETDEWEB)
Jing Hui
2002-12-30
We develop an analytical method for the investigations of quantum dynamics and statistics of double-well atomic condensates with Josephson-like coupling. An interesting collapse and revival phenomenon is shown for any atomic state, and the anti-correlations are revealed between the two atomic modes through an exact result for second-order cross-correlation. Particularly, the possible violation of Cauchy-Schwarz inequality as the sign of nonlocality are exhibited by the combination of intrinsic collisions and external field. The essential difference between the two-mode nonclassical correlation and the collective spin squeezing is also briefly discussed.
Ma, Xiaohe; Shen, Songhua
2006-11-01
This paper mainly introduces theoretical analysis and experimental results of instantaneous characteristics on a certain three level brushless three-phase AC synchronous generators. The analysis, modeling and simulations with Simplorer software of Ansoft Company are carried out. It establishes three level generator models, gives theoretical relation matrix equation, and simulates some instantaneous characteristics. Design of the system requires reliable simulation tools with comprehensive component libraries capable of dealing with complex system behavior. The simulation results verify that the proposed system model can efficiently simulate the instantaneous characteristics of the real AC generator system. It gives better design experiences and digital methods for aeronautic constant speed and frequency AC power system.
Comparison of soft and hard-switching effiency in a three-level single phase 60kW dc-ac converter
DEFF Research Database (Denmark)
Munk-Nielsen, Stig; Teodorescu, Remus; Bech, Michael Møller;
2003-01-01
Efficiency measurements on a three-level single-phase soft-switched converter are presented and show a slightly improved efficiency compared with the hard-switched converter for output powers higher than 25 % of rated power. The resonant converter switches are Zero Voltage Switched (ZVS) and a si......Efficiency measurements on a three-level single-phase soft-switched converter are presented and show a slightly improved efficiency compared with the hard-switched converter for output powers higher than 25 % of rated power. The resonant converter switches are Zero Voltage Switched (ZVS...
Persistent Perfect Entanglement in Atomic Systems
Ali Can, Muhammet
2004-03-01
It has been shown recently [1] that a pure entangled state of two-level atoms can be obtained in an optical resonator through the exchange by cavity photons. Unfortunately, the lifetime of such an entangled state, caused by the radiative decay time for the dipole transitions is very short. The situation can be improved through the use of three-level atoms with lambda-type transition [2]. In this case, the cavity field pumps transition between the lowest (ground) and highest (excited) states. Then, the decay of the excited state can populate the intermediate state. This is just the Raman-type process with emission of Stokes photon in atomic system. Because of the selection rules by the parity conservation, the dipole decay from the intermediate state to the ground state is forbidden. If the Stokes photons created by the transitions from the excited state to the ground state are discarded (through the use of cavity leakage of absorption), the final state of atomic system is stabile or at least durable. In the case of 2n three-level atoms, this can lead to the N-qubit perfect entangled state, where N=2j+1 and j is an odd ``spin'' corresponding to the SU(2) algebra in the Hilbert space H=(C2)^ otimes N In fact, these are the SU(2) phase states of odd ``spin'' have been discussed in [3] in the context of two-level atoms. The possibility to create and observe these states with present experimental technique is discussed. [1] A. Beige, S. Bose, D. Braun, S.F. Huelga, P.L. Knight, M.B. Plenio, and V. Verdal. J. Mod. Optics 47, 2583 (2000). [2] M.A. Can, A.A. Klyachko, and A.S. Shumovsky. Appl. Phys. Lett. 81, 5072 (2002). [3] M.A. Can, A.A. Klyachko, and A.S. Shumovsky. Phys. Rev. A 66, 022111 (2002).
Dynamical symmetry reduction and discrete tomography of a {Xi} atom
Energy Technology Data Exchange (ETDEWEB)
Mahler, Dylan; De Guise, Hubert [Department of Physics, Lakehead University, Thunder Bay (Canada); Klimov, Andrei B, E-mail: dmahler@physics.utoronto.c [Departamento de Fisica, Universidad de Guadalajara, Revolucion 1500, 44410 Guadalajara, Jalisco (Mexico)
2010-09-01
When implemented using a reasonable Hamiltonian, the tomography of a three-level {Xi} atom is complicated by the equidistant energy levels of the atom. This restricts the possible transformations to those in the SO(3) subgroup of SU(3). Although complete reconstruction is possible for a single {Xi} atom using a continuous set of tomograms, the discrete optimal set of tomograms, related to mutually unbiased bases in dimension 3, are not accessible by time evolution. We discuss here the search for an optimal set of discrete basis states compatible with the reduced SO(3) symmetry of the system.
Blomeyer, Christoph A; Bazil, Jason N; Stowe, David F; Dash, Ranjan K; Camara, Amadou K S
2016-06-01
The manner in which mitochondria take up and store Ca(2+) remains highly debated. Recent experimental and computational evidence has suggested the presence of at least two modes of Ca(2+) uptake and a complex Ca(2+) sequestration mechanism in mitochondria. But how Mg(2+) regulates these different modes of Ca(2+) uptake as well as mitochondrial Ca(2+) sequestration is not known. In this study, we investigated two different ways by which mitochondria take up and sequester Ca(2+) by using two different protocols. Isolated guinea pig cardiac mitochondria were exposed to varying concentrations of CaCl2 in the presence or absence of MgCl2. In the first protocol, A, CaCl2 was added to the respiration buffer containing isolated mitochondria, whereas in the second protocol, B, mitochondria were added to the respiration buffer with CaCl2 already present. Protocol A resulted first in a fast transitory uptake followed by a slow gradual uptake. In contrast, protocol B only revealed a slow and gradual Ca(2+) uptake, which was approximately 40 % of the slow uptake rate observed in protocol A. These two types of Ca(2+) uptake modes were differentially modulated by extra-matrix Mg(2+). That is, Mg(2+) markedly inhibited the slow mode of Ca(2+) uptake in both protocols in a concentration-dependent manner, but not the fast mode of uptake exhibited in protocol A. Mg(2+) also inhibited Na(+)-dependent Ca(2+) extrusion. The general Ca(2+) binding properties of the mitochondrial Ca(2+) sequestration system were reaffirmed and shown to be independent of the mode of Ca(2+) uptake, i.e. through the fast or slow mode of uptake. In addition, extra-matrix Mg(2+) hindered Ca(2+) sequestration. Our results indicate that mitochondria exhibit different modes of Ca(2+) uptake depending on the nature of exposure to extra-matrix Ca(2+), which are differentially sensitive to Mg(2+). The implications of these findings in cardiomyocytes are discussed.
Willden, Jeff
2001-01-01
"Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…
The atomic orbitals of the topological atom.
Ramos-Cordoba, Eloy; Salvador, Pedro; Mayer, István
2013-06-07
The effective atomic orbitals have been realized in the framework of Bader's atoms in molecules theory for a general wavefunction. This formalism can be used to retrieve from any type of calculation a proper set of orthonormalized numerical atomic orbitals, with occupation numbers that sum up to the respective Quantum Theory of Atoms in Molecules (QTAIM) atomic populations. Experience shows that only a limited number of effective atomic orbitals exhibit significant occupation numbers. These correspond to atomic hybrids that closely resemble the core and valence shells of the atom. The occupation numbers of the remaining effective orbitals are almost negligible, except for atoms with hypervalent character. In addition, the molecular orbitals of a calculation can be exactly expressed as a linear combination of this orthonormalized set of numerical atomic orbitals, and the Mulliken population analysis carried out on this basis set exactly reproduces the original QTAIM atomic populations of the atoms. Approximate expansion of the molecular orbitals over a much reduced set of orthogonal atomic basis functions can also be accomplished to a very good accuracy with a singular value decomposition procedure.
Dipolar exchange induced transparency with Rydberg atoms
Petrosyan, David
2017-03-01
A three-level atomic medium can be made transparent to a resonant probe field in the presence of a strong control field acting on an adjacent atomic transition to a long-lived state, which can be represented by a highly excited Rydberg state. The long-range interactions between the Rydberg state atoms then translate into strong, non-local, dispersive or absorptive interactions between the probe photons, which can be used to achieve deterministic quantum logic gates and single photon sources. Here we show that long-range dipole–dipole exchange interaction with one or more spins—two-level systems represented by atoms in suitable Rydberg states—can play the role of control field for the optically dense medium of atoms. This induces transparency of the medium for a number of probe photons n p not exceeding the number of spins n s , while all the excess photons are resonantly absorbed upon propagation. In the most practical case of a single spin atom prepared in the Rydberg state, the medium is thus transparent only to a single input probe photon. For larger number of spins n s , all n p ≤ n s photon components of the probe field would experience transparency but with an n p -dependent group velocity.
Institute of Scientific and Technical Information of China (English)
黄春佳; 周明; 厉江帆; 方家元; 黄祖洪; 贺慧勇
2000-01-01
应用全量子理论,研究了非旋波近似下与双模压缩真空场相互作用的二能级原子算符的时间演化规律和偶极压缩性质,数值计算结果表明,虚光场效应主要表现为物理过程中的量子噪声,这种量子噪声的大小与光场的初始压缩参量和原子的初始状态以及系统的耦合强度等因素密切相关.
DEFF Research Database (Denmark)
Panfilov, Dmitry; Husev, Oleksandr; Blaabjerg, Frede
2016-01-01
This study compares a three-phase three-level voltage source inverter with an intermediate dc-dc boost converter and a quasi-Z-source inverter in terms of passive elements values and dimensions, semiconductor stresses, and overall efficiency. A comparative analysis was conducted with relative par...
DEFF Research Database (Denmark)
Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, S.
2012-01-01
In a voltage source inverter, overmodulation is required to extend the range of operation and enhance the dc-link voltage utilization. A carrier-based implementation of a modulation strategy for the three-level neutral-point-clamped inverter is proposed for the overmodulation region. The modulati...
DEFF Research Database (Denmark)
Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, Sergio
2011-01-01
A Neutral-Point-Clamped (NPC) three-level inverter with small DC-link capacitors is presented in this paper. This inverter requires zero average neutral-point current for stable neutral-point potential. A simple carrier based modulation strategy is proposed for achieving zero average neutral-poin...
Choi, Kilchan; Seltzer, Michael
2010-01-01
In studies of change in education and numerous other fields, interest often centers on how differences in the status of individuals at the start of a period of substantive interest relate to differences in subsequent change. In this article, the authors present a fully Bayesian approach to estimating three-level Hierarchical Models in which latent…
Baturo, Annette; Cooper, Tom; Doyle, Katherine; Grant, Edlyn
2007-01-01
This paper describes a three-level framework (technical, domain, and generic) which enables some generalisability across mathematics topics for effective teacher-education (TE) task design. It argues that TE tasks which encompass these levels increase preservice and inservice teachers' interest because they transcend the particular mathematical…
M.F. Janssen (Bas); E. Birnie (Erwin); G.J. Bonsel (Gouke)
2008-01-01
textabstractObjectives: Our aim was to compare the quantitative position of the level descriptors of the standard EQ-5D three-level system (3L) and a newly developed, experimental five-level version (5L) using a direct and a vignette-based indirect method. Methods: Eighty-two respondents took part i
Efficient Scheme for the Generation of Atomic Schroedinger Cat States in an Optical Cavity
Institute of Scientific and Technical Information of China (English)
ZHENGShi-Biao; LINLi-Hua; JIANGYun-Kun
2003-01-01
An efficient scheme is proposed for the generation of atomic Schroedinger cat states in an optical cavity. In the scheme N three-level atoms are loaded in the optical cavity. Raman coupling of two ground states is achieved via a laser tield and the cavity mode. The cavity mode is always in the vacuum state and the atoms have no probability of being populated in the excited state. Thus, the scheme is insensitive to both the cavity decay and spontaneous emission.
Efficient Scheme for the Generation of Atomic Schrodinger Cat States in an Optical Cavity
Institute of Scientific and Technical Information of China (English)
ZHENG Shi-Biao; LIN Li-Hua; JIANG Yun-Kun
2003-01-01
An efficient scheme is proposed for the generation of atomic Schrodinger cat states in an optical cavity. Inthe scheme N three-level atoms are loaded in the optical cavity. Raman coupling of two ground states is achieved via alaser field and the cavity mode. The cavity mode is always in the vacuum state and the atoms have no probability ofbeing populated in the excited state. Thus, the scheme is insensitive to both the cavity decay and spontaneous emission.
TWO MODES OF SUMMER PRECIPITATION VARIATION OF HOLOCENE IN CHINA%全新世中国夏季降水量变化的两种模态
Institute of Scientific and Technical Information of China (English)
王绍武; 黄建斌; 闻新宇; 杨保; 任国玉
2009-01-01
根据气候模拟的夏季降水量及古气候湿润度代用资料,指出全新世中国夏季降水量变化存在两种模态.模态1:降水量异常的中心为一个东北-西南向的带;从东北、内蒙东部、经华北、河套到青藏高原为一正异常中心.模拟结果的EOF分析表明这种模态占模拟的全新世中国夏季降水量变化总方差的75.8%.全新世降水量变化的模拟主要考虑地球轨道要素,其中岁差起着重要作用.因此,这个模态可以称为岁差模.岁差模主要反映近万年全新世降水变化的趋势.模态2:降水量异常分布在中国东部(100°E以东)自北向南表现为负-正-负分布.负异常在内蒙中部到华北,正异常在黄河中游、淮河、到长江流域,江南部分地区又有负异常.这与模拟的大西洋热盐环流减弱所造成的中国夏季降水最异常分布一致.因此,这个模态可能与全新世的气候突变有关,称为气候突变模.覆盖中国的80个代用资料序列给出的9kaB.P.和4kaB.P.干湿分布,证明早全新世气候湿润,晚全新世气候干旱.这种变化趋势丰要反映了岁差的影响.同时,4kaB.P.虽然干旱分布广泛,但是长江流域、关中地区到高原东部则有若干气候湿润的指示.这表明4kaB.P.同时受岁差及气候突变的影响.%Two modes of summer precipitation variation of Holocene in China were identified according to climate modeling and palaeo-climatic humidity data,Mode 1 has such a feature given by EOF_1 of palaeo-climate modeling: positive precipitation anomaly centers are distributed in a NE-SW extended zone from North East China, Eastern Inner Mongolia, North China, the Great Bend of the Yellow River to the Tibet Plateau. This mode is correlated closely to the solar radiation change controlled mainly by precession in Holocene. It can be used to interpret 75.8% of the total variance of the modeled summer precipitation variation of Holocene. The modeling indicates that the
Measurement of the temperature of atomic ensembles via \\emph{which-way} information
León-Montiel, R de J
2011-01-01
We unveil the relationship existing between the temperature of an atomic ensemble of three-level atoms in a $\\Lambda$-configuration, and the width of the emission cone of Stokes photons that are spontaneously emitted when atoms are excited by an optical beam. This relationship, which is based on the amount of \\emph{which-way} information available about where the Stokes photon originated during the interaction, allow us to put forward a new scheme to determine the temperature of atomic clouds by measuring the width of the emission cone. Unlike the commonly used time-of-flight measurements, with this new technique, the atomic cloud is not destroyed during each measurement.
Distributed orbital state quantum cloning with atomic ensembles via quantum Zeno dynamics
Shen, Li-Tuo; Yang, Zhen-Biao
2011-01-01
We propose a scheme for distributed orbital state quantum cloning with atomic ensembles based on the quantum Zeno dynamics. These atomic ensembles which consist of identical three-level atoms are trapped in distant cavities connected by a single-mode integrated optical star coupler. These qubits can be manipulated through appropriate modulation of the coupling constants between atomic ensemble and classical field, and the cavity decay can be largely suppressed as the number of atoms in the ensemble qubits increases. The present scheme provides a new way to construct the quantum communication network.
Institute of Scientific and Technical Information of China (English)
LI Shichun
2004-01-01
Based on the Thomas-Fermi-Dirac-Cheng model, atomic phase diagram or electron density versus atomic radius diagram describing the interaction properties of atoms of different kinds in equilibrium state is developed. Atomic phase diagram is established based on the two-atoms model. Besides atomic radius, electron density and continuity condition for electron density on interfaces between atoms, the lever law of atomic phase diagram involving other physical parameters is taken into account, such as the binding energy, for the sake of simplicity.
Parniak, Michał; Wasilewski, Wojciech
2015-01-01
We analyze the properties of a Raman quantum light-atom interface in long atomic ensemble and its applications as a quantum memory or two-mode squeezed state generator. We include both Stokes and anti-Stokes scattering and the effects of Doppler broadening in buffer gas assuming frequent velocity-averaging collisions. We find the Green functions describing multimode transformation from input to output fields of photons and atomic excitations. Proper mode basis is found via singular value decomposition. It reveals that triples of modes are coupled by a transformation equivalent to a combination of two beamsplitters and a two-mode squeezing operation. We analyze the possible transformations on an example of warm rubidium-87 vapor. We find that the fidelity of the mapping of a single excitation between the memory and light is strictly limited by the fractional contribution of the Stokes scattering in predominantly anti-Stokes process. The model we present bridges the gap between the Stokes only and anti-Stokes o...
Cold Matter Assembled Atom-by-Atom
Endres, Manuel; Keesling, Alexander; Levine, Harry; Anschuetz, Eric R; Krajenbrink, Alexandre; Senko, Crystal; Vuletic, Vladan; Greiner, Markus; Lukin, Mikhail D
2016-01-01
The realization of large-scale fully controllable quantum systems is an exciting frontier in modern physical science. We use atom-by-atom assembly to implement a novel platform for the deterministic preparation of regular arrays of individually controlled cold atoms. In our approach, a measurement and feedback procedure eliminates the entropy associated with probabilistic trap occupation and results in defect-free arrays of over 50 atoms in less than 400 ms. The technique is based on fast, real-time control of 100 optical tweezers, which we use to arrange atoms in desired geometric patterns and to maintain these configurations by replacing lost atoms with surplus atoms from a reservoir. This bottom-up approach enables controlled engineering of scalable many-body systems for quantum information processing, quantum simulations, and precision measurements.
Robust population transfer in atomic beams induced by Doppler shifts
Unanyan, R. G.
2016-10-01
The influence of photon momentum recoil on adiabatic population transfer in an atomic three-level lambda system is studied. It is shown that the Doppler frequency shifts, due to atomic motion, can play an important role in adiabatic population transfer processes of atomic internal states by a pair of laser fields. For the limiting case of slow atoms (Doppler shift much smaller than the photon recoil energy), the atoms occupy the same target state regardless of the order of switching of laser fields, while for the case of fast atoms interacting with the intuitive sequence of pulses, the target state is the intermediate atomic state. Furthermore, it is shown that this novel technique for adiabatic population transfer is related to a level crossing in the bright-intermediate state basis (rather than in the original atomic basis). It is shown that these processes are robust with respect to parameter fluctuations, such as the laser pulse area and the relative spatial offset (delay) of the laser beams. The obtained results can be used for the control of temporal evolution of atomic populations in cold atomic beams by externally adjustable Doppler shifts.
Atom-photon entanglement in the system with competing k-photon and l-photon transitions
Institute of Scientific and Technical Information of China (English)
Wu Qin; Fang Mao-Fa; Hu Yao-Hua
2007-01-01
We have investigated the evolution of the atomic quantum entropy and the entanglement of atom-photon in the system with competing k-photon and l-photon transitions by means of fully quantum theory, and examined the effects of competing photon numbers (k and l), the relative coupling strength between the atom and the two-mode field(λ/g),and the initial photon number of the field on the atomic quantum entropy and the entanglement of atom-photon.The results show that the multiphoton competing transitions or the large relative coupling strength can lead to the strong entanglement between atoms and photons. The maximal atom-photon entanglement can be prepared via the appropriate selection of system parameters and interaction time.
DEFF Research Database (Denmark)
Liu, Dong; Deng, Fujin; Gong, Zheng
2017-01-01
In this paper, the input-parallel output-parallel (IPOP) three-level (TL) DC/DC converters associated with the interleaving control strategy are proposed for minimizing and balancing the capacitor ripple currents. The proposed converters consist of two four-switch half-bridge three-level (HBTL) DC....../DC converters featuring with simple and compact circuit structures, which can reduce the current stresses of the components and increase the power rating of the converter. The combination of the proposed IPOP TL circuit structure and the interleaving control strategy can greatly reduce the ripple currents...... on the two input capacitor not only by doubling the frequencies of these ripple currents as the universal benefit of utilizing the interleaving control strategy but also by counteracting part of these ripple currents due to the operation principle of the proposed IPOP TL circuit structure. More importantly...
Diagnosis method of an open-switch fault for a grid-connected T-type three-level inverter system
DEFF Research Database (Denmark)
Choi, U. M.; Lee, K. B.; Blaabjerg, Frede
2012-01-01
This paper proposes a diagnosis method of an open-switch fault and fault-tolerant control algorithm for a grid-connected T-type three-level inverter. The location of the faulty switch is identified by using the changes of average phase current and the neutral-point voltage. The fault-tolerant con......This paper proposes a diagnosis method of an open-switch fault and fault-tolerant control algorithm for a grid-connected T-type three-level inverter. The location of the faulty switch is identified by using the changes of average phase current and the neutral-point voltage. The fault......-tolerant control algorithm can be used when the open switch fault occurs in the middle switches. It is achieved by simply modifying the conventional SVM method. The proposed methods are advantageous as they do not require additional sensors and they do not involve complex calculations. Therefore, this method...
DEFF Research Database (Denmark)
Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Tidemand-Lichtenberg, Peter;
2010-01-01
Using a tunable external cavity tapered diode laser (ECDL) pumped quasi-three-level Nd:YAG laser, a fivefold reduction in threshold and twofold increase in slope efficiency is demonstrated when compared to a traditional broad area diode laser pump source. A TEM00 power of 800 mW with 65% slope...... efficiency is obtained, the highest reported TEM00 power from any 946 nm Nd:YAG laser pumped by a single emitter diode laser pump source. A quantum efficiency of 0.85 has been estimated from experimental data using a simple quasi-three-level model. The reported value is in good agreement with published...... values, suggesting that the model is adequate. Improvement of the 946 nm laser due to the ECDL's narrow spectrum proves to be less significant when compared to its spatial quality, inferring a broad spectrum tapered diode laser pump source may be most practical. Experimental confirmation of such setup...
DEFF Research Database (Denmark)
Tang, Yi; Zhu, Dexuan; Jin, Chi
2015-01-01
voltage will be fairly constant. The dynamic response of this regulation loop is also very fast and the system is therefore insensitive to external disturbances. Both simulation and experimental results are presented to show the effectiveness of this converter as well as its efficiency improvement against......This paper presents a three-level quasi-two-stage single-phase power factor correction (PFC) converter that has flexible output voltage and improved conversion efficiency. The proposed PFC converter features sinusoidal input current, three-level output characteristic, and a wide range of output dc...... voltages, and it will be very suitable for high-power applications where the output voltage can be either lower or higher than the peak ac input voltage, e.g., plug-in hybrid electric vehicle charging systems. Moreover, the involved dc/dc buck conversion stage may only need to process partial input power...
Storing Quantum Information via Atomic Dark Resonances
Caruso, Filippo
2010-01-01
In this thesis, after a brief review of some concepts of Quantum Optics, we analyze a three-level atomic system in the conditions of electromagnetically induced transparency (EIT), and we investigate the propagation of a gaussian pulse along a cigar-shaped cloud of both cold and hot atoms in EIT regime. In particular, we show that it is possible to amplify a slow propagating pulse without population inversion. We also analyze the regime of anomalous light propagation showing that it is possible to observe superluminal energy propagation. In these conditions, it is possible to imprint reversibly ('write') the information carried by the photons onto the atoms, specifically as a coherent pattern of atomic spins, and later the information stored in the atomic spins can be transferred back ('read') to the light field, implementing in this way a quantum memory. Besides, we analyze the propagation of a quantum field in an EIT medium sustaining dark state polaritons (DSP) in a quasi-particle picture. Here, the decohe...
Classical and quantum dynamics of a model for atomic-molecular Bose--Einstein condensates
Santos Filho, Gilberto Nascimento; Tonel, Arlei Prestes; Foerster, Angela; Links, Jon(Centre for Mathematical Physics, School of Mathematics and Physics, The University of Queensland, 4072, Australia)
2005-01-01
We study a model for a two-mode atomic-molecular Bose--Einstein condensate. Starting with a classical analysis we determine the phase space fixed points of the system. It is found that bifurcations of the fixed points naturally separate the coupling parameter space into four regions. The different regions give rise to qualitatively different dynamics. We then show that this classification holds true for the quantum dynamics.
Nefediev, L. A.; Garnaeva, G. I.; Nizamova, E. I.
2016-09-01
Phase memory in a three-level system that is associated with the correspondence of isochromates of inhomogeneously broadened lines excited by lasers at various resonant frequencies with a common energy level in different time intervals is studied. It is shown that external spatially inhomogeneous electric fields can control such phase memory and could be used to determine the optimum conditions for forming a stimulated photon echo in a threelevel system.
Li, Huajiao; Fang, Wei; An, Haizhong; Yan, LiLi
2014-12-01
Two-mode and multi-mode networks represent new directions of simulating a complex network that can simulate the relationships among the entities more precisely. In this paper, we constructed two different levels of networks: one is the two-mode primitive networks of the energy listed companies and their shareholders on the basis of the two-mode method of complex theory, and the other is the derivative one-mode holding-based network based on the equivalence network theory. We calculated two different topological characteristics of the two networks, that is, the out-degree of the actor nodes of the two-mode network (9003 nodes) and the weights of the edges of the one-mode network (619,766 edges), and we analyzed the distribution features of both of the two topological characteristics. In this paper, we define both the weighted and un-weighted Shareholding Similarity Coefficient, and using the data of the worldwide listed energy companies and their shareholders as empirical study subjects, we calculated and compared both the weighted and un-weighted shareholding similarity coefficient of the worldwide listed energy companies. The result of the analysis indicates that (1) both the out-degree of the actor nodes of the two-mode network and the weights of the edges of the one-mode network follow a power-law distribution; (2) there are significant differences between the weighted and un-weighted shareholding similarity coefficient of the worldwide listed energy companies, and the weighted shareholding similarity coefficient is of greater regularity than the un-weighted one; (3) there are a vast majority of shareholders who hold stock in only one or a few of the listed energy companies; and (4) the shareholders hold stock in the same listed energy companies when the value of the un-weighted shareholding similarity coefficient is between 0.4 and 0.8. The study will be a helpful tool to analyze the relationships of the nodes of the one-mode network, which is constructed based
Ryzhov, I. V.; Vasil'ev, N. A.; Kosova, I. S.; Shtager, M. D.; Malyshev, V. A.
2017-05-01
Cooperative radiation emitted by an ensemble of three-level optical systems with a doublet in the ground state (Λ scheme), which is placed into a cyclic cavity, is studied theoretically. In contrast to the two-level model of emitters, this process with such a configuration of operating transitions may occur without population inversion in the whole, if the doublet is prepared at the initial instant in a superposition (coherent) state. In the ideal case of a Hamilton system, in which the cavity losses and relaxation in the radiator ensemble are disregarded, the conservation laws are derived, which allow a substantial reduction of the dimension of the phase space of the model (ℝ11 → ℝ5) and the application of methods of dynamics of nonlinear systems for analyzing the three-level superradiance under these conditions. The possibility of different (both quasiperiodic and chaotic) scenarios of the three-level superradiance is demonstrated on the basis of Poincaré's mappings. Global bifurcation of the system upon a transition from the conventional superradiance regime to inversionless one is revealed. The effects of cavity losses, as well as homogeneous and inhomogeneous broadening in the system of radiators on the regularities found are also discussed.
Directory of Open Access Journals (Sweden)
Shi-Zhou Xu
2015-01-01
Full Text Available The high-power three-level explosion-proof inverters demand high thermal stability of power devices, and a set of theories and methods is needed to achieve an accurate power-loss calculation of power devices, to establish heat dissipation model, and ultimately to reduce the power loss to improve thermal stability of system. In this paper, the principle of neutral point clamped three-level (NPC3L inverter is elaborated firstly, and a fourth-order RC equivalent circuit of IGBT is derived, on which basis the power-loss model of IGBT and the optimized maternal power-loss thermal model, using an optimized power-loss algorithm, are established. Secondly, in accordance with the optimized maternal power-loss thermal model, the generic formulas of power-loss calculation are deduced to calculate the power-loss modification values of NPC3L and soft switching three-level (S3L inverters, which will be the thermal sources during thermal analysis for maternal power-loss thermal models. Finally, the experiment conducted on the 2.1 MW experimental platform shows that S3L inverter has the same excellent output characteristics with NPC3L inverter, reduces the power loss significantly by 213 W in each half-bridge, and decreases the temperature by 10°C, coinciding with the theoretical calculation, which verifies the accuracy of optimized power-loss algorithm and the effectiveness of the improvement.
Directory of Open Access Journals (Sweden)
Khairy Sayed
2016-07-01
Full Text Available This paper presents the control and simulation of an electric vehicle (EV charging station using a three-level converter on the grid-side as well as on the EV-side. The charging station control schemes with three-level AC/DC power conversion and a bidirectional DC/DC charging regulator are described. The integration of EVs to the power grid provides an improvement of the grid reliability and stability. EVs are considered an asset to the smart grid to optimize effective performance economically and environmentally under various operation conditions, and more significantly to sustain the resiliency of the grid in the case of emergency conditions and disturbance events. The three-level grid side converter (GSC can participate in the reactive power support or grid voltage control at the grid interfacing point or the common coupling point (PCC. A fuzzy logic proportional integral (FL-PI controller is proposed to control the GSC converter. The controllers used are verified and tested by simulation to evaluate their performance using MATLAB/SIMULINK. The comparison of a PI-controller and a PI-Fuzzy controller for the EV charging station shows the effectiveness of the proposed FL-PI controller over conventional PI controller for same circuit operating conditions. A good performance for PI-Fuzzy in terms of settling time and peak overshoot can observed from the simulation results.
Ultimate statistical physics: fluorescence of a single atom
Pomeau, Yves; Le Berre, Martine; Ginibre, Jean
2016-10-01
We discuss the statistics of emission of photons by a single atom or ion illuminated by a laser beam at the frequency of quasi-resonance between two energy levels, a situation that corresponds to real experiments. We extend this to the case of two laser beams resonant with the energy differences between two excited levels and the ground state (three level atom in V-configuration). We use a novel approach to this type of problem by considering a Kolmogorov equation for the probability distribution of the atomic state, which takes into account first the deterministic evolution of this state under the effect of the incoming laser beam and second the random emission of photons during the spontaneous decay of the excited state(s) to the ground state. This approach yields solvable equations in the two level atom case. For the three level atom case we set the problem and clearly define its frame. The results obtained are valid in both opposite limits of rare and frequent spontaneous decay, compared to the period of the optical Rabi oscillations due to the interaction between resonant excitation and atomic levels. Our analysis gives access to various statistical properties of the fluorescence light, including one showing that its fluctuations in time are not invariants under time reversal. This result makes evident the fundamentally irreversible character of quantum measurements, represented here by the emission of photons of fluorescence.
Variations of Positive and Negative Dispersions in Both Highly and Weakly Absorptive Atomic Systems
Abi-Salloum, Tony; Snell, Scott; Davis, Jon; Narducci, Frank
2011-05-01
Positive and negative dispersive media are essential in subluminal, superluminal and negative group velocity pulse propagation applications. Three-level atomic media at resonance, especially the Lambda configuration, are positively dispersive and transparent. In contrast, two-level atomic systems are negatively dispersive and opaque. In this work we study higher level atomic systems comprised of three fields coupled to three levels (double lambda) or four levels (N-Scheme). We explore the systems of interest for critical features such as negative dispersion and transparency, a combination that is needed in numerous applications, e.g. optical gyroscopes. We solve the time dependent equations perturbatively and compare them to well established behavior in three-level systems. Some of the results are analyzed in terms of resonances which control the different features of the observed dispersive and absorptive behaviors.
Theoretical analysis of the spectroscopy of atomic Bose-Hubbard systems
Inaba, Kensuke; Yamashita, Makoto
2016-04-01
We provide a numerical method to calculate comprehensively the microwave and the laser spectra of ultracold bosonic atoms in optical lattices at finite temperatures. Our formulation is built up with the sum rules, up to the second order, derived from the general principle of spectroscopy. The sum rule approach allows us to discuss the physical origins of a spectral peak shift and also a peak broadening. We find that a spectral broadening of superfluid atoms can be determined from number fluctuations of atoms, while that of normal-state atoms is mainly attributed to quantum fluctuations resulting from hopping of atoms. To calculate spectra at finite temperatures, based on the sum rule approach, we provide a two-mode approximation assuming that spectra of the superfluid and normal state atoms can be calculated separately. Our method can properly deal with multipeak structures of spectra resulting from thermal fluctuations and also coexisting of the superfluid and the normal states. By combining the two-mode approximation with a finite temperature Gutzwiller approximation, we calculate spectra at finite temperatures by considering realistic systems, and the calculated spectra show nice agreements with those in experiments.
Energy Technology Data Exchange (ETDEWEB)
Pack, Michael Vern
2008-12-01
This report describes progress in designing a neutral atom trap capable of trapping sub millikelvin atom in a magnetic trap and shuttling the atoms across the atom chip from a collection area to an optical cavity. The numerical simulation and atom chip design are discussed. Also, discussed are preliminary calculations of quantum noise sources in Kerr nonlinear optics measurements based on electromagnetically induced transparency. These types of measurements may be important for quantum nondemolition measurements at the few photon limit.
Atom Lithography with a Chromium Atomic Beam
Institute of Scientific and Technical Information of China (English)
ZHANG Wen-Tao; LI Tong-Bao
2006-01-01
@@ Direct write atom lithography is a new technique in which resonant light is used to pattern an atomic beam and the nanostructures are formed when the atoms deposit on the substrate. We design an experiment setup to fabricate chromium nanolines by depositing an atomic beam of 52 Cr through an off-resonant laser standing wave with the wavelength of 425.55 nm onto a silicon substrate. The resulting nanolines exhibit a period of 215 ± 3 nm with height of 1 nm.
Atomic and molecular manipulation
Mayne, Andrew J
2011-01-01
Work with individual atoms and molecules aims to demonstrate that miniaturized electronic, optical, magnetic, and mechanical devices can operate ultimately even at the level of a single atom or molecule. As such, atomic and molecular manipulation has played an emblematic role in the development of the field of nanoscience. New methods based on the use of the scanning tunnelling microscope (STM) have been developed to characterize and manipulate all the degrees of freedom of individual atoms and molecules with an unprecedented precision. In the meantime, new concepts have emerged to design molecules and substrates having specific optical, mechanical and electronic functions, thus opening the way to the fabrication of real nano-machines. Manipulation of individual atoms and molecules has also opened up completely new areas of research and knowledge, raising fundamental questions of "Optics at the atomic scale", "Mechanics at the atomic scale", Electronics at the atomic scale", "Quantum physics at the atomic sca...
Advances in atomic spectroscopy
Sneddon, J
2000-01-01
This fifth volume of the successful series Advances in Atomic Spectroscopy continues to discuss and investigate the area of atomic spectroscopy.It begins with a description of the use of various atomic spectroscopic methods and applications of speciation studies in atomic spectroscopy. The emphasis is on combining atomic spectroscopy with gas and liquid chromatography. In chapter two the authors describe new developments in tunable lasers and the impact they will have on atomic spectroscopy. The traditional methods of detection, such as photography and the photomultiplier, and how they are being replaced by new detectors is discussed in chapter three. The very active area of glow discharge atomic spectrometry is presented in chapter four where, after a brief introduction and historical review, the use of glow discharge lamps for atomic spectroscopy and mass spectrometry are discussed. Included in this discussion is geometry and radiofrequency power. The future of this source in atomic spectroscopy is also dis...
Microfabricated Waveguide Atom Traps.
Energy Technology Data Exchange (ETDEWEB)
Jau, Yuan-Yu
2017-09-01
A nano - scale , microfabricated waveguide structure can in - principle be used to trap atoms in well - defined locations and enable strong photon - atom interactions . A neutral - atom platf orm based on this microfabrication technology will be pre - aligned , which is especially important for quantum - control applications. At present, there is still no reported demonstration of evanescent - field atom trapping using a microfabricated waveguide structure. We described the capabilities established by our team for future development of the waveguide atom - trapping technology at SNL and report our studies to overcome the technical challenges of loading cold atoms into the waveguide atom traps, efficient and broadband optical coupling to a waveguide, and the waveguide material for high - power optical transmission. From the atomic - physics and the waveguide modeling, w e have shown that a square nano - waveguide can be utilized t o achieve better atomic spin squeezing than using a nanofiber for first time.
Controlling steady-state and dynamical properties of atomic optical bistability
Joshi, Amitabh
2012-01-01
This book provides a comprehensive introduction to the theoretical and experimental studies of atomic optical bistability and multistability, and their dynamical properties in systems with two- and three-level inhomogeneously-broadened atoms inside an optical cavity. By making use of the modified linear absorption and dispersion, as well as the greatly enhanced nonlinearity in the three-level electromagnetically induced transparency system, the optical bistablity and efficient all-optical switching can be achieved at relatively low laser powers, which can be well controlled and manipulated. Un
Electromagnetically Induced Transparency in a Four-Level Atomic System
Institute of Scientific and Technical Information of China (English)
LIJia-Hua; WANGWen-Yi
2004-01-01
In this paper, we analyze and discuss the absorption properties of the probe beam in a four-level atomic system with a nearly hyper-fine doublet structure of two higher-lying excited levels based on electromagnetieally induced transparency (EIT) for the two cases of transient process and steady-state process. The main gain of this work is to investigate theoretically the influence of the nearly hyper-fine levels on the probe absorption. For the transient process, using the numerical calculations by a simple Mathematica code we find that the magnitude of the probe absorption at the line center is small compared to the typical three-level atomic system in the context of electromagnetieally induced transparency. For the case of the steady state, our results show that the probe absorption can be completely eliminated at the line center of the probe transition just as the usual three-level EIT scheme.
Electromagnetically Induced Transparency in a Four-Level Atomic System
Institute of Scientific and Technical Information of China (English)
LI Jia-Hua; WANG Wen-Yi
2004-01-01
In this paper, we analyze and discuss the absorption properties of the probe beam in a four-level atomic system with a nearly hyper-fine doublet structure of two higher-lying excited levels based on electromagnetically induced transparency (EIT) for the two cases of transient process and steady-state process. The main gain of this work is to investigate theoretically the influence of the nearly hyper-fine levels on the probe absorption. For the transient process,using the numerical calculations by a simple Mathematica code we find that the magnitude of the probe absorption at the line center is small compared to the typical three-level atomic system in the context of electromagnetically induced transparency. For the case of the steady state, our results show that the probe absorption can be completely eliminated at the line center of the probe transition just as the usual three-level EIT scheme.
Atomic Particle Detection, Understanding the Atom Series.
Hellman, Hal
This booklet is one of the booklets in the "Understanding the Atom Series" published by the U. S. Atomic Energy Commission for high school science teachers and their students. The instruments used to detect both particles and electromagnetic radiation that emerge from the nucleus are described. The counters reviewed include ionization chambers,…
Light-mediated non-Gaussian entanglement of atomic ensembles
Pettersson, Olov; Byrnes, Tim
2017-04-01
We analyze a similar scheme for producing light-mediated entanglement between atomic ensembles, as first realized by Julsgaard, Kozhekin, and Polzik [Nature (London) 413, 400 (2001), 10.1038/35096524]. In the standard approach to modeling the scheme, a Holstein-Primakoff approximation is made, where the atomic ensembles are treated as bosonic modes, and is only valid for short interaction times. In this paper, we solve the time evolution without this approximation, which extends the region of validity of the interaction time. For short entangling times, we find that this produces a state with characteristics similar to those of a two-mode squeezed state, in agreement with standard predictions. For long entangling times, the state evolves into a non-Gaussian form, and the characteristics of the two-mode squeezed state start to diminish. This is attributed to more exotic types of entangled states being generated. We characterize the states by examining the Fock-state probability distributions, Husimi Q distributions, and nonlocal entanglement between the ensembles. We compare and connect several quantities obtained by using the Holstein-Primakoff approach and our exact time evolution methods.
DEFF Research Database (Denmark)
Zhang, Zhe; Anthon, Alexander; Andersen, Michael A. E.
2014-01-01
frequencyincreases due to high switching loss of the equipped high voltagepower switches. In order to reduce switching loss and herebyenhance efficiency, a newly proposed circuit-level decouplingmodulation (CLDM) scheme is applied for these two widely usedthree-phase three-level inverters, as well...... as their correspondingloss analyses are addressed. The switching loss reduction isevaluated comprehensively undervariant modulation indices andload power factors. The analysis results reveal that the CLDM isan alternative discontinuouspulse-width modulation (DPWM)approach for inverters with high switching frequencies...