Adiabatic change of state of photon gas
The authors introduced and justified the k problem as a thermodynamical contradiction of photon gas. In thermodynamics of photon gas the main contradiction is called the k problem: the piezotropic-autobarotropic equation of state P = u/3 is adiabatic if k = 1 exclusively, while the adiabatic connection PV4/3 = const (or rather the Poisson equation Pρ-4/3 = const, ρ = u/c2) requires that k = 4/3. The present paper shows that the equations of state PV4/3 = const, TV1/3 = const, T-4/3P1/3 = const and P = u/3 cannot be valid for the adiabatic change of state of photon gas, simultaneously. Furthermore, the Planck's distribution -- and so the Wien's law and the Rayleigh-Jeans connection as well -- cannot be invariant in case of adiabatic change of state of photon gas. Namely, in case of adiabatic change of state of photon gas, a new type of ultraviolet catastrophe appears. These results possess a fundamental important in case of arbitrary deformation of electromagnetic radiation fields or quantum plasmas
Physics on the adiabatically changed Finslerian manifold and cosmology
Lipovka, Anton A
2016-01-01
In present paper we confirm our previous result [4] that Planck constant is adiabatic invariant of electromagnetic field propagating on the adiabatically changed Finslerian manifold. Direct calculation from cosmological parameters gives value h=6x10(-27) (erg s). We also confirm that Planck constant (and hence other fundamental constants which depend on h) is varied on time due to changing of geometry. As an example the variation of the fine structure constant is calculated. Its relative variation ((da/dt)/a) consist 1.0x10(-18) (1/s). We show that on the Finsler manifold characterized by adiabatically changed geometry, classical free electromagnetic field is quantized geometrically, from the properties of the manifold in such manner that adiabatic invariant of field is ET=6x10(-27)=h. Electrodynamic equations on the Finslerian manifold are suggested. It is stressed that quantization naturally appears from these equations and is provoked by adiabatically changed geometry of manifold. We consider in details tw...
Pterygium-induced corneal refractive changes
Maheshwari Sejal
2007-01-01
Full Text Available To study the effect of pterygium on corneal topography, a retrospective analysis of 151 eyes with primary pterygia was done. All cases underwent videokeratography preoperatively and one month postoperatively. Statistical analysis of average corneal power (ACP, corneal astigmatism, surface regularity index (SRI and surface asymmetry index (SAI was done before and one month after surgery. Topographic indices were compared statistically for various grades of pterygia. Increase in the grade of pterygia had a significant effect on topographic indices. Corneal astigmatism reduced from 4.40±3.64 diopter (D to 1.55±1.63D ( P value < 0.001 following surgery. The regularity of corneal surface improved and asymmetry of the cornea reduced one month after surgery. Pterygium leads to significant changes in corneal refractive status, which increase with the increase in the grade of pterygia and improve following pterygium excision.
Refractive change after vitrectomy for epiretinal membrane in pseudophakic eyes
Hamoudi, Hassan; Kofod, Mads; La Cour, Morten
2013-01-01
Purpose: To report the change in refraction in pseudophakic eyes following 23-gauge vitrectomy for epiretinal membrane (ERM), without use of silicone oil, intraocular gas or scleral buckling. Methods: Retrospective review of the records of 28 pseudophakic eyes in 28 patients undergoing 23-gauge...... the mean postoperative refraction was -0.41 ± 0.93 D. Thus, a myopic shift was observed following vitrectomy with a mean change in refraction of -0.26 ± 0.60 D (range +0.75 to -2.13 D, p = 0.032). The postoperative change in refraction was within ±0.25, ±0.50 and ±1.00 D in 39%, 68% and 96% of the...... eyes, respectively. The mean absolute refractive error was 0.47 ± 0.44 D. The change in refraction in fellow eyes was +0.01 D (p = 0.82). Conclusion: The change in refraction following 23-gauge pars plana vitrectomy for ERM in pseudophakic eyes was -0.26 D....
Oscillating adiabatic temperature change of 2D diamagnetic materials
Studies on magnetocaloric effect generally concern ferromagnetic materials, due to their high magnetocaloric potential near phase transitions. Recently, this effect on diamagnetic materials was explored and oscillations on the entropy change observed as a consequence of the crossing of the Landau levels through the Fermi energy. The present paper explores the adiabatic temperature change in graphenes and thin films of non-relativistic diamagnetic materials and then compares the results with those from 3D diamagnets. Applying 10 T of magnetic field, the temperature change of a gold thin film reaches 1 K, while for bulk gold the temperature change is smaller than 6 mK. For graphenes, the temperature change reaches 4 K with a field of ∼1 T. - Highlights: • We studied magnetocaloric properties of 2D diamagnetic materials. • Temperature change of low-dimensional materials exhibits an oscillating behavior. • The effect of scattering from impurity in graphene strongly reduces the temperature change. • We propose an application involving field sensors
Posterior corneal curvature changes following Refractive Small Incision Lenticule Extraction
Ganesh, Sri
2015-01-01
Sri Ganesh, Utsav Patel, Sheetal Brar Phaco and Refractive Surgery Department, Nethradhama Superspeciality Eye Hospital, Bengaluru, Karnataka, India Purpose: To compare the posterior corneal curvature changes, in terms of corneal power and asphercity, following Refractive Small Incision Lenticule Extraction (ReLEx SMILE) procedure for low, moderate, and high myopia.Methods: This retrospective, non randomized, comparative, interventional trial; included 52 eyes of 26 patients, divided in thr...
Laser induced changes of refractive index of lead - silicate glasses
The mechanisms of photoinduced changes of refractive index of the TΦ lead - silicate glasses (analogous with the SF glasses from Schott catalog) under the effect of high power laser radiation with quantum energy less bandgap have been studied. It is shown that the laser induced color centers results in increase of refractive index into the exposed bulk during the laser pulse action. This leads to considerable redistribution of irradiance and decrease of laser radiation brightness even in the case of optical elements less 1 mm thickness. The observed effect may be connected both with radiation induced dilatation of matter and heating of interaction region owing to absorption of radiation by color centers. Comparison the kinetics of refractive index change of the glass after exposure by laser pulse at 0.53 μm and the kinetics of color centers decay allowed to draw a conclusion about heat character of observed changes
Measurements of photoinduced refractive index changes in bacteriorhodopsin films
Ravinder Kumar Banyal; B Raghavendra Prasad
2007-03-01
We report the pump-probe measurements of nonlinear refractive index changes in photochromic bacteriorhodopsin films. The photoinduced absorption is caused by pump beam at 532 nm and the accompanying refractive index changes are studied using a probe beam at 633 nm. The proposed technique is based on a convenient and accurate determination of optical path difference using digital interferometry-based local fringe shift. The results are presented for the wild-type as well as genetically modified D96N variant of the bacteriorhodopsin.
Measurements of photoinduced refractive index changes in bacteriorhodopsin films
Banyal, Ravinder Kumar; Raghavendra Prasad, B.
2007-03-01
We report the pump--probe measurements of nonlinear refractive index changes in photochromic bacteriorhodopsin films. The photoinduced absorption is caused by pump beam at 532 nm and the accompanying refractive index changes are studied using a probe beam at 633 nm. The proposed technique is based on a convenient and accurate determination of optical path difference using digital interferometry-based local fringe shift. The results are presented for the wild-type as well as genetically modified D96N variant of the bacteriorhodopsin.
Refractive index change detection based on porous silicon microarray
Chen, Weirong; Jia, Zhenhong; Li, Peng; Lv, Guodong; Lv, Xiaoyi
2016-05-01
By combining photolithography with the electrochemical anodization method, a microarray device of porous silicon (PS) photonic crystal was fabricated on the crystalline silicon substrate. The optical properties of the microarray were analyzed with the transfer matrix method. The relationship between refractive index and reflectivity of each array element of the microarray at 633 nm was also studied, and the array surface reflectivity changes were observed through digital imaging. By means of the reflectivity measurement method, reflectivity changes below 10-3 can be observed based on PS microarray. The results of this study can be applied to the detection of biosensor arrays.
Fishman, S.; Soffer, A.
2016-07-01
We employ the recently developed multi-time scale averaging method to study the large time behavior of slowly changing (in time) Hamiltonians. We treat some known cases in a new way, such as the Zener problem, and we give another proof of the adiabatic theorem in the gapless case. We prove a new uniform ergodic theorem for slowly changing unitary operators. This theorem is then used to derive the adiabatic theorem, do the scattering theory for such Hamiltonians, and prove some classical propagation estimates and asymptotic completeness.
Posterior corneal curvature changes following Refractive Small Incision Lenticule Extraction
Ganesh S
2015-07-01
Full Text Available Sri Ganesh, Utsav Patel, Sheetal Brar Phaco and Refractive Surgery Department, Nethradhama Superspeciality Eye Hospital, Bengaluru, Karnataka, India Purpose: To compare the posterior corneal curvature changes, in terms of corneal power and asphercity, following Refractive Small Incision Lenticule Extraction (ReLEx SMILE procedure for low, moderate, and high myopia.Methods: This retrospective, non randomized, comparative, interventional trial; included 52 eyes of 26 patients, divided in three groups: low myopia (myopia ≤3 D [diopters] spherical equivalent [SE], moderate myopia (myopia >3 D and <6 D SE, and high myopia (myopia ≥6 D SE. All patients were treated for myopia and myopic astigmatism using ReLEx SMILE. The eyes were examined pre-operatively and 3 months post-operatively using SCHWIND SIRIUS, a three-dimensional rotating Scheimpflug camera with a Placido disc topographer to assess corneal changes with regard to keratometric power and asphericity of the cornea.Results: A statistically significant increase in mean keratometric power in the 3, 5, and 7 mm zones of the posterior corneal surface compared with its pre-ReLEx SMILE value was detected after 3 months in the moderate myopia group (pre-operative [pre-op] -6.14±0.23, post-operative [post-op] -6.29±0.22, P<0.001 and high myopia group (pre-op -6.19±0.16, post-op -6.4±0.18, P<0.001, but there was no significant change in keratometric power of the posterior surface in the low myopia group (pre-op -5.87±0.17, post-op -6.06±0.29, P=0.143. Asphericity (Q-value of the posterior surface changed significantly (P<0.001 after ReLEx SMILE in the moderate myopia group in the 3, 5, and 7 mm zones, and in the high myopia group in the 3 and 7 mm zones; but there was no significant change in the Q-value in the low myopia group in all three zones (pre-op 0.23±0.43, post-op -0.40±0.71, P=0.170, and in the high myopia group in the 5 mm zone (P=0.228.Conclusion: ReLEx SMILE causes significant
Within the adiabatic theorem we must explicitly add to the instantaneous adiabatic vectors, parametrized by an external parameter following an open curve, a dynamical as well as a geometrical phase contribution to be able to predict the quantum observables. We give an alternative to Berry's proof for cyclic paths without use of Stokes's theorem that is then generalized to open paths. Recent analyses that argued, for an adiabatic open path case, that there is only dynamical phase change or that the situation is undefined are shown to be incorrect. The noncyclic geometric phase correction is discussed in detail for the spin in a magnetic field, an Aharonov-Bohm experiment and a resonator. Properties of the geometric phase contribution for open paths are studied. First, it is shown that degeneracies play an important role. Second, it is shown to be semiclassically related to a geometric angle shift on the final torus. The revival structure of wavepackets is shown to be affected by the noncyclic geometric phases of the, contributing instantaneous vectors that make the revived wavepacket to be shifted on the final torus by the classical geometric angle. We also propose two measures of quantum sensitivity to initial conditions. The first one is valid for quantum and classical Liouville states and it is given by the different distances of two close states to a third fixed state. The second measure is given by the divergence of the flow lines of suitable quantum phase space representations and reduces to the classical Lyapunov exponent. (author)
Refractive changes after vitrectomy and phacovitrectomy for macular hole and epiretinal membrane
Hamoudi, Hassan; La Cour, Morten
2013-01-01
Several studies have described changes in refraction toward myopia in eyes having vitrectomy and phacovitrectomy. This article reviews studies of the refractive outcome in phakic and pseudophakic eyes after vitrectomy and phacovitrectomy for macular hole or epiretinal membrane. Several factors play...
Mechanisms of the refractive index change in DO11/PMMA due to photodegradation
Anderson, Benjamin R
2014-01-01
Using a white light interferometric microscope (WLIM) we measure the photodamage induced change in the complex index of refraction of disperse orange 11 (DO11) dye-doped (poly)methyl-methacrylate. We find that the change in the imaginary part of the refractive index is consistent with previous measurements of photodamage-induced absorbance change. Additionally, we find that the change in the real refractive index can be separated into a component due to damage to the dye molecules and a component due to irreversible damage to the polymer.
Refractive Index Change and Color Center Formation in LiYF_4 Crystal Induced by a Femtosecond Laser
无
2003-01-01
The refractive index change and color centers formation in LiYF4 crystal at room temperature are induced by a femtosecond laser irradiation. A mechanism for refractive index change and color centers formation is proposed.
Interferometer for Measuring Fast Changes of Refractive Index and Temperature in Transparent Liquids
Miller, Arne; Hussmann, E. K.; McLaughlin, W. L.
1975-01-01
A double‐beam interferometer has been designed for detecting changes of refractive index in transparent liquids associated with the absorption of ionizing radiation energy, due to short electron beam pulses from an accelerator. The response time of the interferometer is less than 0.2 μsec, and...... refractive index changes of the order of 10−7 can be measured, corresponding to a temperature change of ∼10−3 °C and an absorbed dose in water of ∼350 rad. The interferometer can be used as either a real‐time or integrating radiation dosimeter, if the temperature coefficient of the refractive index (dn...
Change in peripheral refraction and curvature of field of the human eye with accommodation
Ho, Arthur; Zimmermann, Frederik; Whatham, Andrew; Martinez, Aldo; Delgado, Stephanie; Lazon de la Jara, Percy; Sankaridurg, Padmaja
2009-02-01
Recent research showed that the peripheral refractive state is a sufficient stimulus for myopia progression. This finding led to the suggestion that devices that control peripheral refraction may be efficacious in controlling myopia progression. This study aims to understand whether the optical effect of such devices may be affected by near focus. In particular, we seek to understand the influence of accommodation on peripheral refraction and curvature of field of the eye. Refraction was measured in twenty young subjects using an autorefractor at 0° (i.e. along visual axis), and 20°, 30° and 40° field angles both nasal and temporal to the visual axis. All measurements were conducted at 2.5 m, 40 cm and 30 cm viewing distances. Refractive errors were corrected using a soft contact lens during all measurements. As field angle increased, refraction became less hyperopic. Peripheral refraction also became less hyperopic at nearer viewing distances (i.e. with increasing accommodation). Astigmatism (J180) increased with field angle as well as with accommodation. Adopting a third-order aberration theory approach, the position of the Petzval surface relative to the retinal surface was estimated by considering the relative peripheral refractive error (RPRE) and J180 terms of peripheral refraction. Results for the estimated dioptric position of the Petzval surface relative to the retina showed substantial asymmetry. While temporal field tended to agree with theoretical predictions, nasal response departed dramatically from the model eye predictions. With increasing accommodation, peripheral refraction becomes less hyperopic while the Petzval surface showed asymmetry in its change in position. The change in the optical components (i.e. cornea and/or lens as opposed to retinal shape or position) is implicated as at least one of the contributors of this shift in peripheral refraction during accommodation.
W. F. Harris
2009-01-01
If an intraocular lens is displaced or if its power is changed what are the consequences for the refractive compensation of the eye? Gaussian optics is used to obtain explicit formulae for the sensitivityof the corneal-plane refractive compensation (also called the refraction, refractive state, etc) to change in power and axial displacement of a thin intraocular lens implanted in a simple eye. In particular, for a pseudophakic Gullstrand simplified eye with intraocular lens placed 5 mm behi...
W. F. Gool; R.D. van Gool
2009-01-01
If an intraocular lens is displaced or if its power is changed what are the consequences for the refractive compensation of the eye? Gaussian optics is used to obtain explicit formulae for the sensitivityof the corneal-plane refractive compensation (also called the refraction, refractive state, etc) to change in power and axial displacement of a thin intraocular lens implanted in a simple eye. In particular, for a pseudophakic Gullstrand simplified eye withintraocular lens placed 5 mm behin...
Arasa, Josep; Pizarro, Carles; Blanco, Patricia
2016-06-01
Injection molded plastic lenses have continuously improved their performance regarding optical quality and nowadays are as usual as glass lenses in image forming devices. However, during the manufacturing process unavoidable fluctuations in material density occur, resulting in local changes in the distribution of refractive index, which degrade the imaging properties of the polymer lens. Such material density fluctuations correlate to phase delays, which opens a path for their mapping. However, it is difficult to transfer the measured variations in refractive index into conventional optical simulation tool. Thus, we propose a method to convert the local variations in refractive index into local changes of one surface of the lens, which can then be described as a free-form surface, easy to introduce in conventional simulation tools. The proposed method was tested on a commercial gradient index (GRIN) lens for a set of six different object positions, using the MTF sagittal and tangential cuts to compare the differences between the real lens and a lens with homogenous refractive index, and the last surface converted into a free-form shape containing the internal refractive index changes. The same procedure was used to reproduce the local refractive index changes of an injected plastic lens with local index changes measured using an in-house built polariscopic arrangement, showing the capability of the method to provide successful results.
Photoinduced changes in refractive index of nanostructured shungite-containing polyimide systems
Kamanina, N. V.; Serov, S. V.; Shurpo, N. A.; Rozhkova, N. N.
2011-10-01
Photoinduced changes in the refractive index of a conjugate polyimide (PI) matrix sensitized by shungite carbon nanoparticles have been studied for the first time. The results are compared to the data of previous investigations of the photorefractive properties of PI matrices doped with fullerenes, carbon nanotubes, and quantum dots. The nonlinear refractive index of the proposed material has been determined using the dynamic holography techniques. The position of conjugate polymer materials of this type among the other nonlinear optical systems is considered.
Mechanisms of a change in the refractive index of an intensely pumped Yb:YAG crystal
Mechanisms of a change in the refractive index appearing in an intensely diode-pumped Yb:YAG-laser disk element are studied with the help of polarisation interferometry and dynamic grating testing. It is found that changes in the electronic component of the refractive index arising upon changing the populations of electronic levels of Yb3+ ions (the ground 2F7/2 state and the upper 2F5/2 level of the laser transition) and caused by the difference in the polarisability of these levels are an order of magnitude greater than thermal changes in the refractive index. It is shown that the difference Δp in the polarisability at the probe wavelength of 633 nm is 1.9 x 10-26 cm3 and at the laser transition wavelength of 1029 nm is 1.6 x 10-26 cm3. (nonlinear optical phenomena)
Digital Waveguide Adiabatic Passage Part 1: Theory
Vaitkus, Jesse A; Greentree, Andrew D
2016-01-01
Spatial adiabatic passage represents a new way to design integrated photonic devices. In conventional adiabatic passage designs require smoothly varying waveguide separations. Here we show modelling of adiabatic passage devices where the waveguide separation is varied digitally. Despite digitisation, our designs show robustness against variations in the input wavelength and refractive index contrast of the waveguides relative to the cladding. This approach to spatial adiabatic passage opens new design strategies and hence the potential for new photonics devices.
Takei, Hiroyuki; Shimizu, Norio
1996-04-01
Bacteriorhodopsin exhibits photoinduced changes in both absorption and refractive index at 633 nm. To explore the possibility of exploiting this property in constructing a photoaddressed spatial light modulator, we investigated the transmission property of a Fabry-Perot interferometer containing a bacteriorhodopsin thin film. Film was formed that had a phase shift of pi /4 and sufficient interference fringe contrast for spatial light modulation. This establishes the possibility of constructing a spatial light modulator that features nonlinear input-output characteristics and can operate at moderate light intensities of the order of tens of milliwatts per centimeter square. spatial light modulation, complex refractive index.
Min Kyu Yang
Full Text Available To assess the characteristic findings and effects of laser capsulotomy in patients with late postoperative capsular bag distension syndrome (CBDS.Twenty patients diagnosed with late postoperative CBDS between July 2010 and August 2013 were retrospectively reviewed. Before and 1 week after capsulotomy, changes in the anterior chamber depth (ACD were assessed using ultrasound biomicroscopy. Changes in the refractive status and uncorrected visual acuity (UCVA were also measured 1 week and 1 month after capsulotomy. For patients who received bilateral cataract surgery, preoperative ACD and axial length measured by IOLMaster were compared between the two eyes.Twenty-two eyes from 20 patients who had undergone laser capsulotomy showed a mean UCVA improvement of 0.27 ± 0.24 logMAR (range, 0.00-0.90. ACD was increased by an average of +0.04 mm (95% confidence interval, +0.01 to +0.06 mm, p = 0.034, equivalent to predicted refractive change of +0.10 D. The discrepancy between actual (+1.33 D and predicted refractive change after capsulotomy suggests that refractive change may not be generated from IOL displacement in late postoperative CBDS. Preoperative ACD was deeper in the eye with late postoperative CBDS in all bilaterally pseudophakic patients (mean, 3.68 mm vs. 3.44 mm in the fellow eye, p = 0.068.Late postoperative CBDS showed refractive changes that were resolved successfully after laser capsulotomy. The convex lens effects of opalescent material in the distended capsular bag may play a major role in myopic shift. A larger preoperative ACD is possibly associated with the development of late postoperative CBDS.
Influence of Temperature and Pressure Change on Adiabatic and Isothermal Methanation Processes
Porubova, Jekaterina; Klemm, Marco; Kiendl, Isabel; Valters, Karlis; Markova, Darja; Repele, Mara; Bazbauers, Gatis
2012-09-01
Energy plans of many countries anticipate an increased use of biomethane for energy supply, i.e., in power and heat production as well as in the transport sector. Existing infrastructure of natural gas storage, supply and application provides a good platform to facilitate transfer to biomethane utilization on a larger scale. One key element of the biomethane system is the upgrade of the biomass-derived synthesis gas originating from different sources, to a quality of natural gas (SNG - Synthesis Natural Gas) via the methanation process for further injection into the natural gas grid.. The maximisation of efficiency of the methanation process is of critical importance in order to make biomethane technology viable for wider application. The aim of the study was to improve efficiency of the methanation process by finding the optimum temperatures and pressure. Theoretical modelling of adiabatic and isothermal methanation processes by using thermodynamic equilibrium calculations was introduced as a method for the study. The results show the impact of temperature and pressure changes on the overall efficiency of methane production. It can be concluded from the study that knowledge about the relation between temperature, pressure and the efficiency of the methanation process makes it possible to optimize the process under various biomass synthesized gas input conditions.
Savolainen, Juha-Matti; Grüner-Nielsen, Lars; Kristensen, Poul; Balling, Peter
2014-01-01
A new method for direct writing of localized, circularly symmetric refractive-index changes in optical fibers with a femtosecond laser is demonstrated. The refractive-index changes are characterized using a novel approach employing comparison of numerical simulations to the measured far...
McCullough, Sara J.; O’Donoghue, Lisa; Saunders, Kathryn J
2016-01-01
Objective To determine six-year spherical refractive error change among white children and young adults in the UK and evaluate differences in refractive profiles between contemporary Australian children and historical UK data. Design Population-based prospective study. Participants The Northern Ireland Childhood Errors of Refraction (NICER) study Phase 1 examined 1068 children in two cohorts aged 6–7 years and 12–13 years. Prospective data for six-year follow-up (Phase 3) are available for 21...
Ozturk, Emine; Sokmen, Ismail
2011-10-01
In this study, both the linear intersubband transitions and the refractive index changes in coupled double quantum well (DQW) with different well shapes for different electric fields are theoretically calculated within framework of the effective mass approximation. Results obtained show that intersubband transitions and the energy levels in coupled DQW can importantly be modified and controlled by the electric field strength and direction. By considering the variation of the energy differences, it should point out that by varying electric field we can obtain a blue or red shift in the intersubband optical transitions. The modulation of the absorption coefficients and the refractive index changes which can be suitable for good performance optical modulators and various infrared optical device applications can be easy obtained by tuning applied electric field strength and direction.
Adamova, M. S.; Zolotovskii, Igor'O.; Sementsov, Dmitrii I.
2009-03-01
Dynamics of soliton-like wave packets in fibres with a travelling refractive-index-change wave is studied. It is shown that both a soliton-like propagation regime of a pulse and a self-compression regime in the region of normal group velocity dispersion are possible. It is also shown that in the case of a copropagating or counterpropagating pulse and optically inhomogeneous wave nonreciprocal effects appear.
In this study, we have calculated the linear, nonlinear and total refractive index changes and absorption coefficients for the transitions 1s–1p, 1p–1d and 1d–1f in a spherical quantum dot with parabolic potential. Quantum Genetic Algorithm (QGA) and Hartree–Fock–Roothaan (HFR) method have been employed to calculate the wavefuctions and energy eigenvalues. The results show that impurity, dot radius, stoichiometric ratio, incident optical intensity and carrier density of the system have important effects on the optical refractive index changes and absorption coefficients. Also, we find that as the transitions between orbitals with big l value move to lower energy region in case with parabolic potential, in case without parabolic potential these transitions move to higher energy region. - Highlights: ► A spherical quantum dot with parabolic potential has been considered. ► Quantum Genetic Algorithm and Hartree–Fock–Roothaan method have been used to calculate the wave functions and the total energy. ► The detailed refractive index changes and absorption coefficients of quantum dot have been investigated.
赵建林; 张鹏; 周俭波; 杨德兴; 杨东升; 李恩普
2003-01-01
We propose a novel approach to visualize the light-induced refractive index changes in photorefractive crystals employing digital holography. The holograms formed in a Mach-Zehnder interferometer are recorded by a twodimensional CCD camera. From these holograms, the phase differences, which contain the information of the index changes in photorefractive crystals, are determined by utilizing digital holographic interferometry. Then the two-dimensional visualizations of index changes in the crystals can be obtained. This method is successfully demonstrated in LiNbO3:Fe, KNSBN:Ce and SBN:Cr crystals.
The analytical expressions of linear and nonlinear optical absorption coefficients and refractive index changes in a quantum dot with a hydrogenic impurity are obtained by using the compact-density-matrix approach and iterative method. The wave functions and the energy levels are obtained by using the variational method. Numerical results show that the optical absorption coefficients and refractive index changes are strongly affected by the hydrogenic impurity. (paper)
A Comparison of Kretschmann-Raether Angular Regimes for Measuring Changes in Bulk Refractive Index
KASUNIC, K.J.
1999-09-16
We compare 2 angular regimes for the measurement of changes in the real refractive index of bulk fluid analytes. The measurements are based on the use of the Kretschmann-Raether configuration to sense a change in reflectivity with index. Specifically, we numerically simulate the relative sensitivities of the total internal reflection (TIR) and surface-plasmon resonance (SPR) regimes. For a fixed-angle apparatus, the method which gives the greatest change in reflectivity varies with metal film thickness. For films thicker than the skin depth, the SPR regime is the most sensitive to index changes. For thinner films, however, the TIR angle is then dominant, with increases in sensitivity on the order of 75% for 10 nm gold or silver media.
Zamani Meymian, Mohammad Reza
2007-12-18
For the study in this thesis {sup 3}He{sup 2+} ions with the energy of about 40 MeV were applied. The results of these studies show a timely very stable anisotrope refractive-index change in the range of some 10{sup -3}. The radiation damages caused by ions cause a decreasement of the ordinary refractive index n{sub o} and an increasement of the extra-ordinary refractive index n{sub e}. While the absolute values for {delta}n{sub o} and {delta}n{sub e} are nearly equal the birefringence of the material (n{sub e}-n{sub o}) smaller. The generated refractive-index change is dose dependent and the curve {delta}n has at increasing dose a strongly nonlinear slope with a characteristic stage at the radiation dose of about 2 x 10{sup 20} ions/m{sup 2}.
Owen, Albert K.
1987-01-01
A computer code was written which utilizes ray tracing techniques to predict the changes in position and geometry of a laser Doppler velocimeter probe volume resulting from refraction effects. The code predicts the position change, changes in beam crossing angle, and the amount of uncrossing that occur when the beams traverse a region with a changed index of refraction, such as a glass window. The code calculates the changes for flat plate, cylinder, general axisymmetric and general surface windows and is currently operational on a VAX 8600 computer system.
... the eye keeps you from focusing well. The cause could be the length of the eyeball (longer or shorter), changes in the shape of the cornea, or aging of the lens. Four common refractive errors are Myopia, or nearsightedness - clear vision close up ...
Refractive index modulation of Sb70Te30 phase-change thin films by multiple femtosecond laser pulses
Lei, Kai; Wang, Yang; Jiang, Minghui; Wu, Yiqun
2016-05-01
In this study, the controllable effective refractive index modulation of Sb70Te30 phase-change thin films between amorphous and crystalline states was achieved experimentally by multiple femtosecond laser pulses. The modulation mechanism was analyzed comprehensively by a spectral ellipsometer measurement, surface morphology observation, and two-temperature model calculations. We numerically demonstrate the application of the optically modulated refractive index of the phase-change thin films in a precisely adjustable color display. These results may provide further insights into ultrafast phase-transition mechanics and are useful in the design of programmable photonic and opto-electrical devices based on phase-change memory materials.
Large refractive index changes in tunable-electron-density InGaAs/InAlAs quantum wells
The authors present measurements of electrorefraction and electroabsorption in a novel multiple quantum well waveguide structure in which each InGaAs quantum well is provided with an individual electron reservoir. External bias transfers electrons into the wells, thus quenching the absorption and producing a refractive index change at wavelengths below the bandedge which is linear in the applied voltage. The authors demonstrate that in this type of structure both the change in refractive index per applied field and the ratio of optical phase to intensity modulation can be significantly enhanced over those found in the quantum confined Stark effect
W. F. Harris
2009-12-01
Full Text Available If an intraocular lens is displaced or if its power is changed what are the consequences for the refractive compensation of the eye? Gaussian optics is used to obtain explicit formulae for the sensitivityof the corneal-plane refractive compensation (also called the refraction, refractive state, etc to change in power and axial displacement of a thin intraocular lens implanted in a simple eye. In particular, for a pseudophakic Gullstrand simplified eye with intraocular lens placed 5 mm behind the cornea the sensitivity to errors in the power of the intraocular lens is about 71 . 0 − 71 for an intraocular lens of power for an intraocular lens of power 20 D, that is, the refractive compensation decreases by about 0.71 dioptres per dioptre increase in the power of the intraocular lens. More generally the sensitivity is approximately ( m 0037 . 0 63 . 0 F − − 0.63 ( 003 . 0 63 . 0 − − (0.0037mF where FI is the power of the intraocular lens. Also for Gullstrand’s simplified eye the sensitivity of refractive compensation to axial displacement of the intraocular lens is approximately linear in FI about (64D FI, in fact. That is, for each dioptre of the power of the intraocular lens the refractive compensation increases by about 0.064 dioptres per millimetre of axial displacement towards the retina.
Rami Reddy Bommareddi
2014-05-01
Full Text Available Optical metrology techniques used to measure changes in thickness; temperature and refractive index are surveyed. Optical heterodyne detection principle and its applications for precision measurements of changes in thickness and temperature are discussed. Theoretical formulations are developed to estimate crystal growth rate, surface roughness and laser cooling/heating of solids. Applications of Michelson and Mach-Zehnder interferometers to measure temperature changes in laser heating of solids are described. A Mach-Zehnder interferometer is used to measure refractive index and concentration variations of solutions in crystal growth experiments. Additionally, fluorescence lifetime sensing and fluorescence ratio method are described for temperature measurement. For all the above techniques, uncertainty calculations are included.
Träger, Jens; Kim, Hee-Cheol; Hampp, Norbert
2006-02-01
Before an intraocular lens (IOL) is implanted during cataract surgery, biometric data of the patient's eye have to be determined to calculate the thickness and shape of the IOL. In particular the postoperative anterior chamber depth is an important parameter to predict the correct shape of the IOL. This value, however, cannot be measured without significant uncertainities. We present a solution to this problem, describe novel polymers suitable for IOLs which refractive indices can be changed non-invasively in a photo-induced process. The focal length can be modified by about 2 D, which is sufficient to achive ideal acuteness of vision for almost all patients with implanted IOLs. The change in refractive index is accomplished by linking or cleaving bonds between a sufficiently large number of side groups of the polymer main chain in a photoinduced cyloaddition or cycloreversion, respectively. The photochemical reaction can also be triggered by a two-photon process (TPA) using a pulsed laser system, i.e. the energy required for bond breaking is provided by two photons in the visible range. Light in the UV as well as the visible range of the spectrum cannot induce undesired changes of the refractive index owing to the strong UV-absorption of the cornea and photon densities much too low for TPA, respectively. Due to the excellent spatial resolution that can be achieved with two-photon processes not only modification of the refractive index of the entire lens but also selectively in well defined areas is possible enabling the correction for aberrations such as astigmatism.
João Jorge Nassaralla Junior
2003-10-01
Full Text Available PURPOSE: A prospective study was conducted to compare the refractive changes after three different types of scleral buckling surgery. METHODS: A total of 100 eyes of 100 patients were divided into three groups according to the type of performed buckling procedure: Group 1, encircling scleral buckling (42 patients; Group 2, encircling with vitrectomy (30 patients; Group 3, encircling with additional segmental buckling (28 patients. Refractive examinations were performed before and at 1, 3 and 6 months after surgery. RESULTS: Changes in spherical equivalent and axial length were significant in all 3 groups. The amount of induced astigmatism was more significant in Group 3. No statistically significant difference was found in the amount of surgically induced changes between Groups 1 and 2, at any postoperative period. CONCLUSIONS: All three types of scleral buckling surgery were found to produce refractive changes. A correlation exists between additional segments and extent of refractive changes.OBJETIVO: Estudo prospectivo foi realizado para comparar as alterações refracionais encontradas após três diferentes tipos de cirurgia com explante escleral. MÉTODOS: Cem olhos de 100 pacientes foram divididos em 3 grupos de acordo com o tipo de cerclagem retiniana realizada: Grupo 1, cerclagem simples (42 pacientes; Grupo 2, cerclagem associada a vitrectomia (30 pacientes; Grupo 3, cerclagem associado a implante escleral segmentar (28 pacientes. Exames refracionais foram realizados antes e após 1, 3 e 6 meses da cirurgia. RESULTADOS: A indução de astigmatismo foi maior no Grupo 3. Alterações no equivalente esférico e no diâmetro ântero-posterior foram significantes nos 3 grupos após a cirurgia. Nenhuma diferença estaticamente significativa foi encontrada nas alterações induzidas pela cirurgia entre os grupos 1 e 2, em nenhum momento após a cirurgia. CONCLUSÃO: Os três tipos de retinopexia causam alteração refracional. Existe correla
W.D.H. Gillan
2006-01-01
Full Text Available Introduction: The investigation of myopia and soft contact lenses is not new. Many reports show that the wearing of silicone hydrogel lenses as opposed to conventional disposable hydrogel lenses results in little progression of myopia in the eyes wearing silicone hydrogels. Method: Six subjects wore a silicone hydro-gel lens on one eye while the other eye wore a habitual disposable hydrogel lens for six months of daily wear. Fifty measurements of refractive state in each eye were taken prior to the subjects wearing a silicone lens in one eye and a conven-tional hydrogel lens in the other eye. After six months of daily wear another fifty measurements of refractive state were taken for each subject. Results: Although there is no statisti-cal support for the findings of this study, comet stereo-pairs are used to show the chang-es in refractive state for each subject. Four of the six subjects showed an increase in myopia in the eye wearing the silicone lens. Discussion: The increase in myopia in eyes wearing a silicone hydrogel lens is contrary to the findings of other studies.
Xu Xiangqun [Institute of Bioscience and Technology, Cranfield University, Silsoe, Bedfordshire MK45 4DT (United Kingdom); Wang, Ruikang K [Institute of Bioscience and Technology, Cranfield University, Silsoe, Bedfordshire MK45 4DT (United Kingdom); Elder, James B [School of Medicine, Keele University, Stoke-on-Trent, ST4 7QB (United Kingdom); Tuchin, Valery V [Department of Optics, Saratov State University, 155 Moskovskaya Str., 410026 Saratov (Russian Federation)
2003-05-07
The purpose of the present study is to investigate systematically the mechanisms of alterations in the optical properties of whole blood immersed in the biocompatible agent dextran, and to define the optimal concentration of dextrans required for blood optical clearing in order to enhance the capability of light penetration depth for optical imaging applications. In the experiments, dextrans with different molecular weights and various concentrations were employed and investigated by the use of the optical coherence tomography technique. Changes in light attenuation, refractive index and aggregation properties of blood immersed in dextrans were studied. It was concluded from the results that the mechanisms for blood optical clearing are characteristic of the types of dextrans employed, their concentrations and the application stages. Among the substances applied, Dx500 at a concentration at 0.5 g dl{sup -1} gives the best result in improving light penetration depth through the blood. The increase of light transmission at the beginning of the addition of dextrans is mainly attributed to refractive index matching between the scattering centres and the ground matter. Thereafter, the transmission change is probably due to a dextran-induced aggregation-disaggregation effect. Overall, light scattering in the blood could be effectively reduced by the application of dextrans. It represents a promising approach to increasing the imaging depth for in vivo optical imaging of biological tissue, for example optical coherence tomography.
The purpose of the present study is to investigate systematically the mechanisms of alterations in the optical properties of whole blood immersed in the biocompatible agent dextran, and to define the optimal concentration of dextrans required for blood optical clearing in order to enhance the capability of light penetration depth for optical imaging applications. In the experiments, dextrans with different molecular weights and various concentrations were employed and investigated by the use of the optical coherence tomography technique. Changes in light attenuation, refractive index and aggregation properties of blood immersed in dextrans were studied. It was concluded from the results that the mechanisms for blood optical clearing are characteristic of the types of dextrans employed, their concentrations and the application stages. Among the substances applied, Dx500 at a concentration at 0.5 g dl-1 gives the best result in improving light penetration depth through the blood. The increase of light transmission at the beginning of the addition of dextrans is mainly attributed to refractive index matching between the scattering centres and the ground matter. Thereafter, the transmission change is probably due to a dextran-induced aggregation-disaggregation effect. Overall, light scattering in the blood could be effectively reduced by the application of dextrans. It represents a promising approach to increasing the imaging depth for in vivo optical imaging of biological tissue, for example optical coherence tomography
Zhang, M.X. [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Liu, J., E-mail: liujian@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zhang, Y.; Dong, J.D.; Yan, A.R. [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Skokov, K.P. [Materials Science, TU Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); Gutfleisch, O. [Materials Science, TU Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); Fraunhofer IWKS, Project Group for Material Cycles and Resource Strategy, 63457 Hanau (Germany)
2015-03-01
We report on the microstructure, phase constitution and magnetocaloric properties in rapidly solidified La(Fe,Mn){sub 11.6}Si{sub 1.4} flakes prepared by strip casting technique. After a relatively short-time annealing at 1323 K for 12 h, LaFe{sub 11.6}Si{sub 1.4} flakes constituting a nearly single NaZn{sub 13}-structured La(Fe,Si){sub 13}, i.e. 1:13 phase, exhibit a large entropy change of 19.2 J/kg K and adiabatic temperature change of 6.5 K when the application of a magnetic field of 2 T at which temperature. These features are comparable to those observed in the bulk samples. More importantly, the thermal and magnetic hysteresis of the present flakes is significantly smaller than that in the bulk alloys. The Curie temperature can be accurately tuned through replacing Fe by Mn. Thus, La–Fe–Si-based strip-cast flakes are promising for magnetic refrigerants in mass production. - Highlights: • La(Fe,Mn){sub 11.6}Si{sub 1.4} flakes were prepared by strip casting technique in kilogram quantities. • La(Fe,Mn){sub 11.6}Si{sub 1.4} flakes show a large magnetocaloric effect accompanied by negligible hysteresis upon short-time annealing. • With replacing Fe by Mn, the Curie temperature of La(Fe,Mn){sub 11.6}Si{sub 1.4} can be accurately tuned.
Jinxin Han
2015-04-01
Full Text Available The light-induced refractive index change in Mn:KLTN crystal, illuminated by focused light sheet, is visualized in situ and quantified by digital holographic interferometry. By numerically retrieving a series of sequential phase maps from recording digital holograms, the spatial distribution of the induced refractive index change can be visualized and estimated readily. This technique enables the observation of the temporal evolution of the refractive index change under different recording situations such as writing laser power, applied voltage, and temperature, and the photoconductivity of Mn:KLTN crystal can be calculated as well, the experimental results are in good agreement with the theory. The research results suggest that the presented method is successful and feasible.
Quantum adiabatic machine learning
Pudenz, Kristen L.; Lidar, Daniel A.
2011-01-01
We develop an approach to machine learning and anomaly detection via quantum adiabatic evolution. In the training phase we identify an optimal set of weak classifiers, to form a single strong classifier. In the testing phase we adiabatically evolve one or more strong classifiers on a superposition of inputs in order to find certain anomalous elements in the classification space. Both the training and testing phases are executed via quantum adiabatic evolution. We apply and illustrate this app...
Sara J McCullough
Full Text Available To determine six-year spherical refractive error change among white children and young adults in the UK and evaluate differences in refractive profiles between contemporary Australian children and historical UK data.Population-based prospective study.The Northern Ireland Childhood Errors of Refraction (NICER study Phase 1 examined 1068 children in two cohorts aged 6-7 years and 12-13 years. Prospective data for six-year follow-up (Phase 3 are available for 212 12-13 year olds and 226 18-20 year olds in each cohort respectively.Cycloplegic refractive error was determined using binocular open-field autorefraction (Shin-Nippon NVision-K 5001, cyclopentolate 1%. Participants were defined by spherical equivalent refraction (SER as myopic SER ≤-0.50D, emmetropic -0.50D
In the present paper, internal composition and size-dependent threshold pump intensity effects on on-center impurity-related linear, third-order nonlinear and total refractive index changes are investigated in wurtzite (In,Ga)N/GaN unstrained spherical quantum dot. The calculation is performed within the framework of parabolic band and single band effective-mass approximations using a combination of Quantum Genetic Algorithm (QGA) and Hartree–Fock–Roothaan (HFR) method. According to the results obtained, (i) a significant red-shift (blue shift) is obtained as the dot size (potential barrier) increases and (ii) a threshold optical pump intensity depending strongly on the size and the internal composition is obtained which constitutes the limit between two behaviors
El Ghazi, Haddou, E-mail: hadghazi@gmail.com [Special Mathematics, CPGE Rabat (Morocco); LPS, Faculty of Science, Dhar El Mehrez, BP 1796 Fes-Atlas (Morocco); A John Peter [P.G. & Research Department of Physics, Goverment Arts and Science College, Melur 625106, Madurai (India)
2015-04-01
In the present paper, internal composition and size-dependent threshold pump intensity effects on on-center impurity-related linear, third-order nonlinear and total refractive index changes are investigated in wurtzite (In,Ga)N/GaN unstrained spherical quantum dot. The calculation is performed within the framework of parabolic band and single band effective-mass approximations using a combination of Quantum Genetic Algorithm (QGA) and Hartree–Fock–Roothaan (HFR) method. According to the results obtained, (i) a significant red-shift (blue shift) is obtained as the dot size (potential barrier) increases and (ii) a threshold optical pump intensity depending strongly on the size and the internal composition is obtained which constitutes the limit between two behaviors.
In this paper, we have studied the simultaneous effects of external electric and magnetic fields on the optical absorption coefficients and refractive index changes of a hydrogenic impurity confined in a cylindrical quantum wire with convex bottom. Energy eigenvalues and eigenvectors are calculated using the direct matrix diagonalization method and optical properties are obtained using the compact density matrix approach. Our results indicate that, the wire radius, convexity parameter, hydrogenic impurity and external electric and magnetic fields have a great influence on the linear and the third-order nonlinear optical absorption coefficients as well as the refractive index changes of the system
Longitudinal Change and Stability of Refractive, Keratometric, and Internal Astigmatism in Childhood
Harvey, Erin M.; Miller, Joseph M.; Twelker, J. Daniel; Sherrill, Duane L.
2015-01-01
Native American children from a tribe with a high prevalence of astigmatism show little change in astigmatism with age. Longitudinal data suggest that internal compensation for keratometric astigmatism may contribute to the stability of astigmatism in Tohono O'odham children.
Adiabatic pumping through quantum dots
A finite charge can be pumped through a mesoscopic system in the absence of an applied bias voltage by changing periodically in time some parameters of the system. If these parameters change slowly with respect to all internal time scales of the system, pumping is adiabatic. The scope of this work is to investigate adiabatic pumping through a quantum dot, in particular the influence of Coulomb interaction between electrons in the dot on the pumped charge. On one hand we develop a formalism based on Green's functions, in order to calculate the pumped charge from the weak-tunnel-coupling regime down to the Kondo regime. We extend our calculations to a system with a superconducting contact. On the other hand we use a systematic perturbation expansion for the calculation of the pumped charge, giving us the possibility to analyze processes which contribute to charge pumping and to highlight the important role of interaction-induced level renormalization. (orig.)
Quantum adiabatic machine learning
Pudenz, Kristen L
2011-01-01
We develop an approach to machine learning and anomaly detection via quantum adiabatic evolution. In the training phase we identify an optimal set of weak classifiers, to form a single strong classifier. In the testing phase we adiabatically evolve one or more strong classifiers on a superposition of inputs in order to find certain anomalous elements in the classification space. Both the training and testing phases are executed via quantum adiabatic evolution. We apply and illustrate this approach in detail to the problem of software verification and validation.
Oreshkov, Ognyan
2010-01-01
We propose a theory of adiabaticity in quantum Markovian dynamics based on a structural decomposition of the Hilbert space induced by the asymptotic behavior of the Lindblad semigroup. A central idea of our approach is that the natural generalization of the concept of eigenspace of the Hamiltonian in the case of Markovian dynamics is a noiseless subsystem with a minimal noisy cofactor. Unlike previous attempts to define adiabaticity for open systems, our approach deals exclusively with physical entities and provides a simple, intuitive picture at the underlying Hilbert-space level, linking the notion of adiabaticity to the theory of noiseless subsystems. As an application of our theory, we propose a framework for decoherence-assisted computation in noiseless codes under general Markovian noise. We also formulate a dissipation-driven approach to holonomic computation based on adiabatic dragging of subsystems that is generally not achievable by non-dissipative means.
Quantum and classical dynamics in adiabatic computation
Crowley, P. J. D.; Duric, T.; Vinci, W.; Warburton, P. A.; Green, A. G.
2014-01-01
Adiabatic transport provides a powerful way to manipulate quantum states. By preparing a system in a readily initialized state and then slowly changing its Hamiltonian, one may achieve quantum states that would otherwise be inaccessible. Moreover, a judicious choice of final Hamiltonian whose ground state encodes the solution to a problem allows adiabatic transport to be used for universal quantum computation. However, the dephasing effects of the environment limit the quantum correlations th...
Comparison of the refractive error changes among young children in ten years interval
Hai-Yan Li
2013-07-01
Full Text Available AIM: To compare the optometric examination results of myopic young children between those diagnosed in the period from 1998 to 2000 and those diagnosed in the period from 2008 to 2010; and to find out the causes of myopia and factors that worsen the condition, and suggest methods of its prevention and treatment.METHODS: This study was a retrospective case study. We randomly selected sample from out-patient department register of cases and divided them into two main groups, ‘ten year before group'(TYBG(1998/2000 year casesand ‘ten years later group'(2008/2010 year cases(TYLG. Each group was further subdivided into three sub-groups by age: under-six years old children group(CG, seven-twelve years old primary-school group(PSGand thirteen-eighteen years old middle-school group(MSG. The optometric examination results were statistically analyzed.RESULTS: The difference of the mean dioptre between the TYBG and TYLG was strongly statistically significant, also forward-lead trend of age when children suffered from myopia was found(P0.01. There was a significant increase of dioptre among PSG and MSG in TYLG compared to TYBG(PCONCLUSION: Our study shows that the age of getting myopia was forward lead, the dioptre increases by 1.00 degree and the prevalence of myopia is increasing gradually. This situation may due to the modern life style and changes of living standard of the population. Therefore, prevention of myopia should concentrate more on younger children at kindergarten and primary school stage students.
Goodrich, C. C.; Scudder, J. D.
1984-01-01
The adiabatic energy gain of electrons in the stationary electric and magnetic field structure of collisionless shock waves was examined analytically in reference to conditions of the earth's bow shock. The study was performed to characterize the behavior of electrons interacting with the cross-shock potential. A normal incidence frame (NIF) was adopted in order to calculate the reversible energy change across a time stationary shock, and comparisons were made with predictions made by the de Hoffman-Teller (HT) model (1950). The electron energy gain, about 20-50 eV, is demonstrated to be consistent with a 200-500 eV potential jump in the bow shock quasi-perpendicular geometry. The electrons lose energy working against the solar wind motional electric field. The reversible energy process is close to that modeled by HT, which predicts that the motional electric field vanishes and the electron energy gain from the electric potential is equated to the ion energy loss to the potential.
Miranda, Guillermo L. [Fisica Teorica y Aplicada, Escuela de Ingenieria de Antioquia, A.A. 7516 Medellin (Colombia); Instituto de Fisica, Universidad de Antioquia, AA 1226 Medellin (Colombia); Mora-Ramos, Miguel E., E-mail: memora@uaem.mx [Fisica Teorica y Aplicada, Escuela de Ingenieria de Antioquia, A.A. 7516 Medellin (Colombia); Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, C.P. 62209 Cuernavaca, Morelos (Mexico); Instituto de Fisica, Universidad de Antioquia, AA 1226 Medellin (Colombia); Duque, Carlos A. [Instituto de Fisica, Universidad de Antioquia, AA 1226 Medellin (Colombia)
2013-01-15
In this work the variations of the exciton-related optical absorption and the change of the refractive index in a GaAs-(Ga,Al)As double quantum well as functions of the geometric parameters of the heterostructure are investigated. The variational method is applied within the framework of the parabolic band and effective mass approximations, in order to obtain the 1s-like exciton energy spectrum. The outcome for the related optical coefficients shows a quenched and redshifted light absorption as a result of the increment in the inner barrier and right-hand well widths, with the possibility of an enhancement of the excitonic contribution to the relative change in the refractive index.
Yuan, Jian-Hui; Zhang, Zhi-Hai
2015-12-01
Guo and Du (2013) reported theirs result for the linear and nonlinear optical absorption coefficients and refractive index changes in asymmetrical Gaussian potential quantum wells with applied electric field. We find both the energy and the corresponding wavefunction for the low-lying state are wrong to applied in their works. For the same set of parameters studied by Guo and Du, we obtain new and reliable results via the differential method.
Wireless adiabatic power transfer
Research highlights: → Efficient and robust mid-range wireless energy transfer between two coils. → The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. → Wireless energy transfer is insensitive to any resonant constraints. → Wireless energy transfer is insensitive to noise in the neighborhood of the coils. - Abstract: We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.
Zou Liner; Wang Gouri; Shen Yun; Chen Baoxue; Mamoru Iso
2011-01-01
The refractive index of as-evaporated amorphous semiconductor As2S8 film upon an annealing and saturation irradiation and annealing cycle is reversible.Upon successive treatment with annealing and non-saturation irradiation and further annealing,the refractive index of the as-evaporated amorphous semiconductor As2 S8 film reaches a maximum value and then its reversibility occurs upon annealing.The annealing of the amorphous semiconductor As2S8 films results in the stabilization of the structure through changes of the S-S bonds in the nearest environment,accompanied by a decrease of film thickness.The As2S8 planar waveguide after annealing (130 ℃)and saturation irradiation and annealing (130 ℃) shows a good propagation characteristic with ca.0.27 dB/cm low propagation loss of the 632.8 nm guided mode.
Adiabatically implementing quantum gates
We show that, through the approach of quantum adiabatic evolution, all of the usual quantum gates can be implemented efficiently, yielding running time of order O(1). This may be considered as a useful alternative to the standard quantum computing approach, which involves quantum gates transforming quantum states during the computing process
Wireless adiabatic power transfer
Rangelov, A. A.; Suchowski, H.; Silberberg, Y.; Vitanov, N. V.
2010-01-01
We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.
Chomát, Miroslav; Berková, Daniela; Matějec, Vlastimil; Kašík, Ivan; Kaňka, Jiří; Slavík, Radan; Jančárek, A.; Bittner, P.
[Monastir] : [Faculté des Sciences de Monastir], 2004. s. 88. [Journees Maghreb-Europe sur les Materiaux et Leurs Applications aux Dispositifs et Capteurs MADICA 2004 /4./. 29.11.2004-01.12.2004, Tunis] R&D Projects: GA ČR GA102/03/0475 Institutional research plan: CEZ:AV0Z2067918 Keywords : optical fibres * fibre optic sensors * refractive index Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Ikeda, Tsunehiko
2014-01-01
Tsunehiko Ikeda,1 Masahiro Minami,1 Kimitoshi Nakamura,2 Teruyo Kida,1 Masanori Fukumoto,1 Takaki Sato,1 Eisuke Ishizaki11Department of Ophthalmology, Osaka Medical College, Osaka, Japan; 2Nakamura Eye Clinic, Nagano, JapanBackground: Nuclear sclerosis (NS) based on the Emery–Little classification and refractive values after lens-sparing vitrectomy was compared between proliferative diabetic retinopathy (DR) patients and nondiabetic patients.Methods: Progression of NS based on the E...
Amendt, Peter; Bellei, Claudio; Wilks, Scott
2012-01-01
The plasma analog of an adiabatic lapse rate (or temperature variation with height) in atmospheric physics is obtained. A new source of plasma temperature gradient in a binary ion species mixture is found that is proportional to the concentration gradient and difference in average ionization states . Application to inertial-confinement-fusion implosions indicates a potentially strong effect in plastic (CH) ablators that is not modeled with mainline (single-fluid) simulations. An associated pl...
Pulsed adiabatic structure and complete population transfer
Population can be transferred between atomic or molecular energy states in a variety of ways. The basic idea of adiabatic transfer, discussed in many textbooks, is as follows. One begins with an atom that is in some single energy state (an eigenstate of an initial Hamiltonian). This energy state is one of many possible states, known variously as the unperturbed states or basis states or diabatic states. Next one begins to change the Hamiltonian very slowly. The changes may occur in either the diagonal elements (the basis state energies) or in the off-diagonal elements (interactions between basis states). If there are off-diagonal elements then the Hamiltonian will no longer commute with the original one. Because the Hamiltonian is no longer the one that was used to define the original basis states, it will cause these states to become mixed. However, if the change is sufficiently slow, the system can remain in a single eigenstate of the changing Hamiltonian -- an adiabatic state, composed of a combination of basis states. Finally, at some later time, one examines the system once again in the original basis. One finds that the population has undergone a change, and now resides in a different unperturbed state. One has produced population transfer. There are many illustrative examples of adiabatic passage, both theory and experiment. The author mentions briefly two common examples, inelastic collisions between atoms, and the static Stark effect in Rydberg atoms, before continuing with the main objective, a discussion of adiabatic passage induced by laser pulses
Exploring adiabatic quantum trajectories via optimal control
Adiabatic quantum computation employs a slow change of a time-dependent control function (or functions) to interpolate between an initial and final Hamiltonian, which helps to keep the system in the instantaneous ground state. When the evolution time is finite, the degree of adiabaticity (quantified in this work as the average ground-state population during evolution) depends on the particulars of a dynamic trajectory associated with a given set of control functions. We use quantum optimal control theory with a composite objective functional to numerically search for controls that achieve the target final state with a high fidelity while simultaneously maximizing the degree of adiabaticity. Exploring the properties of optimal adiabatic trajectories in model systems elucidates the dynamic mechanisms that suppress unwanted excitations from the ground state. Specifically, we discover that the use of multiple control functions makes it possible to access a rich set of dynamic trajectories, some of which attain a significantly improved performance (in terms of both fidelity and adiabaticity) through the increase of the energy gap during most of the evolution time. (paper)
Owen, A. K.
1994-01-01
The laser anemometer has provided the fluid dynamicist with a powerful tool for nonintrusively measuring fluid velocities. One of the more common types of laser anemometers, the laser fringe anemometer, divides a single laser beam into two parallel beams and then focuses them on a point in space called the "probe volume" (PV) where the fluid velocity is measured. Many applications using this method for measuring fluid velocities require the observation of fluids through a window. The passage of the laser beams through materials having different indices of refraction has the following effects: 1) the position of the probe volume will change; 2) the beams will uncross, i.e., no longer lie in the same plane at the probe volume location; and 3) for nonflat plate windows, the crossing angle of the two beams will change. OPTMAIN uses a ray tracing technique, which is not restricted to special cases, to study the changes in probe volume geometry and position due to refraction effects caused by both flat and general smooth windows. Input parameters are the indices of refraction on both sides of the window and of the window itself, the window shape, the assumed position of the probe volume and the actual position of the focusing lens relative to the window, the orientation of the plane which contains the laser beams, the beam crossing angle, and the laser beam wavelength. OPTMAIN is written in FORTRAN 77 for interactive execution. It has been implemented on a DEC VAX 11/780 under VMS 5.0 with a virtual memory requirement of 50K. OPTMAIN was developed in 1987.
W. D. H. Gillan
2006-01-01
Introduction: The investigation of myopia and soft contact lenses is not new. Many reports show that the wearing of silicone hydrogel lenses as opposed to conventional disposable hydrogel lenses results in little progression of myopia in the eyes wearing silicone hydrogels. Method: Six subjects wore a silicone hydro-gel lens on one eye while the other eye wore a habitual disposable hydrogel lens for six months of daily wear. Fifty measurements of refractive state in each eye were taken ...
Zhu, Shan; Pang, Fufei; Huang, Sujuan; Zou, Fang; Guo, Qiang; Wen, Jianxiang; Wang, Tingyun
2016-01-01
Atomic layer deposition (ALD) technology is introduced to fabricate a high sensitivity refractometer based on an adiabatic tapered optical fiber. Different thicknesses of titanium dioxide (TiO₂) nanofilm were coated around the tapered fiber precisely and uniformly under different deposition cycles. Attributed to the higher refractive index of the TiO₂ nanofilm compared to that of silica, an asymmetric Fabry-Perot (F-P) resonator could be constructed along the fiber taper. The central wavelength of the F-P resonator could be controlled by adjusting the thickness of the TiO₂ nanofilm. Such a F-P resonator is sensitive to changes in the surrounding refractive index (SRI), which is utilized to realize a high sensitivity refractometer. The refractometer developed by depositing 50.9-nm-thickness TiO₂ on the tapered fiber shows SRI sensitivity as high as 7096 nm/RIU in the SRI range of 1.3373-1.3500. Due to TiO₂'s advantages of high refractive index, lack of toxicity, and good biocompatibility, this refractometer is expected to have wide applications in the biochemical sensing field. PMID:27537885
Different ability to ion exchange from the salts of lithium-sodium-silicate glass melt containing calcium (or strontium, or barium) and titanium oxides in addition has been shown. CaO, SrO and BaO have negative effect, but TiO2 -positive one on the fullness of ion exchange of lithium-sodium and on the rate of interdiffusion in alkali-silicate glass. The value of change in index of refraction of glass with TiO2 is twice higher than glass with calcium oxide (or strontium, or barium) as the fourth component
Petrov, P. V.; Kolchevsky, N.N.
2013-01-01
Compound concave refractive lenses are used for focusing neutron beam. Investigations of spectral and focusing properties of a refractive neutron lens are presented. Resolution of the imaging system on the base of refractive neutron lenses depends on material properties and parameters of neutron source. Model of refractive neutron lens are proposed. Results of calculation diffraction resolution and focal depth of refractive neutron lens are discussed.
Nonresonance adiabatic photon trap
Popov, S S; Burdakov, A V; Ushkova, M Yu
2016-01-01
Concept of high efficiency photon storage based on adiabatic confinement between concave mirrors is presented and experimentally investigated. The approach is insensitive to typical for Fabri-Perot cells requirements on quality of accumulated radiation, tolerance of resonator elements and their stability. Experiments have been carried out with the trap, which consists from opposed concave cylindrical mirrors and conjugated with them spherical mirrors. In result, high efficiency for accumulation of radiation with large angular spread and spectrum width has been confirmed. As radiation source a commercial fiber laser has been used.
Avron, Joseph
2016-01-01
We derive the relativistically exact Eikonal equation for ring interferometers undergoing adiabatic deformations. The leading term in the adiabatic expansion of the phase shift is independent of the refraction index $n$ and is given by a line integral generalizing results going back to Sagnac to all orders in $\\beta$. The next term in the adiabaticity is of lower order in $\\beta$ and may be as important as the first in nonrelativistic cases. This term is proportional to $n^2$ and has the form of a double integral. It generalizes previous results to fibers with chromatic dispersion and puts Sagnac and Fizeau interferometers under a single umbrella.
J. D. Biamonte
2011-06-01
Full Text Available In his famous 1981 talk, Feynman proposed that unlike classical computers, which would presumably experience an exponential slowdown when simulating quantum phenomena, a universal quantum simulator would not. An ideal quantum simulator would be controllable, and built using existing technology. In some cases, moving away from gate-model-based implementations of quantum computing may offer a more feasible solution for particular experimental implementations. Here we consider an adiabatic quantum simulator which simulates the ground state properties of sparse Hamiltonians consisting of one- and two-local interaction terms, using sparse Hamiltonians with at most three-local interactions. Properties of such Hamiltonians can be well approximated with Hamiltonians containing only two-local terms. The register holding the simulated ground state is brought adiabatically into interaction with a probe qubit, followed by a single diabatic gate operation on the probe which then undergoes free evolution until measured. This allows one to recover e.g. the ground state energy of the Hamiltonian being simulated. Given a ground state, this scheme can be used to verify the QMA-complete problem LOCAL HAMILTONIAN, and is therefore likely more powerful than classical computing.
Frimurer, Thomas M.; Günther, Peter H.; Sørensen, Morten Dahl;
1999-01-01
adiabatic mapping, conformational change, essentialdynamics, free energy simulations, Kunitz type inhibitor *ga3(VI)......adiabatic mapping, conformational change, essentialdynamics, free energy simulations, Kunitz type inhibitor *ga3(VI)...
Adiabatic logic future trend and system level perspective
Teichmann, Philip
2012-01-01
Adiabatic logic is a potential successor for static CMOS circuit design when it comes to ultra-low-power energy consumption. Future development like the evolutionary shrinking of the minimum feature size as well as revolutionary novel transistor concepts will change the gate level savings gained by adiabatic logic. In addition, the impact of worsening degradation effects has to be considered in the design of adiabatic circuits. The impact of the technology trends on the figures of merit of adiabatic logic, energy saving potential and optimum operating frequency, are investigated, as well as degradation related issues. Adiabatic logic benefits from future devices, is not susceptible to Hot Carrier Injection, and shows less impact of Bias Temperature Instability than static CMOS circuits. Major interest also lies on the efficient generation of the applied power-clock signal. This oscillating power supply can be used to save energy in short idle times by disconnecting circuits. An efficient way to generate the p...
Is the sech/tanh Adiabatic Pulse Really Adiabatic?
Rosenfeld, Daniel; Zur, Yuval
1998-05-01
Adiabatic pulses are most conveniently studied in the frequency frame which is a frame of reference rotating at the instantaneous frequency of the pulse. In this frame the adiabatic condition ‖γBeff‖ ≫ |θ≳| sets an upper limit on the sweep rate θ≳ of the Beffvector. This, in turn, places a lower bound on the pulse duration. Adiabatic behavior is studied at the threshold duration and two pulses are examined: (i) a pulse with a constant sweep rate (CAPpulse) and (ii) a conventional sech/tanh adiabatic pulse. It is shown that the sech/tanh pulse performs robust magnetization inversion although it seems to violate the adiabatic condition. This puzzling phenomenon is solved by switching into a second-order rotating frame of reference (SORF) where it is shown that the adiabatic condition is fulfilled. This frame coincides with the frequency frame at the beginning of the pulse. Assuming an RF field along thex-axis of the frequency frame, the SORF then rotates about the commony-axis during the pulse with thez-axis of the new frame aligned with the Beffvector. It is shown that adiabatic motion may be performed in the SORF, in which the sweep rate is increased indefinitely; the adiabatic condition is violated by this motion in the frequency frame but is fulfilled in the SORF. The lower bound on the sweep rate in the frequency frame is thereby lifted.
Adiabatic and non-adiabatic processes in strong Coulomb fields
Adiabatic and non-adiabatic behaviour of relativistic electrons in external Coulomb fields of time-dependent strength is studied within the framework of a model for the description of a shell electron's behaviour during a heavy-ion collision. A classification scheme for types of non-adiabatic behaviour is suggested; its relevance for the analysis of pair production processes in strong Coulomb fields is discussed (K-Shell Ionization). An ansatz for the vacuum polarization potential is introduced and employed to demonstrate the special role of vacuum polarization for adiabatic and non-adiabatic behaviour in very strong Coulomb fields (Zα > 1). The implications of the underlaying specific features of the vacuum polarization charge density in very strong fields for pair production mechanisms are considered. (orig.)
Geometry of the Adiabatic Theorem
Lobo, Augusto Cesar; Ribeiro, Rafael Antunes; Ribeiro, Clyffe de Assis; Dieguez, Pedro Ruas
2012-01-01
We present a simple and pedagogical derivation of the quantum adiabatic theorem for two-level systems (a single qubit) based on geometrical structures of quantum mechanics developed by Anandan and Aharonov, among others. We have chosen to use only the minimum geometric structure needed for the understanding of the adiabatic theorem for this case.…
Karia, S. P.; Pathak, K. N.
2011-03-01
The present study reports the analysis of GPS based TEC for our station Surat (21.16°N, 72.78°E) located at the northern crest of equatorial anomaly region in India at times close to some earthquake events (M ⩾ 5) during the year 2009 in India and its neighbouring regions. The TEC data used in the study are obtained from GPS Ionospheric Scintillation and TEC Monitoring (GISTM) system. The TEC data has been analysed corresponding to 11 earthquakes in low solar activity period and quiet geomagnetic condition. We found that, out of 11 cases of earthquakes (M > 5) there were seven cases in which enhancement in TEC occurred on earthquake day and in other four cases there was depletion in TEC on earthquake day. The variation in refractivity prior to earthquake was significant for the cases in which the epicentre lied within a distance of 600 km from the receiving station. By looking into the features on temporal enhancement and depletion of TEC a prediction was made 3-2 days prior to an earthquake (on 28 October 2009 in Bhuj - India). The paper includes a brief discussion on the method of potentially identifying an impending earthquake from ionospheric data.
... the cornea, or aging of the lens can cause refractive errors. What is refraction? Refraction is the bending of ... for objects at any distance, near or far. Astigmatism is a condition in ... This can cause images to appear blurry and stretched out. Presbyopia ...
In this work we are reporting the energy level spectrum for a quantum system consisting of an n-type double δ-doped quantum well with a Schottky barrier potential in a Gallium Arsenide matrix. The calculated states are taken as the basis for the evaluation of the linear and third-order nonlinear contributions to the optical absorption coefficient and to the relative refractive index change, making particular use of the asymmetry of the potential profile. These optical properties are then reported as a function of the Schottky barrier height (SBH) and the separation distance between the δ-doped quantum wells. Also, the effects of the application of hydrostatic pressure are studied. The results show that the amplitudes of the resonant peaks are of the same order of magnitude of those obtained in the case of single δ-doped field effect transistors; but tailoring the asymmetry of the confining potential profile allows the control the resonant peak positions
Rojas-Briseño, J.G.; Martínez-Orozco, J.C.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad esquina con Paseo la Bufa S/N, C.P. 98060, Zacatecas, Zac. (Mexico); Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia); Duque, C.A., E-mail: cduque@fisica.udea.edu.co [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia)
2013-09-01
In this work we are reporting the energy level spectrum for a quantum system consisting of an n-type double δ-doped quantum well with a Schottky barrier potential in a Gallium Arsenide matrix. The calculated states are taken as the basis for the evaluation of the linear and third-order nonlinear contributions to the optical absorption coefficient and to the relative refractive index change, making particular use of the asymmetry of the potential profile. These optical properties are then reported as a function of the Schottky barrier height (SBH) and the separation distance between the δ-doped quantum wells. Also, the effects of the application of hydrostatic pressure are studied. The results show that the amplitudes of the resonant peaks are of the same order of magnitude of those obtained in the case of single δ-doped field effect transistors; but tailoring the asymmetry of the confining potential profile allows the control the resonant peak positions.
Zuev, V.S.; Korol' kov, K.S.; Netemin, V.N.; Nosach, O.Y.; Orlov, E.P.
1976-11-01
An optical delay method is proposed for investigation of the change in the refractive index of the active medium of a laser at the wavelength of its stimulated emission. Criteria of the validity of this method are obtained and an analysis is made of the errors in the measurement of ..delta..n. A specific optical delay system is described and tested in an experimental determination of the distribution of ..delta..n in an iodine laser pumped by an open discharge. The results of simultaneous measurements of ..delta..n in the light of a ruby laser are also reported. The distributions of ..delta..n at the emission wavelength of the iodine laser (1.315 ..mu..) and at the ruby laser wavelength (0.6943 ..mu..) are identical. The experimental results are used in an estimate of the characteristics of the wave front of the radiation emitted from the iodine laser.
Fiber optic refractive index monitor
Weiss, Jonathan David
2002-01-01
A sensor for measuring the change in refractive index of a liquid uses the lowest critical angle of a normal fiber optic to achieve sensitivity when the index of the liquid is significantly less than the index of the fiber core. Another embodiment uses a liquid filled core to ensure that its index is approximately the same as the liquid being measured.
Non-adiabatic primordial fluctuations
Noller, J
2009-01-01
We consider general non-adiabatic single fluid cosmological perturbations. We derive the second-order action and its curvature variables assuming only the (linearized) Einstein equations for a perfect fluid stress-energy tensor. The derivation is therefore carried out at the same level of generality that has been achieved before for adiabatic modes. We also allow for arbitrary "speed of sound" profiles in our derivation. As a result we find a new conserved super-horizon quantity and relate it to the adiabatically conserved curvature perturbation. We then use the formalism to investigate a family of non-adiabatic hydrodynamical primordial matter models and the power spectra they produce. This yields a new scale-invariant solution that can resolve the horizon problem if implemented in a contracting phase.
Adiabatic frequency conversion of quantum optical information in atomic vapor
Vewinger, Frank; Appel, Juergen; Figueroa, Eden; Lvovsky, A. I.
2006-01-01
We experimentally demonstrate a quantum communication protocol that enables frequency conversion and routing of quantum optical information in an adiabatic and thus robust way. The protocol is based on electromagnetically-induced transparency in systems with multiple excited levels: transfer and/or distribution of optical states between different signal modes is implemented by adiabatically changing the control fields. The proof-of-principle experiment is performed using the hyperfine levels ...
Adiabatic boiling of two-phase coolant in upward flow
A mathematical model of the process of adiabatic boiling (self-condensation) of a two-phase coolant in upward (downward) flow is developed. The model takes account of changes in phase properties with static pressure decrease. The process is investigated numerically. Approximate analytical formulas for design calculations are obtained. It is shown that effects of adiabatic boiling (self-condensation) should be taken into account when calculating two-phase coolant flow in stretched vertical channels
Lee, Min Joung; Lee, Sang Mok; Lee, Hyun Ju; Wee, Won Ryang; Lee, Jin Hak; Kim, Mee Kum
2007-01-01
Purpose To compare forward shift of posterior corneal surface and higher-order aberration (HOA) changes after LASIK, LASEK, and wavefront-guided LASEK surgery in moderate myopia Methods One hundred eighty four eyes undergoing LASIK, LASEK and wavefront-guided LASEK with VISX STAR S4 were included in this study. The posterior corneal elevation was measured with Orbscan before, 2 and 4 months after surgery. Changes of the elevation were assessed using the difference map generated from preoperat...
Naidoo, Kovin S; Jyoti Jaggernath
2012-01-01
Global estimates indicate that more than 2.3 billion people in the world suffer from poor vision due to refractive error; of which 670 million people are considered visually impaired because they do not have access to corrective treatment. Refractive errors, if uncorrected, results in an impaired quality of life for millions of people worldwide, irrespective of their age, sex and ethnicity. Over the past decade, a series of studies using a survey methodology, referred to as Refractive Error S...
Ungan, F., E-mail: fungan@cumhuriyet.edu.tr [Department of Physics, Cumhuriyet University, 58140 Sivas (Turkey); Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Restrepo, R.L. [Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Escuela de Ingeniería de Antioquia AA 7516, Medellín (Colombia); Mora-Ramos, M.E. [Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Morales, A.L.; Duque, C.A. [Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)
2014-02-01
The effects of hydrostatic pressure, temperature, and electric field on the optical absorption coefficients and refractive index changes associated with intersubband transition in a typical GaAs/Ga{sub 0.7}Al{sub 0.3}As graded quantum well under intense laser field have been investigated theoretically. The electron energy eigenvalues and the corresponding eigenfunctions of the graded quantum well are calculated within the effective mass approximation and envelope wave function approach. The analytical expressions of the optical properties are obtained using the compact density-matrix approach and the iterative method. The numerical results show that the linear and nonlinear optical properties depend strongly on the intense laser field and electric field but weakly on the hydrostatic pressure and temperature. Additionally, it has been found that the electronic and optical properties in a GaAs/Ga{sub 0.7}Al{sub 0.3}As graded quantum well under the intense laser field can be tuned by changing these external inputs. Thus, these results give a new degree of freedom in the devices applications.
The effects of hydrostatic pressure, temperature, and electric field on the optical absorption coefficients and refractive index changes associated with intersubband transition in a typical GaAs/Ga0.7Al0.3As graded quantum well under intense laser field have been investigated theoretically. The electron energy eigenvalues and the corresponding eigenfunctions of the graded quantum well are calculated within the effective mass approximation and envelope wave function approach. The analytical expressions of the optical properties are obtained using the compact density-matrix approach and the iterative method. The numerical results show that the linear and nonlinear optical properties depend strongly on the intense laser field and electric field but weakly on the hydrostatic pressure and temperature. Additionally, it has been found that the electronic and optical properties in a GaAs/Ga0.7Al0.3As graded quantum well under the intense laser field can be tuned by changing these external inputs. Thus, these results give a new degree of freedom in the devices applications
AN ADIABATIC APPROACH FOR LOW POWER FULL ADDER DESIGN
Prof. Dinesh Chandra
2011-09-01
Full Text Available Over the past decade, several adiabatic logic styles have been reported. This paper deals with the design of a 1-bit full adder using several adiabatic logic styles, which are derived from static CMOS logic, without a large change. The full adders are designed using 180nm technology parameters provided by predictive technology and simulated using HSPICE. The full adders designed are compared in terms of average power consumption with different values of load capacitance, temperature and input frequency. The different designs of full adder are also compared on the basis of propagation delay exhibit by them. It is found that, full adders designed with adiabatic logic styles tends to consume very low power in comparison to full adder designed with static CMOS logic. Under certain operating conditions, one of adiabatic designs of full adder achieves upto 74% power saving in comparison to the full adder designedwith static CMOS logic.
Dohn, Søren; Greve, Anders; Svendsen, Winnie Edith;
2010-01-01
It has been speculated that the initial bending of cantilevers has a major influence on the detector signal in a cantilever-based sensor using the optical lever readout method. We have investigated theoretically as well as experimentally the changes induced in the detector signal when the optical...... experimentally using an environmental chamber and varying the pressure. We sketch routes to circumvent the problem and formulas suitable for data treatment are given....
Adiabatic graph-state quantum computation
Measurement-based quantum computation (MBQC) and holonomic quantum computation (HQC) are two very different computational methods. The computation in MBQC is driven by adaptive measurements executed in a particular order on a large entangled state. In contrast in HQC the system starts in the ground subspace of a Hamiltonian which is slowly changed such that a transformation occurs within the subspace. Following the approach of Bacon and Flammia, we show that any MBQC on a graph state with generalized flow (gflow) can be converted into an adiabatically driven holonomic computation, which we call adiabatic graph-state quantum computation (AGQC). We then investigate how properties of AGQC relate to the properties of MBQC, such as computational depth. We identify a trade-off that can be made between the number of adiabatic steps in AGQC and the norm of H-dot as well as the degree of H, in analogy to the trade-off between the number of measurements and classical post-processing seen in MBQC. Finally the effects of performing AGQC with orderings that differ from standard MBQC are investigated. (paper)
Iterative supervirtual refraction interferometry
Al-Hagan, Ola
2014-05-02
In refraction tomography, the low signal-to-noise ratio (S/N) can be a major obstacle in picking the first-break arrivals at the far-offset receivers. To increase the S/N, we evaluated iterative supervirtual refraction interferometry (ISVI), which is an extension of the supervirtual refraction interferometry method. In this method, supervirtual traces are computed and then iteratively reused to generate supervirtual traces with a higher S/N. Our empirical results with both synthetic and field data revealed that ISVI can significantly boost up the S/N of far-offset traces. The drawback is that using refraction events from more than one refractor can introduce unacceptable artifacts into the final traveltime versus offset curve. This problem can be avoided by careful windowing of refraction events.
ZHANG; Peng; ZHAO; Jianlin; XU; Honglai; SUN; Yidong; YANG
2005-01-01
According to the Kukhtarev equations and a simplified model based on the photovoltaic charge carriers transport mechanism, the distributions of the index changes (DICs) in LiNbO3:Fe crystals induced by sheet beams with various intensity profiles are theoretically analyzed. The numerically simulated results coincide with the analytic expressions deduced from the simplified model. The DICs in a LiNbO3:Fe crystal induced by sheet beams with rectangular, Gaussian and square law profiles are measured by using the interferometric method. By employing the analytic expressions, the experimental data points are well fitted. By utilizing the angular spectrum theory and the ray equation, the uniformities of the intensity profiles of the writing beams along the propagation directions and the influences of the self-defocusing effect of the crystal are numerically simulated, respectively. The results show that the experimental results are reliable. The numerically simulated method and the analytic expressions can be both employed to predict the DICs induced by sheet beams with various light intensity profiles. Furthermore, utilizing writing beams with proper intensity profiles, any desired index distributions could be obtained.
The split of a generalised Chaplygin gas with an equation of state p=−A/ρα into an interacting mixture of pressureless matter and a dark-energy component with equation of state pΛ=−ρΛ implies the existence of non-adiabatic pressure perturbations. We demonstrate that the square of the effective (non-adiabatic) sound speed cs of the medium is proportional to the ratio of the perturbations of the dark energy to those of the dark matter. Since, as demonstrated explicitly for the particular case α=−1/2, dark-energy perturbations are negligible compared with dark-matter perturbations on scales that are relevant for structure formation, we find |cs2|≪1. Consequently, there are no oscillations or instabilities which have plagued previous adiabatic Chaplygin-gas models
Electro-refractive photonic device
Zortman, William A.; Watts, Michael R.
2015-06-09
The various technologies presented herein relate to phase shifting light to facilitate any of light switching, modulation, amplification, etc. Structures are presented where a second layer is juxtaposed between a first layer and a third layer with respective doping facilitating formation of p-n junctions at the interface between the first layer and the second layer, and between the second layer and the third layer. Application of a bias causes a carrier concentration change to occur at the p-n junctions which causes a shift in the effective refractive index per incremental change in an applied bias voltage. The effective refractive index enhancement can occur in both reverse bias and forward bias. The structure can be incorporated into a waveguide, an optical resonator, a vertical junction device, a horizontal junction device, a Mach-Zehnder interferometer, a tuneable optical filter, etc.
Optimizing adiabaticity in quantum mechanics
MacKenzie, R; Renaud-Desjardins, L
2011-01-01
A condition on the Hamiltonian of a time-dependent quantum mechanical system is derived which, if satisfied, implies optimal adiabaticity (defined below). The condition is expressed in terms of the Hamiltonian and in terms of the evolution operator related to it. Since the latter depends in a complicated way on the Hamiltonian, it is not yet clear how the condition can be used to extract useful information about the optimal Hamiltonian. The condition is tested on an exactly-soluble time-dependent problem (a spin in a magnetic field), where perfectly adiabatic evolution can be easily identified.
Kovin S Naidoo
2012-01-01
Full Text Available Global estimates indicate that more than 2.3 billion people in the world suffer from poor vision due to refractive error; of which 670 million people are considered visually impaired because they do not have access to corrective treatment. Refractive errors, if uncorrected, results in an impaired quality of life for millions of people worldwide, irrespective of their age, sex and ethnicity. Over the past decade, a series of studies using a survey methodology, referred to as Refractive Error Study in Children (RESC, were performed in populations with different ethnic origins and cultural settings. These studies confirmed that the prevalence of uncorrected refractive errors is considerably high for children in low-and-middle-income countries. Furthermore, uncorrected refractive error has been noted to have extensive social and economic impacts, such as limiting educational and employment opportunities of economically active persons, healthy individuals and communities. The key public health challenges presented by uncorrected refractive errors, the leading cause of vision impairment across the world, require urgent attention. To address these issues, it is critical to focus on the development of human resources and sustainable methods of service delivery. This paper discusses three core pillars to addressing the challenges posed by uncorrected refractive errors: Human Resource (HR Development, Service Development and Social Entrepreneurship.
Optimization of Adiabatic Selective Pulses
Rosenfeld, Daniel; Panfil, Shimon L.; Zur, Yuval
1997-06-01
Adiabatic RF pulses play an important role in spin inversion due to their robust behavior in presence of inhomogeneous RF fields. These pulses are characterized by the trajectory swept by the tip of theBeffvector and the rate of motion upon it. In this paper, a method is described for optimizing adiabatic inversion pulses to achieve a frequency-selective magnetization inversion over a given bandwidth in a shorter time and to improve slice profile. An efficient adiabatic pulse is used as an initial condition. This pulse allows for flexibility in choosing its parameters; in particular, the transition sharpness may be traded off against the inverted bandwidth. The considerations for selecting the parameters of the pulse according to the requirements of the design are discussed. The optimization process then improves the slice profile by optimizing the rate of motion along the trajectory of the pulse while preserving the trajectory itself. The adiabatic behavior of the optimized pulses is fully preserved over a twofold range of variation in the RF amplitude which is sufficient for imaging applications in commercial high-field MRI machines. Design examples demonstrate the superiority of the optimized pulses over the conventional sech/tanh pulse.
A Many Particle Adiabatic Invariant
Hjorth, Poul G.
For a system of N charged particles moving in a homogeneous, sufficiently strong magnetic field, a many-particle adiabatic invariant constrains the collisional exchange of energy between the degrees of freedom perpendicular to and parallel to the magnetic field. A description of the phenomenon in...
Studies in Chaotic adiabatic dynamics
Chaotic adiabatic dynamics refers to the study of systems exhibiting chaotic evolution under slowly time-dependent equations of motion. In this dissertation the author restricts his attention to Hamiltonian chaotic adiabatic systems. The results presented are organized around a central theme, namely, that the energies of such systems evolve diffusively. He begins with a general analysis, in which he motivates and derives a Fokker-Planck equation governing this process of energy diffusion. He applies this equation to study the open-quotes goodnessclose quotes of an adiabatic invariant associated with chaotic motion. This formalism is then applied to two specific examples. The first is that of a gas of noninteracting point particles inside a hard container that deforms slowly with time. Both the two- and three-dimensional cases are considered. The results are discussed in the context of the Wall Formula for one-body dissipation in nuclear physics, and it is shown that such a gas approaches, asymptotically with time, an exponential velocity distribution. The second example involves the Fermi mechanism for the acceleration of cosmic rays. Explicit evolution equations are obtained for the distribution of cosmic ray energies within this model, and the steady-state energy distribution that arises when this equation is modified to account for the injection and removal of cosmic rays is discussed. Finally, the author re-examines the multiple-time-scale approach as applied to the study of phase space evolution under a chaotic adiabatic Hamiltonian. This leads to a more rigorous derivation of the above-mentioned Fokker-Planck equation, and also to a new term which has relevance to the problem of chaotic adiabatic reaction forces (the forces acting on slow, heavy degrees of freedom due to their coupling to light, fast chaotic degrees)
Design of Selective Adiabatic Inversion Pulses Using the Adiabatic Condition
Rosenfeld, Daniel; Panfil, Shimon L.; Zur, Yuval
1997-12-01
Adiabatic RF pulses play an important role in spin inversion due to their robust behavior in the presence of inhomogeneous RF fields. These pulses are characterized by the trajectory swept by the tip of theBeffvector and the rate of motion along it. In this paper, we describe a method by which optimized modulation functions can be constructed to render insensitivity toB1inhomogeneity over a predeterminedB1range and over a wide band of frequencies. This is accomplished by requiring that the optimized pulse fulfill the adiabatic condition over this range ofB1inhomogeneity and over the desired frequency band for the complete duration of the pulse. A trajectory similar to the well-known sech/tanh adiabatic pulse, i.e., a half-ellipse, is used. The optimization process improves the slice profile by optimizing the rate of motion along this trajectory. The optimized pulse can be tailored to the specific design requirements; in particular, the transition sharpness may be traded off against the inverted bandwidth. Two design examples, including experimental results, demonstrate the superiority of the optimized pulses over the conventional sech/tanh pulse: in the first example, a large frequency band is to be inverted using a weak RF amplitude in a short time. In the second example, a pulse with a very sharp transition is required.
Complete text of publication follows. The effect of Vis-IR laser irradiation at various energy densities on refractive index and thickness of SiO2 thin film onto polycarbonate was reported in this paper. Transmittance spectra were used for determination the above characteristics of these films by application of analytical formulas was to the interference extrema. (Swanepoel method). It has been found that the thickness of films decrease by increasing the photon energy of laser and its energy density. It has been observed that the transmittance decreases with the increase of film thickness. From transmittance data, the dispersion of refractive index of sample has been studied. It was found that at high energy density (50 .35 J/cm2), the refractive index of sample was more increased. The highest increased in refractive index (Δn ∼ 0.1) was found for sample which irradiated by 532 nm laser beam with 50.35 J/cm2 energy density.
Adiabatic theory for the bipolaron
A translation-invariant adiabatic theory is constructed for the bipolaron. It is shown that motions in the bipolaron are divided: the relative electron coordinates describe fast electron oscillations in the induced polarization well and the center of mass coordinates represent slow electron movement followed by polarization. Nonlinear differential bipolaron equations are derived which are asymptotically exact in the adiabatic limit. Particlelike solutions of these equations correspond to the bipolaron bound state. The exact solution yields the value of the ion critical parameter η=0.31 for which the bipolaron state is stable, where η=ε∞/ε0 and ε∞,ε0 are high-frequency and static dielectric permittivities. The energy, the total energy, the effective mass, the radius, and the critical values of the electron-phonon coupling constants are calculated for the bipolaron. The results obtained are generalized to the case of two-dimensional bipolarons
Bending light via adiabatic optical transition in longitudinally modulated photonic lattices
Han, Bin; Xu, Lei; Dou, Yiling; Xu, Jingjun; Zhang, Guoquan
2015-10-01
Bending light in a controllable way is desired in various applications such as beam steering, navigating and cloaking. Different from the conventional way to bend light by refractive index gradient, transformation optics or special beams through wavefront design such as Airy beams and surface plasmons, we proposed a mechanism to bend light via resonant adiabatic optical transition between Floquet-Bloch (FB) modes from different FB bands in longitudinally modulated photonic lattices. The band structure of longitudinally modulated photonic lattices was calculated by employing the concept of quasi-energy based on the Floquet-Bloch theory, showing the existence of band discontinuities at specific resonant points which cannot be revealed by the coupled-mode theory. Interestingly, different FB bands can be seamlessly connected at these resonant points in longitudinally modulated photonic lattices driven by adiabatically varying the longitudinal modulation period along the propagation direction, which stimulates the adiabatic FB mode transition between different FB bands.
Quantum Adiabatic Pumping by Modulating Tunnel Phase in Quantum Dots
Taguchi, Masahiko; Nakajima, Satoshi; Kubo, Toshihiro; Tokura, Yasuhiro
2016-08-01
In a mesoscopic system, under zero bias voltage, a finite charge is transferred by quantum adiabatic pumping by adiabatically and periodically changing two or more control parameters. We obtained expressions for the pumped charge for a ring of three quantum dots (QDs) by choosing the magnetic flux penetrating the ring as one of the control parameters. We found that the pumped charge shows a steplike behavior with respect to the variance of the flux. The value of the step heights is not universal but depends on the trajectory of the control parameters. We discuss the physical origin of this behavior on the basis of the Fano resonant condition of the ring.
Adiabatic collapse of rotating gas clouds
The gravitational, axisymmetric and adiabatic collapse of rotating gas clouds with various initial conditions has been calculated numerically by means of Fluid-In-Cell method. We have assumed that the gas is ideal and its change is adiabatic except for heat production by shock waves and that, initially, a cloud has no motion in a meridional plane and has spherical and polytropic distributions of mass and temperature. The results of calculations show that a cloud which has initially larger rotational energy bounced more easily, i.e., bounces at lower central density. The bounce occurs first in the direction of the rotation axis and next in direction perpendicular to it. A shock wave generated by the bounce is strong especially in the vicinity of the rotation axis. At first the shock front is nearly parallel to the equatorial plane but it becomes gradually spherical as it propagates outwards. Calculations have been performed until the mass enclosed inside the shock front becomes as large as 95 percent of the total mass. At this final stage either a rotating spheroidal core or a rotating ring is left in the central region; a ring is formed if initially a cloud is rotating more rapidly, less centrally condensed and at lower temperature. (auth.)
Colina, M., E-mail: monica.colina.brito@upm.e [Centro Laser UPM, Univ. Politecnica de Madrid, Ctra. de Valencia Km 7.3, 28031 Madrid (Spain); Molpeceres, C.; Holgado, M. [Centro Laser UPM, Univ. Politecnica de Madrid, Ctra. de Valencia Km 7.3, 28031 Madrid (Spain); Gandia, J. [Dept. de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda, Complutense 22, 28040 Madrid (Spain); Nos, O. [CeRMAE Dept. Fisica Aplicada i Optica, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona (Spain); Ocana, J.L. [Centro Laser UPM, Univ. Politecnica de Madrid, Ctra. de Valencia Km 7.3, 28031 Madrid (Spain)
2010-07-01
Laser scribing of hydrogenated amorphous silicon (a-Si:H) is a crucial step in the fabrication of thin film photovoltaic modules. During such process, inherent thermo-mechanical effects associated to laser ablation mechanisms lead to thermal damages. In that sense, the state of the material remaining in the vicinity of the ablated area has a critical influence on the electrical properties of the final devices. In this work, a comprehensive analysis of refractive index variations for the material surrounding the ablated area by means of Infrared-Visible Fourier transform spectrometry is proposed. Besides, in order to evaluate the material microstructure, Raman spectroscopy is employed as a complimentary technique. It was seen that the refractive index variation decreased as the distance from the center of the ablated groove was increased. Likewise, a clear transition from highly crystalline to amorphous material could be also observed as a function of the distance from the groove.
Adiabatic Mass Loss Model in Binary Stars
Ge, H. W.
2012-07-01
onset of dynamical time scale mass transfer; if the ratio of donor to accretor masses exceeds this critical value, the dynamical time scale mass transfer ensues. The grid of criterion for all stars can be used to be the basic input as the binary population synthetic method, which will be improved absolutely. In common envelope evolution, the dissipation of orbital energy of the binary provides the energy to eject the common envelope; the energy budget for this process essentially consists of the initial orbital energy of the binary and the initial binding energies of the binary components. We emphasize that, because stellar core and envelope contribute mutually to each other's gravitational potential energy, proper evaluation of the total energy of a star requires integration over the entire stellar interior, not the ejected envelope alone as commonly assumed. We show that the change in total energy of the donor star, as a function of its remaining mass along an adiabatic mass-loss sequence, can be calculated. This change in total energy of the donor star, combined with the requirement that both remnant donor and its companion star fit within their respective Roche lobes, then circumscribes energetically possible survivors of common envelope evolution. It is the first time that we can calculate the accurate total energy of the donor star in common envelope evolution, while the results with the old method are inconsistent with observations.
Adiabatic processes in monatomic gases
A kinetic model is used to predict the temperature evolution of a monatomic ideal gas undergoing an adiabatic expansion or compression at a constant finite rate, and it is then generalized to treat real gases. The effects of interatomic forces are considered, using as examples the gas with the square-well potential and the van der Waals gas. The model is integrated into a Carnot cycle operating at a finite rate to compare the efficiency's rate-dependent behavior with the reversible result. Limitations of the model, rate penalties, and their importance are discussed
Additional adiabatic heating of plasma
A theoretical possibility of a plasma additional adiabatic heating up to temperatures needed for the begin of D-T thermonuclear fusion reaction, has been found on the base of the polyenergetic conjugation expression, developed in the Thermodynamics of Accumulation Processes. TAP is a branch of the non-equilibrium thermodynamics. The thermodynamics of irreversible processes is another branch of the entire non-equilibrium thermodynamics. TAP deals with the phenomena associated with the introduction, conversion and accumulation of mass or energy or both in the affected, open or closed systems. (author) 2 refs
Adiabatic Floquet model for the optical response in femtosecond filaments
Hofmann, Michael
2016-01-01
The standard model of femtosecond filamentation is based on phenomenological assumptions which suggest that the ionization-induced carriers can be treated as free according to the Drude model, while the nonlinear response of the bound carriers follows the all-optical Kerr effect. Here, we demonstrate that the additional plasma generated at a multiphoton resonance dominates the saturation of the nonlinear refractive index. Since resonances are not captured by the standard model, we propose a modification of the latter in which ionization enhancements can be accounted for by an ionization rate obtained from non-Hermitian Floquet theory. In the adiabatic regime of long pulse envelopes, this augmented standard model is in excellent agreement with direct quantum mechanical simulations. Since our proposal maintains the structure of the standard model, it can be easily incorporated into existing codes of filament simulation.
A New Approach to the Quantum Adiabatic Condition
The quantum adiabatic theorem is the basis of adiabatic quantum computation. However, the exact necessary and sufficient conditions for adiabatic evolution are still under debate. We discuss the adiabatic condition of a system undergoing a special evolution route, and obtain an explicit formula that is necessary and sufficient for the adiabatic evolution in this route. Based on this formula, we find that the traditional adiabatic condition is neither sufficient nor necessary. Finally, we show that no adiabatic process can occur even the evolution speed goes to 0 in some examples, which is surprising since the adiabatic theorem states that if the evolution of a system is slow enough, the adiabatic process could occur
Rice, Daniel
2012-10-01
A threshold aerogel Cherenkov detector is being constructed at CUA to allow for the study of kaons in experiments at the Jefferson Laboratory. These subatomic particles move faster than light through the aerogel material, emitting Cherenkov radiation. Photomultiplier Tubes (PMTs) convert the photons from the Cherenkov radiation into electrons and multiply the electrons sufficiently to get a readable electronic signal, which can be analyzed. An important part of a threshold aerogel Cherenkov detector is its use of aerogel material of several refractive indices to cover the full dynamic range over which one wants to detect the particles of interest (in this case the kaon). Uniform coverage in refractive index is important as the location of the incoming particle will not be constant throughout the testing. In addition to testing for uniform coverage, we must also verify these refractive indices to ensure that the particles we are detecting are in fact kaons. The last test on the aerogel that needs to be performed is the measurement of transparency. Although aerogel is highly transparent, it is still necessary to find the amount of light being absorbed, reflected, or scattered versus how much will actually be measured by the PMTs used.
Variable refractive index in environment matte
ZHAO Ming-tian; XIAO Shuang-jiu; YANG Xu-bo; MA Li-zhuang
2006-01-01
Environment matting and compositing is a technique to extract a foreground object, including color, opacity, reflective and refractive properties, from a real-world scene, and synthesize new images by placing it into new environments. The description of the captured object is named environment matte. Recent matting and compositing techniques can produce quite realistic images for objects with complex optical properties. This paper presents an approximate method to transform the matte by simulating variation of the foreground object's refractive index. Our algorithms can deal with achromatous-and-transparent objects and the experimental results are visually acceptable. Our idea and method can be applied to produce some special video effects, which could be very useful in film making, compared with the extreme difficulty of physically changing an object's refractive index.
Complete Adiabatic Quantum Search in Unsorted Databases
Xu, Nanyang; Peng, Xinhua; Shi, Mingjun; Du, Jiangfeng
2008-01-01
We propose a new adiabatic algorithm for the unsorted database search problem. This algorithm saves two thirds of qubits than Grover's algorithm in realizations. Meanwhile, we analyze the time complexity of the algorithm by both perturbative method and numerical simulation. The results show it provides a better speedup than the previous adiabatic search algorithm.
Shortcut to adiabatic gate teleportation
Santos, Alan C.; Silva, Raphael D.; Sarandy, Marcelo S.
2016-01-01
We introduce a shortcut to the adiabatic gate teleportation model of quantum computation. More specifically, we determine fast local counterdiabatic Hamiltonians able to implement teleportation as a universal computational primitive. In this scenario, we provide the counterdiabatic driving for arbitrary n -qubit gates, which allows to achieve universality through a variety of gate sets. Remarkably, our approach maps the superadiabatic Hamiltonian HSA for an arbitrary n -qubit gate teleportation into the implementation of a rotated superadiabatic dynamics of an n -qubit state teleportation. This result is rather general, with the speed of the evolution only dictated by the quantum speed limit. In particular, we analyze the energetic cost for different Hamiltonian interpolations in the context of the energy-time complementarity.
Adiabatic Rearrangement of Hollow PV Towers
Eric A Hendricks
2010-10-01
Full Text Available Diabatic heating from deep moist convection in the hurricane eyewall produces a towering annular structure of elevated potential vorticity (PV. This structure has been referred to as a hollow PV tower. The sign reversal of the radial gradient of PV satisfies the Charney-Stern necessary condition for combined barotropic-baroclinic instability. For thin enough annular structures, small perturbations grow exponentially, extract energy from the mean flow, and lead to hollow tower breakdown, with significant vortex structural and intensity change. The three-dimensional adiabatic rearrangements of two prototypical hurricane-like hollow PV towers (one thick and one thin are examined in an idealized framework. For both hollow towers, dynamic instability causes air parcels with high PV to be mixed into the eye preferentially at lower levels, where unstable PV wave growth rates are the largest. Little or no mixing is found to occur at upper levels. The mixing at lower and middle levels is most rapid for the breakdown of the thin hollow tower, consistent with previous barotropic results. For both hollow towers, this advective rearrangement of PV affects the tropical cyclone structure and intensity in a number of ways. First, the minimum central pressure and maximum azimuthal mean velocity simultaneously decrease, consistent with previous barotropic results. Secondly, isosurfaces of absolute angular momentum preferentially shift inward at low levels, implying an adiabatic mechanism by which hurricane eyewall tilt can form. Thirdly, a PV bridge, similar to that previously found in full-physics hurricane simulations, develops as a result of mixing at the isentropic levels where unstable PV waves grow most rapidly. Finally, the balanced mass field resulting from the PV rearrangement is warmer in the eye between 900 and 700 hPa. The location of this warming is consistent with observed warm anomalies in the eye, indicating that in certain instances the hurricane
Demming, Anna
2012-12-01
Refractive index effects using nanoscale systems are frequently applied in new imaging, sensing and even visibility cloaking technology. In this issue, researchers in Japan use simulations and experiments to describe the confinement of optical vortices in nanoscale fin structures and the sensitivity of these systems to the refractive index of the surrounding media [1]. The effects of refraction as light rays pass between different media were recorded as long ago as the first century AD, by Ptolemy [2]. Over the following centuries the phenomena inspired Ibn Sahl in 984 [3], Thomas Harriot in 1602 [4], Willebrord Snellius in 1621 [5] and Rene Descartes in 1637 [6] to independently derive the more accurate and elegant equation for refraction so familiar to us today. Recent studies of the interactions between light and matter continue to reveal a wealth of phenomena that originate in the effects of the refractive indices of materials. Nanostructures can be used to manipulate conditions that affect the refractive indices of materials, such as temperature. A E Aliev et al at the University of Texas reported a striking demonstration of temperature-dependent refractive index effects using a free-standing, highly aligned carbon nanotube aerogel sheet [7]. They used the extremely low thermal capacitance and high heat transfer ability of transparent carbon nanotube sheets to enable high-frequency modulation of the sheet temperature over an enormous temperature range. The resulting sharp, rapidly changing gradient of the refractive index in the surrounding liquid or gas makes objects seem to disappear and can be used for visibility cloaking. Light-matter interaction resonances, where light is confined at the nanoscale, can be extremely sensitive to changes in the refractive index of the surrounding media [8], even allowing single-molecule detection [9]. Plasmons, the collective oscillations of electrons in response to incident light, are a typical example. Researchers at Rice
Quantum gates with controlled adiabatic evolutions
Hen, Itay
2015-02-01
We introduce a class of quantum adiabatic evolutions that we claim may be interpreted as the equivalents of the unitary gates of the quantum gate model. We argue that these gates form a universal set and may therefore be used as building blocks in the construction of arbitrary "adiabatic circuits," analogously to the manner in which gates are used in the circuit model. One implication of the above construction is that arbitrary classical boolean circuits as well as gate model circuits may be directly translated to adiabatic algorithms with no additional resources or complexities. We show that while these adiabatic algorithms fail to exhibit certain aspects of the inherent fault tolerance of traditional quantum adiabatic algorithms, they may have certain other experimental advantages acting as quantum gates.
Yesilgul, U., E-mail: uyesilgul@cumhuriyet.edu.tr [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Ungan, F. [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Sakiroglu, S. [Dokuz Eylül University, Physics Department, 35160 Buca, İzmir (Turkey); Mora-Ramos, M.E. [Facultad de Ciencias Universidad Autonoma del Estado de Morelos, Ave. Universidad 1001, C.P. 62209 Cuernavaca, Morelos (Mexico); Duque, C.A. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Kasapoglu, E.; Sarı, H. [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Sökmen, I. [Dokuz Eylül University, Physics Department, 35160 Buca, İzmir (Turkey)
2014-01-15
The effects of the intense high-frequency laser field on the optical absorption coefficients and the refractive index changes in a GaAs/GaAlAs parabolic quantum well under the applied electric field have been investigated theoretically. The electron energy levels and the envelope wave functions of the parabolic quantum well are calculated within the effective mass approximation. Analytical expressions for optical properties are obtained using the compact density-matrix approach. The numerical results show that the intense high-frequency laser field has a large effect on the optical characteristics of these structures. Also we can observe that the refractive index and absorption coefficient changes are very sensitive to the electric field in large dimension wells. Thus, this result gives a new degree of freedom in the optoelectronic device applications. -- Highlights: • ILF has a large effect on the optical properties of parabolic quantum wells. • The total absorption coefficients increase as the ILF increases. • The RICs increase as the ILF increases.
The effects of the intense high-frequency laser field on the optical absorption coefficients and the refractive index changes in a GaAs/GaAlAs parabolic quantum well under the applied electric field have been investigated theoretically. The electron energy levels and the envelope wave functions of the parabolic quantum well are calculated within the effective mass approximation. Analytical expressions for optical properties are obtained using the compact density-matrix approach. The numerical results show that the intense high-frequency laser field has a large effect on the optical characteristics of these structures. Also we can observe that the refractive index and absorption coefficient changes are very sensitive to the electric field in large dimension wells. Thus, this result gives a new degree of freedom in the optoelectronic device applications. -- Highlights: • ILF has a large effect on the optical properties of parabolic quantum wells. • The total absorption coefficients increase as the ILF increases. • The RICs increase as the ILF increases
On the statistical mechanics of an adiabatic ensemble
S.N.Andreev
2004-01-01
Full Text Available Different descriptions of an adiabatic process based on statistical thermodynamics and statistical mechanics are discussed. Equality of the so-called adiabatic and isolated susceptibilities and its generalization as well as adiabatic invariants are essentially used to describe adiabatic processes in the framework of quantum and classical statistical mechanics. It is shown that distribution function in adiabatic ensemble differs from a quasi-equilibrium canonical form provided the heat capacity of the system is not constant in adiabatic process.
Koshel', K. V.; Shishkarev, A. A.
1993-02-01
A perturbation theory for complex propagation constants is considered, based on the invariant imbedding method. This approach makes it possible to describe the effect of nonstratified fluctuations of the refractive index on transhorizon propagation of ultrashort waves in the framework of the adiabatic approximation in the case when an evaporation duct exists. Examples of calculations are presented, and characteristic stochastic effects are studied.
Refractive index based measurements
2014-01-01
In a method for performing a refractive index based measurement of a property of a fluid such as chemical composition or temperature by observing an apparent angular shift in an interference fringe pattern produced by back or forward scattering interferometry, ambiguities in the measurement caused...... by the apparent shift being consistent with one of a number of numerical possibilities for the real shift which differ by 2n are resolved by combining measurements performed on the same sample using light paths therethrough of differing lengths....
Negative refractive index metamaterials
Willie J. Padilla
2006-07-01
Full Text Available Engineered materials composed of designed inclusions can exhibit exotic and unique electromagnetic properties not inherent in the individual constituent components. These artificially structured composites, known as metamaterials, have the potential to fill critical voids in the electromagnetic spectrum where material response is limited and enable the construction of novel devices. Recently, metamaterials that display negative refractive index – a property not found in any known naturally occurring material – have drawn significant scientific interest, underscoring the remarkable potential of metamaterials to facilitate new developments in electromagnetism.
Partial evolution based local adiabatic quantum search
Recently, Zhang and Lu provided a quantum search algorithm based on partial adiabatic evolution, which beats the time bound of local adiabatic search when the number of marked items in the unsorted database is larger than one. Later, they found that the above two adiabatic search algorithms had the same time complexity when there is only one marked item in the database. In the present paper, following the idea of Roland and Cerf [Roland J and Cerf N J 2002 Phys. Rev. A 65 042308], if within the small symmetric evolution interval defined by Zhang et al., a local adiabatic evolution is performed instead of the original “global” one, this “new” algorithm exhibits slightly better performance, although they are progressively equivalent with M increasing. In addition, the proof of the optimality for this partial evolution based local adiabatic search when M = 1 is also presented. Two other special cases of the adiabatic algorithm obtained by appropriately tuning the evolution interval of partial adiabatic evolution based quantum search, which are found to have the same phenomenon above, are also discussed. (general)
Refractive laser surgery for myopia
2008-01-01
BACKGROUND: The prevalence of myopia is increasing. Constant near-work, race, gender and genes are associated with development of myopia. Refractive laser surgery is eye surgey aimed at altering the refractive power of the cornea, and the procedures are among the most commonly performed in medicine. The main indication for refractive surgery of myopia is cosmetic; patients deem it a good alternative to wearing contact lenses and glasses. PURPOSE: This paper gives an overview of the histor...
Digital Waveguide Adiabatic Passage Part 2: Experiment
Ng, Vincent; Chaboyer, Zachary J; Nguyen, Thach; Dawes, Judith M; Withford, Michael J; Greentree, Andrew D; Steel, M J
2016-01-01
Using a femtosecond laser writing technique, we fabricate and characterise three-waveguide digital adiabatic passage devices, with the central waveguide digitised into five discrete waveguidelets. Strongly asymmetric behaviour was observed, devices operated with high fidelity in the counter-intuitive scheme while strongly suppressing transmission in the intuitive. The low differential loss of the digital adiabatic passage designs potentially offers additional functionality for adiabatic passage based devices. These devices operate with a high contrast ($>\\!90\\%$) over a 60~nm bandwidth, centered at $\\sim 823$~nm.
Adiabatic Compression of Oxygen: Real Fluid Temperatures
Barragan, Michelle; Wilson, D. Bruce; Stoltzfus, Joel M.
2000-01-01
The adiabatic compression of oxygen has been identified as an ignition source for systems operating in enriched oxygen atmospheres. Current practice is to evaluate the temperature rise on compression by treating oxygen as an ideal gas with constant heat capacity. This paper establishes the appropriate thermodynamic analysis for the common occurrence of adiabatic compression of oxygen and in the process defines a satisfactory equation of state (EOS) for oxygen. It uses that EOS to model adiabatic compression as isentropic compression and calculates final temperatures for this system using current approaches for comparison.
Fermat's principle with complex refractive indices and local light-ray rotation
Sundar, Bhuvanesh; Courtial, Johannes
2008-01-01
We describe local light-ray rotation in terms of complex refractive indices. We show that Fermat's principle holds, and we derive an extended Snell's law. The change in the angle of a light ray with respect to the normal to a refractive-index interface is described by the modulus of the refractive-index ratio, the rotation around the interface normal is described by the argument of the refractive-index ratio.
Thermoelectric Effects under Adiabatic Conditions
George Levy
2013-10-01
Full Text Available This paper investigates not fully explained voltage offsets observed by several researchers during the measurement of the Seebeck coefficient of high Z materials. These offsets, traditionally attributed to faulty laboratory procedures, have proven to have an irreducible component that cannot be fully eliminated in spite of careful laboratory procedures. In fact, these offsets are commonly observed and routinely subtracted out of commercially available Seebeck measurement systems. This paper offers a possible explanation based on the spontaneous formation of an adiabatic temperature gradient in the presence of a force field. The diffusion-diffusion heat transport mechanism is formulated and applied to predict two new thermoelectric effects. The first is the existence of a temperature gradient across a potential barrier in a semiconductor and the second is the Onsager reciprocal of the first, that is, the presence of a measureable voltage that arises across a junction when the temperature gradient is forced to zero by a thermal clamp. Suggested future research includes strategies for utilizing the new thermoelectric effects.
Dispersion tuning with a varifocal diffractive-refractive hybrid lens.
Harm, Walter; Roider, Clemens; Jesacher, Alexander; Bernet, Stefan; Ritsch-Marte, Monika
2014-03-10
We present a hybrid diffractive-refractive optical lens doublet consisting of a varifocal Moiré Fresnel lens and a polymer lens of tunable refractive power. The wide range of focal tunability of each lens and the opposite dispersive characteristics of the diffractive and the refractive element are exploited to obtain an optical system where both the Abbe number and the refractive power can be changed separately. We investigate the performance of the proposed hybrid lens at zero overall refractive power by tuning the Abbe number of a complementary standard lens while maintaining a constant overall focal length for the central wavelength. As an application example, the hybrid lens is used to tune to an optimal operating regime for quantitative phase microscopy based on a two-color transport of intensity (TIE) approach which utilizes chromatic aberrations rather than intensity recordings at several planes to reconstruct the optical path length of a phase object. PMID:24663866
Comparison Between Radar and Automatic Weather Station Refractivity Variability
Hallali, Ruben; Dalaudier, Francis; Parent du Chatelet, Jacques
2016-08-01
Weather radars measure changes in the refractive index of air in the atmospheric boundary layer. The technique uses the phase of signals from ground targets located around the radar to provide information on atmospheric refractivity related to meteorological quantities such as temperature, pressure and humidity. The approach has been successfully implemented during several field campaigns using operational S-band radars in Canada, UK, USA and France. In order to better characterize the origins of errors, a recent study has simulated temporal variations of refractivity based on Automatic Weather Station (AWS) measurements. This reveals a stronger variability of the refractivity during the summer and in the afternoon when the refractivity is the most sensitive to humidity, probably because of turbulence close to the ground. This raises the possibility of retrieving information on the turbulent state of the atmosphere from the variability in radar refractivity. An analysis based on a 1-year dataset from the operational C-band radar at Trappes (near Paris, France) and AWS refractivity variability measurements was used to measure those temporal and spatial variabilities. Particularly during summer, a negative bias increasing with range is observed between radar and AWS estimations, and is well explained by a model based on Taylor's hypotheses. The results demonstrate the possibility of establishing, depending on season, a quantitative and qualitative link between radar and AWS refractivity variability that reflects low-level coherent turbulent structures.
Adiabatic Invariance of Oscillons/I-balls
Kawasaki, Masahiro; Takeda, Naoyuki
2015-01-01
Real scalar fields are known to fragment into spatially localized and long-lived solitons called oscillons or $I$-balls. We prove the adiabatic invariance of the oscillons/$I$-balls for a potential that allows periodic motion even in the presence of non-negligible spatial gradient energy. We show that such potential is uniquely determined to be the quadratic one with a logarithmic correction, for which the oscillons/$I$-balls are absolutely stable. For slightly different forms of the scalar potential dominated by the quadratic one, the oscillons/$I$-balls are only quasi-stable, because the adiabatic charge is only approximately conserved. We check the conservation of the adiabatic charge of the $I$-balls in numerical simulation by slowly varying the coefficient of logarithmic corrections. This unambiguously shows that the longevity of oscillons/$I$-balls is due to the adiabatic invariance.
Adiabatic hydrodynamics: The eightfold way to dissipation
Haehl, Felix M; Rangamani, Mukund
2015-01-01
We provide a complete solution to hydrodynamic transport at all orders in the gradient expansion compatible with the second law constraint. The key new ingredient we introduce is the notion of adiabaticity, which allows us to take hydrodynamics off-shell. Adiabatic fluids are such that off-shell dynamics of the fluid compensates for entropy production. The space of adiabatic fluids is quite rich, and admits a decomposition into seven distinct classes. Together with the dissipative class this establishes the eightfold way of hydrodynamic transport. Furthermore, recent results guarantee that dissipative terms beyond leading order in the gradient expansion are agnostic of the second law. While this completes a transport taxonomy, we go on to argue for a new symmetry principle, an Abelian gauge invariance that guarantees adiabaticity in hydrodynamics. We suggest that this symmetry is the macroscopic manifestation of the microscopic KMS invariance. We demonstrate its utility by explicitly constructing effective ac...
Adiabatic Connection for Strictly-Correlated Electrons
Liu, Zhenfei; Burke, Kieron
2009-01-01
Modern density functional theory (DFT) calculations employ the Kohn-Sham (KS) system of non-interacting electrons as a reference, with all complications buried in the exchange-correlation energy (Exc). The adiabatic connection formula gives an exact expression for Exc. We consider DFT calculations that instead employ a reference of strictly-correlated electrons. We define a "decorrelation energy" that relates this reference to the real system, and derive the corresponding adiabatic connection...
Adiabatic Approximation, Semiclassical Scattering, and Unidirectional Invisibility
Mostafazadeh, Ali
2014-01-01
arXiv:1401.4315v3 [quant-ph] 27 Feb 2014 Adiabatic Approximation, Semiclassical Scattering, and Unidirectional Invisibility Ali Mostafazadeh∗ Department of Mathematics, Ko¸c University, 34450 Sarıyer, Istanbul, Turkey Abstract The transfer matrix of a possibly complex and energy-dependent scattering potential can be identified with the S-matrix of a two-level time-dependent non-Hermitian Hamiltonian H( ). We show that the application of the adiabatic approximation ...
On adiabatic invariant in generalized Galileon theories
Ema, Yohei; Jinno, Ryusuke; Mukaida, Kyohei; Nakayama, Kazunori
2015-01-01
We consider background dynamics of generalized Galileon theories in the context of inflation, where gravity and inflaton are non-minimally coupled to each other. In the inflaton oscillation regime, the Hubble parameter and energy density oscillate violently in many cases, in contrast to the Einstein gravity with minimally coupled inflaton. However, we find that there is an adiabatic invariant in the inflaton oscillation regime in any generalized Galileon theory. This adiabatic invariant is us...
Adiabatic compression of elongated field-reversed configurations
The simplest model of plasma dynamics is the adiabatic model. In this model the plasma is assumed to be in MHD equilibrium at each instant of time. The equilibria are connected by the requirement that they all have the same entropy per unit flux, i.e., the equilibria form a sequence generated by adiabatic changes. The standard way of computing such a sequence of equilibria was developed by Grad, but its practical use requires a fairly complicated code. It would be helpful if approximately the same results could be gotten either with a much simpler code or by analytical techniques. A one-dimensional equilibrium code is described and its results are checked against a two-dimensional equilibrium. An even simpler analytic calculation is then presented
Influence of accommodation and refractive status on the peripheral refractive profile
Davies, Leon Nicholas; Mallen, Edward Arthur Harry
2009-01-01
Abstract Background: To determine, objectively and non-invasively, whether changes in accommodative demand modify differentially the peripheral refraction in emmetropic and myopic human eyes. Methods: Forty subjects (19 male, 21 female) aged 20 to 30 years (mean?SD: 22.7?2.8 years), twenty-one emmetropes (mean spherical equivalent refractive error [MSE]?SD: -0.13?0.29D) and 19 myopes (MSE?SD: -2.95?1.76D) participated in the study. Ametropia was corrected with soft ...
An Integrated Programming and Development Environment for Adiabatic Quantum Optimization
Humble, Travis S.; McCaskey, Alex J.; Bennink, Ryan S.; Billings, Jay J.; D'Azevedo, Ed F.; Sullivan, Blair D.; Klymko, Christine F.; Seddiqi, Hadayat
2013-01-01
Adiabatic quantum computing is a promising route to the computational power afforded by quantum information processing. The recent availability of adiabatic hardware has raised challenging questions about how to evaluate adiabatic quantum optimization programs. Processor behavior depends on multiple steps to synthesize an adiabatic quantum program, which are each highly tunable. We present an integrated programming and development environment for adiabatic quantum optimization called JADE tha...
On criterion of modal adiabaticity
WANG; Ning(
2001-01-01
［1］Pierce, A. D., Extension of the method of normal modes to sound propagation in an almost-stratified medium, J. Acoust.Soc. Am., 1965, 37: 19－27.［2］Wang, D. Z. , Shang, E. C., Underwater Acoustics (in Chinese), Beijing: Science Press, 1981.［3］Zhang Renhe, Li Fenghua, Beam-displacement rya-mode theory of sound propagation in shallow water, Science in China, Ser.A, 1999, 42(7): 739－749.［4］Zhou Jixun, Zhang Xuezhen, Rogers P., Resonance interaction of sound waves with internal solitons in coastal zone, J.Acoust. Soc. Am., 1991, 90: 2042－2054.［5］Shang, E. C., Wang, Y. Y., The impact of mesoscale oceanic structure on global-scale acoustic propagation, in Theoretical and Computational Acoustics (ed. Ding Lee et al. ), Singapore: World Scientific Publishing Co. , 1996, 409－431.［6］Milder, D. M., Ray and wave invariants for SOFAR channel propagation, J. Acoust. Soc. Am., 1969, 46: 1259－1263.［7］Nag l, A., Milder, D. M., Adiabatic mode theory of underwater sound propagation in a range-dependent environment, J.Acoust. Soc. Am., 1978, 63: 739－749.［8］Brekhovskikh, L. M., Waves in Layered Media, 2nd ed., New York: Academic Press Inc., 1973.［9］Brekhovskikh, L. M., Lysanov, Yu., Fundamental of Ocean Acoustics, Ch. 7, Sec. 7.2, Berlin: Springer-Verlag, 1982.［10］Evans, R. B., A coupled mode solution for acoustic propagation in a wave-guide with stepwise depth variations of a penerable bottom, J. Acoust. Soc. A.m., 1983, 74: 188－195.［11］Jensen, F. B., Kuperman, W. A., Porter, M. B. et al., Computational Ocean Acoustics, New York: Springer-Verlag,1992.［12］Wang Ning, Inverse scattering problem for the coupled second order ODE, Journal of The Physical Society of Japan, 1995, 64(12): 4907－4915.
Adiabatic Shear Mechanisms for the Hard Cutting Process
YUE Caixu; WANG Bo; LIU Xianli; FENG Huize; CAI Chunbin
2015-01-01
The most important consequence of adiabatic shear phenomenon is formation of sawtooth chip. Lots of scholars focused on the formation mechanism of sawtooth, and the research often depended on experimental approach. For the present, the mechanism of sawtooth chip formation still remalns some ambiguous aspects. This study develops a combined numerical and experimental approach to get deeper understanding of sawtooth chip formation mechanism for Polycrystalline Cubic Boron Nitride (PCBN) tools orthogonal cutting hard steel GCr15. By adopting the Johnson-Cook material constitutive equations, the FEM simulation model established in this research effectively overcomes serious element distortions and cell singularity in high straln domaln caused by large material deformation, and the adiabatic shear phenomenon is simulated successfully. Both the formation mechanism and process of sawtooth are simulated. Also, the change features regarding the cutting force as well as its effects on temperature are studied. More specifically, the contact of sawtooth formation frequency with cutting force fluctuation frequency is established. The cutting force and effect of cutting temperature on mechanism of adiabatic shear are investigated. Furthermore, the effects of the cutting condition on sawtooth chip formation are researched. The researching results show that cutting feed has the most important effect on sawtooth chip formation compared with cutting depth and speed. This research contributes a better understanding of mechanism, feature of chip formation in hard turning process, and supplies theoretical basis for the optimization of hard cutting process parameters.
Adiabatic shear mechanisms for the hard cutting process
Yue, Caixu; Wang, Bo; Liu, Xianli; Feng, Huize; Cai, Chunbin
2015-05-01
The most important consequence of adiabatic shear phenomenon is formation of sawtooth chip. Lots of scholars focused on the formation mechanism of sawtooth, and the research often depended on experimental approach. For the present, the mechanism of sawtooth chip formation still remains some ambiguous aspects. This study develops a combined numerical and experimental approach to get deeper understanding of sawtooth chip formation mechanism for Polycrystalline Cubic Boron Nitride (PCBN) tools orthogonal cutting hard steel GCr15. By adopting the Johnson-Cook material constitutive equations, the FEM simulation model established in this research effectively overcomes serious element distortions and cell singularity in high strain domain caused by large material deformation, and the adiabatic shear phenomenon is simulated successfully. Both the formation mechanism and process of sawtooth are simulated. Also, the change features regarding the cutting force as well as its effects on temperature are studied. More specifically, the contact of sawtooth formation frequency with cutting force fluctuation frequency is established. The cutting force and effect of cutting temperature on mechanism of adiabatic shear are investigated. Furthermore, the effects of the cutting condition on sawtooth chip formation are researched. The researching results show that cutting feed has the most important effect on sawtooth chip formation compared with cutting depth and speed. This research contributes a better understanding of mechanism, feature of chip formation in hard turning process, and supplies theoretical basis for the optimization of hard cutting process parameters.
Refracting profiles and generalized holodiagrams
Criado, C; Rabal, H
2004-01-01
The recently developed concept of refracting profiles and that of refraction holodiagrams are combined so that the classical Abramson holodiagrams can be generalized taking into account a wider class of wave fronts and refraction at an interface, whenever regions of caustics are avoided. These holodiagrams are obtained as envelopes of specific families of Cartesian Ovals with an appropriate parametrization. Classical and reflecting holodiagrams are particular cases of this class. Several of the properties of the classical holodiagrams are shared by their richer generalized versions
Adiabatic cooling of a single trapped ion
Poulsen, Gregers
2012-01-01
We present experimental results on adiabatic cooling of a single 40Ca+ ion in a linear radiofrequency trap. After a period of laser cooling, the secular frequency along the rf-field-free axis is adiabatically lowered by nearly a factor of eight from 583 kHz to 75 kHz. For an ion originally Doppler laser cooled to a temperature of 0.65 +/- 0.03 mK, a temperature of 87 +/- 7 \\mu K is measured after the adiabatic expansion. Applying the same adiabatic cooling procedure to a single sideband cooled ion in the ground state (P0 = 0.978 +/- 0.002) resulted in a final ground state occupation of 0.947 +/- 0.005. Both results are in excellent agreement with an essentially fully adiabatic behavior. The results have a wide range of perspectives within such diverse fields as ion based quantum information science, high resolution molecular ion spectroscopy and ion chemistry at ultra-low temperatures.
Symmetry-Protected Quantum Adiabatic Transistors
Williamson, Dominic J.; Bartlett, Stephen D.
2014-03-01
An essential development in the history of computing was the invention of the transistor as it allowed logic circuits to be implemented in a robust and modular way. The physical characteristics of semiconductor materials were the key to building these devices. We aim to present an analogous development for quantum computing by showing that quantum adiabatic transistors (as defined by Flammia et al.) are built upon the essential qualities of symmetry-protected (SP) quantum ordered phases in one dimension. Flammia et al. and Renes et al. have demonstrated schemes for universal adiabatic quantum computation using quantum adiabatic transistors described by interacting spin chain models with specifically chosen Hamiltonian terms. We show that these models can be understood as specific examples of the generic situation in which all SP phases lead to quantum computation on encoded edge degrees of freedom by adiabatically traversing a symmetric phase transition into a trivial symmetric phase. This point of view is advantageous as it allows us to readily see that the computational properties of a quantum adiabatic transistor arise from a phase of matter rather than due to carefully tuned interactions.
Accurate adiabatic correction in the hydrogen molecule
Pachucki, Krzysztof, E-mail: krp@fuw.edu.pl [Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw (Poland); Komasa, Jacek, E-mail: komasa@man.poznan.pl [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań (Poland)
2014-12-14
A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10{sup −12} at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H{sub 2}, HD, HT, D{sub 2}, DT, and T{sub 2} has been determined. For the ground state of H{sub 2} the estimated precision is 3 × 10{sup −7} cm{sup −1}, which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels.
Adiabatic process reversibility: microscopic and macroscopic views
The reversibility of adiabatic processes was recently addressed by two publications. In the first (Miranda 2008 Eur. J. Phys. 29 937-43), an equation was derived relating the initial and final volumes and temperatures for adiabatic expansions of an ideal gas, using a microscopic approach. In that relation the parameter r accounts for the process reversibility, ranging between 0 and 1, which corresponds to the free and reversible expansion, respectively. In the second (Anacleto and Pereira 2009 Eur. J. Phys. 30 177-83), the authors have shown that thermodynamics can effectively and efficiently be used to obtain the general law for adiabatic processes carried out by an ideal gas, including compressions, for which r≥1. The present work integrates and extends the aforementioned studies, providing thus further insights into the analysis of the adiabatic process. It is shown that Miranda's work is wholly valid for compressions. In addition, it is demonstrated that the adiabatic reversibility coefficient given in terms of the piston velocity and the root mean square velocity of the gas particles is equivalent to the macroscopic description, given just by the quotient between surroundings and system pressure values. (letters and comments)
Steering and collimating ballistic electrons with amphoteric refraction
We show that amphoteric refraction of ballistic electrons, i.e., positive or negative refraction depending on the incidence angle, occurs at an interface between an isotropic and an anisotropic medium and can be employed to steer and collimate electron beams. The steering angle is determined by the materials’ parameters, but the degree of collimation can be tuned in a significant range by changing the energy of ballistic electrons.
ZHANG; Tao
2007-01-01
The roles of the magnetic field and electric field of the light are investigated when the light is refracted in the medium. The model of the electron cloud conductor is presented. Electron cloud in a molecule is treated as a conductor and the Faraday's Law is applied to this conductor that is in the alternating magnetic field of the light. dBM/dt of the light gives rise to an alternating induced current on the electron cloud conductor, and the light exchanges energy, i.e. the refractive energy, with the electron cloud conductor. Formulas of refractive index, which is the ratio of light speed in vacuum to that in the medium, are derived with this model. These formulas are tested with several mediums and Langevin's diamagnetic susceptibility of helium gas, and the results are in good agreement with the measured data. The anisotropy and the nonlinearity of the refractive index are explained with the theory described in this work.
Nonadiabatic exchange dynamics during adiabatic frequency sweeps
Barbara, Thomas M.
2016-04-01
A Bloch equation analysis that includes relaxation and exchange effects during an adiabatic frequency swept pulse is presented. For a large class of sweeps, relaxation can be incorporated using simple first order perturbation theory. For anisochronous exchange, new expressions are derived for exchange augmented rotating frame relaxation. For isochronous exchange between sites with distinct relaxation rate constants outside the extreme narrowing limit, simple criteria for adiabatic exchange are derived and demonstrate that frequency sweeps commonly in use may not be adiabatic with regard to exchange unless the exchange rates are much larger than the relaxation rates. Otherwise, accurate assessment of the sensitivity to exchange dynamics will require numerical integration of the rate equations. Examples of this situation are given for experimentally relevant parameters believed to hold for in-vivo tissue. These results are of significance in the study of exchange induced contrast in magnetic resonance imaging.
Energy efficiency of adiabatic superconductor logic
Adiabatic superconductor logic (ASL), including adiabatic quantum-flux-parametron (AQFP) logic, exhibits high energy efficiency because its bit energy can be decreased below the thermal energy through adiabatic switching operations. In the present paper, we present the general scaling laws of ASL and compare the energy efficiency of ASL with those of other energy-efficient logics. Also, we discuss the minimum energy-delay product (EDP) of ASL at finite temperature. Our study shows that there is a maximum temperature at which the EDP can reach the quantum limit given by ħ/2, which is dependent on the superconductor material and the Josephson junction quality, and that it is reasonable to operate ASL at cryogenic temperatures in order to achieve an EDP that approaches ħ/2. (paper)
Experimental study on the adiabatic shear bands
Four martensitic steels (Z50CDV5 steel, 28CND8 steel, 35NCDV16 steel and 4340 steel) with different hardness between 190 and 600 Hsub(B) (Brinell hardness), have been studied by means of dynamic compressive tests on split Hopkinson pressure bar. Microscopic observations show that the fracture are associated to the development of adiabatic shear bands (except 4340 steel with 190 Hsub(B) hardness). By means of tests for which the deformation is stopped at predetermined levels, the measurement of shear and hardness inside the band and the matrix indicates the chronology of this phenomenon: first the localization of shear, followed by the formation of adiabatic shear band and ultimatly crack initiation and propagation. These results correlated with few simulations by finite elements have permitted to suggest two mecanisms of deformation leading to the formation of adiabatic shear bands in this specific test
The Optics of Refractive Substructure
Johnson, Michael D; Narayan, Ramesh
2016-01-01
Newly recognized effects of refractive scattering in the ionized interstellar medium have broad implications for very long baseline interferometry (VLBI) at extreme angular resolutions. Building upon work by Blandford & Narayan (1985), we present a simplified, geometrical optics framework, which enables rapid, semi-analytic estimates of refractive scattering effects. We show that these estimates exactly reproduce previous results based on a more rigorous statistical formulation. We then deriv...
Staying adiabatic with unknown energy gap
Nehrkorn, J; Ekert, A; Smerzi, A; Fazio, R; Calarco, T
2011-01-01
We introduce an algorithm to perform an optimal adiabatic evolution that operates without an apriori knowledge of the system spectrum. By probing the system gap locally, the algorithm maximizes the evolution speed, thus minimizing the total evolution time. We test the algorithm on the Landau-Zener transition and then apply it on the quantum adiabatic computation of 3-SAT: The result is compatible with an exponential speed-up for up to twenty qubits with respect to classical algorithms. We finally study a possible algorithm improvement by combining it with the quantum Zeno effect.
Ramsey numbers and adiabatic quantum computing
Gaitan, Frank; Clark, Lane
2011-01-01
The graph-theoretic Ramsey numbers are notoriously difficult to calculate. In fact, for the two-color Ramsey numbers $R(m,n)$ with $m,n\\geq 3$, only nine are currently known. We present a quantum algorithm for the computation of the Ramsey numbers $R(m,n)$. We show how the computation of $R(m,n)$ can be mapped to a combinatorial optimization problem whose solution can be found using adiabatic quantum evolution. We numerically simulate this adiabatic quantum algorithm and show that it correctl...
Superconducting system for adiabatic quantum computing
We study the Hamiltonian of a system of inductively coupled flux qubits, which has been theoretically proposed for adiabatic quantum computation to handle NP problems. We study the evolution of a basic structure consisting of three coupled rf-SQUIDs upon tuning the external flux bias, and we show that the adiabatic nature of the evolution is guaranteed by the presence of the single-SQUID gap. We further propose a scheme and the first realization of an experimental device suitable for verifying the theoretical results
On black hole spectroscopy via adiabatic invariance
Jiang Qingquan, E-mail: qqjiangphys@yeah.net [College of Physics and Electronic Information, China West Normal University, Nanchong, Sichuan 637002 (China); Han Yan [College of Mathematic and Information, China West Normal University, Nanchong, Sichuan 637002 (China)
2012-12-05
In this Letter, we obtain the black hole spectroscopy by combining the black hole property of adiabaticity and the oscillating velocity of the black hole horizon. This velocity is obtained in the tunneling framework. In particular, we declare, if requiring canonical invariance, the adiabatic invariant quantity should be of the covariant form I{sub adia}= Contour-Integral p{sub i}dq{sub i}. Using it, the horizon area of a Schwarzschild black hole is quantized independently of the choice of coordinates, with an equally spaced spectroscopy always given by {Delta}A=8{pi}l{sub p}{sup 2} in the Schwarzschild and Painleve coordinates.
Complexity of the Quantum Adiabatic Algorithm
Hen, Itay
2013-01-01
The Quantum Adiabatic Algorithm (QAA) has been proposed as a mechanism for efficiently solving optimization problems on a quantum computer. Since adiabatic computation is analog in nature and does not require the design and use of quantum gates, it can be thought of as a simpler and perhaps more profound method for performing quantum computations that might also be easier to implement experimentally. While these features have generated substantial research in QAA, to date there is still a lack of solid evidence that the algorithm can outperform classical optimization algorithms.
Adiabatic Flame Temperature for Combustion of Methane
Rebeca Pupo
2011-01-01
Full Text Available This project calculated the adiabatic flame temperature of a combustion reaction of pure methane and oxygen, assuming that all of the heat liberated by the combustion reaction goes into heating the resulting mixture. Mole fractions of methane to oxygen were computed from 0.05 to 0.95, in increments of 0.05, and then an integral was computed was computed with respect to temperature using the moles of product produced or leftover moles of reactants from the starting mole fraction times the specific heat of each respective gas. The highest adiabatic flame temperature evaluated, occurred at a mole fraction of 0.35.
Numerical studies of optical forces from adiabatic rapid passage
Stack, Daniel; Elgin, John; Metcalf, Harold [Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800 (United States); Anisimov, Petr M. [Hearne Institute for Theoretical Physics and Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)
2011-07-15
We present a numerical study of the properties of optical forces on moving atoms derived from purely stimulated processes produced by multiple adiabatic rapid-passage sequences. The optical Bloch equations are solved for a carefully timed sequence of frequency-swept pulses that can produce a force much larger than the ordinary radiative force. We describe the effects of the sweep range, peak intensity, sweep direction, number of pulses, atomic velocity, and spontaneous emission. Since the momentum of thermal atoms is much larger than that transferred by a single absorption-stimulated emission cycle, multiple repetitions are needed to make a significant velocity change.
Marcelo F. Gaal Vadas
2001-08-01
Full Text Available Objetivo: Estudar o comportamento da refração e da curvatura corneana em pacientes com esotropia essencial submetidos à cirurgia monocular para correção do estrabismo. Métodos: Estudo prospectivo em que 42 olhos de 21 pacientes com esotropia essencial de ângulo moderado, sem quaisquer outros estrabismos associados, foram selecionados e submetidos ao exame oftalmológico completo e à cirurgia monocular. O olho contralateral serviu como grupo controle. Foram feitas avaliações de pré-operatório, pós-operatório de 1 mês e pós-operatório de 6 meses. O astigmatismo pré-operatório foi confrontado com os astigmatismos pós-operatórios por análise vetorial e cálculo do valor polar. Resultados: Obtivemos, nos olhos operados, redução significante (pPurpose: To evaluate changes in refraction and corneal curvature following surgery for correction of acquired esotropia. Methods: 42 eyes of 21 patients with acquired moderate angle esotropia without any other form of strabismus were prospectively enrolled and submitted to a complete ophthalmological examination followed by recess/resect procedure in a single eye. Data from the fellow eye were selected as control. Ophthalmological assessment was carried out preoperatively, 1 month after surgery and 6 months after surgery, where astigmatism was compared using vector analysis and the polar value concept. Results: The eyes submitted to surgery revealed a significant (p<0.05 decrease in spherical equivalent, from 3.28 ± 1.98 diopters to 3.05 ± 1.95 diopters. Refraction data disclosed a significant increase in the 90° component of net astigmatism, from 0.458 ± 0.594 diopters to 1.002 ± 0.718 diopters, which was also observed in keratometric readings:1.083 ± 0.560 diopters to 1.690 ± 0.591 diopters. Surgically induced astigmatism, assessed using refraction data was 0.63 ± 0.27 diopters at an average axis of 92.30 ± 14.91 degrees, and 0.71 ± 0.27 diopters at an average axis of 94.45
Adiabatic transition probability for a tangential crossing
Watanabe, Takuya
2006-01-01
We consider a time-dependent Schrödinger equation whose Hamiltonian is a $2\\times 2$ real symmetric matrix. We study, using an exact WKB method, the adiabatic limit of the transition probability in the case where several complex eigenvalue crossing points accumulate to one real point.
On the double adiabatic continuous spectrum
In earlier work it has been found that the Alfven and cusp (or slow) continuous spectra can become unstable in toroidal geometry, as judged from the linearized double adiabatic equations. In this paper the validity of fluid approaches to the present problem is investigated. The physical implications of the stability conditions are discussed. (Author)
Adiabatic reversible compression: a molecular view
The adiabatic compression (or expansion) of an ideal gas has been analysed. Using the kinetic theory of gases the usual relation between temperature and volume is obtained, while textbooks follow a thermodynamic approach. In this way we show, once again, the agreement between a macroscopic view (thermodynamics) and a microscopic one (kinetic theory). (author)
Semi adiabatic theory of seasonal Markov processes
Talkner, P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
1999-08-01
The dynamics of many natural and technical systems are essentially influenced by a periodic forcing. Analytic solutions of the equations of motion for periodically driven systems are generally not known. Simulations, numerical solutions or in some limiting cases approximate analytic solutions represent the known approaches to study the dynamics of such systems. Besides the regime of weak periodic forces where linear response theory works, the limit of a slow driving force can often be treated analytically using an adiabatic approximation. For this approximation to hold all intrinsic processes must be fast on the time-scale of a period of the external driving force. We developed a perturbation theory for periodically driven Markovian systems that covers the adiabatic regime but also works if the system has a single slow mode that may even be slower than the driving force. We call it the semi adiabatic approximation. Some results of this approximation for a system exhibiting stochastic resonance which usually takes place within the semi adiabatic regime are indicated. (author) 1 fig., 8 refs.
Recent adiabaticity results from orbit calculations
There has been much activity recently in an attempt to find a straightforward method of predicting the limits of adiabatic behavior in high-beta magnetic-mirror configurations. The particle-orbit code TIBRO was used to obtain numerical results on nonadiabatic behavior with which the predictions of theoretical expressions can be compared. These results are summarized. (MOW)
Adiabatic Excitation of Longitudinal Bunch Shape Oscillations
By modulating the rf voltage at near twice the synchrotrons frequency we are able to modulate the longitudinal bunch shape. We show experimentally that this can be done while preserving the longitudinal emittance when the rf voltage modulation is turned on adiabatically. Experimental measurements will be presented along with theoretical predictions
Communication: Adiabatic and non-adiabatic electron-nuclear motion: Quantum and classical dynamics
Albert, Julian; Kaiser, Dustin; Engel, Volker
2016-05-01
Using a model for coupled electronic-nuclear motion we investigate the range from negligible to strong non-adiabatic coupling. In the adiabatic case, the quantum dynamics proceeds in a single electronic state, whereas for strong coupling a complete transition between two adiabatic electronic states takes place. It is shown that in all coupling regimes the short-time wave-packet dynamics can be described using ensembles of classical trajectories in the phase space spanned by electronic and nuclear degrees of freedom. We thus provide an example which documents that the quantum concept of non-adiabatic transitions is not necessarily needed if electronic and nuclear motion is treated on the same footing.
The dynamic instability of adiabatic blast waves
Ryu, Dongsu; Vishniac, Ethan T.
1991-01-01
Adiabatic blastwaves, which have a total energy injected from the center E varies as t(sup q) and propagate through a preshock medium with a density rho(sub E) varies as r(sup -omega) are described by a family of similarity solutions. Previous work has shown that adiabatic blastwaves with increasing or constant postshock entropy behind the shock front are susceptible to an oscillatory instability, caused by the difference between the nature of the forces on the two sides of the dense shell behind the shock front. This instability sets in if the dense postshock layer is sufficiently thin. The stability of adiabatic blastwaves with a decreasing postshock entropy is considered. Such blastwaves, if they are decelerating, always have a region behind the shock front which is subject to convection. Some accelerating blastwaves also have such region, depending on the values of q, omega, and gamma where gamma is the adiabatic index. However, since the shock interface stabilizes dynamically induced perturbations, blastwaves become convectively unstable only if the convective zone is localized around the origin or a contact discontinuity far from the shock front. On the other hand, the contact discontinuity of accelerating blastwaves is subject to a strong Rayleigh-Taylor instability. The frequency spectra of the nonradial, normal modes of adiabatic blastwaves have been calculated. The results have been applied to the shocks propagating through supernovae envelopes. It is shown that the metal/He and He/H interfaces are strongly unstable against the Rayleigh-Taylor instability. This instability will induce mixing in supernovae envelopes. In addition the implications of this work for the evolution of planetary nebulae is discussed.
Influence of viscosity and the adiabatic index on planetary migration
Bitsch, B.; Boley, A.; Kley, W.
2013-02-01
Context. The strength and direction of migration of low mass embedded planets depends on the disk's thermodynamic state. It has been shown that in active disks, where the internal dissipation is balanced by radiative transport, migration can be directed outwards, a process which extends the lifetime of growing embryos. Very important parameters determining the structure of disks, and hence the direction of migration, are the viscosity and the adiabatic index. Aims: In this paper we investigate the influence of different viscosity prescriptions (α-type and constant) and adiabatic indices on disk structures. We then determine how this affects the migration rate of planets embedded in such disks. Methods: We perform three-dimensional numerical simulations of accretion disks with embedded planets. We use the explicit/implicit hydrodynamical code NIRVANA that includes full tensor viscosity and radiation transport in the flux-limited diffusion approximation, as well as a proper equation of state for molecular hydrogen. The migration of embedded 20 MEarth planets is studied. Results: Low-viscosity disks have cooler temperatures and the migration rates of embedded planets tend toward the isothermal limit. Hence, in these disks, planets migrate inwards even in the fully radiative case. The effect of outward migration can only be sustained if the viscosity in the disk is large. Overall, the differences between the treatments for the equation of state seem to play a more important role in disks with higher viscosity. A change in the adiabatic index and in the viscosity changes the zero-torque radius that separates inward from outward migration. Conclusions: For larger viscosities, temperatures in the disk become higher and the zero-torque radius moves to larger radii, allowing outward migration of a 20-MEarth planet to persist over an extended radial range. In combination with large disk masses, this may allow for an extended period of the outward migration of growing
Inverse engineering rigorous adiabatic Hamiltonian for non-Hermitian system
Wu, Qi-Cheng; Chen, Ye-Hong; Huang, Bi-Hua; Xia, Yan; Song, Jie
2016-01-01
We generalize the quantum adiabatic theorem to the non-Hermitian system and build a rigorous adiabaticity condition with respect to the adiabatic phase. The non-Hermitian Hamiltonian inverse engineering method is proposed for the purpose to adiabatically drive a artificial quantum state. For the sake of clearness, we take a concrete two-level system as an example to show the usefulness of the inverse engineering method. The numerical simulation result shows that our scheme can work well even ...
Perturbation to Mei symmetry and adiabatic invariants for Hamilton systems
Ding Ning; Fang Jian-Hui
2008-01-01
Based on the concept of adiabatic invariant,this paper studies the perturbation to Mei symmetry and adiabatic invariants for Hamilton systems.The exact invaxiants of Mei symmetry for the system without perturbation are given.The perturbation to Mei symmetry is discussed and the adiabatic invariants induced from the perturbation to Mei symmetry of the system are obtained.
Characterising Conical Refraction Optical Tweezers
McDonald, Craig; Rafailov, Edik; McGloin, David
2014-01-01
Conical refraction occurs when a beam of light travels through an appropriately cut biaxial crystal. By focussing the conically refracted beam through a high numerical aperture microscope objective, conical refraction optical tweezers can be created, allowing for particle manipulation in both Raman spots and in the Lloyd/Poggendorff rings. We present a thorough quantification of the trapping properties of such a beam, focussing on the trap stiffness and how this varies with trap power and trapped particle location. We show that the lower Raman spot can be thought of as a single-beam optical gradient force trap, while radiation pressure dominates in the upper Raman spot, leading to optical levitation rather than trapping. Particles in the Lloyd/Poggendorff rings experience a lower trap stiffness than particles in the lower Raman spot but benefit from rotational control.
Perfect imaging without negative refraction
Leonhardt, Ulf
2009-01-01
Perfect imaging has been believed to rely on negative refraction, but here we show that an ordinary positively-refracting optical medium may form perfect images as well. In particular, we establish a mathematical proof that Maxwell's fish eye in two-dimensional integrated optics makes a perfect instrument with a resolution not limited by the wavelength of light. We also show how to modify the fish eye such that perfect imaging devices can be made in practice. Our method of perfect focusing ma...
Perfect imaging without negative refraction
Leonhardt, Ulf
2009-01-01
Perfect imaging has been believed to rely on negative refraction, but here we show that an ordinary positively-refracting optical medium may form perfect images as well. In particular, we establish a mathematical proof that Maxwell's fish eye in two-dimensional integrated optics makes a perfect instrument with a resolution not limited by the wavelength of light. We also show how to modify the fish eye such that perfect imaging devices can be made in practice. Our method of perfect focusing may also find applications outside of optics, in acoustics, fluid mechanics or quantum physics, wherever waves obey the two-dimensional Helmholtz equation.
The Optics of Refractive Substructure
Johnson, Michael D
2016-01-01
Newly recognized effects of refractive scattering in the ionized interstellar medium have broad implications for very long baseline interferometry (VLBI) at extreme angular resolutions. Building upon work by Blandford & Narayan (1985), we present a simplified, geometrical optics framework, which enables rapid, semi-analytic estimates of refractive scattering effects. We show that these estimates exactly reproduce previous results based on a more rigorous statistical formulation. We then derive new expressions for the scattering-induced fluctuations of VLBI observables such as closure phase, and we demonstrate how to calculate the fluctuations for arbitrary quantities of interest using a Monte Carlo technique.
Zhong Lin
Full Text Available To investigate the association between maternal reproductive age and their children' refractive error progression in Chinese urban students.The Beijing Myopia Progression Study was a three-year cohort investigation. Cycloplegic refraction of these students at both baseline and follow-up vision examinations, as well as non-cycloplegic refraction of their parents at baseline, were performed. Student's refractive change was defined as the cycloplegic spherical equivalent (SE of the right eye at the final follow-up minus the cycloplegic SE of the right eye at baseline.At the final follow-up, 241 students (62.4% were reexamined. 226 students (58.5% with completed refractive data, as well as completed parental reproductive age data, were enrolled. The average paternal and maternal age increased from 29.4 years and 27.5 years in 1993-1994 to 32.6 years and 29.2 years in 2003-2004, respectively. In the multivariate analysis, students who were younger (β = 0.08 diopter/year/year, P<0.001, with more myopic refraction at baseline (β = 0.02 diopter/year/diopter, P = 0.01, and with older maternal reproductive age (β = -0.18 diopter/year/decade, P = 0.01, had more myopic refractive change. After stratifying the parental reproductive age into quartile groups, children with older maternal reproductive age (trend test: P = 0.04 had more myopic refractive change, after adjusting for the children's age, baseline refraction, maternal refraction, and near work time. However, no significant association between myopic refractive change and paternal reproductive age was found.In this cohort, children with older maternal reproductive age had more myopic refractive change. This new risk factor for myopia progression may partially explain the faster myopic progression found in the Chinese population in recent decades.
Integrated Microfibre Device for Refractive Index and Temperature Sensing
Sulaiman W. Harun
2012-08-01
Full Text Available A microfibre device integrating a microfibre knot resonator in a Sagnac loop reflector is proposed for refractive index and temperature sensing. The reflective configuration of this optical structure offers the advantages of simple fabrication and ease of sensing. To achieve a balance between responsiveness and robustness, the entire microfibre structure is embedded in low index Teflon, except for the 0.5–2 mm diameter microfibre knot resonator sensing region. The proposed sensor has exhibited a linear spectral response with temperature and refractive index. A small change in free spectral range is observed when the microfibre device experiences a large refractive index change in the surrounding medium. The change is found to be in agreement with calculated results based on dispersion relationships.
ADIABATIC MASS LOSS IN BINARY STARS. I. COMPUTATIONAL METHOD
binary provides the energy to eject the common envelope; the energy budget for this process consists essentially of the initial orbital energy of the binary and the initial self-energies of the binary components. We emphasize that, because the stellar core and envelope contribute mutually to each other's gravitational potential energy, proper evaluation of the total energy of a star requires integration over the entire stellar interior, and not just over the ejected envelope alone as commonly assumed. We show that the change in total energy of the donor star, as a function of its remaining mass along an adiabatic mass-loss sequence, can be calculated either by integration over initial and final models, or by a path integral along the mass-loss sequence. That change in total energy of the donor star, combined with the requirement that both remnant donor and its companion star fit within their respective Roche lobes, then circumscribes energetically possible survivors of common envelope evolution.
陈瑛; 马进; 朱铁培
2011-01-01
Objective To compare the changes in refractive status after 25-gauge sutureless vitrectomy and 20-gauge standard vitrectomy. Methods One hundred and twenty-one eyes of 121 patients who presented with vitreoretinal disease were included in this prospective study. Patients were randomly divided into two groups, the A group, 61 eyes that underwent 20-gauge standard vitrectomy, and the B group, 60 eyes that underwent 25-gauge vitrectomy. Outcome measures included visual acuity, refractive power, and changes in corneal topography after surgery. Data were analyzed with chi-square test, independent samples t test, one-way ANOVA and Mann-Whitney test. Results The visual acuity of the B group was much better than that of the A group at one week and one month after surgery (x2=8.81, P=0.012; x2=65, P=0.036). The postoperative refractive error in the A group developed into hyperopia, then gradually returned to baseline at three months after surgery. The spherical and astigmatism powers for each timepoint were significantly different in the A group (F=530.12, P＜0.05, F=392.06, P＜0.05), but no significant difference was found in the B group. In the A group, changes of spherical power at 1 week, 4 weeks, 12 weeks after surgery were (+1.93±0.07)D, (+1.06±0.04)D, (+0.15±0.03)D, and changes of astigmatism power were (1.62±0.07)D, (1.05±0.05)D, (0.41±0.03)D. In the B group, changes of spherical power at 1 week, 4 weeks, 12 weeks after surgery were (-0.06±0.02)D, (-0.04±0.03)D, (-0.03±0.02)D, and changes of astigmatism power were (0.05±0.01)D, (0.03±0.01)D, (0.03±0.02)D. Change of spherical power between the A and B groups at 1 week, 4 weeks, 12 weeks after surgery was significant different (t=200.6, 159.3, 26.0, P＜0.01 for all), as well as astigmatism power (t= 173.4, 156.3, 82.3, P＜0.01 for all). At one week after surgery, corneal topography analysis showed that corneal SimK1-K2, surface asymmetry index (SAI), and surface regularity index (SRI) were
On the power of coherently controlled quantum adiabatic evolutions
We provide a new approach to adiabatic state preparation that uses coherent control and measurement to average different adiabatic evolutions in ways that cause their diabatic errors to cancel, allowing highly accurate state preparations using less time than conventional approaches. We show that this new model for adiabatic state preparation is polynomially equivalent to conventional adiabatic quantum computation by providing upper bounds on the cost of simulating such evolutions on a circuit-based quantum computer. Finally, we show that this approach is robust to small errors in the quantum control register and that the system remains protected against noise on the adiabatic register by the spectral gap. (paper)
Cherkezyan, Lusik; Subramanian, Hariharan; Stoyneva, Valentina; Rogers, Jeremy D.; Yang, Seungmoo; Damania, Dhwanil; Taflove, Allen; Backman, Vadim
2012-01-01
Various staining techniques are commonly used in biomedical research to investigate cellular morphology. By inducing absorption of light, staining dyes change the intracellular refractive index due to the Kramers-Kronig relationship. We present a method for creating 2-D maps of real and imaginary refractive indices of stained biological cells using their thickness and absorptance. We validate our technique on dyed polystyrene microspheres and quantify the alteration in refractive index of sta...
Weinberg Soft Theorems from Weinberg Adiabatic Modes
Mirbabayi, Mehrdad
2016-01-01
Soft theorems for the scattering of low energy photons and gravitons and cosmological consistency conditions on the squeezed-limit correlation functions are both understood to be consequences of invariance under large gauge transformations. We apply the same method used in cosmology -- based on the identification of an infinite set of "adiabatic modes" and the corresponding conserved currents -- to derive flat space soft theorems for electrodynamics and gravity. We discuss how the recent derivations based on the asymptotic symmetry groups (BMS) can be continued to a finite size sphere surrounding the scattering event, when the soft photon or graviton has a finite momentum. We give a finite distance derivation of the antipodal matching condition previously imposed between future and past null infinities, and explain why all but one radiative degrees of freedom decouple in the soft limit. In contrast to earlier works on BMS, we work with adiabatic modes which correspond to large gauge transformations that are $...
Quantum adiabatic evolution with energy degeneracy levels
Zhang, Qi
2016-01-01
A classical-kind phase-space formalism is developed to address the tiny intrinsic dynamical deviation from what is predicted by Wilczek-Zee theorem during quantum adiabatic evolution on degeneracy levels. In this formalism, the Hilbert space and the aggregate of degenerate eigenstates become the classical-kind phase space and a high-dimensional subspace in the phase space, respectively. Compared with the previous analogous study by a different method, the current result is qualitatively different in that the first-order deviation derived here is always perpendicular to the degeneracy subspace. A tripod-scheme Hamiltonian with two degenerate dark states is employed to illustrate the adiabatic deviation with degeneracy levels.
Adiabatic Quantum Optimization for Associative Memory Recall
Hadayat eSeddiqi
2014-12-01
Full Text Available Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO. Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are stored in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.
Adiabatic Quantum Simulation of Quantum Chemistry
Babbush, Ryan; Love, Peter J.; Aspuru-Guzik, Alán
2014-10-01
We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.
Overview of Laser Refractive Surgery
Hung-Chi Jesse Chen
2008-06-01
Full Text Available Since approval of the use of the excimer laser in 1995 toreshape the cornea, significant developments in the correctionof refractive errors such as myopia, hyperopia, and astigmatismhave been achieved. Combined with other advanced ophthalmologicalinstruments (e.g. anterior segment imaging systems,the femtosecond laser, wavefront-guided customized ablationand the knowledge accumulated concerning the basic scienceof refractive errors (e.g. biomechanics and wound healing ofthe cornea, higher-order aberrations, laser refractive surgeryhas promisingly outshone other conventional techniques (e.g.radial keratotomy [RK], automated lamellar keratectomy[ALK] in terms of both safety and efficacy. Photorefractivekeratectomy (PRK produces stable and predictable resultswith a safe profile. Similarly, laser in situ keratomileusis(LASIK is also safe and efficacious with the additional advantagesof rapid visual recovery and minimal postoperative pain. The choice between the twomethods is made only after thoughtful discussion between the surgeon and the patient.Despite these advances, certain limitations and complications do exist. There are also specificand controversial circumstances for which studies should be conducted to make furtherbreakthroughs and avoid annoying complications. In this review, the basic knowledge, surgicalissues, and clinical outcomes, of laser refractive surgery, as well as complex cases, willbe presented.
Robust Classification with Adiabatic Quantum Optimization
Denchev, Vasil S.; Ding, Nan; Vishwanathan, S. V. N.; Neven, Hartmut
2012-01-01
We propose a non-convex training objective for robust binary classification of data sets in which label noise is present. The design is guided by the intention of solving the resulting problem by adiabatic quantum optimization. Two requirements are imposed by the engineering constraints of existing quantum hardware: training problems are formulated as quadratic unconstrained binary optimization; and model parameters are represented as binary expansions of low bit-depth. In the present work we...
Adiabatic density surface, neutral density surface, potential density surface, and mixing path
HUANG Rui-xin
2014-01-01
In this paper, adiabatic density surface, neutral density surface and potential density surface are compared. The adiabatic density surface is defined as the surface on which a water parcellcan move adiabatically, without changing its potential temperature and salinity. For a water parcelltaken at a given station and pressure level, the corresponding adiabatic density surface can be determined through simple calculations. This family of surface is neutrally buoyant in the world ocean, and different from other surfaces that are not truly neutrally buoyant. In order to explore mixing path in the ocean, a mixing ratio m is introduced, which is defined as the portion of potential temperature and salinity of a water parcellthat has exchanged with the environment during a segment of migration in the ocean. Two extreme situations of mixing path in the ocean are m=0 (no mixing), which is represented by the adiabatic density curve, and m=1, where the original information is completely lost through mixing. The latter is represented by the neutral density curve. The reality lies in between, namely, 0
Interpolation approach to Hamiltonian-varying quantum systems and the adiabatic theorem
Pan, Yu; James, Matthew R. [Australian National University, Research School of Engineering, Canberra (Australia); Miao, Zibo [The University of Melbourne, Department of Electrical and Electronic Engineering, Melbourne (Australia); Amini, Nina H. [CNRS, Laboratoire des Signaux et Systemes (L2S) Supelec, Gif-Sur-Yvette (France); Ugrinovskii, Valery [University of New South Wales at ADFA, School of Engineering and Information Technology, Canberra (Australia)
2015-12-15
Quantum control could be implemented by varying the system Hamiltonian. According to adiabatic theorem, a slowly changing Hamiltonian can approximately keep the system at the ground state during the evolution if the initial state is a ground state. In this paper we consider this process as an interpolation between the initial and final Hamiltonians. We use the mean value of a single operator to measure the distance between the final state and the ideal ground state. This measure resembles the excitation energy or excess work performed in thermodynamics, which can be taken as the error of adiabatic approximation. We prove that under certain conditions, this error can be estimated for an arbitrarily given interpolating function. This error estimation could be used as guideline to induce adiabatic evolution. According to our calculation, the adiabatic approximation error is not linearly proportional to the average speed of the variation of the system Hamiltonian and the inverse of the energy gaps in many cases. In particular, we apply this analysis to an example in which the applicability of the adiabatic theorem is questionable. (orig.)
Pterygium-induced corneal refractive changes
Maheshwari Sejal
2007-01-01
To study the effect of pterygium on corneal topography, a retrospective analysis of 151 eyes with primary pterygia was done. All cases underwent videokeratography preoperatively and one month postoperatively. Statistical analysis of average corneal power (ACP), corneal astigmatism, surface regularity index (SRI) and surface asymmetry index (SAI) was done before and one month after surgery. Topographic indices were compared statistically for various grades of pterygia. Increase in the grade of...
Enhanced nonlinear refractive index in epsilon-near-zero materials
Caspani, L; Clerici, M; Ferrera, M; Roger, T; Di Falco, A; Kim, J; Kinsey, N; Shalaev, V M; Boltasseva, A; Faccio, D
2016-01-01
New propagation regimes for light arise from the ability to tune the dielectric permittivity to extremely low values. Here we demonstrate a universal approach based on the low linear permittivity values attained in the epsilon-near-zero (ENZ) regime for enhancing the nonlinear refractive index, which enables remarkable light-induced changes of the material properties. Experiments performed on Al-doped ZnO (AZO) thin films show a six-fold increase of the Kerr nonlinear refractive index ($n_2$) at the ENZ wavelength, located in the 1300 nm region. This in turn leads to light-induced refractive index changes of the order of unity, thus representing a new paradigm for nonlinear optics.
Enhanced Nonlinear Refractive Index in ε-Near-Zero Materials.
Caspani, L; Kaipurath, R P M; Clerici, M; Ferrera, M; Roger, T; Kim, J; Kinsey, N; Pietrzyk, M; Di Falco, A; Shalaev, V M; Boltasseva, A; Faccio, D
2016-06-10
New propagation regimes for light arise from the ability to tune the dielectric permittivity to extremely low values. Here, we demonstrate a universal approach based on the low linear permittivity values attained in the ε-near-zero (ENZ) regime for enhancing the nonlinear refractive index, which enables remarkable light-induced changes of the material properties. Experiments performed on Al-doped ZnO (AZO) thin films show a sixfold increase of the Kerr nonlinear refractive index (n_{2}) at the ENZ wavelength, located in the 1300 nm region. This in turn leads to ultrafast light-induced refractive index changes of the order of unity, thus representing a new paradigm for nonlinear optics. PMID:27341234
Bifurcation-based adiabatic quantum computation with a nonlinear oscillator network
Goto, Hayato
2016-02-01
The dynamics of nonlinear systems qualitatively change depending on their parameters, which is called bifurcation. A quantum-mechanical nonlinear oscillator can yield a quantum superposition of two oscillation states, known as a Schrödinger cat state, via quantum adiabatic evolution through its bifurcation point. Here we propose a quantum computer comprising such quantum nonlinear oscillators, instead of quantum bits, to solve hard combinatorial optimization problems. The nonlinear oscillator network finds optimal solutions via quantum adiabatic evolution, where nonlinear terms are increased slowly, in contrast to conventional adiabatic quantum computation or quantum annealing, where quantum fluctuation terms are decreased slowly. As a result of numerical simulations, it is concluded that quantum superposition and quantum fluctuation work effectively to find optimal solutions. It is also notable that the present computer is analogous to neural computers, which are also networks of nonlinear components. Thus, the present scheme will open new possibilities for quantum computation, nonlinear science, and artificial intelligence.
Non-adiabatic dynamics in 10Be with the microscopic alpha+alpha+n+n model
Ito, M
2006-01-01
The alpha+6He low-energy reactions and the structural changes of 10Be in the microscopic alpha+alpha+n+n model are studied by the generalized two-center cluster model with the Kohn-Hulthen-Kato variation method. It is found that, in the inelastic scattering to the alpha+6He(2+) channel, characteristic enhancements are expected as the results of the parity-dependent non-adiabatic dynamics. In the positive parity state, the enhancement originates from the no-adiabatic eigenstate generated by the radial excitation of the relative motion between two alpha-cores. On the other hand, the enhancement in the negative parity state is induced by the Landau-Zener level-crossing. These non-adiabatic processes are discussed in connection to the formation of the inversion doublet in the compound system of 10Be.
Bifurcation-based adiabatic quantum computation with a nonlinear oscillator network.
Goto, Hayato
2016-01-01
The dynamics of nonlinear systems qualitatively change depending on their parameters, which is called bifurcation. A quantum-mechanical nonlinear oscillator can yield a quantum superposition of two oscillation states, known as a Schrödinger cat state, via quantum adiabatic evolution through its bifurcation point. Here we propose a quantum computer comprising such quantum nonlinear oscillators, instead of quantum bits, to solve hard combinatorial optimization problems. The nonlinear oscillator network finds optimal solutions via quantum adiabatic evolution, where nonlinear terms are increased slowly, in contrast to conventional adiabatic quantum computation or quantum annealing, where quantum fluctuation terms are decreased slowly. As a result of numerical simulations, it is concluded that quantum superposition and quantum fluctuation work effectively to find optimal solutions. It is also notable that the present computer is analogous to neural computers, which are also networks of nonlinear components. Thus, the present scheme will open new possibilities for quantum computation, nonlinear science, and artificial intelligence. PMID:26899997
Refractive Status and Prevalence of Refractive Errors in Suburban School-age Children
Lian-Hong Pi, Lin Chen, Qin Liu, Ning Ke, Jing Fang, Shu Zhang, Jun Xiao, Wei-Jiang Ye, Yan Xiong, Hui Shi, Zheng-Qin Yin
2010-01-01
Full Text Available Objective: This study investigated the distribution pattern of refractive status and prevalence of refractive errors in school-age children in Western China to determine the possible environmental factors. Methods: A random sampling strategy in geographically defined clusters was used to identify children aged 6-15 years in Yongchuan, a socio-economically representative area in Western China. We carried out a door-to-door survey and actual eye examinations, including visual acuity measurements, stereopsis examination, anterior segment and eyeball movements, fundus examinations, and cycloplegic retinoscopy with 1% cyclopentolate. Results: A total of 3469 children living in 2552 households were selected, and 3070 were examined. The distributions of refractive status were positively-skewed for 6-8-year-olds, and negatively-skewed for 9-12 and 13-15-year-olds. The prevalence of hyperopia (≥+2.00 D spherical equivalent [SE], myopia (≤-0.50 D SE, and astigmatism (≥1.00 diopter of cylinder [DC] were 3.26%, 13.75%, and 3.75%, respectively. As children's ages increased, the prevalence rate of hyperopia decreased (P<0.001 and that of myopia increased significantly (P<0.001. Children in academically challenging schools had a higher risk of myopia (P<0.001 and astigmatism (≥1.00DC, P =0.04 than those in regular schools. Conclusion: The distribution of refractive status changes gradually from positively-skewed to negatively-skewed distributions as age increases, with 9-year-old being the critical age for the changes. Environmental factors and study intensity influence the occurrence and development of myopia.
Refractive index dependence of Papilio Ulysses butterfly wings reflectance spectra
Isnaeni, Muslimin, Ahmad Novi; Birowosuto, Muhammad Danang
2016-02-01
We have observed and utilized butterfly wings of Papilio Ulysses for refractive index sensor. We noticed this butterfly wings have photonic crystal structure, which causes blue color appearance on the wings. The photonic crystal structure, which consists of cuticle and air void, is approximated as one dimensional photonic crystal structure. This photonic crystal structure opens potential to several optical devices application, such as refractive index sensor. We have utilized small piece of Papilio Ulysses butterfly wings to characterize refractive index of several liquid base on reflectance spectrum of butterfly wings in the presence of sample liquid. For comparison, we simulated reflectance spectrum of one dimensional photonic crystal structure having material parameter based on real structure of butterfly wings. We found that reflectance spectrum peaks shifted as refractive index of sample changes. Although there is a slight difference in reflectance spectrum peaks between measured spectrum and calculated spectrum, the trend of reflectance spectrum peaks as function of sample's refractive index is the similar. We assume that during the measurement, the air void that filled by sample liquid is expanded due to liquid pressure. This change of void shape causes non-similarity between measured spectrum and calculated spectrum.
AB INITIO SIMULATIONS FOR MATERIAL PROPERTIES ALONG THE JUPITER ADIABAT
We determine basic thermodynamic and transport properties of hydrogen-helium-water mixtures for the extreme conditions along Jupiter's adiabat via ab initio simulations, which are compiled in an accurate and consistent data set. In particular, we calculate the electrical and thermal conductivity, the shear and longitudinal viscosity, and diffusion coefficients of the nuclei. We present results for associated quantities like the magnetic and thermal diffusivity and the kinematic shear viscosity along an adiabat that is taken from a state-of-the-art interior structure model. Furthermore, the heat capacities, the thermal expansion coefficient, the isothermal compressibility, the Grüneisen parameter, and the speed of sound are calculated. We find that the onset of dissociation and ionization of hydrogen at about 0.9 Jupiter radii marks a region where the material properties change drastically. In the deep interior, where the electrons are degenerate, many of the material properties remain relatively constant. Our ab initio data will serve as a robust foundation for applications that require accurate knowledge of the material properties in Jupiter's interior, e.g., models for the dynamo generation.
General background conditions for K-bounce and adiabaticity
Romano, Antonio Enea
2016-01-01
We study the background conditions for a bounce in a single scalar field model with a generalized kinetic term $K(X)$. At the background level we impose the existence of two turning points where the derivative of the Hubble parameter $H$ changes sign and of a bounce point where the Hubble parameter vanishes. We find the conditions for $K(X)$ and the potential which ensure the above requirements. We then give the examples of two models constructed according to these conditions. One is based on a quadratic $K$, and the other on a $K$ which is avoiding divergences of the second time derivative of the scalar field, which may otherwise occur. An appropriate choice of the initial conditions can lead to a sequence of consecutive bounces. In models where the bounce occurs when the potential is not constant, large non adiabatic perturbations are produced, which can in turn source the growth of anisotropies. In the region where these models have a constant potential they became adiabatic on any scale and because of thi...
Prevalence of refractive errors in Mexican patients with keratoconus
Cruz-Becerril A
2015-06-01
correction is the spherical rigid contact lens. Finally, the parameters to adjust contact lenses change according to disease progression. Keywords: keratoconus, visual acuity, refractive errors, rigid contact lens
Mathematical description and measurement of refractive parameters of freeform spectacle lenses.
Yu, Jing; Qiu, Zhongjun; Fang, Fengzhou
2014-08-01
Refractive parameters are the main design and evaluation parameters of freeform spectacle lenses. In this paper, the mathematical model of refractive parameters is established, and the refractive power distribution on the whole surface is drawn with a radial basis function. The measurement methods are analyzed, and typical freeform spectacle lenses are measured with a freeform verifier. The refractive power distribution on the whole surface, the cylinder view, and the refractive power curve along the progressive corridor are drawn up. There are no evident image changes on the whole surface. The refractive power smoothly varies along the progressive corridor. In comparing the results with the analysis, measurement results are in agreement with the calculation. PMID:25090322
Past and present of corneal refractive surgery
Vestergaard, Anders Højslet
Surgical correction of refractive errors is becoming increasingly popular. In the 1990s, the excimer laser revolutionized the field of corneal refractive surgery with PRK and LASIK, and lately refractive lenticule extraction (ReLEx) of intracorneal tissue, using only a femtosecond laser, has become...
Refracting surface plasmon polaritons with nanoparticle arrays
Radko, I.P.; Evlyukhin, A.B.; Boltasseva, Alexandra;
2008-01-01
Refraction of surface plasmon polaritons (SPPs) by various structures formed by a 100-nm-period square lattice of gold nanoparticles on top of a gold film is studied by leakage radiation microscopy. SPP refraction by a triangular-shaped nanoparticle array indicates that the SPP effective refractive...... design nanoparticle arrays for specific applications requiring in-plane SPP manipulation....
Super-Virtual Refraction Interferometric Redatuming: Enhancing the Refracted Energy
Aldawood, Ali
2012-02-26
onshore seismic data processing. Refraction tomography is becoming a common way to estimate an accurate near surface velocity model. One of the problems with refraction tomography is the low signal to noise ration in far offset data. To improve, we propose using super-virtual refraction interferometry to enhance the weak energy at far offsets. We use Interferometric Green\\'s functions to redatum sources by cross-correlating two traces recorded at receiver stations, A and B, from a source at location W. The result is a redatumed trace with a virtual source at A and a receiver at B, which can also be obtained by correlating two traces recorded at A and B from different shots. Stacking them would enhance the signal-to-noise ratio of this "virtual" trace. We next augment redatuming with convolution and stacking. The trace recorded at B from a virtual source at A is convolved with the original trace recorded at A from a source at W. The result is a "super-virtual" trace at B in the far-offset from a source at W. Stacking N traces gives a vN-improvement. We applied our method to noisy synthetic and field data recorded over a complex near-surface and we could pick more traces at far offsets. It was possible to accommodate more picks resulting in a better subsurface coverage
Second order nonlinear refraction measurement of dithiooxamide using moire deflectometry method
In this paper, we measure the second order nonlinear refractive index of saturated water solution of Dithiooxamide (NH2CSCSNH2) using the moire deflectometry technique. By this method, the sign and the magnitude of nonlinear refractive index (n2) are obtained. In this experiment, the nonlinear refractive index (n2) and the nonlinear refractive change (Δn) were obtained - 5.8*10-6 (cm2/W) and -3.13*10-5 respectively, using a 6.6 milliwatt He-Ne laser with wavelength 632.8 nanometer.
Modification of Low Refractive Index Polycarbonate for High Refractive Index Applications
Rakesh Kumar Khandal
2009-01-01
Full Text Available Polycarbonates and polythiourethanes are the most popular materials in use today, for optical applications. Polycarbonates are of two types which fall in the category of low refractive index and medium refractive index. The present paper describes the conversion of low refractive index polycarbonates into high refractive index material by the use of a high refractive index monomer, polythiol, as an additive. Novel polycarbonates, where the properties of refractive index and Abbe number can be tailor made, have been obtained. Thermal studies and refractive index determination indicate the formation of a new polymer with improved properties and suitable for optical applications.
Negative refraction by photonic nanostructures
Wu, Qi
Artificially engineered optical materials composed of nano-structures have unique optical properties which are not available with naturally occurring materials. Thanks to the rapid development in nano-fabrication and numerical modeling technologies, photonic nano-structures such as metamaterials and photonic crystals and various optical devices made by these optical materials create many novel applications and offer new prospects for manipulating light. For instance, both metamaterials and photonic crystals can exhibit negative refraction and negative refractive indexes. As a result, superlens with the capability of achieving imaging with sub-wavelength resolution can be realized. In this dissertation, a new negative index metamaterial architecture based on metallic nanoclusters, negative refraction phenomena in photonic crystals and optical devices implemented with negative index photonic crystals for imaging applications are presented. The nanocluster based metamaterials, which utilizes the magnetic Mie resonances of clusters of metallic inclusions, allow us to achieve negative index materials at optical frequency region. Meanwhile, bottom-up fabrication techniques such as self-assembly can be used, which is suitable for large-scale manufacturing and applicable to 3D structures. On the other hand, negative refraction and sub-wavelength imaging by a mechanically tunable photonic crystal structure were investigated. Using a honeycomb lattice photonic crystal composed of a silicon-polyimide membrane, a mechanically tunable superlens with a tunable frequency bandwidth was numerically demonstrated. Additionally, a graded negative index lens made of photonic crystals, which is capable of focusing plane waves, exhibits superior focusing properties such as low chromatic aberrations and broadband operation. Prisms structures made of negative index photonic crystals can offer useful imaging properties such as image inversion and magnification. These devices have the
Strategies for the management and prevention of complications in refractive laser surgery
F. Hafezi (Farhad)
2008-01-01
textabstractObjective. Reoperations after refractive surgery have increased in frequency during the past 10 years. The spectrum of the indications for repeat LASIK may have changed. Methods. All cases of reoperations after refractive surgery performed between May 1, 2004 and April 30, 2005 at the In
Bond selective chemistry beyond the adiabatic approximation
Butler, L.J. [Univ. of Chicago, IL (United States)
1993-12-01
One of the most important challenges in chemistry is to develop predictive ability for the branching between energetically allowed chemical reaction pathways. Such predictive capability, coupled with a fundamental understanding of the important molecular interactions, is essential to the development and utilization of new fuels and the design of efficient combustion processes. Existing transition state and exact quantum theories successfully predict the branching between available product channels for systems in which each reaction coordinate can be adequately described by different paths along a single adiabatic potential energy surface. In particular, unimolecular dissociation following thermal, infrared multiphoton, or overtone excitation in the ground state yields a branching between energetically allowed product channels which can be successfully predicted by the application of statistical theories, i.e. the weakest bond breaks. (The predictions are particularly good for competing reactions in which when there is no saddle point along the reaction coordinates, as in simple bond fission reactions.) The predicted lack of bond selectivity results from the assumption of rapid internal vibrational energy redistribution and the implicit use of a single adiabatic Born-Oppenheimer potential energy surface for the reaction. However, the adiabatic approximation is not valid for the reaction of a wide variety of energetic materials and organic fuels; coupling between the electronic states of the reacting species play a a key role in determining the selectivity of the chemical reactions induced. The work described below investigated the central role played by coupling between electronic states in polyatomic molecules in determining the selective branching between energetically allowed fragmentation pathways in two key systems.
Fabrication process and system for neutron refractive optics
The authors developed a new fabrication process and system for neutron refractive optics, and propose a new design for Fresnel lens refracting cold-neutron beam in this paper. Applying the ultraprecision electrolytic in-process dressing (ELID) micro-grinding technique using cast-iron-bonded diamond wheels with edges sharpened by electrical and mechanical processes, the authors successfully fabricated the required element with sharp and smooth V-faced Fresnel structures using quartz glass or MgF2 glass. The relationship of the form accuracy of the fabricated Fresnel lens and changes in grinding wheel shape is also discussed
Accuracy vs run time in adiabatic quantum search
Rezakhani, A T; Lidar, D A
2010-01-01
Adiabatic quantum algorithms are characterized by their run time and accuracy. The relation between the two is essential for quantifying adiabatic algorithmic performance, yet is often poorly understood. We study the dynamics of a continuous time, adiabatic quantum search algorithm, and find rigorous results relating the accuracy and the run time. Proceeding with estimates, we show that under fairly general circumstances the adiabatic algorithmic error exhibits a behavior with two discernible regimes: the error decreases exponentially for short times, then decreases polynomially for longer times. We show that the well known quadratic speedup over classical search is associated only with the exponential error regime. We illustrate the results through examples of evolution paths derived by minimization of the adiabatic error. We also discuss specific strategies for controlling the adiabatic error and run time.
Hypergraph Ramsey Numbers and Adiabatic Quantum Algorithm
Qu, Ri; Bao, Yan-ru
2012-01-01
Gaitan and Clark [Phys. Rev. Lett. 108, 010501 (2012)] have recently presented a quantum algorithm for the computation of the Ramsey numbers R(m, n) using adiabatic quantum evolution. We consider that the two-color Ramsey numbers R(m, n; r) for r-uniform hypergraphs can be computed by using the similar ways in [Phys. Rev. Lett. 108, 010501 (2012)]. In this comment, we show how the computation of R(m, n; r) can be mapped to a combinatorial optimization problem whose solution be found using adi...
Adiabatic quantum algorithm for search engine ranking
Garnerone, Silvano; Lidar, Daniel A
2011-01-01
We propose an adiabatic quantum algorithm to evaluate the PageRank vector, the most widely used tool in ranking the relative importance of internet pages. We present extensive numerical simulations which provide evidence that this quantum algorithm outputs any component of the PageRank vector-and thus the ranking of the corresponding webpage-in a time which scales polylogarithmically in the number of webpages. This would constitute an exponential speed-up with respect to all known classical algorithms designed to evaluate the PageRank.
Adiabatic chaos in the spin orbit problem
Benettin, Giancarlo; Guzzo, Massimiliano; Marini, Valerio
2008-05-01
We provide evidences that the angular momentum of a symmetric rigid body in a spin orbit resonance can perform large scale chaotic motions on time scales which increase polynomially with the inverse of the oblateness of the body. This kind of irregular precession appears as soon as the orbit of the center of mass is non-circular and the angular momentum of the body is far from the principal directions with minimum (maximum) moment of inertia. We also provide a quantitative explanation of these facts by using the theory of adiabatic invariants, and we provide numerical applications to the cases of the 1:1 and 1:2 spin orbit resonances.
Adiabatic fission barriers in superheavy nuclei
Jachimowicz, P.; Kowal, M; Skalski, J.
2016-01-01
Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy we calculated static fission barriers $B_{f}$ for 1305 heavy and superheavy nuclei $98\\leq Z \\leq 126$, including even - even, odd - even, even - odd and odd - odd systems. For odd and odd-odd nuclei, adiabatic potential energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from ...
Brane World Dynamics and Adiabatic Matter creation
Gopakumar, P
2006-01-01
We have treated the adiabatic matter creation process in various three-brane models by applying thermodynamics of open systems. The matter creation rate is found to affect the evolution of scale factor and energy density of the universe. We find modification at early stages of cosmic dynamics. In GB and RS brane worlds, by chosing appropriate parameters we obtain standard scenario, while the warped DGP model has different Friedmann equations. During later stages, since the matter creation is negligible the evolution reduces to FRW expansion, in RS and GB models.
Dark Energy and Dark Matter from an additional adiabatic fluid
Dunsby, Peter K. S.; Luongo, Orlando; Reverberi, Lorenzo
2016-01-01
The Dark Sector is described by an additional barotropic fluid which evolves adiabatically during the universe's history and whose adiabatic exponent $\\gamma$ is derived from the standard definitions of specific heats. Although in general $\\gamma$ is a function of the redshift, the Hubble parameter and its derivatives, we find that our assumptions lead necessarily to solutions with $\\gamma = $ constant in a FLRW universe. The adiabatic fluid acts effectively as the sum of two distinct compone...
Adiabatic Flame Temperature and Specific Heat of Combustion Gases
Torii, Shuichi; Yano, Toshiaki; Tsunoda, Yukio; トリイ, シュウイチ; ヤノ, トシアキ; ツノダ, ユキオ; 鳥居, 修一; 矢野, 利明; 角田, 幸男
1992-01-01
The aim of the present work is to examine adiabatic flame temperature and the specific heat of combustion gases for both hydrocarbon-air and alcohol-air mixtures by means of a method of chemical equilibrium calculation. Emphasis is placed on the elucidation of simplified correlation equations capable of predicting (i) adiabatic flame temperature at any equivalence ratio and (ii) the specific heat of combustion gases when the adiabatic flame temperature, the gas temperature and the equivalence...
Adiabatic renormalization in theories with modified dispersion relations
Nacir, D. Lopez; Mazzitelli, F. D.; Simeone, C.
2007-01-01
We generalize the adiabatic renormalization to theories with dispersion relations modified at energies higher than a new scale $M_C$. We obtain explicit expressions for the mean value of the stress tensor in the adiabatic vacuum, up to the second adiabatic order. We show that for any dispersion relation the divergences can be absorbed into the bare gravitational constants of the theory. We also point out that, depending on the renormalization prescription, the renormalized stress tensor may c...
Symmetry of the adiabatic condition in the piston problem
This study addresses a controversial issue in the adiabatic piston problem, namely that of the piston being adiabatic when it is fixed but no longer so when it can move freely. It is shown that this apparent contradiction arises from the usual definition of adiabatic condition. The issue is addressed here by requiring the adiabatic condition to be compatible with the invariance of total entropy under a system-surroundings interchange. This paper also strengthens some recently published ideas concerning the concepts of heat and dissipative work, and is primarily intended for teachers and graduate students, as well as for all who are interested in this fascinating problem.
Magnesium Diboride Superconducting Coils for Adiabatic Demagnetization Refrigerators (ADR's) Project
National Aeronautics and Space Administration — For Adiabatic Demagnetization Refrigerators (ADRs) in space applications, it is desirable to have very light weight, small diameter, high current density...
A quantum search algorithm based on partial adiabatic evolution
Zhang Ying-Yu; Hu He-Ping; Lu Song-Feng
2011-01-01
This paper presents and implements a specified partial adiabatic search algorithm on a quantum circuit. It studies the minimum energy gap between the first excited state and the ground state of the system Hamiltonian and it finds that, in the case of M=1, the algorithm has the same performance as the local adiabatic algorithm. However, the algorithm evolves globally only within a small interval, which implies that it keeps the advantages of global adiabatic algorithms without losing the speedup of the local adiabatic search algorithm.
A quantum search algorithm based on partial adiabatic evolution
This paper presents and implements a specified partial adiabatic search algorithm on a quantum circuit. It studies the minimum energy gap between the first excited state and the ground state of the system Hamiltonian and it finds that, in the case of M = 1, the algorithm has the same performance as the local adiabatic algorithm. However, the algorithm evolves globally only within a small interval, which implies that it keeps the advantages of global adiabatic algorithms without losing the speedup of the local adiabatic search algorithm. (general)
Non-adiabatic perturbations in decaying vacuum cosmology
We investigate a spatially flat Friedmann-Lemaître-Robertson-Walker cosmology in which a decaying vacuum term causes matter production at late times. Assuming a decay proportional to the Hubble rate, the ratio of the background energy densities of dark matter and dark energy changes with the cosmic scale factor as a−3/2. The intrinsically non-adiabatic two-component perturbation dynamics of this model is reduced to a single second-order equation. Perturbations of the vacuum term are shown to be negligible on scales that are relevant for structure formation. On larger scales, dark-energy perturbations give a somewhat higher contribution but remain always smaller than the dark-matter perturbations
Adiabatic quantum pump in a zigzag graphene nanoribbon junction
张林
2015-01-01
The adiabatic electron transport is theoretically studied in a zigzag graphene nanoribbon (ZGNR) junction with two time-dependent pumping electric fields. By modeling a ZGNR p–n junction and applying the Keldysh Green’s function method, we find that a pumped charge current is flowing in the device at a zero external bias, which mainly comes from the photon-assisted tunneling process and the valley selection rule in an even-chain ZGNR junction. The pumped charge current and its ON and OFF states can be efficiently modulated by changing the system parameters such as the pumping frequency, the pumping phase difference, and the Fermi level. A ferromagnetic ZGNR device is also studied to generate a pure spin current and a fully polarized spin current due to the combined spin pump effect and the valley valve effect. Our finding might pave the way to manipulate the degree of freedom of electrons in a graphene-based electronic device.
Adiabatic cooling of solar wind electrons
Sandbaek, Ornulf; Leer, Egil
1992-01-01
In thermally driven winds emanating from regions in the solar corona with base electron densities of n0 not less than 10 exp 8/cu cm, a substantial fraction of the heat conductive flux from the base is transfered into flow energy by the pressure gradient force. The adiabatic cooling of the electrons causes the electron temperature profile to fall off more rapidly than in heat conduction dominated flows. Alfven waves of solar origin, accelerating the basically thermally driven solar wind, lead to an increased mass flux and enhanced adiabatic cooling. The reduction in electron temperature may be significant also in the subsonic region of the flow and lead to a moderate increase of solar wind mass flux with increasing Alfven wave amplitude. In the solar wind model presented here the Alfven wave energy flux per unit mass is larger than that in models where the temperature in the subsonic flow is not reduced by the wave, and consequently the asymptotic flow speed is higher.
Sigismondi, C.; Boscardin, S.
2014-10-01
Ptolemy (about 150 AC) modeled atmospheric refraction influencing Al Farghani (831), Alhazen (1020), Sacrobosco (1256) and Witelo (1278): the Sun was supposed bigger at horizon like a coin appears under water in a curved bottle. The correct work of Ibn Sahl (984) remained forgotten. Tycho measured the refraction on the 1572 supernova at various altitudes. Harriot, Kepler, Snell and Descartes found independently the refraction law after 1600. A modern formulation of vertical (0.5" zenithal to 35' at horizon) and horizontal (0.5" at all altitudes) differential refraction of solar diameter appears in Du Séjour (1786). Laplace's formula (1805) computes the vertical deformation of the solar disk, while the horizontal reduction of 0.5" is proportional to the chord's length. Dicke (1967) measured the solar oblateness to determine dynamical constraints to alternative theories of General Relativity. The Astrolabe of Rio de Janeiro measured in 1998-2009 the solar diameter at all heliolatitudes, by timing solar transits across fixed altitude circles: an equatorial excess larger than RHESSI (2008) and SDS (1992-2011) data remains after refraction's corrections. Meridian transits series measured at Rome Campidoglio (1877-1937) and Greenwich (1850-1940) behave as Rio data: the scatters between annual averages were larger than statistical dispersions of each value (Gething, 1955). Anomalous refractions measured with Rio Heliometer (2013) are low frequency seeing (0.01 Hz) acting to scales of the solar diameter (32'): they affect transits measurements with random perturbations hundreds times larger than the expected values calculated from the timing accuracy. These perturbations enlarge the differences between averages values binned either in time or heliolatitude: they are larger than statistical dispersions, suggesting a wider binning. The ``adiabatic" approach of Rio Heliometer with high frequency measurements ``freezes" the slow seeing image motion component.
Koshel, Konstantin V.; Shishkarev, A. A.
1993-09-01
On the basis of invariant imbedding method the disturbance theory for complex constants of the propagation is proposed. This approach allowed us to consider influence of layer and anisotropic fluctuations of refractive index on the beyond-the-horizon propagation in the adiabatic approximation at the existence of the evaporation duct. Finally, the paper considers some examples of the calculations and investigates stochastic effects.
Theory of supervirtual refraction interferometry
Bharadwaj, Pawan
2012-01-01
Inverting for the subsurface velocity distribution by refraction traveltime tomography is a well-accepted imaging method by both the exploration and earthquake seismology communities. A significant drawback, however, is that the recorded traces become noisier with increasing offset from the source position, and so accurate picking of traveltimes in far-offset traces is often prevented. To enhance the signal-to-noise ratio (SNR) of the far-offset traces, we present the theory of supervirtual refraction interferometry where the SNR of far-offset head-wave arrivals can be theoretically increased by a factor proportional to; here, N is the number of receiver or source positions associated with the recording and generation of the head-wave arrival. There are two steps to this methodology: correlation and summation of the data to generate traces with virtual head-wave arrivals, followed by the convolution of the data with the virtual traces to create traces with supervirtual head-wave arrivals. This method is valid for any medium that generates head-wave arrivals recorded by the geophones. Results with both synthetic traces and field data demonstrate the feasibility of this method. There are at least four significant benefits of supervirtual interferometry: (1) an enhanced SNR of far-offset traces so the first-arrival traveltimes of the noisy far-offset traces can be more reliably picked to extend the useful aperture of the data, (2) the SNR of head waves in a trace that arrive later than the first arrival can be enhanced for accurate traveltime picking and subsequent inversion by later-arrival traveltime tomography, (3) common receiver-pair gathers can be analysed to detect the presence of diving waves in the first arrivals, which can be used to assess the nature of the refracting boundary, and (4) the source statics term is eliminated in the correlation operations so that the timing of the virtual traces is independent of the source excitation time. This suggests the
Determination of the complex refractive index of cell cultures by reflectance spectrometry
Calin, Mihaela Antonina; Calin, Marian Romeo; Munteanu, Constantin
2014-06-01
In this paper we propose a new approach to using reflectance spectrometry in connection with the Kramers-Kronig analysis for the determination of the complex refractive index of biological cells. Applying this procedure, the real and imaginary parts of the refractive index (refractive index and extinction coefficient) can be simultaneously determined. The accuracy of this procedure in the determination of the refractive index and extinction coefficient of culture media proved to be comparable with spectroscopic ellipsometry. Applying this procedure on the human umbilical vein endothelial cells (HUVEC), the results obtained from time-series measurements showed significant changes in the complex refractive index of cell cultures within 72h, the most important increases for both real and imaginary parts of the refractive index being recorded in the first 24h, when synthesis processes are happening. Thus, the analysis of the time-dependent changes in the complex refractive index provides information about the frequencies of the modifications that occur on both organizational structure and cells composition during the cell cycle. In conclusion, the combination of reflectance spectrometry with the Kramers-Kronig analysis is a feasible way to determine the complex refractive index of biological cells and to assess the events taking place during the cell cycle.
Stabilisation of refraction following extracapsular cataract extraction.
Baranyovits, P.
1990-01-01
Regular serial refraction was used to determine the rate of stabilisation of refraction following routine extracapsular cataract surgery in 85 eyes. Patients were divided into four groups depending on wound closure technique: limbal section closed by interrupted 8-0 virgin silk, 9-0 polydioxanone or 10-0 nylon sutures, and corneal section closed by continuous 10-0 nylon suture. Stabilisation of refraction, sufficient to prescribe satisfactory glasses, occurred at three months except in the in...
Refractive lens for hard x-rays
The refractive lens for hard X-rays on the base of glass capillary is presented. The fabrication techniques for lens production are described. The model of refractive lens for hard X-ray is proposed. The model assume that the compound lens work similar one thin lens the complex refraction index of which is following: n=1-δ N + i β N. On the base of this model the parameters of focussed beam are calculated and the images of object are constructed
Psychophysiology of Refractive Accommodative Esotropia
Ungsoo Samuel Kim
2014-01-01
Full Text Available Purpose. To investigate the psychophysiologic aspects of refractive accommodative esotropia (RAE. Methods. I prospectively recruited patients aged 3–6 years with more than 3.0 diopters of hyperopia who presented at Kim’s Eye Hospital from January 2011 to March 2013. I compared Korean Child Behavior Checklist (K-CBCL which consists of internalizing factors (social withdrawal, somatic complaints, anxiety, and depression and externalizing factors (social problems, thought problems, attention problems, delinquent behavior, and aggressive behavior between RAE group and control group. Results. Two out of three internalizing indexes were significantly different between groups (somatic complaints: RAE children 50.1±4.6 and controls 46.6±5.8, P=0.026; depression/anxiety: RAE children 48.8±7.9 and controls 43.9±6.8, P=0.024. Although there was no significant difference, RAE children scored slightly higher on the externalizing behavior index. In the RAE group, the far angle of esodeviation showed a moderate correlation with withdrawn behaviors. Conclusion. Hypermetropic children with high scores on the somatic complaint and depression/anxiety subscales of the CBCL could be at high risk for developing RAE. Psychosocial problems might be related to the pathogenesis of refractive accommodative esotropia.
Plasmas in particle accelerators: adiabatic theories for bunched beams
Three different formalisms for discussing Vlasov's equation for bunched beam problems with anharmonic space charge forces are outlined. These correspond to the use of a drift kinetic equation averaged over random betatron motions; a fluidkinetic adiabatic regime analogous to the theory of Chew, Goldberger, and Low; and an adiabatic hydrodynamic theory
Teleportation of an Unknown Atomic State via Adiabatic Passage
无
2007-01-01
We propose a scheme for teleporting an unknown atomic state via adiabatic passage. Taking advantage of adiabatic passage, the atom has no probability of being excited and thus the atomic spontaneous emission is suppressed.We also show that the fidelity can reach 1 under certain condition.
Examination of the adiabatic approximation in open systems
We examine the notion of the adiabatic approximation in open systems by applying it to closed systems. Our results shows that the notion is equivalent to the standard adiabatic approximation if the systems are initially in eigenstates, and it leads to a more general expression if the systems are in mixed states
Adiabat-shaping in indirect drive inertial confinement fusion
Adiabat-shaping techniques were investigated in indirect drive inertial confinement fusion experiments on the National Ignition Facility as a means to improve implosion stability, while still maintaining a low adiabat in the fuel. Adiabat-shaping was accomplished in these indirect drive experiments by altering the ratio of the picket and trough energies in the laser pulse shape, thus driving a decaying first shock in the ablator. This decaying first shock is designed to place the ablation front on a high adiabat while keeping the fuel on a low adiabat. These experiments were conducted using the keyhole experimental platform for both three and four shock laser pulses. This platform enabled direct measurement of the shock velocities driven in the glow-discharge polymer capsule and in the liquid deuterium, the surrogate fuel for a DT ignition target. The measured shock velocities and radiation drive histories are compared to previous three and four shock laser pulses. This comparison indicates that in the case of adiabat shaping the ablation front initially drives a high shock velocity, and therefore, a high shock pressure and adiabat. The shock then decays as it travels through the ablator to pressures similar to the original low-adiabat pulses when it reaches the fuel. This approach takes advantage of initial high ablation velocity, which favors stability, and high-compression, which favors high stagnation pressures
High Fidelity Adiabatic Quantum Computation via Dynamical Decoupling
Quiroz, Gregory
2012-01-01
We introduce high-order dynamical decoupling strategies for open system adiabatic quantum computation. Our numerical results demonstrate that a judicious choice of high-order dynamical decoupling method, in conjunction with an encoding which allows computation to proceed alongside decoupling, can dramatically enhance the fidelity of adiabatic quantum computation in spite of decoherence.
Quantum adiabatic algorithm for factorization and its experimental implementation.
Peng, Xinhua; Liao, Zeyang; Xu, Nanyang; Qin, Gan; Zhou, Xianyi; Suter, Dieter; Du, Jiangfeng
2008-11-28
We propose an adiabatic quantum algorithm capable of factorizing numbers, using fewer qubits than Shor's algorithm. We implement the algorithm in a NMR quantum information processor and experimentally factorize the number 21. In the range that our classical computer could simulate, the quantum adiabatic algorithm works well, providing evidence that the running time of this algorithm scales polynomially with the problem size. PMID:19113467
Sensitivity of inertial confinement fusion hot spot properties to the deuterium-tritium fuel adiabat
Melvin, J.; Lim, H.; Rana, V.; Cheng, B.; Glimm, J.; Sharp, D. H.; Wilson, D. C.
2015-02-01
We determine the dependence of key Inertial Confinement Fusion (ICF) hot spot simulation properties on the deuterium-tritium fuel adiabat, here modified by addition of energy to the cold shell. Variation of this parameter reduces the simulation to experiment discrepancy in some, but not all, experimentally inferred quantities. Using simulations with radiation drives tuned to match experimental shots N120321 and N120405 from the National Ignition Campaign (NIC), we carry out sets of simulations with varying amounts of added entropy and examine the sensitivities of important experimental quantities. Neutron yields, burn widths, hot spot densities, and pressures follow a trend approaching their experimentally inferred quantities. Ion temperatures and areal densities are sensitive to the adiabat changes, but do not necessarily converge to their experimental quantities with the added entropy. This suggests that a modification to the simulation adiabat is one of, but not the only explanation of the observed simulation to experiment discrepancies. In addition, we use a theoretical model to predict 3D mix and observe a slight trend toward less mixing as the entropy is enhanced. Instantaneous quantities are assessed at the time of maximum neutron production, determined dynamically within each simulation. These trends contribute to ICF science, as an effort to understand the NIC simulation to experiment discrepancy, and in their relation to the high foot experiments, which features a higher adiabat in the experimental design and an improved neutron yield in the experimental results.
Sensitivity of inertial confinement fusion hot spot properties to the deuterium-tritium fuel adiabat
Melvin, J.; Lim, H.; Rana, V.; Glimm, J. [Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York 11794-3600 (United States); Cheng, B.; Sharp, D. H.; Wilson, D. C. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2015-02-15
We determine the dependence of key Inertial Confinement Fusion (ICF) hot spot simulation properties on the deuterium-tritium fuel adiabat, here modified by addition of energy to the cold shell. Variation of this parameter reduces the simulation to experiment discrepancy in some, but not all, experimentally inferred quantities. Using simulations with radiation drives tuned to match experimental shots N120321 and N120405 from the National Ignition Campaign (NIC), we carry out sets of simulations with varying amounts of added entropy and examine the sensitivities of important experimental quantities. Neutron yields, burn widths, hot spot densities, and pressures follow a trend approaching their experimentally inferred quantities. Ion temperatures and areal densities are sensitive to the adiabat changes, but do not necessarily converge to their experimental quantities with the added entropy. This suggests that a modification to the simulation adiabat is one of, but not the only explanation of the observed simulation to experiment discrepancies. In addition, we use a theoretical model to predict 3D mix and observe a slight trend toward less mixing as the entropy is enhanced. Instantaneous quantities are assessed at the time of maximum neutron production, determined dynamically within each simulation. These trends contribute to ICF science, as an effort to understand the NIC simulation to experiment discrepancy, and in their relation to the high foot experiments, which features a higher adiabat in the experimental design and an improved neutron yield in the experimental results.
王学滨
2004-01-01
A method for calculation of temperature distribution in adiabatic shear band is proposed in terms of gradient-dependent plasticity where the characteristic length describes the interactions and interplaying among microstructures. First, the increment of the plastic shear strain distribution in adiabatic shear band is obtained based on gradient-dependent plasticity. Then, the plastic work distribution is derived according to the current flow shear stress and the obtained increment of plastic shear strain distribution. In the light of the well-known assumption that 90% of plastic work is converted into the heat resulting in increase in temperature in adiabatic shear band, the increment of the temperature distribution is presented. Next, the average temperature increment in the shear band is calculated to compute the change in flow shear stress due to the thermal softening effect. After the actual flow shear stress considering the thermal softening effect is obtained according to the Johnson-Cook constitutive relation, the increment of the plastic shear strain distribution, the plastic work and the temperature in the next time step are recalculated until the total time is consumed. Summing the temperature distribution leads to rise in the total temperature distribution. The present calculated maximum temperature in adiabatic shear band in titanium agrees with the experimental observations. Moreover, the temperature profiles for different flow shear stresses are qualitatively consistent with experimental and numerical results. Effects of some related parameters on the temperature distribution are also predicted.
Robust Classification with Adiabatic Quantum Optimization
Denchev, Vasil S; Vishwanathan, S V N; Neven, Hartmut
2012-01-01
We propose a non-convex training objective for robust binary classification of data sets in which label noise is present. The design is guided by the intention of solving the resulting problem by adiabatic quantum optimization. Two requirements are imposed by the engineering constraints of existing quantum hardware: training problems are formulated as quadratic unconstrained binary optimization; and model parameters are represented as binary expansions of low bit-depth. In the present work we validate this approach by using a heuristic classical solver as a stand-in for quantum hardware. Testing on several popular data sets and comparing with a number of existing losses we find substantial advantages in robustness as measured by test error under increasing label noise. Robustness is enabled by the non-convexity of our hardware-compatible loss function, which we name q-loss.
Number Partitioning via Quantum Adiabatic Computation
Smelyanskiy, Vadim N.; Toussaint, Udo; Clancy, Daniel (Technical Monitor)
2002-01-01
We study both analytically and numerically the complexity of the adiabatic quantum evolution algorithm applied to random instances of combinatorial optimization problems. We use as an example the NP-complete set partition problem and obtain an asymptotic expression for the minimal gap separating the ground and exited states of a system during the execution of the algorithm. We show that for computationally hard problem instances the size of the minimal gap scales exponentially with the problem size. This result is in qualitative agreement with the direct numerical simulation of the algorithm for small instances of the set partition problem. We describe the statistical properties of the optimization problem that are responsible for the exponential behavior of the algorithm.
Entropy in adiabatic regions of convection simulations
Tanner, Joel D; Demarque, Pierre
2016-01-01
One of the largest sources of uncertainty in stellar models is caused by the treatment of convection in stellar envelopes. One dimensional stellar models often make use of the mixing length or equivalent approximations to describe convection, all of which depend on various free parameters. There have been attempts to rectify this by using 3D radiative-hydrodynamic simulations of stellar convection, and in trying to extract an equivalent mixing length from the simulations. In this paper we show that the entropy of the deeper, adiabatic layers in these simulations can be expressed as a simple function of og g and log T_{eff} which holds potential for calibrating stellar models in a simple and more general manner.
Adiabatic theory for anisotropic cold molecule collisions
We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment 4He(1s2s 3S) + HD(1s2) → 4He(1s2) + HD+(1s) + e− [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings
Adiabatic theory for anisotropic cold molecule collisions.
Pawlak, Mariusz; Shagam, Yuval; Narevicius, Edvardas; Moiseyev, Nimrod
2015-08-21
We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment (4)He(1s2s (3)S) + HD(1s(2)) → (4)He(1s(2)) + HD(+)(1s) + e(-) [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings. PMID:26298122
Adiabatic theory for anisotropic cold molecule collisions
Pawlak, Mariusz [Schulich Faculty of Chemistry, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń (Poland); Shagam, Yuval; Narevicius, Edvardas [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Moiseyev, Nimrod [Schulich Faculty of Chemistry, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Faculty of Physics, Technion–Israel Institute of Technology, Haifa 32000 (Israel)
2015-08-21
We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment {sup 4}He(1s2s {sup 3}S) + HD(1s{sup 2}) → {sup 4}He(1s{sup 2}) + HD{sup +}(1s) + e{sup −} [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings.
Adiabatic Liquid Piston Compressed Air Energy Storage
Petersen, Tage; Elmegaard, Brian; Pedersen, Allan Schrøder
This project investigates the potential of a Compressed Air Energy Storage system (CAES system). CAES systems are used to store mechanical energy in the form of compressed air. The systems use electricity to drive the compressor at times of low electricity demand with the purpose of converting the...... compensates the added investment. •When comparing ALP-CAES to an adiabatic CAES system, where compression heat is stored in thermal oil, the ALP-CAES system is found only to be competitive under a very specific set of operating/design conditions, including very high operation pressure and the use of very...... primarily due to the investment in turbine/generator, heat exchangers, and a large quantity of thermal oil. To improve the economy, it would be relevant to investigate the possibility of replacing the thermal oil by water, for example by injecting the water directly into the air flow between the different...
Adiabatic approximation, semiclassical scattering, and unidirectional invisibility
The transfer matrix of a possibly complex and energy-dependent scattering potential can be identified with the S-matrix of a two-level time-dependent non-Hermitian Hamiltonian H(τ). We show that the application of the adiabatic approximation to H(τ) corresponds to the semiclassical description of the original scattering problem. In particular, the geometric part of the phase of the evolving eigenvectors of H(τ) gives the pre-exponential factor of the WKB wave functions. We use these observations to give an explicit semiclassical expression for the transfer matrix. This allows for a detailed study of the semiclassical unidirectional reflectionlessness and invisibility. We examine concrete realizations of the latter in the realm of optics. (paper)
Parametric Erosion Investigation: Propellant Adiabatic Flame Temperature
P. J. Conroy
2002-01-01
Full Text Available The influence of quasi-independent parameters and their potential influence on erosion in guns have been investigated. Specifically, the effects of flame temperature and the effect of assuming that the Lewis number (ratio of mass-to-heat transport to the surface, Le = 1, has been examined. The adiabatic flame temperature for a propellant was reduced by the addition of a diluent from a high temperature of 3843 K (similar to that of M9 down to 3004 K, which is near the value for M30A1 propellant. Mass fractions of critical species at the surface with and without the assumption of Le = 1 are presented, demonstrating that certain species preferentially reach the surface providing varied conditions for the surface reactions. The results for gun tube bore surface regression qualitatively agree with previous studies and with current experimental data.
Index Theory and Adiabatic Limit in QFT
Wawrzycki, Jaroslaw
2011-01-01
The paper has the form of a proposal concerned with the relationship between the three mathematically rigorous approaches to quantum field theory: 1) local algebraic formulation of Haag, 2) Wightman formulation and 3) the perturbative formulation based on the microlocal renormalization method. In this project we investigate the relationship between 1) and 3) and utilize the known relationships between 1) and 2). The main goal of the proposal lies in obtaining obstructions for the existence of the adiabatic limit (confinement problem in the phenomenological standard model approach). We extend the method of deformation of D\\"utsch and Fredenhagen (in the Bordeman-Waldmann sense) and apply Fedosov construction of the formal index -- an analog of the index for deformed symplectic manifolds, generalizing the Atiyah-Singer index. We present some first steps in realization of the proposal.
Index Theory and Adiabatic Limit in QFT
Wawrzycki, Jarosław
2013-08-01
The paper has the form of a proposal concerned with the relationship between the three mathematically rigorous approaches to quantum field theory: (1) local algebraic formulation of Haag, (2) Wightman formulation and (3) the perturbative formulation based on the microlocal renormalization method. In this project we investigate the relationship between (1) and (3) and utilize the known relationships between (1) and (2). The main goal of the proposal lies in obtaining obstructions for the existence of the adiabatic limit ( confinement problem in the phenomenological standard model approach). We extend the method of deformation of Dütsch and Fredenhagen (in the Bordeman-Waldmann sense) and apply Fedosov construction of the formal index—an analog of the index for deformed symplectic manifolds, generalizing the Atiyah-Singer index. We present some first steps in realization of the proposal.
The adiabatic approximation in multichannel scattering
Using two-dimensional models, an attempt has been made to get an impression of the conditions of validity of the adiabatic approximation. For a nucleon bound to a rotating nucleus the Coriolis coupling is neglected and the relation between this nuclear Coriolis coupling and the classical Coriolis force has been examined. The approximation for particle scattering from an axially symmetric rotating nucleus based on a short duration of the collision, has been combined with an approximation based on the limitation of angular momentum transfer between particle and nucleus. Numerical calculations demonstrate the validity of the new combined method. The concept of time duration for quantum mechanical collisions has also been studied, as has the collective description of permanently deformed nuclei. (C.F.)
Entropy in Adiabatic Regions of Convection Simulations
Tanner, Joel D.; Basu, Sarbani; Demarque, Pierre
2016-05-01
One of the largest sources of uncertainty in stellar models is caused by the treatment of convection in stellar envelopes. One-dimensional stellar models often make use of the mixing length or equivalent approximations to describe convection, all of which depend on various free parameters. There have been attempts to rectify this by using 3D radiative-hydrodynamic simulations of stellar convection, and in trying to extract an equivalent mixing length from the simulations. In this Letter, we show that the entropy of the deeper, adiabatic layers in these simulations can be expressed as a simple function of {log}g and {log}{T}{{eff}}, which holds potential for calibrating stellar models in a simple and more general manner.
Adiabatic motion of charged dust grains in rotating magnetospheres
Dust grains in the ring systems and rapidly rotating magnetospheres of the outer planets such as Jupiter and Saturn may be sufficiently charged that the magnetic and electric forces on them are comparable with the gravitational force. The adiabatic theory of charged particle motion has previously been applied to electrons and atomic size particles. But it is also applicable to these charged dust grains in the micrometer and smaller size range. We derive here the guiding center equation of motion, drift velocity, and parallel equation of motion for these grains in a rotating magnetosphere. The effects of periodic grain charge-discharge have not been treated previously and have been included in this analysis. Grain charge is affected by the surrounding plasma properties and by the grain plasma velocity (among other factors), both of which may vary over the gyrocircle. The resulting charge-discharge process at the gyrofrequency destroys the invariance of the magnetic moment and causes a grain to move radially. The magnetic moment may increase or decrease, depending on the gyrophase of the charge variation. If it decreases, the motion is always toward synchronous radius for an equatorial grain. But the orbit becomes circular before the grain reaches synchronous radius, a conclusion that follows from an exact constant of the motion. This circularization can be viewed as a consequence of the gradual reduction in the magnetic moment. This circularization also suggests that dust grains leaving Io could not reach the region of the Jovian ring, but several effects could change that conclusion. Excellent qualitative and quantitative agreement is obtained between adiabatic theory and detailed numerical orbit integrations
Refractive index of plant cell walls
Gausman, H. W.; Allen, W. A.; Escobar, D. E.
1974-01-01
Air was replaced with media of higher refractive indices by vacuum infiltration in leaves of cucumber, blackeye pea, tomato, and string bean plants, and reflectance of noninfiltrated and infiltrated leaves was spectrophotometrically measured. Infiltrated leaves reflected less light than noninfiltrated leaves over the 500-2500-nm wavelength interval because cell wall-air interfaces were partly eliminated. Minimal reflectance should occur when the average refractive index of plant cell walls was matched by the infiltrating fluid. Although refractive indices that resulted in minimal reflectance differed among the four plant genera, an average value of 1.425 approximates the refractive index of plant cell walls for the four plant genera.
Adiabatic and Isocurvature Perturbation Projections in Multi-Field Inflation
Gordon, Chris
2013-01-01
Current data are in good agreement with the predictions of single field inflation. However, the hemispherical asymmetry seen in the cosmic microwave background data, may hint at a potential problem. Generalizing to multi-field models may provide one possible explanation. A useful way of modeling perturbations in multi-field inflation is to investigate the projection of the perturbation along and perpendicular to the background fields' trajectory. These correspond to the adiabatic and isocurvature perturbations. However, it is important to note that in general there are no corresponding adiabatic and isocurvature fields. The purpose of this article is to highlight the distinction between a field redefinition and a perturbation projection. We provide a detailed derivation of the evolution of the adiabatic perturbation to show that no assumption of an adiabatic or isocurvature field is needed. We also show how this evolution equation is consistent with the field covariant evolution equations for the adiabatic pe...
How detrimental is decoherence in adiabatic quantum computation?
Albash, Tameem
2015-01-01
Recent experiments with increasingly larger numbers of qubits have sparked renewed interest in adiabatic quantum computation, and in particular quantum annealing. A central question that is repeatedly asked is whether quantum features of the evolution can survive over the long time-scales used for quantum annealing relative to standard measures of the decoherence time. We reconsider the role of decoherence in adiabatic quantum computation and quantum annealing using the adiabatic quantum master equation formalism. We restrict ourselves to the weak-coupling and singular-coupling limits, which correspond to decoherence in the energy eigenbasis and in the computational basis, respectively. We demonstrate that decoherence in the instantaneous energy eigenbasis does not necessarily detrimentally affect adiabatic quantum computation, and in particular that a short single-qubit $T_2$ time need not imply adverse consequences for the success of the quantum adiabatic algorithm. We further demonstrate that boundary canc...
Power spectra in the eikonal approximation with adiabatic and non-adiabatic modes
Bernardeau, Francis; Vernizzi, Filippo
2012-01-01
We use the so-called eikonal approximation, recently introduced in the context of cosmological perturbation theory, to compute power spectra for multi-component fluids. We demonstrate that, at any given order in standard perturbation theory, multi-point power spectra do not depend on the large-scale adiabatic modes. Moreover, we employ perturbation theories to decipher how non-adiabatic modes, such as a relative velocity between two different components, damp the small-scale matter power spectrum, a mechanism recently described in the literature. In particular, we do an explicit calculation at 1-loop order of this effect. While the 1-loop result eventually breaks down, we show how the damping effect can be fully captured by the help of the eikonal approximation. A relative velocity not only induces mode damping but also creates large-scale anisotropic modulations of the matter power spectrum amplitude. We illustrate this for the Local Group environment.
Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation
Zamstein, Noa; Tannor, David J. [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel)
2012-12-14
We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schroedinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.
Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation
We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schrödinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.
Pump-induced refractive index modulation and dispersions in Er3+-doped fibers
Thirstrup, Carsten; Shi, Yuan
1996-01-01
A novel measurement system provides determination of pump induced phase shifts in erbium doped fibers with an accuracy of ~π/20. Using this system, a systematical analysis of the pump induced modulation of the refractive index and dispersions for a signal at 1550 nm and a pump at 980 nm is reported....... The analysis contains measurements of pump induced refractive index changes as function of wavelength, pump power, and doping concentration. A model taking account of the contribution to the refractive index changes from optical transitions between 4 I15/2 states and 4I13/2 states in Er3+ yields good...
Measurement of air refractive index fluctuation based on a laser synthetic wavelength interferometer
A novel method for measuring air refractive index fluctuation based on a laser synthetic wavelength interferometer is proposed. The change of air refractive index is regarded as an equivalent measured displacement in the measurement arm, which can be realized by tracking a large compensative displacement of the reference mirror in the reference arm of the laser synthetic wavelength interferometer. The merit of the proposed method is that the slight air refractive index fluctuation is magnified to a large displacement on the order of millimeters or micrometers. To verify the feasibility of the proposed method, the correlation experiment between the displacement of the reference mirror and the air refractive index fluctuation and the comparison experiments with Edlén equations both in short time and long time were performed. Experimental results show that the measurement accuracy of the air refractive index fluctuation is better than 3.7 × 10–8. (paper)
Detection of analyte refractive index and concentration using liquid-core photonic Bragg fibers
Li, Jingwen; Qu, Hang; Skorobogatiy, Maksim
2016-03-01
We demonstrate detection of liquid analyte refractive index by using a hollow-core photonic Bragg fiber. We apply this fiber sensor to monitor concentrations of commercial cooling oil. The sensor operates on a spectral modality. Variation in the analyte refractive index modifies the bandgap guidance of a fiber, leading to spectral shifts in the fiber transmission spectrum. The sensitivity of the sensor to changes in the analyte refractive index filling in the fiber core is found to be 1460nm/Refractive index unit (RIU). By using the spectral modality and effective medium theory, we determine the concentrations of commercial fluid from the measured refractive indices with an accuracy of ~0.42%. The presented fiber sensor can be used for on-line monitoring of concentration of many industrial fluids and dilutions with sub-1%v accuracy.
Stadnyk, V. Yo.; Andriyevsky, B. V.; Gaba, V. M.; Kogut, Z. A.
2016-06-01
Temperature dependences of optical path difference δΔi and the relative changes in thickness δ l i/ l of TGS crystals doped with L-valine are studied. Temperature dependences of the relative changes in refractive indices δ n i/( n-1) are calculated. The anisotropy coefficients of refractive indices An-1(T) and linear expansion Aα(T) are calculated, and a characteristic minimum of these dependences is found near the phase transition temperature.
About negative refraction and left handed materials
Ye, Zhen
2004-01-01
Here I present an overview of recent studies of the phenomenon of negative refraction and left-handed materials. I will discuss some basic questions pertinent to the problem. It is pointed out that the current claims of negative refraction and left handed materials are not conclusive. To support our consideration, I will start with the fundamental physics.
Microstructured optical fiber refractive index sensor
Town, Graham E.; McCosker, Ravi; Yuan, Scott Wu;
2010-01-01
We describe a dual-core microstructured optical fiber designed for refractive index sensing of fluids. We show that by using the exponential dependence of intercore coupling on analyte refractive index, both large range and high sensitivity can be achieved in the one device. We also show that sel...
Retinal Image Simulation of Subjective Refraction Techniques.
Sara Perches
Full Text Available Refraction techniques make it possible to determine the most appropriate sphero-cylindrical lens prescription to achieve the best possible visual quality. Among these techniques, subjective refraction (i.e., patient's response-guided refraction is the most commonly used approach. In this context, this paper's main goal is to present a simulation software that implements in a virtual manner various subjective-refraction techniques-including Jackson's Cross-Cylinder test (JCC-relying all on the observation of computer-generated retinal images. This software has also been used to evaluate visual quality when the JCC test is performed in multifocal-contact-lens wearers. The results reveal this software's usefulness to simulate the retinal image quality that a particular visual compensation provides. Moreover, it can help to gain a deeper insight and to improve existing refraction techniques and it can be used for simulated training.
Retinal Image Simulation of Subjective Refraction Techniques.
Perches, Sara; Collados, M Victoria; Ares, Jorge
2016-01-01
Refraction techniques make it possible to determine the most appropriate sphero-cylindrical lens prescription to achieve the best possible visual quality. Among these techniques, subjective refraction (i.e., patient's response-guided refraction) is the most commonly used approach. In this context, this paper's main goal is to present a simulation software that implements in a virtual manner various subjective-refraction techniques--including Jackson's Cross-Cylinder test (JCC)--relying all on the observation of computer-generated retinal images. This software has also been used to evaluate visual quality when the JCC test is performed in multifocal-contact-lens wearers. The results reveal this software's usefulness to simulate the retinal image quality that a particular visual compensation provides. Moreover, it can help to gain a deeper insight and to improve existing refraction techniques and it can be used for simulated training. PMID:26938648
Hayato Goto
2015-01-01
The dynamics of nonlinear systems qualitatively change depending on their parameters, which is called bifurcation. A quantum-mechanical nonlinear oscillator can yield a quantum superposition of two oscillation states, known as a Schr\\"odinger cat state, via quantum adiabatic evolution through its bifurcation point. Here we propose a quantum computer comprising such quantum nonlinear oscillators, instead of quantum bits, to solve hard combinatorial optimization problems. The nonlinear oscillat...
Are the reactions of quinones on graphite adiabatic?
Outer sphere electron transfer reactions on pure metal electrodes are often adiabatic and hence independent of the electrode material. Since it is not clear, whether adiabatic electron transfer can also occur on a semi-metal like graphite, we have re-investigated experimental data presented in a recent communication by Nissim et al. [Chemical Communications 48 (2012) 3294] on the reactions of quinones on graphite. We have supplemented their work by DFT calculations and conclude, that these reactions are indeed adiabatic. This contradicts the assertion of Nissim et al. that the rates are proportional to the density of states at the Fermi level
Approximability of optimization problems through adiabatic quantum computation
Cruz-Santos, William
2014-01-01
The adiabatic quantum computation (AQC) is based on the adiabatic theorem to approximate solutions of the Schrödinger equation. The design of an AQC algorithm involves the construction of a Hamiltonian that describes the behavior of the quantum system. This Hamiltonian is expressed as a linear interpolation of an initial Hamiltonian whose ground state is easy to compute, and a final Hamiltonian whose ground state corresponds to the solution of a given combinatorial optimization problem. The adiabatic theorem asserts that if the time evolution of a quantum system described by a Hamiltonian is l
A note on the geometric phase in adiabatic approximation
Tong, D M; Kwek, L C; Oh, C H
2004-01-01
It is widely held that the Berry phase of a quantum system is the geometric phase in adiabatic approximation. However, Pati and Rajagopal recently claimed that the Berry phase vanishes under strict adiabatic evolution. In this note, we reexamine and address this issue. In particular, we show that the use of the adiabatic theorem does not lead to this inconsistency. We also examine the difference between the Berry phase and the exact geometric phase. Here we find that the Berry phase may differ appreciably from the exact geometric phase if the evolution time is large enough.
Effects of refractive index mismatch in optical CT imaging of polymer gel dosimeters
Manjappa, Rakesh; Makki S, Sharath; Kanhirodan, Rajan, E-mail: rajan@physics.iisc.ernet.in [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Kumar, Rajesh [Radiological Physics and Advisory Division, BARC, Mumbai 400094 (India)
2015-02-15
Purpose: Proposing an image reconstruction technique, algebraic reconstruction technique-refraction correction (ART-rc). The proposed method takes care of refractive index mismatches present in gel dosimeter scanner at the boundary, and also corrects for the interior ray refraction. Polymer gel dosimeters with high dose regions have higher refractive index and optical density compared to the background medium, these changes in refractive index at high dose results in interior ray bending. Methods: The inclusion of the effects of refraction is an important step in reconstruction of optical density in gel dosimeters. The proposed ray tracing algorithm models the interior multiple refraction at the inhomogeneities. Jacob’s ray tracing algorithm has been modified to calculate the pathlengths of the ray that traverses through the higher dose regions. The algorithm computes the length of the ray in each pixel along its path and is used as the weight matrix. Algebraic reconstruction technique and pixel based reconstruction algorithms are used for solving the reconstruction problem. The proposed method is tested with numerical phantoms for various noise levels. The experimental dosimetric results are also presented. Results: The results show that the proposed scheme ART-rc is able to reconstruct optical density inside the dosimeter better than the results obtained using filtered backprojection and conventional algebraic reconstruction approaches. The quantitative improvement using ART-rc is evaluated using gamma-index. The refraction errors due to regions of different refractive indices are discussed. The effects of modeling of interior refraction in the dose region are presented. Conclusions: The errors propagated due to multiple refraction effects have been modeled and the improvements in reconstruction using proposed model is presented. The refractive index of the dosimeter has a mismatch with the surrounding medium (for dry air or water scanning). The algorithm
On the persistence of adiabatic shear bands
Bassim M.N.
2012-08-01
Full Text Available It is generally agreed that the initiation and development of adiabatic shear bands (ASBs are manifestations of damage in metallic materials subjected to high strain rates and large strains as those due to impact in a Hopkinson Bar system. Models for evolution of these bands have been described in the literature. One question that has not received attention is how persistent these bands are and whether their presence and effect can be reversed or eliminated by using a process of thermal (heat treatment or thermo-mechanical treatment that would relieve the material from the high strain associated with ASBs and their role as precursors to crack initiation and subsequent failure. Since ASBs are more prevalent and more defined in BCC metals including steels, a study was conducted to investigate the best conditions of generating ASBs in a heat treatable steel, followed by determining the best conditions for heat treatment of specimens already damaged by the presence of ASBs in order to relieve the strains due to ASBs and restore the material to an apparent microstructure without the “scars” due to the previous presence of ASBs. It was found that heat treatment achieves the curing from ASBs. This presentation documents the process undertaken to achieve this objective.
Graph isomorphism and adiabatic quantum computing
Gaitan, Frank; Clark, Lane
2014-03-01
In the Graph Isomorphism (GI) problem two N-vertex graphs G and G' are given and the task is to determine whether there exists a permutation of the vertices of G that preserves adjacency and maps G --> G'. If yes (no), then G and G' are said to be isomorphic (non-isomorphic). The GI problem is an important problem in computer science and is thought to be of comparable difficulty to integer factorization. We present a quantum algorithm that solves arbitrary instances of GI, and which provides a novel approach to determining all automorphisms of a graph. The algorithm converts a GI instance to a combinatorial optimization problem that can be solved using adiabatic quantum evolution. Numerical simulation of the algorithm's quantum dynamics shows that it correctly distinguishes non-isomorphic graphs; recognizes isomorphic graphs; and finds the automorphism group of a graph. We also discuss the algorithm's experimental implementation and show how it can be leveraged to solve arbitrary instances of the NP-Complete Sub-Graph Isomorphism problem.
Adiabatic fission barriers in superheavy nuclei
Jachimowicz, P; Skalski, J
2016-01-01
Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy we calculated static fission barriers $B_{f}$ for 1305 heavy and superheavy nuclei $98\\leq Z \\leq 126$, including even - even, odd - even, even - odd and odd - odd systems. For odd and odd-odd nuclei, adiabatic potential energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from the 10-th below to the 10-th above the Fermi level. The parameters of the model that have been fixed previously by a fit to masses of even-even heavy nuclei were kept unchanged. A search for saddle points has been performed by the "Imaginary Water Flow" method on a basic five-dimensional deformation grid, including triaxiality. Two auxiliary grids were used for checking the effects of the mass asymmetry and hexadecapole non-axiallity. The ground states were found by energy minimization over configurations and deformations...
About the correctness of laser refractive surgery in children
V. V. Kurenkov
2016-01-01
Full Text Available Disturbances of refraction are one of the most urgent problems of pediatric ophthalmology. Late and incomplete correction of refractive errors leads to the development of amblyopia, disturbances of binocular vision, the appearance of strabismus. Such complications reduce the quality of life, drastically limit the choice of professional child. Pediatric Ophthalmology always face a choice: many drugs and technologies are not approved for use in pediatric patients, practitioners are forced to use their «off-label», but such situations require great care and strict medical indications. For example, refractive surgery has worked well in adults, but its use remains controversial in children for security reasons and unpredictable effects. Several authors have described the use of laser refractive surgery in children under the age of 18 years, but there are no results of a multicenter, controlled study evaluating the safety, efficacy, and especially long-term results. In all the studies, the calculation was performed on adult nomograms ablation, while not proved how they are accurate for children. Long-term results and data on the endothelial cell density, corneal curvature changes in catamnesis are presented no longer than two years. Despite the fact that currently there is insufficient information about the results of remote application keratorefractive laser surgery in children, and there are no indication system and contraindications, modern achievements in medicine should be used in pediatric patients, and our successful track record proves it clearly. Undoubtedly, the positive experience of the laser surgery use in a child with clouding of the cornea in the outcome of herpetic keratitis, which provided a positive result: high visual acuity, binocular vision and lack of infection relapses for 2 years, requires study, evidence multicenter studies, and possibly expansion of indications for refractive laser surgery.
When an adiabatic irreversible expansion or compression becomes reversible
This paper aims to contribute to a better understanding of the concepts of a reversible process and entropy. For this purpose, an adiabatic irreversible expansion or compression is analysed, by considering that an ideal gas is expanded (compressed), from an initial pressure Pi to a final pressure Pf, by being placed in contact with a set of N work reservoirs with pressures decreasing (increasing) in a geometric or arithmetic progression. The gas entropy change ΔS is evaluated and it is clearly shown that ΔS > 0 for any finite N, but as the number of work reservoirs goes to infinity the entropy change goes to zero, i.e. the process becomes reversible. Additionally, this work draws attention to the work reservoir concept, which is virtually ignored in the literature, and to its analogy with the commonly used heat reservoir concept. Finally, it complements and reinforces an earlier study dealing with irreversible cooling or heating so that the synergy created by the two studies is important from both theoretical and educational standpoints
The temperature dependence of refractive index of hemoglobin at the wavelengths 930 and 1100 nm
Lazareva, Ekaterina N.; Tuchin, Valery V.
2016-04-01
In this study, the refractive index of hemoglobin was measured at different temperatures within a physiological range and above that is characteristic to light-blood interaction at laser therapy. Measurements were carried out using the multi-wavelength Abbe refractometer (Atago, Japan). The refractive index was measured at two NIR wavelengths of 930 nm and 1100 nm. Samples of hemoglobin solutions with concentration of 80, 120 and 160 g/l were investigated. The temperature was varied between 25 and 55 °C. It was shown that the dependence of the refractive index of hemoglobin is nonlinear with temperature, which may be associated with changes in molecular structure of hemoglobin.
A new approach is proposed for correcting the eye refraction by controlled variation of the mechanical properties of the sclera and cornea upon nondestructive laser heating. Experimental ex vivo studies of rabbit and pig eyes show that laser-induced local denaturation of the sclera changes the refraction of the cornea by 3 diopters on the average, and the subsequent nondestructive irradiation of the cornea increases its plasticity, which leads to a further increase in its radius of curvature and a decrease in refraction down to 7 diopters.
Sensing of refractive index based on mode interference in a five-layer slab waveguide
Tang, Tingting; Ma, Wenying; Liu, Wenli; He, Xiujun
2015-01-01
We propose a refractive index sensor based on the mode interference in a five-layer waveguide. The propagation properties are analyzed by the coupled mode theory, and the function of the waveguide as a refractive index sensor is also explored based on simulation results. Taking into consideration a trade-off between the sensitivity and the size of the proposed sensor, we can get a very compact device of 10.8 μm×1 μm, and the sensing resolution of the proposed refractive index can reach 2.25×10-5 RIU for index change at around 1.455.
Refractive index modulation in polymer film doped with diazo Meldrum's acid
Zanutta, Alessio; Villa, Filippo; Bertarelli, Chiara; Bianco, Andrea
2016-08-01
Diazo Meldrum's acid undergoes a photoreaction induced by UV light and it is used as photosensitizer in photoresists. Upon photoreaction, a change in refractive index occurs, which makes this system interesting for volume holography. We report on the sublimation effect at room temperature and the effect of photoirradiation on the refractive index in thin films of CAB (Cellulose acetate butyrate) doped with different amount of diazo Meldrum's acid. A net modulation of the refractive index of 0.01 is achieved with 40% of doping ratio together with a reduction of the film thickness.
Dark refraction shift with allowance for astigmatism
W.D.H. Gillan
2005-01-01
Full Text Available Purpose: To show that the dark refraction shift (dark focus is a more complicated phenomenon than implied when presented as spherical. Methods: Fifty autorefractor measurements of refractive state of the right eye were obtained in light and dark conditions. Multivariate methods were used to analyze the data and stereo-pair scat-ter plots, polar meridional profiles and other means of presenting results are used to show important characteristics of the dark refraction shift. Results: The complexity of the dark refrac-tion shift is indicated by stereo-pair scatter plots showing the amount of stigmatic and antistigmatic variation that occurs in light and dark conditions. The mean dark refraction shift is presented in a complete manner including all three components of refractive state. The greater variance and covari-ance under dark conditions is clearly shown by the term-by-term dark-light variance-covariance ratio and polar profiles of variance and covariance.Conclusions: The dark refraction shift is a more complicated phenomenon than implied by representations as purely spherical in nature.
Negative Refraction experiments in Photonic Crystal prisms
Vodo, Plarenta; Parimi, Patanjali. V.; Lu, Wentao. T.; di Gennaro, Emiliano; Sridhar, Srinivas
2004-03-01
We have experimentally demonstrated negative refraction in metallic photonic crystal (PC) prisms [1]. The refracted fields in the parallel plate waveguide (PPW) are measured by an automated dipole antenna, which scans the desired area, while the free space (FS) measurements, performed in a anechoic chamber, are measured by a rectangular X-band horn that swings in an arc in far field area. Both TE and TM excitation modes are used in FS experiments. Numerical calculations of the band structure and equi-frequency surface simulations are used to determine frequency regions of negative refraction of the triangular lattice PC. Angle of refraction determined by theoretical simulations and experimental results, are in exceptional good agreement, yielding the negative refraction index. FS and PPW refraction experimental results agree remarkably with simulations. 1. "Negative Refraction and Left-handed electromagnetism in Microwave Photonic Crystals", P.V Parimi, W.T Lu, P.Vodo J. Sokoloff and S.Sridhar, cond-mat/0306109 (2003)
A simple optical probing technique for nonlinearly induced refractive index
Banerjee, Partha; Abeywickrema, Ujitha
2013-09-01
Self phase modulation is a nonlinear effect that is observed when a laser beam is focused on to a high-absorbing thermal medium. A regular tea sample in a plastic cuvette is used as the nonlinear absorbing sample. The change in the refractive index of the medium occurs due to the heat generated by the focused pump beam, which in turn changes the refractive index. In this paper, self phase modulation is investigated in different ways. An Ar-Ion laser of 514 nm is used as the pump beam and a 632 nm He-Ne laser is used as the probe beam. The probe beam is introduced from the opposite side of the pump beam. Ring patterns are observed from the each side of the sample. Regular far field ring patterns are observed from the pump beam, and two sets of rings are observed with the probe beam. The behaviors of these inner and outer rings are monitored for different pump powers. The steady state heat equation is solved to obtain an exact solution for the radial heat distribution and far field ring patterns are simulated using the Fresnel-Kirchhoff diffraction integral. Ring patterns are theoretically explained using simulations results, and compared with experimental observations. Finally, an interferometric setup using the low power He-Ne laser is also used to determine the induced change in refractive index. Results are compared with those obtained directly from self-phase modulation and from the probe beam method.
General dynamical description of quasi-adiabatically encircling exceptional points
Milburn, Thomas J; Holmes, Catherine A; Portolan, Stefano; Rotter, Stefan; Rabl, Peter
2014-01-01
The appearance of so-called exceptional points in the complex spectra of non-Hermitian systems is often associated with phenomena that contradict our physical intuition. One example of particular interest is the state-exchange process predicted for an adiabatic encircling of an exceptional point. In this work we analyze this process for the generic system of two coupled oscillator modes with loss or gain. We identify a characteristic system evolution consisting of periods of quasi-stationarity interrupted by abrupt non-adiabatic transitions. Our findings explain the breakdown of the adiabatic theorem as well as the chiral behavior noticed previously in this context, and we provide a unified framework to describe quasi-adiabatic dynamical effects in non-Hermitian systems in a qualitative and quantitative way.
Adiabatic and isocurvature perturbation projections in multi-field inflation
Current data are in good agreement with the predictions of single field inflation. However, the hemispherical asymmetry, seen in the cosmic microwave background data, may hint at a potential problem. Generalizing to multi-field models may provide one possible explanation. A useful way of modeling perturbations in multi-field inflation is to investigate the projection of the perturbation along and perpendicular to the background fields' trajectory. These correspond to the adiabatic and isocurvature perturbations. However, it is important to note that in general there are no corresponding adiabatic and isocurvature fields. The purpose of this article is to highlight the distinction between a field redefinition and a perturbation projection. We provide a detailed derivation of the evolution of the isocurvature perturbation to show that no assumption of an adiabatic or isocurvature field is needed. We also show how this evolution equation is consistent with the field covariant evolution equations for the adiabatic perturbation in the flat field space limit
Magnesium Diboride Superconducting Coils for Adiabatic Demagnetization Refrigerators (ADR's) Project
National Aeronautics and Space Administration — For Adiabatic Demagnetization Refrigerators(ADR's) for space it is desirable to have very light weight, small diameter, high current density superconducting wires...
Application of adiabatic calorimetry to metal systems. Final report
Research on the application of adiabatic calorimetry to metal systems is described. Investigations into formation of pearlite in steels, ferromagnetic effects, cold working and annealing, solid solution alloys, pure solid metals, and pure liquid metals, are briefly described
Case Study of Indirect Adiabatic Cooling System in Historical Building
Brahmanis, A; Lešinskis, A; Krūmiņš, A
2013-01-01
The objective of the present study is to investigate the efficiency of indirect adiabatic chiller-based cooling system efficiency dependence of outdoor air humidity. The system is located in historical building, in temperate climate of Latvia.
How to incorporate generic refraction models into multistatic tracking algorithms
Crouse, D. F.
The vast majority of literature published on target tracking ignores the effects of atmospheric refraction. When refraction is considered, the solutions are generally tailored to a simple exponential atmospheric refraction model. This paper discusses how arbitrary refraction models can be incorporated into tracking algorithms. Attention is paid to multistatic tracking problems, where uncorrected refractive effects can worsen track accuracy and consistency in centralized tracking algorithms, and can lead to difficulties in track-to-track association in distributed tracking filters. Monostatic and bistatic track initialization using refraction-corrupted measurements is discussed. The results are demonstrated using an exponential refractive model, though an arbitrary refraction profile can be substituted.
Adiabatic instability in coupled dark energy-dark matter models
Bean, Rachel; Flanagan, Eanna E.; Trodden, Mark
2007-01-01
We consider theories in which there exists a nontrivial coupling between the dark matter sector and the sector responsible for the acceleration of the universe. Such theories can possess an adiabatic regime in which the quintessence field always sits at the minimum of its effective potential, which is set by the local dark matter density. We show that if the coupling strength is much larger than gravitational, then the adiabatic regime is always subject to an instability. The instability, whi...
Hybrid adiabatic potentials in the QCD string model
Kalashnikova, Yu S; Kalashnikova, Yu.S.
2003-01-01
The short- and intermediate-distance behaviour of the hybrid adiabatic potentials is calculated in the framework of the QCD string model. The calculations are performed with the inclusion of Coulomb force. Spin-dependent force and the so-called string correction term are treated as perturbation at the leading potential-type regime. Reasonably good agreement with lattice measurements takes place for adiabatic curves excited with magnetic components of field strength correlators.
Adiabatic CMB perturbations in pre-big bang string cosmology
Enqvist, Kari; Enqvist, Kari; Sloth, Martin S.
2002-01-01
We consider the pre-big bang scenario with a massive axion field which starts to dominate energy density when oscillating in an instanton-induced potential and subsequently reheats the universe as it decays into photons, thus creating adiabatic CMB perturbations. We find that the fluctuations in the axion field can give rise to a nearly flat spectrum of adiabatic perturbations with a spectral tilt $\\Delta n$ in the range $-0.1 \\lesssim \\Delta n \\lesssim 0.3$.
Realization of adiabatic Aharonov-Bohm scattering with neutrons
Sjöqvist, Erik; Almquist, Martin; Mattsson, Ken; Gürkan, Zeynep Nilhan; Hessmo, Björn
2015-11-01
The adiabatic Aharonov-Bohm (AB) effect is a manifestation of the Berry phase acquired when some slow variables take a planar spin around a loop. While the effect has been observed in molecular spectroscopy, direct measurement of the topological phase shift in a scattering experiment has been elusive in the past. Here, we demonstrate an adiabatic AB effect by explicit simulation of the dynamics of unpolarized very slow neutrons that scatter on a long straight current-carrying wire.
Dependence of adiabatic population transfer on pulse profile
S Dasgupta; T kushwaha; D Goswami
2006-06-01
Control of population transfer by rapid adiabatic passage has been an established technique wherein the exact amplitude profile of the shaped pulse is considered to be insignificant. We study the effect of ultrafast shaped pulses for two-level systems, by density-matrix approach. However, we find that adiabaticity depends simultaneously on pulse profile as well as the frequency modulation under non-resonant conditions.
Adiabatic Invariant Treatment of a Collapsing Sphere of Quantized Dust
Roberto CasadioDipartimento di Fisica, Universita' di Bologna and INFN, Bologna; Fabio Finelli(Dipartimento di Fisica, Universita' di Bologna and INFN, Bologna); Giovanni Venturi(Department of Physics, University of Bologna, and Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, Italy)
2015-01-01
The semiclassical collapse of a sphere of quantized dust is studied. A Born-Oppenheimer decomposition is performed for the wave function of the system and the semiclassical limit is considered for the gravitational part. The method of adiabatic invariants for time dependent Hamiltonians is then employed to find (approximate) solutions to the quantum dust equations of motions. This allows us to obtain corrections to the adiabatic approximation of the dust states associated with the time evolut...
Time Development of Exponentially Small Non-Adiabatic Transitions
Hagedorn, George A.; Joye, Alain
2003-01-01
Optimal truncations of asymptotic expansions are known to yield approximations to adiabatic quantum evolutions that are accurate up to exponentially small errors. In this paper, we rigorously determine the leading order non--adiabatic corrections to these approximations for a particular family of two--level analytic Hamiltonian functions. Our results capture the time development of the exponentially small transition that takes place between optimal states by means of a particular switching fu...
Adiabatic Quantum Programming: Minor Embedding With Hard Faults
Klymko, Christine; Sullivan, Blair D.; Humble, Travis S.
2012-01-01
Adiabatic quantum programming defines the time-dependent mapping of a quantum algorithm into an underlying hardware or logical fabric. An essential step is embedding problem-specific information into the quantum logical fabric. We present algorithms for embedding arbitrary instances of the adiabatic quantum optimization algorithm into a square lattice of specialized unit cells. These methods extend with fabric growth while scaling linearly in time and quadratically in footprint. We also provi...
Vacuum vessel eddy current modeling for TFTR adiabatic compression experiments
DeLucia, J.; Bell, M.; Wong, K.L.
1985-07-01
A relatively simple current filament model of the TFTR vacuum vessel is described. It is used to estimate the three-dimensional structure of magnetic field perturbations in the vicinity of the plasma that arise from vacuum vessel eddy currents induced during adiabatic compression. Eddy currents are calculated self-consistently with the plasma motion. The Shafranov formula and adiabatic scaling laws are used to model the plasma. Although the specific application is to TFTR, the present model is of generation applicability.
Vacuum vessel eddy current modeling for TFTR adiabatic compression experiments
A relatively simple current filament model of the TFTR vacuum vessel is described. It is used to estimate the three-dimensional structure of magnetic field perturbations in the vicinity of the plasma that arise from vacuum vessel eddy currents induced during adiabatic compression. Eddy currents are calculated self-consistently with the plasma motion. The Shafranov formula and adiabatic scaling laws are used to model the plasma. Although the specific application is to TFTR, the present model is of generation applicability
Non Adiabatic Centrifugal Compressor Gas Dynamic Performance Definition
Soldatova, Kristina
2014-01-01
Most centrifugal compressors operate in conditions with negligible heat transfer (adiabatic compression). Their plant tests conditions are similar or close to adiabatic conditions. Test regulations establish measures to diminish influence of a heat transfer “compressor body – atmospheric air” to an exit temperature. Therefore a temperature rise in a compressor is used to calculate a work input coefficient and efficiency. Unlike it high pressure centrifugal compressors of gas turbines and supe...
Refractive Indices of Semiconductors from Energy gaps
Tripathy, S K
2015-01-01
An empirical relation based on energy gap and refractive index data has been proposed in the present study to calculate the refractive index of semiconductors. The proposed model is then applied to binary as well as ternary semiconductors for a wide range of energy gap. Using the relation, dielectric constants of some III-V group semiconductors are calculated. The calculated values for different group of binary semiconductors, alkali halides and ternary semiconductors fairly agree with other calculations and known values over a wide range of energy gap. The temperature variation of refractive index for some binary semiconductors have been calculated.
HADAMARD'S FUNDAMENTAL SOLUTION AND CONICAL REFRACTION
Qi Minyou
2000-01-01
Conical refraction in anisotropic media shows two different light speeds,hence the characteristic conoid is composed of two sheets. In a special case that two of the dielectric constants are equal, conic refraction is depicted by a partial differential operator which is factorizable. Thus the singular support of the fundamental solution should also be composed of two sheets. In this paper, the author gives the Hadamard construction of the fundamental solution which is just singular on these two sheets. In case of conic refraction considered, these two sheets are tangent to each other along two bi-characteristic curves, and a special singularity of the boundary-layer type appears there.
Critique of Optical Negative Refraction Superlensing
Christou, George
2010-01-01
Has the ten-year old quest for the optical superlens, based on Veselago's hypothesis of negative refraction, been a chimera? We argue that Pendry's alternative prescription of the silver superlens is nothing more than an application of the natural phenomenon of surface plasmon resonance that occurs in the noble metal films. This phenomenon does not predict the reality of Veselago's negative refractive index materials. We give a simple explanation of how this resonance achieves a field intensity enhancement at the interface of silver and air without involving the concept of negative refraction.
We study the adiabatic tunneling of Bose—Einstein condensates in a symmetric double-well potential when the interaction strength between the atoms is modulated linearly or in a cosine periodic form. It is shown that the system evolves along a nonlinear eigenstate path. In the case of linear modulation under the adiabatic approximation conditions, the tunneling probability of the condensate atoms to the other potential well is half. However, when the system is periodically scanned in the adiabatic process, we find an interesting phenomenon. A small change in the cycle period can lead to the condensate atoms returning to the right well or tunneling to the left well. The system comes from a linear eigenstate back to a nonlinear one, which is completely different from the linear eigenstate evolution. We explain the results by using the energy level and the phase diagram. (general)
Intensity correlations in random media induced by refractive index tuning (RIT)
Faez, Sanli; Lagendijk, Ad
2009-01-01
We introduce a new approach for measuring both the transport and the effective medium properties of light propagation in inhomogeneous media. These properties include the diffusion constant, the path length distribution, and the effective index of refraction. Our method utilizes the equivalence of frequency variation with a change in the index of refraction. A new correlation function that describes correlations in both frequency and index of refraction is introduced. Experimentally, we measure this correlation via spectrally resolved refractive index tuning (RIT), controlling the latter via changes in the ambient pressure. Our new generic measurement technique can be used to characterize a wide variety of materials, including photonic crystals, random photonic media, photonic meta-materials, and certain porous biological samples like bone and wood.
Rhim, W. K.; Burum, D. P.; Elleman, D. D.
1977-01-01
Adiabatic demagnetization (ADRF) can be achieved in a dipolar coupled nuclear spin system in solids by applying a string of short RF pulses and gradually modulating the pulse amplitudes or pulse angles. This letter reports an adiabatic inverse polarization effect in solids and a rotary spin echo phenomenon observed in liquids when the pulse angle is gradually changed across integral multiples of pi during a string of RF pulses. The RF pulse sequence used is illustrated along with the NMR signal from a CaF2 single crystal as observed between the RF pulses and the rotary spin echo signal observed in liquid C6F6 for n = 2. The observed effects are explained qualitatively on the basis of average Hamiltonian theory.
Adiabatic and non-adiabatic charge pumping in a single-level molecular motor
We propose a design for realizing quantum charge pump based on a recent proposal for a molecular motor (Seldenthuis J S et al 2010 ACS Nano 4 6681). Our design is based on the presence of a moiety with a permanent dipole moment which can rotate, thereby modulating the couplings to metallic contacts at both ends of the molecule. Using the non-equilibrium Keldysh Green’s function formalism (NEGF), we show that our design indeed generates a pump current. In the non-interacting pump, the variation of frequency from adiabatic to non-adiabatic regime, can be used to control the direction as well as the amplitude of the average current. The effect of Coulomb interaction is considered within the first- and the second- order perturbation. The numerical implementation of the scheme is quite demanding, and we develop an analytical approximation to obtain a speed-up giving results within a reasonable time. We find that the amplitude of the average pumped current can be controlled by both the driving frequency and the Coulomb interaction. The direction of of pumped current is shown to be determined by the phase difference between left and right anchoring groups. (paper)
Entanglement Generation by Time Varying Refractive Index: Analogy with Cosmological Model
Moradi, Shahpoor
2012-01-01
Generation of entanglement between modes of a electromagnetic fields by sudden change of the refractive index of a medium is considered. We use the analogy between the Fock-space formulation of pair creation caused by the contraction and expansion of the universe on one hand and the pair creation in time-dependent electric fields on the other hand. It is shown that entanglement between photons encodes information concerning the underlying refractive index of a medium.
González-Pérez, Javier; Villa-Collar, César; Sobrino Moreiras, Tomás; Lema Gesto, Isabel; González-Méijome, José Manuel; Rodríguez Ares, María T.; Parafita, Manuel A.
2012-01-01
OBJECTIVES: To study changes in tear film inflammatory mediators following continuous wear of silicone-hydrogel lenses and corneal refractive therapy with reverse geometry contact lenses. DESIGN: A prospective, case-control study. METHODS: Twenty-eight subjects had worn silicone-hydrogel lenses on a 30-night continuous wear basis. Thirty-two subjects had worn corneal refractive therapy lenses on an overnight basis. Thirty-two matched control subjects were also recruited. Tear samples ...
Coupled radiative-conductive heat transfer inside an absorbing-emitting-scattering semitransparent slab is solved. The refractive index of the media is distributed spatially in a linear relationship. The two boundary surfaces are diffuse and opaque. In this paper, the media with graded refractive index is simulated by using multilayer composite model, and in each sub-layer the refractive index is supposed to be constant and the rays of thermal radiation travel in a straight line. The multilayer model is developed by ray-tracing method combined with node analysis. A comparison of the present results with previous results shows that the multilayer simulation of media with graded refractive index is rational and correct. Considering isotropic scattering of thermal radiation, with the changes in the extinction coefficient, surface emissivities and the scattering albedo, the influences of refractive index distribution on the temperature and the radiative heat flux fields are investigated. The results show that the gradient distributing of refractive indexes can cause very different thermal behavior concerned with radiative transfer in semitransparent media compared with constant refractive indexes
Savolainen, Juha-Matti; Grüner-Nielsen, Lars; Kristensen, Poul; Balling, Peter
2013-01-01
A refractive-index change is written inside an optical fiber close to the end face by femtosecond laser light. The induced phase change is measured by analyzing the far-field intensity profiles before and after the irradiation.......A refractive-index change is written inside an optical fiber close to the end face by femtosecond laser light. The induced phase change is measured by analyzing the far-field intensity profiles before and after the irradiation....
The Steen River Crater Seismic Refraction Project
Mazur, M. J.; Hildebrand, A. R.; Hladiuk, D.; Schafer, A.; Pilkington, M.
2002-03-01
Rim uplift, slump blocks, CDC edge, central uplift, and inverted flap are indicated by refraction methods. The inverted flap also has a gravity high and may explain the puzzling partly annular gravity high ringing the CDC at the Chicxulub crater.
The refractive index of relic gravitons
Giovannini, Massimo
2016-06-01
The dynamical evolution of the refractive index of the tensor modes of the geometry produces a specific class of power spectra characterized by a blue (i.e. slightly increasing) slope which is directly determined by the competition of the slow-roll parameter and of the rate of variation of the refractive index. Throughout the conventional stages of the inflationary and post-inflationary evolution, the microwave background anisotropies measurements, the pulsar timing limits and the big-bang nucleosynthesis constraints set stringent bounds on the refractive index and on its rate of variation. Within the physically allowed region of the parameter space the cosmic background of relic gravitons leads to a potentially large signal for the ground-based detectors (in their advanced version) and for the proposed space-borne interferometers. Conversely, the lack of direct detection of the signal will set a qualitatively new bound on the dynamical variation of the refractive index.
The refractive index of relic gravitons
Giovannini, Massimo
2016-01-01
The dynamical evolution of the refractive index of the tensor modes of the geometry produces a specific class of power spectra characterized by a blue (i.e. slightly increasing) slope which is directly determined by the competition of the slow-roll parameter and of the rate of variation of the refractive index. Throughout the conventional stages of the inflationary and post-inflationary evolution, the microwave background anisotropies measurements, the pulsar timing limits and the big-bang nucleosythesis constraints set stringent bounds on the refractive index and on its rate of variation. Within the physically allowed region of the parameter space the cosmic background of relic gravitons leads to a potentially large signal for the ground based detectors (in their advanced version) and for the proposed space-borne interferometers. Conversely, the lack of direct detection of the signal will set a qualitatively new bound on the dynamical variation of the refractive index.
Development of a subjective refraction simulator
Perches, S.; Ares, J.; Collados, M. V.
2013-11-01
We have developed simulation software by Matlab (MathworksInc.) with a graphical interface designed for non-expert users. This simulator allows you to complete the process of subjective refraction starting from the aberrometry of the patients and analyse the influence of different factors during the exam. In addition to explain the graphical interface and its working, we show two examples about a complete process of subjective refraction with the influence of high order aberrations and without them showing the retinal image obtained in each step of the refraction process. When the Jackson Cross-Cylinder technique is made with this software, it becomes clear the difficulty of chosen between two images when high order aberrations are present. Therefore, the variability of response during the refraction can be a problem when the examiner has to reach an adequate optical prescription.
Refractive Index Compensation in Over-Determined Interferometric Systems
Zdeněk Buchta
2012-10-01
Full Text Available We present an interferometric technique based on a differential interferometry setup for measurement under atmospheric conditions. The key limiting factor in any interferometric dimensional measurement are fluctuations of the refractive index of air representing a dominating source of uncertainty when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of an over-determined interferometric setup where a reference length is derived from a mechanical frame made from a material with a very low thermal coefficient. The technique allows one to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third evaluates the changes in the measuring range, acting as a tracking refractometer. The principle is demonstrated in an experimental setup.
Adiabatic photo-steering theory in topological insulators
Feasible external control of material properties is a crucial issue in condensed matter physics. A new approach to achieving this aim, named adiabatic photo-steering, is reviewed. The core principle of this scheme is that several material constants are effectively turned into externally tunable variables by irradiation of monochromatic laser light. Two-dimensional topological insulators are selected as the optimal systems that exhibit a prominent change in their properties following the application of this method. Two specific examples of photo-steered quantum phenomena, which reflect topological aspects of the electronic systems at hand, are presented. One is the integer quantum Hall effect described by the Haldane model, and the other is the quantum spin Hall effect described by the Kane–Mele model. The topological quantities associated with these phenomena are the conventional Chern number and spin Chern number, respectively. A recent interesting idea, time-reversal symmetry breaking via a temporary periodic external stimulation, is also discussed. (focus issue review)
Adiabatic quantum pump in a zigzag graphene nanoribbon junction
Zhang, Lin
2015-11-01
The adiabatic electron transport is theoretically studied in a zigzag graphene nanoribbon (ZGNR) junction with two time-dependent pumping electric fields. By modeling a ZGNR p-n junction and applying the Keldysh Green’s function method, we find that a pumped charge current is flowing in the device at a zero external bias, which mainly comes from the photon-assisted tunneling process and the valley selection rule in an even-chain ZGNR junction. The pumped charge current and its ON and OFF states can be efficiently modulated by changing the system parameters such as the pumping frequency, the pumping phase difference, and the Fermi level. A ferromagnetic ZGNR device is also studied to generate a pure spin current and a fully polarized spin current due to the combined spin pump effect and the valley valve effect. Our finding might pave the way to manipulate the degree of freedom of electrons in a graphene-based electronic device. Project supported by the National Natural Science Foundation of China (Grant No. 110704033), the Natural Science Foundation of Jiangsu Province, China (Grant No. BK2010416), and the Natural Science Foundation for Colleges and Universities in Jiangsu Province, China (Grant No. 13KJB140005).
Frings, Andreas; Richard, Gisbert; Steinberg, Johannes; Skevas, Christos; Druchkiv, Vasyl; Katz, Toam; Linke, Stephan J.
2015-01-01
Purpose In eyes with a preoperative plano refractive cylinder, it would appear that there is no rationale for astigmatic treatment. The aim of this retrospective, cross-sectional data analysis was to determine the amount of topographic astigmatism in refractive plano eyes that results in reduced efficacy after myopic laser in situ keratomileusis (LASIK). Methods This study included 267 eyes from 267 consecutive myopic patients with a refractive plano cylinder. Receiver operating characteristi...
Critique of Optical Negative Refraction Superlensing
Christou, George; Mias, Christos
2010-01-01
Has the ten-year old quest for the optical superlens, based on Veselago's hypothesis of negative refraction, been a chimera? We argue that Pendry's alternative prescription of the silver superlens is nothing more than an application of the natural phenomenon of surface plasmon resonance that occurs in the noble metal films. This phenomenon does not predict the reality of Veselago's negative refractive index materials. We give a simple explanation of how this resonance achieves a field intensi...
Classical gravity does not refract negatively.
McCall, Martin W
2007-03-01
We appraise recent claims that classical gravitation can induce negative refraction of electromagnetic radiation in vacuum. By recasting the previous literature in covariant notation, we show that the criterion used hitherto for determining negative refraction in vacuum is inappropriate, and can even be satisfied by parametrized transformations in Minkowski spacetime. Using instead a covariantly acceptable definition, we find that in classical vacuum the power flux of a plane electromagnetic wave points in the direction of phase advance. PMID:17359145
Exploded representation of a refracting surface
W.H. Heath
2005-01-01
Full Text Available The concept of the exploded refracting sur-face is useful in the optics of contact lenses and vision underwater. The purpose of this paper is to show how to represent a refracting surface as an exploded pair of surfaces separated by a gap of zero width. The analysis is in terms of linear optics and allows for astigmatic and non-coaxial cases.
Negative Refractive Index Metasurfaces for Enhanced Biosensing
Dragan Tanasković
2010-12-01
Full Text Available In this paper we review some metasurfaces with negative values of effective refractive index, as scaffolds for a new generation of surface plasmon polariton-based biological or chemical sensors. The electromagnetic properties of a metasurface may be tuned by its full immersion into analyte, or by the adsorption of a thin layer on it, both of which change its properties as a plasmonic guide. We consider various simple forms of plasmonic crystals suitable for this purpose. We start with the basic case of a freestanding, electromagnetically symmetrical plasmonic slab and analyze different ultrathin, multilayer structures, to finally consider some two-dimensional “wallpaper” geometries like split ring resonator arrays and fishnet structures. A part of the text is dedicated to the possibility of multifunctionalization where a metasurface structure is simultaneously utilized both for sensing and for selectivity enhancement. Finally we give an overview of surface-bound intrinsic electromagnetic noise phenomena that limits the ultimate performance of a metasurfaces sensor.
Dynamical fluctuations in classical adiabatic processes: General description and their implications
Zhang, Qi; Gong, Jiangbin; Oh, C. H.
2010-01-01
Dynamical fluctuations in classical adiabatic processes are not considered by the conventional classical adiabatic theorem. In this work a general result is derived to describe the intrinsic dynamical fluctuations in classical adiabatic processes. Interesting implications of our general result are discussed via two subtopics, namely, an intriguing adiabatic geometric phase in a dynamical model with an adiabatically moving fixed-point solution, and the possible "pollution" to Hannay's angle or...
Solar refractive secondary concentrator technology overview
Refractive secondary concentrators, coupled with advanced primary concentrators, can efficiently convert solar energy to heat for a wide variety of space applications including power generation, thermal propulsion, and furnaces. These applications typically require very high temperatures (as high as 2000 K) and high concentration ratios (10,000 to 1). To enable concentration systems that meet these requirements, the NASA Glenn Research Center is developing the refractive secondary concentrator, which uses refraction and total internal reflection to concentrate and direct solar energy. Presented is an overview of the refractive secondary concentrator technology development effort, including a description of benefits, past accomplishments, and future plans. Highlighted is a recent proof-of-concept test of a prototype sapphire refractive secondary concentrator performed in a solar vacuum environment that demonstrated throughput efficiency of 87%. It is anticipated that the application of an optical coating to the inlet surface of the refractive secondary to reduce the reflection losses at this surface can improve the throughput efficiency to 93%. Plans to conduct additional solar thermal vacuum tests to demonstrate high temperatures and high throughput power are also presented (up to 2000 K and 5 kW)
Refractive index contrast in porous silicon multilayers
Nava, R.; Mora, M.B. de la; Tagueena-Martinez, J. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Temixco, Morelos (Mexico); Rio, J.A. del [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Temixco, Morelos (Mexico); Centro Morelense de Innovacion y Transferencia Tecnologica, Consejo de Ciencia y Tecnologia del Estado de Morelos (Mexico)
2009-07-15
Two of the most important properties of a porous silicon multilayer for photonic applications are flat interfaces and a relative large refractive index contrast between layers in the optical wavelength range. In this work, we studied the effect of the current density and HF electrolyte concentration on the refractive index of porous silicon. With the purpose of increasing the refractive index contrast in a multilayer, the refractive index of porous silicon produced at low current was studied in detail. The current density applied to produce the low porosity layers was limited in order to keep the electrolyte flow through the multilayer structure and to avoid deformation of layer interfaces. We found that an electrolyte composed of hydrofluoric acid, ethanol and glycerin in a ratio of 3:7:1 gives a refractive index contrast around 1.3/2.8 at 600 nm. Several multilayer structures with this refractive index contrast were fabricated, such as dielectric Bragg mirrors and microcavities. Reflectance spectra of the structures show the photonic quality of porous silicon multilayers produced under these electrochemical conditions. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
WANG Xue-bin
2008-01-01
The coexistent phenomenon of deformed and transformed adiabatic shear bands(ASBs) of ductile metal was analyzed using the JOHNSON-COOK model and gradient-dependent plasticity(GDP). The effects of melting point, density, heat capacity and work to heat conversion factor were investigated. Higher work to heat conversion factor, lower density, lower heat capacity and higher melting point lead to wider transformed ASB and higher local plastic shear deformation between deformed and transformed ASBs. Higher work to heat conversion factor, lower density, lower heat capacity and lower melting point cause higher local plastic shear deformation in the deformed ASB. Three reasons for the scatter in experimental data on the ASB width were pointed out and the advantages of the work were discussed. If the transformed ASB width is used to back-calculate the internal length parameter in the GDP, undoubtedly, the parameter will be extremely underestimated.
A Refractive Index Sensor Based on the Resonant Coupling to Cladding Modes in a Fiber Loop
Reyes, Mauricio; Monzón-Hernández, David; Martínez-Ríos, Alejandro; Silvestre, Enrique; Díez, Antonio; Cruz, José Luis; Andrés, Miguel V.
2013-01-01
We report an easy-to-build, compact, and low-cost optical fiber refractive index sensor. It consists of a single fiber loop whose transmission spectra exhibit a series of notches produced by the resonant coupling between the fundamental mode and the cladding modes in a uniformly bent fiber. The wavelength of the notches, distributed in a wavelength span from 1,400 to 1,700 nm, can be tuned by adjusting the diameter of the fiber loop and are sensitive to refractive index changes of the external medium. Sensitivities of 170 and 800 nm per refractive index unit for water solutions and for the refractive index interval 1.40–1.442, respectively, are demonstrated. We estimate a long range resolution of 3 × 10−4 and a short range resolution of 2 × 10−5 for water solutions. PMID:23979478
Goetz, Sebastian; Razinskas, Gary; Krauss, Enno; Dreher, Christian; Wurdack, Matthias; Geisler, Peter; Pawłowska, Monika; Hecht, Bert; Brixner, Tobias
2016-04-01
The nonlinear refractive index of plasmonic materials may be used to obtain nonlinear functionality, e.g., power-dependent switching. Here, we investigate the nonlinear refractive index of single-crystalline gold in thin layers and nanostructures on dielectric substrates. In a first step, we implement a z-scan setup to investigate ~100-µm-sized thin-film samples. We determine the nonlinear refractive index of fused silica, n 2(SiO2) = 2.9 × 10-20 m2/W, in agreement with literature values. Subsequent z-scan measurements of single-crystalline gold films reveal a damage threshold of 0.22 TW/cm2 and approximate upper limits of the real and imaginary parts of the nonlinear refractive index, | n 2'(Au)| crystalline gold film). An upper limit for the nonlinear power-dependent phase change between two propagating near-field modes is determined to Δ φ < 0.07 rad.
Adiabatic condition and the quantum hitting time of Markov chains
We present an adiabatic quantum algorithm for the abstract problem of searching marked vertices in a graph, or spatial search. Given a random walk (or Markov chain) P on a graph with a set of unknown marked vertices, one can define a related absorbing walk P' where outgoing transitions from marked vertices are replaced by self-loops. We build a Hamiltonian H(s) from the interpolated Markov chain P(s)=(1-s)P+sP' and use it in an adiabatic quantum algorithm to drive an initial superposition over all vertices to a superposition over marked vertices. The adiabatic condition implies that, for any reversible Markov chain and any set of marked vertices, the running time of the adiabatic algorithm is given by the square root of the classical hitting time. This algorithm therefore demonstrates a novel connection between the adiabatic condition and the classical notion of hitting time of a random walk. It also significantly extends the scope of previous quantum algorithms for this problem, which could only obtain a full quadratic speedup for state-transitive reversible Markov chains with a unique marked vertex.
Global adiabaticity and non-Gaussianity consistency condition
Romano, Antonio Enea; Sasaki, Misao
2016-01-01
In the context of single-field inflation, the conservation of the curvature perturbation on comoving slices, $R_c$, on super-horizon scales is one of the assumptions necessary to derive the consistency condition between the squeezed limit of the bispectrum and the spectrum of the primordial curvature perturbation. However, the conservation of $R_c$ holds only after the perturbation has reached the adiabatic limit where the constant mode of $R_c$ dominates over the other (usually decaying) mode. In this case, the non-adiabatic pressure perturbation defined in the thermodynamic sense, $\\delta P_{nad}\\equiv\\delta P-c_w^2\\delta\\rho$ where $c_w^2=\\dot P/\\dot\\rho$, usually becomes also negligible on superhorizon scales. Therefore one might think that the adiabatic limit is the same as thermodynamic adiabaticity. This is in fact not true. In other words, thermodynamic adiabaticity is not a sufficient condition for the conservation of $R_c$ on super-horizon scales. In this paper, we consider models that satisfies $\\d...
Interplay between electric and magnetic effect in adiabatic polaritonic systems
Alabastri, Alessandro
2013-01-01
We report on the possibility of realizing adiabatic compression of polaritonic wave on a metallic conical nano-structure through an oscillating electric potential (quasi dynamic regime). By comparing this result with an electromagnetic wave excitation, we were able to relate the classical lighting-rod effect to adiabatic compression. Furthermore, we show that while the magnetic contribution plays a marginal role in the formation of adiabatic compression, it provides a blue shift in the spectral region. In particular, magnetic permeability can be used as a free parameter for tuning the polaritonic resonances. The peculiar form of adiabatic compression is instead dictated by both the source and the metal permittivity. The analysis is performed by starting from a simple electrostatic system to end with the complete electromagnetic one through intermediate situations such as the quasi-electrostatic and quasi-dynamic regimes. Each configuration is defined by a particular set of equations which allows to clearly determine the individual role played by the electric and magnetic contribution in the generation of adiabatic compression. We notice that these findings can be applied for the realization of a THz nano-metric generator. © 2013 Optical Society of America.
Focusing on Plates: Controlling Guided Waves using Negative Refraction
Philippe, Franck D.; Murray, Todd W.; Prada, Claire
2015-06-01
Elastic waves are guided along finite structures such as cylinders, plates, or rods through reflection, refraction, and mode conversion at the interfaces. Such wave propagation is ubiquitous in the world around us, and studies of elastic waveguides first emerged in the later part of the 19th century. Early work on elastic waveguides revealed the presence of backward propagating waves, in which the phase velocity and group velocity are anti-parallel. While backward wave propagation exists naturally in very simple finite elastic media, there has been remarkably little attention paid to this phenomenon. Here we report the development of a tunable acoustic lens in an isotropic elastic plate showing negative refraction over a finite acoustic frequency bandwidth. As compared to engineered acoustic materials such as phononic crystals and metamaterials, the design of the acoustic lens is very simple, with negative refraction obtained through thickness changes rather than internal periodicity or sub-wavelength resonant structures. A new class of acoustic devices, including resonators, filters, lenses, and cloaks, may be possible through topography optimization of elastic waveguide structures to exploit the unique properties of backward waves.
Kim, Jeong-Gil; Hsieh, Chih-Hung; Choi, Hyungryul J; Gardener, Jules; Singh, Bipin; Knapitsch, Arno; Lecoq, Paul; Barbastathis, George
2015-08-24
We propose, analyze and optimize a two-dimensional conical photonic crystal geometry to enhance light extraction from a high refractive index material, such as an inorganic scintillator. The conical geometry suppresses Fresnel reflections at an optical interface due to adiabatic impedance matching from a gradient index effect. The periodic array of cone structures with a pitch larger than the wavelength of light diffracts light into higher-order modes with different propagating angles, enabling certain photons to overcome total internal reflection (TIR). The numerical simulation shows simultaneous light yield gains relative to a flat surface both below and above the critical angle and how key parameters affect the light extraction efficiency. Our optimized design provides a 46% gain in light yield when the conical photonic crystals are coated on an LSO (cerium-doped lutetium oxyorthosilicate) scintillator. PMID:26368241
Refractive Secondary Concentrators for Solar Thermal Applications
Wong, Wayne A.; Macosko, Robert P.
1999-01-01
The NASA Glenn Research Center is developing technologies that utilize solar energy for various space applications including electrical power conversion, thermal propulsion, and furnaces. Common to all of these applications is the need for highly efficient, solar concentration systems. An effort is underway to develop the innovative single crystal refractive secondary concentrator, which uses refraction and total internal reflection to efficiently concentrate and direct solar energy. The refractive secondary offers very high throughput efficiencies (greater than 90%), and when used in combination with advanced primary concentrators, enables very high concentration ratios (10,0(X) to 1) and very high temperatures (greater than 2000 K). Presented is an overview of the refractive secondary concentrator development effort at the NASA Glenn Research Center, including optical design and analysis techniques, thermal modeling capabilities, crystal materials characterization testing, optical coatings evaluation, and component testing. Also presented is a discussion of potential future activity and technical issues yet to be resolved. Much of the work performed to date has been in support of the NASA Marshall Space Flight Center's Solar Thermal Propulsion Program. The many benefits of a refractive secondary concentrator that enable efficient, high temperature thermal propulsion system designs, apply equally well to other solar applications including furnaces and power generation systems such as solar dynamics, concentrated thermal photovoltaics, and thermionics.
Adiabaticity and gravity theory independent conservation laws for cosmological perturbations
Romano, Antonio Enea; Sasaki, Misao
2015-01-01
We carefully study the implications of adiabaticity for the behavior of cosmological perturbations. There are essentially three similar but different definitions of non-adiabaticity: one is appropriate for a thermodynamic fluid $\\delta P_{nad}$, another is for a general matter field $\\delta P_{c,nad}$, and the last one is valid only on superhorizon scales. The first two definitions coincide if $c_s^2=c_w^2$ where $c_s$ is the propagation speed of the perturbation, while $c_w^2=\\dot P/\\dot\\rho$. Assuming the adiabaticity in the general sense, $\\delta P_{c,nad}=0$, we derive a relation between the lapse function in the comoving slicing $A_c$ and $\\delta P_{nad}$ valid for arbitrary matter field in any theory of gravity, by using only momentum conservation. The relation implies that as long as $c_s\
Integrated polarization rotator/converter by stimulated Raman adiabatic passage.
Xiong, Xiao; Zou, Chang-Ling; Ren, Xi-Feng; Guo, Guang-Can
2013-07-15
We proposed a polarization rotator inspired by stimulated Raman adiabatic passage model from quantum optics, which is composed of a signal waveguide and an ancillary waveguide. The two orthogonal modes in signal waveguide and the oblique mode in ancillary waveguide form a Λ-type three-level system. By controlling the width of signal waveguide and the gap between two waveguides, adiabatic conversion between two orthogonal modes can be realized in the signal waveguide. With such adiabatic passage, polarization conversion is completed within 150 μm length, with the efficiencies over 99% for both conversions between horizontal polarization and vertical polarization. In addition, such a polarization rotator is quite robust against fabrication error, allowing a wide range of tolerances for the rotator geometric parameters. Our work is not only significative to photonic simulations of coherent quantum phenomena with engineered photonic waveguides, but also enlightens the practical applications of these phenomena in optical device designs. PMID:23938558
Monitoring of temperature-mediated adipose tissue phase transitions by refractive-index measurements
Yanina, I. Yu.; Popov, A. P.; Bykov, A. V.; Tuchin, V. V.
2014-10-01
Monitoring of temperature-mediated adipose tissue phase transitions were studied in vitro using an Abbe refractometer. The 1-2-mm thick porcine fat tissues slices were used in the experiments. The observed change in the tissue was associated with several phase transitions of lipid components of the adipose tissue. It was found that overall heating of a sample from the room to higher temperature led to more pronounced and tissue changes in refractive index if other experimental conditions were kept constant. We observed an abrupt change in the refractive index in the temperature range of 37-60 °C.
Adiabatic fluctuations from cosmic strings in a contracting universe
We show that adiabatic, super-Hubble, and almost scale invariant density fluctuations are produced by cosmic strings in a contracting universe. An essential point is that isocurvature perturbations produced by topological defects such as cosmic strings on super-Hubble scales lead to a source term which seeds the growth of curvature fluctuations on these scales. Once the symmetry has been restored at high temperatures, the isocurvature seeds disappear, and the fluctuations evolve as adiabatic ones in the expanding phase. Thus, cosmic strings may be resurrected as a mechanism for generating the primordial density fluctuations observed today
Non-adiabatic pumping through interacting quantum dots
Cavaliere, Fabio; Governale, Michele; König, Jürgen
2009-01-01
We study non-adiabatic two-parameter charge and spin pumping through a single-level quantum dot with Coulomb interaction. For the limit of weak tunnel coupling and in the regime of pumping frequencies up to the tunneling rates, $\\Omega \\lesssim \\Gamma/\\hbar$, we perform an exact resummation of contributions of all orders in the pumping frequency. As striking non-adiabatic signatures, we find frequency-dependent phase shifts in the charge and spin currents, which allow for an effective single-...
Adiabatic theory of ionization of atoms by intense laser pulses
As a first step towards the adiabatic theory of ionization of atoms by intense laser pulses, here we consider the simplest one-dimensional zero-range potential model. The asymptotic solution to the time-dependent Schroedinger equation in the adiabatic regime is obtained and the photoelectron spectrum is calculated. The factorization formula for the photoelectron spectrum in the back-rescattering region, first suggested by Morishita et al. [Phys. Rev. Lett. 100, 013903 (2008)] on the basis of ab initio calculations, is derived analytically.
Classical nuclear motion coupled to electronic non-adiabatic transitions
Agostini, Federica; Gross, E K U
2014-01-01
We present a detailed derivation and numerical tests of a new mixed quantum-classical scheme to deal with non-adiabatic processes. The method is presented as the zero-th order approximation to the exact coupled dynamics of electrons and nuclei offered by the factorization of the electron-nuclear wave function [A. Abedi, N. T. Maitra and E. K. U. Gross, Phys. Rev. Lett., 105 (2010)]. Numerical results are presented for a model system for non-adiabatic charge transfer in order to test the performance of the method and to validate the underlying approximations.
Classical nuclear motion coupled to electronic non-adiabatic transitions
Agostini, Federica; Abedi, Ali; Gross, E. K. U.
2014-12-01
Based on the exact factorization of the electron-nuclear wave function, we have recently proposed a mixed quantum-classical scheme [A. Abedi, F. Agostini, and E. K. U. Gross, Europhys. Lett. 106, 33001 (2014)] to deal with non-adiabatic processes. Here we present a comprehensive description of the formalism, including the full derivation of the equations of motion. Numerical results are presented for a model system for non-adiabatic charge transfer in order to test the performance of the method and to validate the underlying approximations.
Classical nuclear motion coupled to electronic non-adiabatic transitions
Agostini, Federica; Abedi, Ali; Gross, E. K. U. [Max-Planck Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany)
2014-12-07
Based on the exact factorization of the electron-nuclear wave function, we have recently proposed a mixed quantum-classical scheme [A. Abedi, F. Agostini, and E. K. U. Gross, Europhys. Lett. 106, 33001 (2014)] to deal with non-adiabatic processes. Here we present a comprehensive description of the formalism, including the full derivation of the equations of motion. Numerical results are presented for a model system for non-adiabatic charge transfer in order to test the performance of the method and to validate the underlying approximations.
Classical nuclear motion coupled to electronic non-adiabatic transitions
Based on the exact factorization of the electron-nuclear wave function, we have recently proposed a mixed quantum-classical scheme [A. Abedi, F. Agostini, and E. K. U. Gross, Europhys. Lett. 106, 33001 (2014)] to deal with non-adiabatic processes. Here we present a comprehensive description of the formalism, including the full derivation of the equations of motion. Numerical results are presented for a model system for non-adiabatic charge transfer in order to test the performance of the method and to validate the underlying approximations
Resonances and adiabatic invariance in classical and quantum scattering theory
Jain, S R
2004-01-01
We discover that the energy-integral of time-delay is an adiabatic invariant in quantum scattering theory and corresponds classically to the phase space volume. The integral thus found provides a quantization condition for resonances, explaining a series of results recently found in non-relativistic and relativistic regimes. Further, a connection between statistical quantities like quantal resonance-width and classical friction has been established with a classically deterministic quantity, the stability exponent of an adiabatically perturbed periodic orbit. This relation can be employed to estimate the rate of energy dissipation in finite quantum systems.
Nanoscale resolution for fluorescence microscopy via adiabatic passage
Rubio, Juan Luis; Ahufinger, Verònica; Mompart, Jordi
2015-01-01
We propose the use of the subwavelength localization via adiabatic passage technique for fluorescence microscopy with nanoscale resolution in the far field. This technique uses a {\\Lambda}-type medium coherently coupled to two laser pulses: the pump, with a node in its spatial profile, and the Stokes. The population of the {\\Lambda} system is adiabatically transferred from one ground state to the other except at the node position, yielding a narrow population peak. This coherent localization allows fluorescence imaging with nanometer lateral resolution. We derive an analytical expression to asses the resolution and perform a comparison with the coherent population trapping and the stimulated-emission-depletion techniques.
Adiabatic and isothermal compressibility in the liquid state
The paper reviews the work carried out on the adiabatic and isothermal compressibility of liquid alkali metals. Saturated liquid states are discussed, including thermodynamic relations, adiabatic compressibility and isothermal compressibility. Results for the compressibility, and other related quantities, for the saturated liquids: lithium, potassium, rubidium, caesium and sodium, over the temperature range approx.= 300 - 18000 K, are presented. Subcooled liquid states are also examined with respect to its thermodynamic relations, and compressibility results (and other related quantities) for the same elements are given. An assessment of errors and data reliability is briefly discussed. (U.K.)
High beta lasing in micropillar cavities with adiabatic layer design
Lermer, M.; Gregersen, Niels; Lorke, M.;
2013-01-01
We report on lasing in optically pumped adiabatic micropillar cavities, based on the AlAs/GaAs material system. A detailed study of the threshold pump power and the spontaneous emission β factor in the lasing regime for different diameters dc is presented. We demonstrate a reduction of the thresh...... threshold pump power by over 2 orders of magnitude from dc = 2.25 μm down to 0.95 μm. Lasing with β factors exceeding 0.5 shows that adiabatic micropillars are operating deeply in the cavity quantum electrodynamics regime....
Refraction by a spherical nematic bubble
Sherman, Richard David
1989-08-01
A formalism is developed to study refraction by a spherical nematic bubble. It is applicable to bubbles that are larger than light wavelengths, but smaller than the dimensions for excitation of director-fluctuation-induced scattering. The technique yields a nonlinear differential equation and an associated integral which govern the trajectory of a ray inside a nematic region for an arbitrary director configuration. Explicit solutions are provided for five simple interior arrangements-isotropic, onion skin, radial star, horizontal (bottle brush), and vertical. It is then demonstrated that for extraordinary-ordinary refractive-index difference small compared to either, interfacial refraction at the bubble surface is the dominant contribution; deviations from a rectilinear path are small. When ranked in terms of decreasing scattering effectiveness, the sequence is horizontal, onion, isotropic, radial, and vertical if the light is linearly polarized and coupling optimally to the extraordinary index component; for unpolarized incoherent light the order becomes isotropic, horizontal, onion, radial, and vertical.
Seismic refraction analysis: the path forward
Haines, Seth S.; Zelt, Colin; Doll, William
2012-01-01
Seismic Refraction Methods: Unleashing the Potential and Understanding the Limitations; Tucson, Arizona, 29 March 2012 A workshop focused on seismic refraction methods took place on 29 May 2012, associated with the 2012 Symposium on the Application of Geophysics to Engineering and Environmental Problems. This workshop was convened to assess the current state of the science and discuss paths forward, with a primary focus on near-surface problems but with an eye on all applications. The agenda included talks on these topics from a number of experts interspersed with discussion and a dedicated discussion period to finish the day. Discussion proved lively at times, and workshop participants delved into many topics central to seismic refraction work.
Utilisation of the refraction seismic method
Seismic refraction surveys have been carried out in the same traditional way since the 1950's. The development of seismics has been concentrated in improvement of the data processing techniques. The latest advance in the refraction method is the Generalised Reciprocal Method, GRM, developed in Australia during the last decade. The new method is actually a widening of the well-known ABC-method. The GRM-method makes it easier to determine the origins in soil layers or in the bedrock of the velocity anomalies found in refraction data. A FORTRAN-77 program is implemented on IBM-PC to calculate the time-depths and velocity analyses of the GRM-method. A FFT-routine needed in the wave form analysis is also programmed. These codes as well as plotting routines written in BASIC can be obtained from the Geotechnical Laboratory of the Technical Research Centre of Finland. In the traditional refraction survey only the first arrival of the elastic waves has been measured. Seismographs used in these surveys have usually an analog output on paper. Only two digital seismographs have been used in Finland, but at least three new digital systems will be bought this year. Digital seismographs are able to record the whole wave form, which gives the possibility to analyse also later arrivals. Examples from abroad show that the the quality of shallow bedrock can be interpreted quantitatively when the attenuation of the waves is studied. The bedrock reflection can also be recorded in digital seismograms. The integration of the refraction and reflection methods will increase the accuracy of the shallow seismic method significantly. In discussion with the interpreters of main Finnish companies running seismic surveys the most common problems met in the praxis and the needs for development work to improve the interpretation of digital refraction data were mapped
Corneal refractive surgery: Is intracorneal the way to go and what are the needs for technology?
Hjortdal, Jesper; Ivarsen, Anders
2014-02-01
Corneal refractive surgery aims to reduce or eliminate refractive errors of the eye by changing the refractive power of the cornea. For the last 20 years controlled excimer laser ablation of corneal tissue, either directly from the corneal stromal surface or from the corneal interior after creation of a superficial corneal flap has become widely used to correct myopia, hyperopia, and astigmatism. Recently, an intrastromal refractive procedure whereby a tissue lenticule is cut free in the corneal stroma by a femtosecond laser and removed through a small peripheral incision has been introduced. This procedure avoids creation of a corneal flap and the potential associated risks while avoiding the slow visual recovery of surface ablation procedures. Precise intrastromal femtosecond laser cutting of the fine lenticule requires very controlled laser energy delivery in order to avoid lenticule irregularities, which would compromise the refractive result and visual acuity. This newly introduced all-femtosecond based flap-free intracorneal refractive procedure has been documented to be a predictable, efficient, and safe procedure for correction of myopia and astigmatism. Technological developments related to further improved cutting quality, hyperopic and individualized treatments are desirable.
Focussing Image Slicers Refractive and Reflective
Richardson, E H; Tilleman, T; Crampton, D S; Crampton, David
1999-01-01
A number of design options for image slicers for NGST and Gemini are being investigated. These image slicers are all of the focussing type and both refractive and reflective solutions are being explored. One such device, an image slicer that focuses 10 slices on a spectrograph slit is now in operation at the McMath Solar telescope. It consists of three lenslet arrays, and additionally acts as a focal reducer and provides correction for astigmatism of the telescope. A combined refractive and reflective slicer designed for use on NGST delivers near-diffraction limited images for up to 40 slices.
Refraction of Gluon jet in QGP
Zhang, Hanzhong; Wang, Enke
2008-01-01
We introduce photon-like refraction for gluon jet in quark gluon plasma created in high energy nucleus-nucleus collisions. A quark jet goes straightly while a gluon jet is assumed to bend in the non-homogeneous medium. Combining refraction and energy loss, we calculate the away-side dihadron $\\Delta\\phi$ distribution in central $Au+Au$ collisions at RHIC energy. The dihadrons from quark-quark pair center around $\\Delta\\phi=\\pi$, while the dihadrons from quark-gluon and gluon-gluon pair are de...
A Liquid Prism for Refractive Index Studies
Edmiston, Michael D.
2001-11-01
A hollow glass prism filled with liquid becomes a "liquid prism". A simple method for constructing hollow glass prisms is presented. A method is given for a demonstration that uses the liquid prism with a laser or laser pointer so the audience can observe differences in refractive index for various liquids. The demonstration provides a quick and easy determination of the sugar content of soft drinks and juices. The prism makes it easy to determine a numerical value for the refractive index of a liquid.
A Colorful Demonstration of Thermal Refraction
Ciotola, Mark
2014-01-01
The wave nature of heat flow mechanisms, such as lattice waves is discussed. Tan and Holland's Tangent Law of heat flow refraction is reviewed. A classroom demonstration of heat flow refraction through conductors in series is presented, and sample results are examined for consistency with the Tangent Law. To predict results, the Tangent Law is derived from the Principle of Least Resistance for this demonstration. User-modifiable simulations in Ruby and Ruby on Rails are presented, along with simulation results for various combinations of conductors. Results are interpreted in terms of the Principle of Least Time, illustrating a powerful unification in physics between disparate areas such as optics and thermodynamics.
Calculational schemes enabling to go beyond crude Condon approximation in non-adiabatic electron transfer reactions are discussed with the use of continuum approximation for the solvent polarization. An algorithm for the self-consistent introduction of an effective reaction coordinate in the adiabatic transition is suggested. Effects due to deviations from the Born-Oppenheimer approximation in bridge-assisted electron transfer reactions are discussed. Interpolation formulae covering limits of coherent and sequential electron transfer in bridge-assisted processes are presented. Simple equations determining a parametric dependence of the transition probability on the reaction free energy in crude Condon approximation are included. (author)
Demystifying back scatter interferometry: a sensitive refractive index detector
Jepsen, Søren Terpager; Jørgensen, Thomas Martini; Trydal, Torleif;
2014-01-01
BACKGROUND: Back Scatter Interferometry (BSI) is a sensitive method for detecting changes of the refractive index (RI) in small capillaries. The method was originally developed as an off-axial column detector for use in Liquid Chromatography or Capillary Electrophoresis systems, but it has been...... acting like a common-path interferometer. METHODS: A HeNe laser is directed at a glass capillary with inner diameter of 1.4 mm and reflected light from air/glass and liquid/glass interfaces interfere to form an RI dependent intensity fringe pattern at a CCD detector. The fringe shift relative...
Ultraviolet light induced refractive index structures in germanosilica
Svalgaard, Mikael
1997-01-01
bulk optics. Finally, I have developed a new method for direct UV writing of planar waveguide devices using a focussed continuous wave UV laser beam which is scanned across a photosensitive thin film deposited on a silicon wafer. Contrary to other waveguide fabrication techniques this method requires...... application of a scanning near-field optical microscope to obtain high resolution images of UV induced refractive index structures and by monitoring the dynamics of UV induced index changes and luminescence. During part of my ph.d. project I have worked at the National Institute of Standards and Technolgy in...
Wave-vector and polarization dependence of conical refraction
Turpin, A; Kalkandjiev, T K; Tomizawa, H; Mompart, J
2014-01-01
We experimentally address the wave-vector and polarization dependence of the internal conical refraction phenomenon by demonstrating that an input light beam of elliptical transverse profile refracts into two beams after passing along one of the optic axes of a biaxial crystal, i.e. it exhibits double refraction instead of refracting conically. Such double refraction is investigated by the independent rotation of a linear polarizer and a cylindrical lens. Expressions to describe the position and the intensity pattern of the refracted beams are presented and applied to predict the intensity pattern for an axicon beam propagating along the optic axis of a biaxial crystal.
Transient energy excitation in shortcuts to adiabaticity for the time dependent harmonic oscillator
Chen, Xi
2010-01-01
There is recently a surge of interest to cut down the time it takes to change the state of a quantum system adiabatically. We study for the time-dependent harmonic oscillator the transient energy excitation in speed-up processes designed to reproduce the initial populations at some predetermined final frequency and time, providing lower bounds and examples. Implications for the limits imposed to the process times and for the principle of unattainability of the absolute zero, in a single expansion or in quantum refrigerator cycles, are drawn.
Jayter Silva de Paula
2009-12-01
Full Text Available PURPOSE: Intermittent exotropia may be decreased by stimulation of accommodative convergence. Once excessive accommodation has been related to myopia, our objective was to evaluate refractive errors changes in children under overcorrecting minus lens therapy. METHODS: A retrospective chart review of 21 children with intermittent exotropia was performed. All patients were treated with occlusion, and a 13-patient subset of them received overminus lens therapy (group A. Eight children received spectacles as necessary (group B. Initial age, age interval, initial spherical equivalent (SE, and magnitude of overcorrection were considered as co-variables of the mean variation in refractive error (SE of each eye between groups, through a multivariate analysis. RESULTS: Overcorrection used in group A ranged from 0.5 D to 3.5 D (2.46 ± 0.87 D. Although initial SE of each eye was significant different between group A and B (OD - p=0.02; OS - p=0.01, initial age (p=0.69, age interval (p=0.90, and mean variation in refractive errors (p=0.36 did not differ between groups. Multivariate analysis with linear regression showed no significantly difference regarding all co-variables enrolled. CONCLUSIONS: Treatment of intermittent exotropia with overcorrecting minus lens did not induce refractive errors changes, even considering age, treatment period, initial spherical equivalent and overcorrection magnitude used.OBJETIVO: A exotropia intermitente pode ser diminuída pela estimulação da convergência acomodativa. Uma vez que uma acomodação excessiva tem sido relacionada à miopização, o objetivo deste trabalho foi o de avaliar alterações nos vícios de refração de crianças submetidas à hipercorreção com lentes negativas. MÉTODOS: Foi realizada revisão dos prontuários de 21 crianças com exotropia intermitente. Todos os pacientes foram tratados com oclusão, sendo que 13 deles foram submetidos à hipercorreção com lentes negativas (grupo A. As 8
On Models of Nonlinear Evolution Paths in Adiabatic Quantum Algorithms
In this paper, we study two different nonlinear interpolating paths in adiabatic evolution algorithms for solving a particular class of quantum search problems where both the initial and final Hamiltonian are one-dimensional projector Hamiltonians on the corresponding ground state. If the overlap between the initial state and final state of the quantum system is not equal to zero, both of these models can provide a constant time speedup over the usual adiabatic algorithms by increasing some another corresponding “complexity. But when the initial state has a zero overlap with the solution state in the problem, the second model leads to an infinite time complexity of the algorithm for whatever interpolating functions being applied while the first one can still provide a constant running time. However, inspired by a related reference, a variant of the first model can be constructed which also fails for the problem when the overlap is exactly equal to zero if we want to make up the 'intrinsic' fault of the second model — an increase in energy. Two concrete theorems are given to serve as explanations why neither of these two models can improve the usual adiabatic evolution algorithms for the phenomenon above. These just tell us what should be noted when using certain nonlinear evolution paths in adiabatic quantum algorithms for some special kind of problems. (general)
Scalings for a traveling mirror adiabatic magnetic compressor
Bellan, P. M.
1982-01-01
Detailed practical scaling relations for a traveling mirror adiabatic magnetic compressor are derived, and an example is given of how this technique could be used to translate, compress, and heat the Los Alamos FRX-C reversed field theta pinch plasma.
Adiabatic waves along interfacial layers near the critical point
Gouin, Henri
2008-01-01
Near the critical point, isothermal interfacial zones are investigated starting from a non-local density of energy. From the equations of motion of thermocapillary fluids, we point out a new kind of adiabatic waves propagating along the interfacial layers. The waves are associated with the second derivatives of densities and propagate with a celerity depending on the proximity of the critical point.
When an Adiabatic Irreversible Expansion or Compression Becomes Reversible
Anacleto, Joaquim; Ferreira, J. M.; Soares, A. A.
2009-01-01
This paper aims to contribute to a better understanding of the concepts of a "reversible process" and "entropy". For this purpose, an adiabatic irreversible expansion or compression is analysed, by considering that an ideal gas is expanded (compressed), from an initial pressure P[subscript i] to a final pressure P[subscript f], by being placed in…
Digitized adiabatic quantum computing with a superconducting circuit.
Barends, R; Shabani, A; Lamata, L; Kelly, J; Mezzacapo, A; Las Heras, U; Babbush, R; Fowler, A G; Campbell, B; Chen, Yu; Chen, Z; Chiaro, B; Dunsworth, A; Jeffrey, E; Lucero, E; Megrant, A; Mutus, J Y; Neeley, M; Neill, C; O'Malley, P J J; Quintana, C; Roushan, P; Sank, D; Vainsencher, A; Wenner, J; White, T C; Solano, E; Neven, H; Martinis, John M
2016-06-01
Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable. PMID:27279216
Evolutions of Yang Phase Under Cyclic Condition and Adiabatic Condition
QIAN Shang-Wu; GU Zhi-Yu
2005-01-01
There are three non-integrable phases in literatures: Berry phase, Aharonov-Anandan phase, and Yang phase. This article discusses the evolutions of Yang phase under the cyclic condition and the adiabatic condition for the generaltime-dependent harmonic oscillator, thus reveals the intimate relations between these three non-integrable phases.
Adiabatic CMB perturbations in pre-big bang string cosmology
Enqvist, Kari; Sloth, Martin Snoager
2001-01-01
We consider the pre-big bang scenario with a massive axion field which starts to dominate energy density when oscillating in an instanton-induced potential and subsequently reheats the universe as it decays into photons, thus creating adiabatic CMB perturbations. We find that the fluctuations in...
Digitized adiabatic quantum computing with a superconducting circuit
Barends, R.; Shabani, A.; Lamata, L.; Kelly, J.; Mezzacapo, A.; Heras, U. Las; Babbush, R.; Fowler, A. G.; Campbell, B.; Chen, Yu; Chen, Z.; Chiaro, B.; Dunsworth, A.; Jeffrey, E.; Lucero, E.; Megrant, A.; Mutus, J. Y.; Neeley, M.; Neill, C.; O’Malley, P. J. J.; Quintana, C.; Roushan, P.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T. C.; Solano, E.; Neven, H.; Martinis, John M.
2016-06-01
Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable.
Evolutions of Yang Phase Under Cyclic Condition and Adiabatic Condition
There are three non-integrable phases in literatures: Berry phase, Aharonov-Anandan phase, and Yang phase. This article discusses the evolutions of Yang phase under the cyclic condition and the adiabatic condition for the general time-dependent harmonic oscillator, thus reveals the intimate relations between these three non-integrable phases.
Adiabatic single scan two-dimensional NMR spectrocopy.
Pelupessy, Philippe
2003-10-01
New excitation schemes, based on the use adiabatic pulses, for single scan two-dimensional NMR experiments (Frydman et al., Proc. Nat. Acad. Sci. 2002, 99, 15 858-15 862) are introduced. The advantages are discussed. Applications in homo- and heteronuclear experiments are presented. PMID:14519020
A Quantum Adiabatic Algorithm for Factorization and Its Experimental Implementation
Peng, Xinhua; Liao, Zeyang; Xu, Nanyang; Qin, Gan; Zhou, Xianyi; Suter, Dieter; Du, Jiangfeng
2008-01-01
We propose an adiabatic quantum algorithm capable of factorizing numbers, using fewer qubits than Shor's algorithm. We implement the algorithm in an NMR quantum information processor and experimentally factorize the number 21. Numerical simulations indicate that the running time grows only quadratically with the number of qubits.
Adiabatic and diabatic aerosol transport to the Jungfraujoch
Lugauer, M.; Baltensperger, U.; Furger, M.; Jost, D.T.; Schwikowski, M.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
1997-09-01
Synoptic scale vertical motion, here detected by the geopotential height of the 500 hPa surface, mainly accounts for the aerosol transport to the Jungfraujoch in winter. In summer, diabatic convection provides the dominant vertical transport mechanism. Nevertheless, synoptic scale adiabatic motion still determines whether diabatic convection can develop. (author) 2 figs., 2 refs.
Dark Energy and Dark Matter from an additional adiabatic fluid
Dunsby, Peter K S; Reverberi, Lorenzo
2016-01-01
The Dark Sector is described by an additional barotropic fluid which evolves adiabatically during the universe's history and whose adiabatic exponent $\\gamma$ is derived from the standard definitions of specific heats. Although in general $\\gamma$ is a function of the redshift, the Hubble parameter and its derivatives, we find that our assumptions lead necessarily to solutions with $\\gamma = $ constant in a FLRW universe. The adiabatic fluid acts effectively as the sum of two distinct components, one evolving like non-relativistic matter and the other depending on the value of the adiabatic index. This makes the model particularly interesting as a way of simultaneously explaining the nature of both Dark Energy and Dark Matter, at least at the level of the background cosmology. The $\\Lambda$CDM model is included in this family of theories when $\\gamma = 0$. We fit our model to SNIa, $H(z)$ and BAO data, discussing the model selection criteria. The implications for the early-universe and the growth of small per...
On the hydrogen-air adiabatic isochoric complete combustion pressure
A simple and fast method for calculating the AICC state (adiabatic Isochoric Complete Combustion) for the hydrogen-air reaction is presented. By comparison with more detailed algorithms it is shown that the proposed method produces satisfactory results, and is thus a viable alternative in situations where the use of detailed algorithms or of tables is too time-consuming. (orig.)
Wave refraction studies off Agonda beach (Goa)
Krishnakumar, V.; Pathak, M.C.; Kotnala, K.L.
Analysis of wave refraction and longshore current has been carried out for a narrow strip off the shores of Agonda (Goa, India). Zones with high wave energy and rip currents have been demarcated. It is found from the analysis that the southern part...
Refractivity estimation from radar sea clutter
Huang Si-Xun; Zhao Xiao-Feng; Sheng Zheng
2009-01-01
This paper addresses the problem of estimating lower atmospheric refractivity under the nonstandard propagation conditions frequently encountered in low altitude maritime radar applications. The vertical structure of the refractive environment is modeled by using a five-parameter model, and the horizontal structure is modeled as range-independent. The electromagnetic propagation in the troposphere is simulated by using a split-step fast Fourier transform based on parabolic approximation to the wave equation. A global search marked as a modified genetic algorithm (MGA) for the 5 environmental parameters is performed by using a genetic algorithm (GA) integrated with a simulated annealing technique. The retrieved results from simulated runs demonstrate the ability of this method to make atmospheric refractivity estimations. A comparison with the classical GA and the Bayesian Markov Chain Monte Carlo (Bayesian-MCMC) technique shows that the MGA can not only shorten the inverse time but also improve the inverse precision. For real data cases, the inversion values do not match the reference data very well. The inverted profile, however, can be used to synoptically describe the real refractive structure.
A Mechanical Analogue of the Refracting Telescope
Vannoni, Maurizio; Molesini, Giuseppe; Sordini, Andrea; Straulino, Samuele
2011-01-01
The recent celebration of the discoveries made by Galileo four centuries ago has attracted new attention to the refracting telescope and to its use as an instrument for the observation of the night sky. This has offered the opportunity for addressing in the classroom the basic principles explaining the operation of the telescope. When doing so, a…
Refractive surgery in systemic and autoimmune disease
Majed AlKharashi
2014-01-01
Full Text Available Patients with underlying systemic disease represent challenging treatment dilemma to the refractive surgeon. The refractive error in this patient population is accompanied by a systemic disease that may have an ocular or even a corneal component. The literature is rather sparse about the use of laser refractive surgery (LRS and such procedure is not approved by the United States Food and Drug Administration (FDA in this patient population. Patients with collagen vascular disease, diabetes mellitus (DM, allergic and atopic disease, or human immunodeficiency virus (HIV are never ideal for LRS. Patients with uncontrolled systemic disease or ocular involvement of the disease should not undergo LRS. However, a patient with well-controlled and mild disease, no ocular involvement, and not on multidrug regimen may be a suitable candidate if they meet stringent criteria. There is a need for a large, multicenter, controlled trial to address the safety and efficacy of LRS in patients with systemic disease before such technology can be widely adopted by the refractive surgery community.
Refractive index dispersion law of silica aerogel
This paper presents measurements of the refractive index of a hygroscopic silica aerogel block at several wavelengths. The measurements, performed with a monochromator, have been compared with different parameterisations for n(λ), in order to determine the best chromaticity law for the aerogel. This is an important input for design and operation of RICH detectors with silica aerogel radiator. (orig.)
Effect of photo irradiation on the refractive indices of spirobenzopyran film
Kim, E K; Lee, M H; Han, S G; Keum, S R
1999-01-01
The effect of photo irradiation on the refractive index of spirobenzopyran (SP) polymer was investigated. Spirobenzopyran polymers were prepared by a radical polymerization using 6-(p-methacryloyloxy-hexyloxyphenyl)carbonylspirobenzopyran, styrene, and butylmethacrylate. Films with spirobenzopyran polymers showed color change from pale yellow to deep blue upon irradiation of a monochromatic light of 340 nm, The colored films were bleached either spontaneously or by light of 580 nm. The refractive index changes of the spirobenzopyran polymers were 5x10 sup - sup 4 and 9x10 sup - sup 4 for 20 wt% and 35 wt% of the spirobenzopyran content, respectively.
Modification of the refractive index of dielectrica by means of ionizing radiation
Refractive-index changes are studied, which result by interaction of ionizing radiation with dielectric, optically transparent solids. As examples two materials are studied. At the one hand it deals with polymethylmethacrylate (PMMA), a polymer, which is irradiated with synchrotron radiation, and at the other hand with lithium niobate (LiNbO3), an oxidic crystal, which is irradiated by fast helium ions. In both materials refractive-index changes in the range 10-4 to 10-3 can be produced, which is very interesting for many applications in photonics
Theoretical Design of adiabatic capillary tube of a domestic refrigerator using refrigerant R-600a.
Sahoo. K. C
2016-08-01
Full Text Available This paper develops a more accurate theoretical procedure for the design of adiabatic capillary tube of a domestic refrigerator considering a rigorous pressure drop analysis on the refrigerant R-600a while expanding through that tube accompanied with phase change through flash vaporization. Here this eliminates the contradiction of existing concepts on the negative value of the frictional pressure drop after a short distance of expansion due to a large part contribution of the actual pressure drop towards the momentum gain pressure drop. Also this verifies that the momentum gain through phase change is by consumption of internal energy part of the enthalpy and no part of the actual pressure drop energy is used in this respect. So with the concept of nearly total pressure drop being used in overcoming the friction the design of an adiabatic capillary tube of available I mm diameter for 0.1 ton refrigeration capacity has been carried out here. This design procedure causes some increase in the required length of the capillary for a given refrigeration capacity due to the omission of momentum pressure drop concept of different references, but is more accurate with consideration of actual changes involved in the expansion. The procedure is applicable for any other refrigerant of any refrigeration capacity
Electrodynamics of moving media inducing positive and negative refraction
Negative refraction is a phenomenon that has been recently reported with left-handed media (either isotropic or not), photonic crystals, and rotated uniaxial media. In this Brief Report, we identify another origin of negative refraction, due to the motion of the transmitted medium parallel to the interface at which refraction occurs. Previous works in this domain have concentrated on media velocities that are above the Cerenkov limit, while we show here that negative refraction is in fact achievable at any velocities of the transmitted medium. A possible experimental implementation is proposed to verify this effect. Next, we consider an isotropic frequency-dispersive medium for which the index of refraction can take negative values, and we study the wave refraction phenomenon as a function of frequency and medium velocity. It is found that the motion of the medium induces a rotation of refraction, which can either enhance or attenuate the natural negative refraction of the medium
Electrically tunable refractive index in the dark conglomerate phase of a bent-core liquid crystal
Nagaraj, M.; Görtz, V.; Goodby, J. W.; Gleeson, H. F.
2014-01-01
Here we report an electrically tunable refractive index observed in an isotropic liquid crystal phase known as the dark conglomerate (DC) phase. This unusual change in the refractive index which has not been reported before in the DC phase of other bent-core liquid crystals occurs because of a series of electric-field-driven transformations that take place in the DC phase of the studied bent-core liquid crystal. These transformations give rise to a decrease in the refractive index of the system, when an electric field is applied across the device, and no change in the birefringence is seen during such behavior. The electro-optic phenomenon is described in detail and the possibility of exploiting this for a number of liquid crystal based device applications is discussed.
Yu-Ting Li
2013-11-01
Full Text Available AIM: To investigate the epidemiological status of refractive state among school-age children of 5 to 12 years in Chengguan district of Lanzhou city, and to analyze the correlation with axial length(AL, horizontal and vertical corneal refractive power(K1, K2, anterior chamber depth(ACDand corneal diameter(W-W. METHODS: The value of AL, K1, K2, ACD and W-W of 813 school-age children(1626 eyesaged 8.46±2.30 years old(5-12 yearswere measured by IOL-Master, refractive error was measured by computer refractor. The eyes were divided into 5 groups according to different mean spherical equivalent(SEdiopter: high myopia, moderate myopia, low myopia, emmetropia and hyperopia. The correlation between diopter and different refractive parameters of different ages and different diopter groups were analyzed respectively, the SPSS 19.0 was used for the statistical analysis.RESULTS: There were statistically significant difference(PPPPPr=-0.764, Pr=-0.498, PCONCLUSION: The increase of AL plays an important role in the changes of refractive among school-age children of 5-12 years, AL is the main morphological variable related to myopia. Meanwhile, refractive changes may be affected by corneal refractive power(K1, K2, ACD and corneal diameter(W-W. 7-8 years old can be regarded as the main phase from emmetropization to myopization of school-age children.
Sanjeev Kumar Puri
2016-04-01
Results: Among 227 students, the prevalence of myopia was 89.42% and hypermetropia was 10.13%.There was one case of keratoconus (0.44%. None of them had undergone refractive surgery. 84.14 % were using only spectacles for correction of refractive error. 13.21% were using contact lenses. 0.88% was using both. Among spectacle users, 71.35% were satisfied with the use of spectacles, the reasons being ease of use and maintenance. 35.41% were not satisfied with spectacles and the main reason was dependency. Among the spectacle users, 23.56% wanted to switch over to contact lenses and the main reason was cosmetic. 92.51% were aware of refractive surgery, out of which 36.66% were willing to undergo refractive surgery. 65.92% were not willing to undergo refractive surgery, the main reason being risk of complications. Conclusions: The preference and willingness to undergo refractive surgery was less due to the fear of complications and the cost of the procedure. Spectacles remain the most preferred method the main reason being ease of use and it is maintenance free. Contact lenses are the next preferred method and the main reason was cosmetic. [Int J Res Med Sci 2016; 4(4.000: 1031-1034
Refractive Errors Affect the Vividness of Visual Mental Images
Palermo, Liana; Nori, Raffaella; Piccardi, Laura; Zeri, Fabrizio; Babino, Antonio; Giusberti, Fiorella; Guariglia, Cecilia
2013-01-01
The hypothesis that visual perception and mental imagery are equivalent has never been explored in individuals with vision defects not preventing the visual perception of the world, such as refractive errors. Refractive error (i.e., myopia, hyperopia or astigmatism) is a condition where the refracting system of the eye fails to focus objects sharply on the retina. As a consequence refractive errors cause blurred vision. We subdivided 84 individuals according to their spherical equivalent refr...
Computational and analytical modeling of eye refractive surgery
Cabrera, Delia
As the number of corneal refractive procedures increases annually, concerns about their long-term stability and predictability have become the center of attention in the ophthalmic community. This thesis focuses on developing quantitative biomechanical models of the cornea that will overcome shortcomings of previous models and incorporate new observations of corneal elastic properties. Our intent is to provide a more accurate model of the corneal structure to guide current and future developments. The second chapter shows that neural networks could rapidly prototype practical solutions to obtain a better estimate of the average corneal power using the contrast and image size parameters provided by the topographic systems. After establishing improved measurements of the corneal shape the thesis focuses on the development of various corneal models. The analytical model proposed shows that geometric optics, corneal structural properties and surgical nomograms could be used to gain a better understanding of corneal response to surgical interventions. The predictions of this model are closer to the values provided by the published nomograms and clinical data than that obtained by the traditional geometric model. Three surgical procedures (Ultrafast Laser-Automated Lamellar Keratomileusis, Corneal Transplant and Intrastromal Refractive Keratectomy) were simulated using the finite element method. A new formulation was developed that simulates the changes on corneal curvature after refractive surgery when the stiffness inhomogeneities across the corneal thickness are considered. It has been shown that the predictability of the surgical outcome is improved when the stiffness inhomogeneities and nonlinearities of the deformations are included in the finite element simulations. Moreover, a finite element formulation has been developed first time to characterize the intrastromal refractive keratectomy procedure. An inhomogeneous (small displacements) model was identified as an
Refractive indices of metal working fluid emulsion components
Glasse, Benjamin; Zerwas, Alexander; Guardani, Roberto; Fritsching, Udo
2014-03-01
Metal working fluids (MWF) used in machining processes are typically formulated as oil-in-water emulsions, consisting of an aqueous base with an emulsified oleous phase and additives. These emulsions degenerate over their lifetime leading to changed physical attributes, for instance increased droplet size or concentration. This temporal change may be monitored via optical measurement techniques, which require knowledge of the refractive index of the aqueous and oleous phases for the droplet size measurement. The optical dispersion of the aqueous phase is widely documented in the literature; however, there are no proper references available for the oleous phase for MWF. Thus, in this study the dependence of refractive indices on the wavelength of light of oils that are typically used for the formulation of MWF was determined. The measurements were performed using an Abbe refractometer at room temperature (22 ± 2 °C) in the visible light range at wavelengths between 430 and 680 nm. The results were fitted to the Cauchy dispersion equation describing the optical dispersion of the systems.
Refractive indices of metal working fluid emulsion components
Metal working fluids (MWF) used in machining processes are typically formulated as oil-in-water emulsions, consisting of an aqueous base with an emulsified oleous phase and additives. These emulsions degenerate over their lifetime leading to changed physical attributes, for instance increased droplet size or concentration. This temporal change may be monitored via optical measurement techniques, which require knowledge of the refractive index of the aqueous and oleous phases for the droplet size measurement. The optical dispersion of the aqueous phase is widely documented in the literature; however, there are no proper references available for the oleous phase for MWF. Thus, in this study the dependence of refractive indices on the wavelength of light of oils that are typically used for the formulation of MWF was determined. The measurements were performed using an Abbe refractometer at room temperature (22 ± 2 °C) in the visible light range at wavelengths between 430 and 680 nm. The results were fitted to the Cauchy dispersion equation describing the optical dispersion of the systems. (paper)
Adiabatic Theorems and Reversible Isothermal Processes
Abou-Salem, W K
2005-01-01
Reversible isothermal processes of a finitely extended, driven quantum system in contact with an infinite heat bath are studied from the point of view of quantum statistical mechanics. Notions like heat flux, work and entropy are defined for trajectories of states close to, but distinct from states of joint thermal equilibrium. A theorem characterizing reversible isothermal processes as quasi-static processes ("isothermal theorem") is described. Corollaries concerning the changes of entropy and free energy in reversible isothermal processes and on the 0th law of thermodynamics are outlined.
Perera, Chamanei; Cheng, Elliot; Sathian, Juna; Jaatinen, Esa; Davis, Timothy
2016-01-01
Summary In this paper we report the design and experimental realisation of a novel refractive index sensor based on coupling between three nanoscale stripe waveguides. The sensor is highly compact and designed to operate at a single wavelength. We demonstrate that the sensor exhibits linear response with a resolution of 6 × 10−4 RIU (refractive index unit) for a change in relative output intensity of 1%. Authors expect that the outcome of this paper will prove beneficial in highly compact, label-free and highly sensitive refractive index analysis. PMID:27335763
Wavefront Derived Refraction and Full Eye Biometry in Pseudophakic Eyes
Mao, Xinjie; Banta, James T.; Ke, Bilian; Jiang, Hong; He, Jichang; Liu, Che; Wang, Jianhua
2016-01-01
Purpose To assess wavefront derived refraction and full eye biometry including ciliary muscle dimension and full eye axial geometry in pseudophakic eyes using spectral domain OCT equipped with a Shack-Hartmann wavefront sensor. Methods Twenty-eight adult subjects (32 pseudophakic eyes) having recently undergone cataract surgery were enrolled in this study. A custom system combining two optical coherence tomography systems with a Shack-Hartmann wavefront sensor was constructed to image and monitor changes in whole eye biometry, the ciliary muscle and ocular aberration in the pseudophakic eye. A Badal optical channel and a visual target aligning with the wavefront sensor were incorporated into the system for measuring the wavefront-derived refraction. The imaging acquisition was performed twice. The coefficients of repeatability (CoR) and intraclass correlation coefficient (ICC) were calculated. Results Images were acquired and processed successfully in all patients. No significant difference was detected between repeated measurements of ciliary muscle dimension, full-eye biometry or defocus aberration. The CoR of full-eye biometry ranged from 0.36% to 3.04% and the ICC ranged from 0.981 to 0.999. The CoR for ciliary muscle dimensions ranged from 12.2% to 41.6% and the ICC ranged from 0.767 to 0.919. The defocus aberrations of the two measurements were 0.443 ± 0.534 D and 0.447 ± 0.586 D and the ICC was 0.951. Conclusions The combined system is capable of measuring full eye biometry and refraction with good repeatability. The system is suitable for future investigation of pseudoaccommodation in the pseudophakic eye. PMID:27010674
Compositional dependence of optical band gap and refractive index in lead and bismuth borate glasses
Mallur, Saisudha B.; Czarnecki, Tyler; Adhikari, Ashish; Babu, Panakkattu K.
2015-08-15
Highlights: • Refractive indices increase with increasing PbO/Bi{sub 2}O{sub 3} content. • Optical band gap arises due to direct forbidden transition. • Optical band gaps decrease with increasing PbO/Bi{sub 2}O{sub 3} content. • New empirical relation between the optical band gap and the refractive index. - Abstract: We prepared a series of lead and bismuth borate glasses by varying PbO/Bi{sub 2}O{sub 3} content and studied refractive index and optical band gap as a function of glass composition. Refractive indices were measured very accurately using a Brewster’s angle set up while the optical band gaps were determined by analyzing the optical absorption edge using the Mott–Davis model. Using the Lorentz–Lorentz method and the effective medium theory, we calculated the refractive indices and then compared them with the measured values. Bismuth borate glasses show better agreement between the calculated values of the refractive index and experimental values. We used a differential method based on Mott–Davis model to obtain the type of transition and optical band gap (E{sub opt}) which in turn was compared with the value of E{sub opt} obtained using the extinction coefficient. Our analysis shows that in both lead and bismuth borate glasses, the optical band gap arises due to direct forbidden transition. With increasing PbO/Bi{sub 2}O{sub 3} content, the absorption edge shifts toward longer wavelengths and the optical band gap decreases. This behavior can be explained in terms of changes to the Pb−O/Bi−O chemical bonds with glass composition. We obtained a new empirical relation between the optical band gap and the refractive index which can be used to accurately determine the electronic oxide polarizability in lead and bismuth oxide glasses.
Compositional dependence of optical band gap and refractive index in lead and bismuth borate glasses
Highlights: • Refractive indices increase with increasing PbO/Bi2O3 content. • Optical band gap arises due to direct forbidden transition. • Optical band gaps decrease with increasing PbO/Bi2O3 content. • New empirical relation between the optical band gap and the refractive index. - Abstract: We prepared a series of lead and bismuth borate glasses by varying PbO/Bi2O3 content and studied refractive index and optical band gap as a function of glass composition. Refractive indices were measured very accurately using a Brewster’s angle set up while the optical band gaps were determined by analyzing the optical absorption edge using the Mott–Davis model. Using the Lorentz–Lorentz method and the effective medium theory, we calculated the refractive indices and then compared them with the measured values. Bismuth borate glasses show better agreement between the calculated values of the refractive index and experimental values. We used a differential method based on Mott–Davis model to obtain the type of transition and optical band gap (Eopt) which in turn was compared with the value of Eopt obtained using the extinction coefficient. Our analysis shows that in both lead and bismuth borate glasses, the optical band gap arises due to direct forbidden transition. With increasing PbO/Bi2O3 content, the absorption edge shifts toward longer wavelengths and the optical band gap decreases. This behavior can be explained in terms of changes to the Pb−O/Bi−O chemical bonds with glass composition. We obtained a new empirical relation between the optical band gap and the refractive index which can be used to accurately determine the electronic oxide polarizability in lead and bismuth oxide glasses
Reflection and Refraction on Implicit Surfaces
Wei Hu; Kai-Huai Qin; Hua-Wei Wang; Ya-Feng Li
2006-01-01
Implicit surfaces are often used in computer graphics. They can be easily modeled and rendered, and many objects are composed of them in our daily life. In this paper, based on the concept of virtual objects, a novel method of real-time rendering is presented for reflection and refraction on implicit surface. The method is used to construct virtual objects from real objects quickly, and then render the virtual objects as if they were real objects except for one more step of merging their images with the real objects' images. Characteristics of implicit surfaces are used to compute virtual objects effectively and quickly. GPUs (Graphics Processing Units) are used to compute virtual vertices quickly and further accelerate the computing and rendering processes. As a result, realistic effects of reflections and refractions on implicit surfaces are rendered in real time.
Neutrino refraction by the cosmic neutrino background
Diaz, J S
2015-01-01
We have determined the dispersion relation of a neutrino test particle propagating in the cosmic neutrino background. Describing the relic neutrinos and antineutrinos from the hot big bang as a dense medium, a matter potential or refractive index is obtained. The vacuum neutrino mixing angles are unchanged, but the energy of each mass state is modified. Using a matrix in the space of neutrino species, the induced potential is decomposed into a part which produces signatures in beta-decay experiments and another part which modifies neutrino oscillations. The low temperature of the relic neutrinos makes a direct detection extremely challenging. From a different point of view, the identified refractive effects of the cosmic neutrino background constitute an ultralow background for future experimental studies of nonvanishing Lorentz violation in the neutrino sector.
Neutrino refraction by the cosmic neutrino background
Díaz, J. S.; Klinkhamer, F. R.
2016-03-01
We have determined the dispersion relation of a neutrino test particle propagating in the cosmic neutrino background. Describing the relic neutrinos and antineutrinos from the hot big bang as a dense medium, a matter potential or refractive index is obtained. The vacuum neutrino mixing angles are unchanged, but the energy of each mass state is modified. Using a matrix in the space of neutrino species, the induced potential is decomposed into a part which produces signatures in beta-decay experiments and another part which modifies neutrino oscillations. The low temperature of the relic neutrinos makes a direct detection extremely challenging. From a different point of view, the identified refractive effects of the cosmic neutrino background constitute an ultralow background for future experimental studies of nonvanishing Lorentz violation in the neutrino sector.
Refractive index determination by coherence scanning interferometry.
Yoshino, H; Kaminski, P M; Smith, R; Walls, J M; Mansfield, D
2016-05-20
Coherence scanning interferometry is established as a powerful noncontact, three-dimensional, metrology technique used to determine accurate surface roughness and topography measurements with subnanometer precision. The helical complex field (HCF) function is a topographically defined helix modulated by the electrical field reflectance, originally developed for the measurement of thin films. An approach to extend the capability of the HCF function to determine the spectral refractive index of a substrate or absorbing film has recently been proposed. In this paper, we confirm this new capability, demonstrating it on surfaces of silicon, gold, and a gold/palladium alloy using silica and zirconia oxide thin films. These refractive index dispersion measurements show good agreement with those obtained by spectroscopic ellipsometry. PMID:27411157
Non-adiabatic dynamics of molecules in optical cavities
Kowalewski, Markus, E-mail: mkowalew@uci.edu; Bennett, Kochise; Mukamel, Shaul, E-mail: smukamel@uci.edu [Department of Chemistry, University of California, Irvine, California 92697-2025 (United States)
2016-02-07
Strong coupling of molecules to the vacuum field of micro cavities can modify the potential energy surfaces thereby opening new photophysical and photochemical reaction pathways. While the influence of laser fields is usually described in terms of classical field, coupling to the vacuum state of a cavity has to be described in terms of dressed photon-matter states (polaritons) which require quantized fields. We present a derivation of the non-adiabatic couplings for single molecules in the strong coupling regime suitable for the calculation of the dressed state dynamics. The formalism allows to use quantities readily accessible from quantum chemistry codes like the adiabatic potential energy surfaces and dipole moments to carry out wave packet simulations in the dressed basis. The implications for photochemistry are demonstrated for a set of model systems representing typical situations found in molecules.
On some issues of gravitationally induced adiabatic particle productions
Pan, Supriya; Pramanik, Souvik
2016-01-01
In this work, we investigate the current accelerating universe driven by the gravitationally induced adiabatic matter creation process. To elaborate the underlying cognitive content, here we consider three models of adiabatic particle creation and constrain the model parameters by fitting the models with the Union 2.1 data set using $\\chi^2$ minimization technique. The models are analyzed by two geometrical and model independent tests, viz., cosmography and $Om$-diagnostic, which are widely used to distinguish the cosmological models from $\\Lambda$CDM. We also compared present values of those model independent parameters with that of the flat $\\Lambda$CDM model. Finally, the validity of the generalized second law of thermodynamics and the condition of thermodynamic equilibrium for the particle production models have been tested.
Adiabatic far-field sub-diffraction imaging
Cang, Hu; Salandrino, Alessandro; Wang, Yuan; Zhang, Xiang
2015-08-01
The limited resolution of a conventional optical imaging system stems from the fact that the fine feature information of an object is carried by evanescent waves, which exponentially decays in space and thus cannot reach the imaging plane. We introduce here an adiabatic lens, which utilizes a geometrically conformal surface to mediate the interference of slowly decompressed electromagnetic waves at far field to form images. The decompression is satisfying an adiabatic condition, and by bridging the gap between far field and near field, it allows far-field optical systems to project an image of the near-field features directly. Using these designs, we demonstrated the magnification can be up to 20 times and it is possible to achieve sub-50 nm imaging resolution in visible. Our approach provides a means to extend the domain of geometrical optics to a deep sub-wavelength scale.
Improved Refrigerant Characteristics Flow Predictions in Adiabatic Capillary Tube
Shodiya Sulaimon
2012-07-01
Full Text Available This study presents improved refrigerant characteristics flow predictions using homogenous flow model in adiabatic capillary tube, used in small vapor compression refrigeration system. The model is based on fundamental equations of mass, momentum and energy. In order to improve the flow predictions, the inception of vaporization in the capillary tube is determined by evaluating initial vapor quality using enthalpy equation of refrigerant at saturation point and the inlet entrance effect of the capillary tube is also accounted for. Comparing this model with experimental data from open literature showed a reasonable agreement. Further comparison of this new model with earlier model of Bansal showed that the present model could be use to improve the performance predictions of refrigerant flow in adiabatic capillary tube.
Non-adiabatic theoretical observables in Delta Scuti stars
Moya, A; Dupret, M A
2004-01-01
Phase differences and amplitude ratios at different colour photometric bands are currently being used to discriminate pulsation modes in order to facilitate mode identification of kappa-driven non-radial pulsating stars. In addition to physical inputs (e.g., mass, T_eff, etc.), these quantities depend on the non-adiabatic treatment of the atmosphere. This paper presents theoretical results concerning Delta Scuti pulsating stars. The envelope of each of these stellar structures possesses a convection zone whose development is determined by various factors. An interacting pulsation-atmosphere physical treatment is introduced which supplies two basic non-adiabatic physical quantities: the relative effective temperature variation and the phase lag phi^T, defined as the angle between effective temperature variations and radial displacement. These quantities can be used to derive the phase differences and amplitude ratios. Numerical values for these quantities depend critically on the alpha MLT parameter used to ca...
The adiabatic motion of charged dust grains in rotating magnetospheres
Northrop, T. G.; Hill, J. R.
1983-01-01
Adiabatic equations of motion are derived for the micrometer-sized dust grains detected in the Jovian and Saturn magnetospheres by the Pioneer 10 and 11 spacecraft. The adiabatic theory of charged particle motion is extended to the case of variable grain charge. Attention is focused on the innermost and outermost limits to the grain orbit evolution, with all orbits tending to become circular with time. The parameters such as the center equation of motion, the drift velocity, and the parallel equation of motion are obtained for grains in a rotating magnetosphere. Consideration is given to the effects of periodic grain charge-discharge, which are affected by the ambient plasma properties and the grain plasma velocity. The charge-discharge process at the gyrofrequency is determined to eliminate the invariance of the magnetic moment and cause the grain to exhibit radial movement. The magnetic moment increases or decreases as a function of the gyrophase of the charge variation.
Crack propagation of Ti alloy via adiabatic shear bands
This study was focused on the characterization of the origin and mechanism of crack propagation as a result of hot induction bending of Ti alloy. Plates of Ti–6Al–4V alloy with 12.5 mm of thickness were submitted to hot induction bending below the beta transus temperature. Optical and scanning electron microscopy analysis showed crack formation in the tensile zone. Microstructural evidence showed that cracks propagate through the adiabatic shear bands by Dimple-Void mechanism. However, voids formation before shear banding also occurred. In both mechanisms adiabatic shear bands are formed via dynamic recrystallization where the alpha–beta interphase works as stress concentrator promoting the formation of dimples and voids
Stellar oscillations. II The non-adiabatic case
Samadi, R; Sonoi, T
2015-01-01
A leap forward has been performed due to the space-borne missions, MOST, CoRoT and Kepler. They provided a wealth of observational data, and more precisely oscillation spectra, which have been (and are still) exploited to infer the internal structure of stars. While an adiabatic approach is often sufficient to get information on the stellar equilibrium structures it is not sufficient to get a full understanding of the physics of the oscillation. Indeed, it does not permit one to answer some fundamental questions about the oscillations, such as: What are the physical mechanisms responsible for the pulsations inside stars? What determines the amplitudes? To what extent the adiabatic approximation is valid? All these questions can only be addressed by considering the energy exchanges between the oscillations and the surrounding medium. This lecture therefore aims at considering the energetical aspects of stellar pulsations with particular emphasis on the driving and damping mechanisms. To this end, the full non-...
Excitation energies along a range-separated adiabatic connection
Rebolini, Elisa; Teale, Andrew M; Helgaker, Trygve; Savin, Andreas
2014-01-01
We present a study of the variation of total energies and excitationenergies along a range-separated adiabatic connection. This connectionlinks the non-interacting Kohn-Sham electronic system to the physicalinteracting system by progressively switching on theelectron-electron interactions whilst simultaneously adjusting aone-electron effective potential so as to keep the ground-statedensity constant. The interactions are introduced in arange-dependent manner, first introducing predominantly long-range,and then all-range, interactions as the physical system is approached,as opposed to the conventional adiabatic connection where theinteractions are introduced by globally scaling the standard Coulomb interaction.Reference data are reported for the He and Be atoms and the H2molecule, obtained by calculating the short-range effective potentialat the full configuration-interaction level using Lieb'sLegendre-transform approach. As the strength of the electron-electroninteractions increases, the excitation energies, ...
Crack propagation of Ti alloy via adiabatic shear bands
Mendoza, I., E-mail: ivanmendozabravo@gmail.com [Instituto Tecnológico de Veracruz (Mexico); Villalobos, D. [Instituto Tecnológico de Veracruz (Mexico); Alexandrov, B.T. [The Ohio State University (United States)
2015-10-01
This study was focused on the characterization of the origin and mechanism of crack propagation as a result of hot induction bending of Ti alloy. Plates of Ti–6Al–4V alloy with 12.5 mm of thickness were submitted to hot induction bending below the beta transus temperature. Optical and scanning electron microscopy analysis showed crack formation in the tensile zone. Microstructural evidence showed that cracks propagate through the adiabatic shear bands by Dimple-Void mechanism. However, voids formation before shear banding also occurred. In both mechanisms adiabatic shear bands are formed via dynamic recrystallization where the alpha–beta interphase works as stress concentrator promoting the formation of dimples and voids.
Non-adiabatic dynamics of molecules in optical cavities
Kowalewski, Markus; Mukamel, Shaul
2016-01-01
Strong coupling of molecules to the vacuum field of micro cavities can modify the potential energy surfaces opening new photophysical and photochemical reaction pathways. While the influence of laser fields is usually described in terms of classical field, coupling to the vacuum state of a cavity has to be described in terms of dressed photon-matter states (polaritons) which require quantized fields. We present a derivation of the non-adiabatic couplings for single molecules in the strong coupling regime suitable for the calculation of the dressed state dynamics. The formalism allows to use quantities readily accessible from quantum chemistry codes like the adiabatic potential energy surfaces and dipole moments to carry out wave packet simulations in the dressed basis. The implications for photochemistry are demonstrated for a set of model systems representing typical situations found in molecules.
Adiabatic theorem for the time-dependent wave operator
The application of time-dependent wave operator theory to the development of a quantum adiabatic perturbation theory is treated both theoretically and numerically, with emphasis on the description of field-matter interactions which involve short laser pulses. It is first shown that the adiabatic limit of the time-dependent wave operator corresponds to a succession of instantaneous static Bloch wave operators. Wave operator theory is then shown to be compatible with the two-time Floquet theory of light-matter interaction, thus allowing the application of Floquet theory to cases which require the use of a degenerate active space. A numerical study of some problems shows that the perturbation strength associated with nonadiabatic processes can be reduced by using multidimensional active spaces and illustrates the capacity of the wave operator approach to produce a quasiadiabatic treatment of a nominally nonadiabatic Floquet dynamical system
Microscopic expression for heat in the adiabatic basis.
Polkovnikov, Anatoli
2008-11-28
We derive a microscopic expression for the instantaneous diagonal elements of the density matrix rho(nn)(t) in the adiabatic basis for an arbitrary time-dependent process in a closed Hamiltonian system. If the initial density matrix is stationary (diagonal) then this expression contains only squares of absolute values of matrix elements of the evolution operator, which can be interpreted as transition probabilities. We then derive the microscopic expression for the heat defined as the energy generated due to transitions between instantaneous energy levels. If the initial density matrix is passive [diagonal with rho(nn)(0) monotonically decreasing with energy] then the heat is non-negative in agreement with basic expectations of thermodynamics. Our findings also can be used for systematic expansion of various observables around the adiabatic limit. PMID:19113464
Influence of viscosity and the adiabatic index on planetary migration
Bitsch, B; Kley, W
2013-01-01
The strength and direction of migration of low mass embedded planets depends on the disk's thermodynamic state, where the internal dissipation is balanced by radiative transport, and the migration can be directed outwards, a process which extends the lifetime of growing embryos. Very important parameters determining the structure of disks, and hence the direction of migration, are the viscosity and the adiabatic index. In this paper we investigate the influence of different viscosity prescriptions (alpha-type and constant) and adiabatic indices on disk structures and how this affects the migration rate of planets embedded in such disks. We perform 3D numerical simulations of accretion disks with embedded planets. We use the explicit/implicit hydrodynamical code NIRVANA that includes full tensor viscosity and radiation transport in the flux-limited diffusion approximation, as well as a proper equation of state for molecular hydrogen. The migration of embedded 20Earthmass planets is studied. Low-viscosity disks...
DESIGN OF TERNARY COUNTER BASED ON ADIABATIC DOMINO CIRCUIT
Yang Qiankun; Wang Pengjun; Zheng Xuesong
2013-01-01
By researching the ternary counter and low power circuit design method,a novel design of low power ternary Domino counter on switch-level is proposed.Firstly,the switch-level structure expression of ternary loop operation circuit with enable pin is derived according to the switch-signal theory,and the one bit ternary counter is obtained combining the ternary adiabatic Domino literal operation circuit and buffer.Then the switch-level structure expression of enable signal circuit is derived,and the four bits ternary counter is obtained by cascade connection.Finally,the circuit is simulated by Spice tool and the output waveforms transform in proper order indicating that the logic function is correct.The energy consumption of the four bits ternary adiabatic Domino counter is 63％ less than the conventional Domino counterpart.
Adjustable hybrid diffractive/refractive achromatic lens
Valley, Pouria; Savidis, Nickolaos; Schwiegerling, Jim; Dodge, Mohammad Reza; Peyman, Gholam; N. Peyghambarian
2011-01-01
We demonstrate a variable focal length achromatic lens that consists of a flat liquid crystal diffractive lens and a pressure-controlled fluidic refractive lens. The diffractive lens is composed of a flat binary Fresnel zone structure and a thin liquid crystal layer, producing high efficiency and millisecond switching times while applying a low ac voltage input. The focusing power of the diffractive lens is adjusted by electrically modifying the sub-zones and re-establishing phase wrapping po...
Trends in refractive surgery at an academic center: 2007-2009
Kuo Irene C
2011-05-01
Full Text Available Abstract Background The United States officially entered a recession in December 2007, and it officially exited the recession in December 2009, according to the National Bureau of Economic Research. Since the economy may affect not only the volume of excimer laser refractive surgery, but also the clinical characteristics of patients undergoing surgery, our goal was to compare the characteristics of patients completing excimer laser refractive surgery and the types of procedures performed in the summer quarter in 2007 and the same quarter in 2009 at an academic center. A secondary goal was to determine whether the volume of astigmatism- or presbyopia-correcting intraocular lenses (IOLs has concurrently changed because like laser refractive surgery, these "premium" IOLs involve out-of-pocket costs for patients. Methods Retrospective case series. Medical records were reviewed for all patients completing surgery at the Wilmer Laser Vision Center in the summer quarter of 2007 and the summer quarter of 2009. Outcome measures were the proportions of treated refractive errors, the proportion of photorefractive keratectomy (PRK vs. laser-assisted in-situ keratomileusis (LASIK, and the mean age of patients in each quarter. Chi-square test was used to compare the proportions of treated refractive errors and the proportions of procedures; two-tailed t-test to compare the mean age of patients; and two-tailed z-test to compare proportions of grouped refractive errors in 2007 vs. 2009; alpha = 0.05 for all tests. Refractive errors were grouped by the spherical equivalent of the manifest refraction and were considered "low myopia" for 6 diopters (D of myopia or less, "high myopia" for more than 6 D, and "hyperopia" for any hyperopia. Billing data were reviewed to obtain the volume of premium IOLs. Results Volume of laser refractive procedures decreased by at least 30%. The distribution of proportions of treated refractive errors did not change (p = 0.10. The
The Adiabatic Piston and the Second Law of Thermodynamics
Crosignani, B; Conti, C
2002-01-01
A detailed analysis of the adiabatic-piston problem reveals peculiar dynamical features that challenge the general belief that isolated systems necessarily reach a static equilibrium state. In particular, the fact that the piston behaves like a perpetuum mobile, i.e., it never stops but keeps wandering, undergoing sizable oscillations, around the position corresponding to maximum entropy, has remarkable implications on the entropy variations of the system and on the validity of the second law when dealing with systems of mesoscopic dimensions.
Single-parameter adiabatic charge pumping in carbon nanotube resonators
Perroni, C. A.; Nocera, A.; Cataudella, V.
2013-01-01
Single-parameter adiabatic charge pumping, induced by a nearby radio-frequency antenna, is achieved in suspended carbon nanotubes close to the mechanical resonance. The charge pumping is due to an important dynamic adjustment of the oscillating motion to the antenna signal and it is different from the mechanism active in the two-parameter pumping. Finally, the second harmonic oscillator response shows an interesting relationship with the first harmonic that should be experimentally observed.
Quantum pumping with adiabatically modulated barriers in graphene
Zhu, Rui; Chen, Huiming
2009-01-01
We study the adiabatic quantum pumping characteristics in the graphene modulated by two oscillating gate potentials out of phase. The angular and energy dependence of the pumped current is presented. The direction of the pumped current can be reversed when a high barrier demonstrates stronger transparency than a low one, which results from the Klein paradox. The underlying physics of the pumping process is illuminated.
Geometry of adiabatic Hamiltonians for two-level quantum systems
We present the formulation of the problem of the coherent dynamics of quantum mechanical two-level systems in the adiabatic region in terms of the differential geometry of plane curves. We show that there is a natural plane curve corresponding to the Hamiltonian of the system for which the geometrical quantities have a simple physical interpretation. In particular, the curvature of the curve has the role of the nonadiabatic coupling. (paper)
High-Fidelity Entangled Bell States via Shortcuts to Adiabaticity
Paul, Koushik
2016-01-01
We present a couple of protocols based on shortcut to adiabaticity techniques for rapid generation of robust entangled Bell states in a system of two two-state systems. Our protocols rely on the so-called transitionless quantum driving (TQD) algorithm and Lewis-Riesenfeld invariant (LRI) method. Both TQD and LRI methods result in high fidelity in population transfer.Our study shows that it is possible to prepare an entangled state in infinitely short time without losing robustness and efficiency.
Adiabaticity and gravity theory independent conservation laws for cosmological perturbations
Romano, Antonio Enea; Mooij, Sander; Sasaki, Misao
2016-04-01
We carefully study the implications of adiabaticity for the behavior of cosmological perturbations. There are essentially three similar but different definitions of non-adiabaticity: one is appropriate for a thermodynamic fluid δPnad, another is for a general matter field δPc,nad, and the last one is valid only on superhorizon scales. The first two definitions coincide if cs2 = cw2 where cs is the propagation speed of the perturbation, while cw2 = P ˙ / ρ ˙ . Assuming the adiabaticity in the general sense, δPc,nad = 0, we derive a relation between the lapse function in the comoving slicing Ac and δPnad valid for arbitrary matter field in any theory of gravity, by using only momentum conservation. The relation implies that as long as cs ≠cw, the uniform density, comoving and the proper-time slicings coincide approximately for any gravity theory and for any matter field if δPnad = 0 approximately. In the case of general relativity this gives the equivalence between the comoving curvature perturbation Rc and the uniform density curvature perturbation ζ on superhorizon scales, and their conservation. This is realized on superhorizon scales in standard slow-roll inflation. We then consider an example in which cw =cs, where δPnad = δPc,nad = 0 exactly, but the equivalence between Rc and ζ no longer holds. Namely we consider the so-called ultra slow-roll inflation. In this case both Rc and ζ are not conserved. In particular, as for ζ, we find that it is crucial to take into account the next-to-leading order term in ζ's spatial gradient expansion to show its non-conservation, even on superhorizon scales. This is an example of the fact that adiabaticity (in the thermodynamic sense) is not always enough to ensure the conservation of Rc or ζ.
Adiabatic Hyperspherical Approach to the Problems of Muon Catalyzed Fusion
The adiabatic hyperspherical approach (AHSA) is applied for the numerical investigation of the scattering processes and resonances in Coulomb three-body mesic atomic systems. The results of the calculations of elastic and inelastic cross sections in low-energy collisions aμ + b (a, b = p, d, t), energies, lifetimes and local characteristics of resonant states of mesic molecular ions nHeaμ+ (n = 3, 4) are presented.
Linear response of galactic halos to adiabatic gravitational perturbations
Murali, Chigurupati; Tremaine, Scott
1997-01-01
We determine the response of a self-similar isothermal stellar system to small adiabatic gravitational perturbations. For odd spherical harmonics, the response is identical to the response of the analogous isothermal fluid system. For even spherical harmonics, the response can be regarded as an infinite series of wavetrains in $\\log r$, implying alternating compression and rarefaction in equal logarithmic radius intervals. Partly because of the oscillatory nature of the solutions, tidal field...
Highly stripped ions on hydrogen atoms: the adiabatic approach
The simple Lorentzian form for the adiabatic radial matrix elements which dominate low-energy charge transfer in highly stripped systems is exploited to derive the S matrix for the Asub(Z)sup(Z+) + H(1s) → Asub(Z)sup(Z-1)+ + H+ scattering process. The approximations used are discussed and the results of the theory are compared with measured He2+ + H(1s) → He+ + H+ cross sections. Agreement is satisfactory for low velocities. (author)
The Adiabatic Piston and the Second Law of Thermodynamics
Crosignani, B.; Di Porto, P.; de Conti, C.
2002-01-01
A detailed analysis of the adiabatic-piston problem reveals peculiar dynamical features that challenge the general belief that isolated systems necessarily reach a static equilibrium state. In particular, the fact that the piston behaves like a perpetuum mobile, i.e., it never stops but keeps wandering, undergoing sizable oscillations, around the position corresponding to maximum entropy, has remarkable implications on the entropy variations of the system and on the validity of the second law...
X-ray refraction-contrast imaging
The conventional x-ray imaging for soft tissue often produced some adverse effects because of contrast medium and high-dose radiation. This report outlines the recently developed a very sensitive x-ray imaging method called as refraction contrast method or x-ray Schlieren method, which allows to detect density difference and irregularity in the soft tissue. In the apparatus (SPring-8 BL47XU), a light emitted from undulator was monochromatized by two-crystal x-ray spectroscope and x-ray passed through a sample was caught by imaging detector equipped with a combination of relay lens and CCD. When a glass capillary (outer diameter: 660 μm, inner diameter: 220 μm) was used as a measuring sample, it was confirmed that the image through geometrical refraction was obtained. When x-ray images of a dragonfly wing obtained by the Schlieren method (sample-detector distance: 5 m) and the conventional contact method were compared, it was demonstrated that reticulate structure of the wing was clearly observed by the former method but not at all by the latter one. At present, the study on efficacy of the refraction contrast imaging is under way using rodents. (M.N.)
Vortex ring refraction at large Froude numbers
Kuehn, Kerry; Schultz, Michael; Sanfelippo, Daniel
2009-01-01
We have experimentally studied the impact of a planar axisymmetric vortex ring, incident at an oblique angle, upon a sharp gravity-induced interface separating two fluids of differing densities. After impact, the vortex ring was found to exhibit a variety of subsequent trajectories, which we have organized according to both the incidence angle, and the ratio of the Atwood and Froude numbers, A/F. For relatively small angles of incidence, the vortices tended to penetrate the interface. In such cases, the more slowly moving vortices, having values of A/F \\gtrsim 0.004, tended to subsequently curve back up toward the interface. Quickly moving vortices, on the other hand, tended to refract downward, similar to a light ray entering a medium having a higher refractive index. A simplistic application of Snell's law of refraction cannot, however, account for the observed trajectories. For grazing angles of incidence, fast moving vortices tended to penetrate the interface, whereas slower vortices tended to reflect fro...
Compound Refractive Lenses for Thermal Neutron Applications
Gary, Charles K.
2013-11-12
This project designed and built compound refractive lenses (CRLs) that are able to focus, collimate and image using thermal neutrons. Neutrons are difficult to manipulate compared to visible light or even x rays; however, CRLs can provide a powerful tool for focusing, collimating and imaging neutrons. Previous neutron CRLs were limited to long focal lengths, small fields of view and poor resolution due to the materials available and manufacturing techniques. By demonstrating a fabrication method that can produce accurate, small features, we have already dramatically improved the focal length of thermal neutron CRLs, and the manufacture of Fresnel lens CRLs that greatly increases the collection area, and thus efficiency, of neutron CRLs. Unlike a single lens, a compound lens is a row of N lenslets that combine to produce an N-fold increase in the refraction of neutrons. While CRLs can be made from a variety of materials, we have chosen to mold Teflon lenses. Teflon has excellent neutron refraction, yet can be molded into nearly arbitrary shapes. We designed, fabricated and tested Teflon CRLs for neutrons. We demonstrated imaging at wavelengths as short as 1.26 ? with large fields of view and achieved resolution finer than 250 μm which is better than has been previously shown. We have also determined designs for Fresnel CRLs that will greatly improve performance.
3D super-virtual refraction interferometry
Lu, Kai
2014-08-05
Super-virtual refraction interferometry enhances the signal-to-noise ratio of far-offset refractions. However, when applied to 3D cases, traditional 2D SVI suffers because the stationary positions of the source-receiver pairs might be any place along the recording plane, not just along a receiver line. Moreover, the effect of enhancing the SNR can be limited because of the limitations in the number of survey lines, irregular line geometries, and azimuthal range of arrivals. We have developed a 3D SVI method to overcome these problems. By integrating along the source or receiver lines, the cross-correlation or the convolution result of a trace pair with the source or receiver at the stationary position can be calculated without the requirement of knowing the stationary locations. In addition, the amplitudes of the cross-correlation and convolution results are largely strengthened by integration, which is helpful to further enhance the SNR. In this paper, both synthetic and field data examples are presented, demonstrating that the super-virtual refractions generated by our method have accurate traveltimes and much improved SNR.
NMR implementation of adiabatic SAT algorithm using strongly modulated pulses.
Mitra, Avik; Mahesh, T S; Kumar, Anil
2008-03-28
NMR implementation of adiabatic algorithms face severe problems in homonuclear spin systems since the qubit selective pulses are long and during this period, evolution under the Hamiltonian and decoherence cause errors. The decoherence destroys the answer as it causes the final state to evolve to mixed state and in homonuclear systems, evolution under the internal Hamiltonian causes phase errors preventing the initial state to converge to the solution state. The resolution of these issues is necessary before one can proceed to implement an adiabatic algorithm in a large system where homonuclear coupled spins will become a necessity. In the present work, we demonstrate that by using "strongly modulated pulses" (SMPs) for the creation of interpolating Hamiltonian, one can circumvent both the problems and successfully implement the adiabatic SAT algorithm in a homonuclear three qubit system. This work also demonstrates that the SMPs tremendously reduce the time taken for the implementation of the algorithm, can overcome problems associated with decoherence, and will be the modality in future implementation of quantum information processing by NMR. PMID:18376911
Dynamics of Quantum Adiabatic Evolution Algorithm for Number Partitioning
Smelyanskiy, Vadius; vonToussaint, Udo V.; Timucin, Dogan A.; Clancy, Daniel (Technical Monitor)
2002-01-01
We have developed a general technique to study the dynamics of the quantum adiabatic evolution algorithm applied to random combinatorial optimization problems in the asymptotic limit of large problem size n. We use as an example the NP-complete Number Partitioning problem and map the algorithm dynamics to that of an auxiliary quantum spin glass system with the slowly varying Hamiltonian. We use a Green function method to obtain the adiabatic eigenstates and the minimum exitation gap, gmin = O(n2(sup -n/2)), corresponding to the exponential complexity of the algorithm for Number Partitioning. The key element of the analysis is the conditional energy distribution computed for the set of all spin configurations generated from a given (ancestor) configuration by simultaneous flipping of a fixed number of spins. For the problem in question this distribution is shown to depend on the ancestor spin configuration only via a certain parameter related to the energy of the configuration. As the result, the algorithm dynamics can be described in terms of one-dimensional quantum diffusion in the energy space. This effect provides a general limitation of a quantum adiabatic computation in random optimization problems. Analytical results are in agreement with the numerical simulation of the algorithm.
Non-adiabatic molecular dynamics by accelerated semiclassical Monte Carlo
Non-adiabatic dynamics, where systems non-radiatively transition between electronic states, plays a crucial role in many photo-physical processes, such as fluorescence, phosphorescence, and photoisomerization. Methods for the simulation of non-adiabatic dynamics are typically either numerically impractical, highly complex, or based on approximations which can result in failure for even simple systems. Recently, the Semiclassical Monte Carlo (SCMC) approach was developed in an attempt to combine the accuracy of rigorous semiclassical methods with the efficiency and simplicity of widely used surface hopping methods. However, while SCMC was found to be more efficient than other semiclassical methods, it is not yet as efficient as is needed to be used for large molecular systems. Here, we have developed two new methods: the accelerated-SCMC and the accelerated-SCMC with re-Gaussianization, which reduce the cost of the SCMC algorithm up to two orders of magnitude for certain systems. In most cases shown here, the new procedures are nearly as efficient as the commonly used surface hopping schemes, with little to no loss of accuracy. This implies that these modified SCMC algorithms will be of practical numerical solutions for simulating non-adiabatic dynamics in realistic molecular systems
Non-adiabatic energy dissipation in metal homoepitaxy
Hagemann, Ulrich; Huba, Kornelia; Krix, David; Nienhaus, Hermann [Experimental Physics, University of Duisburg-Essen (Germany)
2009-07-01
The growth of metal films releases energies of typically a few eV per metal atom. By now, the energy is believed to be dissipated adiabatically by direct excitation of phonons. We present data which give strong evidence for the creation of electron-hole pairs during Mg homoepitaxy, i.e., for a non-adiabatic dissipation channel. To detect the generated hot charge carriers, large-area ultrathin metal film Mg/p-Si(001) Schottky diodes were fabricated. The homogeneous Schottky barrier height was determined as 0.52 eV and the reverse current could be reduced to below 1 nA at low temperatures. During exposure of the diodes to a thermal Mg atom beam internal currents in the 100 pA range are observed. The currents can be attributed to two mechanisms: first the internal exoemission process (chemicurrent effect) due to non-adiabatic energy dissipation and second the photocurrent due to the infrared radiation of the evaporator. By varying the evaporator temperature and the Mg film thickness the two current contributions can be distinguished. The chemicurrent during Mg homoepitaxy depends exponentially on the evaporation temperature yielding the Mg evaporation enthalpy of 1.3 eV. The strong exponential attenuation of the chemicurrent with increasing Mg film thickness further supports the concept of generation of ballistic charge carriers by the metal formation process.
Non-adiabatic molecular dynamics by accelerated semiclassical Monte Carlo
Non-adiabatic dynamics, where systems non-radiatively transition between electronic states, plays a crucial role in many photo-physical processes, such as fluorescence, phosphorescence, and photoisomerization. Methods for the simulation of non-adiabatic dynamics are typically either numerically impractical, highly complex, or based on approximations which can result in failure for even simple systems. Recently, the Semiclassical Monte Carlo (SCMC) approach was developed in an attempt to combine the accuracy of rigorous semiclassical methods with the efficiency and simplicity of widely used surface hopping methods. However, while SCMC was found to be more efficient than other semiclassical methods, it is not yet as efficient as is needed to be used for large molecular systems. Here, we have developed two new methods: the accelerated-SCMC and the accelerated-SCMC with re-Gaussianization, which reduce the cost of the SCMC algorithm up to two orders of magnitude for certain systems. In many cases shown here, the new procedures are nearly as efficient as the commonly used surface hopping schemes, with little to no loss of accuracy. This implies that these modified SCMC algorithms will be of practical numerical solutions for simulating non-adiabatic dynamics in realistic molecular systems
Analysis of adiabatic transfer in cavity quantum electrodynamics
Joyee Ghosh; R Ghosh; Deepak Kumar
2011-10-01
A three-level atom in a conﬁguration trapped in an optical cavity forms a basic unit in a number of proposed protocols for quantum information processing. This system allows for efﬁcient storage of cavity photons into long-lived atomic excitations, and their retrieval with high ﬁdelity, in an adiabatic transfer process through the ‘dark state’ by a slow variation of the control laser intensity. We study the full quantum mechanics of this transfer process with a view to examine the non-adiabatic effects arising from inevitable excitations of the system to states involving the upper level of , which is radiative. We ﬁnd that the ﬁdelity of storage is better, the stronger the control ﬁeld and the slower the rate of its switching off. On the contrary, unlike the adiabatic notion, retrieval is better with faster rates of switching on of an optimal control ﬁeld. Also, for retrieval, the behaviour with dissipation is non-monotonic. These results lend themselves to experimental tests. Our exact computations, when applied to slow variations of the control intensity for strong atom–photon couplings, are in very good agreement with Berry’s superadiabatic transfer results without dissipation.
Irreconcilable difference between quantum walks and adiabatic quantum computing
Wong, Thomas G.; Meyer, David A.
2016-06-01
Continuous-time quantum walks and adiabatic quantum evolution are two general techniques for quantum computing, both of which are described by Hamiltonians that govern their evolutions by Schrödinger's equation. In the former, the Hamiltonian is fixed, while in the latter, the Hamiltonian varies with time. As a result, their formulations of Grover's algorithm evolve differently through Hilbert space. We show that this difference is fundamental; they cannot be made to evolve along each other's path without introducing structure more powerful than the standard oracle for unstructured search. For an adiabatic quantum evolution to evolve like the quantum walk search algorithm, it must interpolate between three fixed Hamiltonians, one of which is complex and introduces structure that is stronger than the oracle for unstructured search. Conversely, for a quantum walk to evolve along the path of the adiabatic search algorithm, it must be a chiral quantum walk on a weighted, directed star graph with structure that is also stronger than the oracle for unstructured search. Thus, the two techniques, although similar in being described by Hamiltonians that govern their evolution, compute by fundamentally irreconcilable means.
Adiabatic microcalorimetry in shielding benchmark experiments
The application of a newly developed microcalorimeter is described : (1) for measuring energy-deposition rates in the mixed radiation fields of zero-energy reactors and shielding benchmark experiments. Methods of calculation for energy-deposition (n + γ) are usually validated by measuring the neutron component with the aid of activation detectors and the gamma-ray component using TLDs or ion-chambers. The major limitation with the use of calorimeters in low-power radiation fields has been lack of sensitivity. The aim of the present work has been to investigate the performance of a calorimeter which can measure heating-rates in the range down to 10 μW/g by comparison with conventional dosimetry techniques in a graphite benchmark experiment conducted in the NESSUS reference field in the NESTOR reactor at Winfrith. Major problems have been encountered with the neutron sensitivity of both TLDs and gamma-ray ion-chambers. When appropriate corrections are made good agreement can be achieved between all the dosimetry techniques and the results provide a benchmark test of calculational methods for energy-deposition in graphite. In power reactors, steel-walled calorimeters are used for the dosimetry of materials such as graphite and the net effect of electron migration between the sample and steel walls significantly increases the heating rate in the specimen. In the NESSUS experiments, an increase of 18% was observed in the graphite heating rate above that expected from the enhanced gamma source, when the calorimeter wall was changed from graphite to iron. (author)
The use of a conical lens to find the refractive index of liquids
In this work, the basic idea is to determine the refractive index of liquids unknown using a conical lens. The measurement of the refractive index of liquids is an important work in engineering and science since is one of the most important optical parameter. The adulteration problem is increasing day by day; therefore it is necessary to implement new and simple devices for measure the refractive index of several materials. There is a great variety of interferometric methods that may be used for determining the refractive index. However, these methods either need sophisticated equipment or have low accuracy. Our system consists of a conical lens coupled to a cylindrical container with a liquid whose composition can be changed easily or adulterated. The diameter of the emergent beam of the container is associated to the specific index of refraction of each substance. Any adulteration of the liquid will be reflected in the diameter of the beam, which will be detected by a charge-coupled device (CCD). Our hypothesis is supported by developed mathematical calculations and numerical simulations.
The use of a conical lens to find the refractive index of liquids
Anguiano-Morales, Marcelino; Salas Peimbert, Didia P; Trujillo-Schiaffino, Gerardo, E-mail: manguiano@itchihuahua.edu.mx [Instituto Tecnologico de Chihuahua, Division de Estudios de Posgrado e Investigacion, Av. Tecnologico No 2909, Chihuahua, Chih., 31310 (Mexico)
2011-01-01
In this work, the basic idea is to determine the refractive index of liquids unknown using a conical lens. The measurement of the refractive index of liquids is an important work in engineering and science since is one of the most important optical parameter. The adulteration problem is increasing day by day; therefore it is necessary to implement new and simple devices for measure the refractive index of several materials. There is a great variety of interferometric methods that may be used for determining the refractive index. However, these methods either need sophisticated equipment or have low accuracy. Our system consists of a conical lens coupled to a cylindrical container with a liquid whose composition can be changed easily or adulterated. The diameter of the emergent beam of the container is associated to the specific index of refraction of each substance. Any adulteration of the liquid will be reflected in the diameter of the beam, which will be detected by a charge-coupled device (CCD). Our hypothesis is supported by developed mathematical calculations and numerical simulations.
Dong, G Y; Yang, X L; Cai, L Z
2010-08-01
We have investigated for the first time the anomalous refractive effects of a photonic crystal (PhC) formed by holographic lithography (HL) with triangular rods arranged in a honeycomb lattice in air. Possibilities of left-handed negative refraction and superlens are discussed for the case of TM2 band with the index contrast n = 3.4:1. In contrast to the conventional honeycomb PhC made of regular rods in air, the HL PhCs show left-handed negative refraction over a wider and higher frequency range with high transmissivity (>90%), and the effective indices quite close to -1 for a wide range of incident angles with a larger all-angle left-handed negative refraction (AALNR) frequency range (Deltaomega/omega approximately 14.8%). Calculations and FDTD simulations demonstrate the high-performance negative refraction properties can happen in the holographic structures for a wide filling ratio and can be modulated by changing the filling ratio easily. PMID:20721016
Engineering of refractive index in sulfide chalcogenide glass by direct laser writing
Zhang, Yaping
2010-01-01
Arsenic trisulfide (As2S3) glass is an interesting material for photonic integrated circuits (PICs) as infrared (IR) or nonlinear optical components. In this paper, direct laser writing was applied to engineer the refractive index of As2S3 thin film. Film samples were exposed to focused above bandgap light with wavelength at 405 nm using different fluence adjusted by laser power and exposure time. The index of refraction before and after laser irradiation was calculated by fitting the experimental data obtained from Spectroscopic Ellipsometer (SE) measurement to Tauc-Lorenz dispersion formula. A positive change in refractive index (Δn = 0.19 at 1.55 μm) as well as an enhancement in anisotropy was achieved in As2S3 film by using 10 mW, 0.3 μs laser irradiation. With further increasing the fluence, refractive index increased while anisotropic property weakened. Due to the rapid and large photo-induced modification of refractive index obtainable with high spatial resolution, this process is promising for integrated optic device fabrication.
Binocular Vision Problems in Refractive Surgery Patients: Vision Therapy Case Reports
Gina Day, OD
2015-02-01
Full Text Available Background: Some post-LASIK patients complain of blurry distance vision months after refractive surgery, despite good corneal healing and negligible refractive error. We postulated that perceiving blur in the absence of refractive error or significant monocular aberrations might result from poor binocular control. Binocular vision testing in a series of such patients revealed convergence problems in 83% of cases. Case Reports: We report on 8 patients (average age 37.4 yrs who completed up to 40 sessions of vision therapy (VT, either completely via computer or in a combination of computer orthoptics and office vision therapy. Seven patients had received LASIK; one had PRK. Optometric measurements and symptoms were recorded before and after VT treatment, starting at least 3 months after refractive surgery. Near point of convergence improved in 7 cases following VT, and convergence break and/or recovery improved in 6 cases. Six cases reported symptom reduction, and pre-presbyopic cases tended to improve accommodative facility. The number of binocular functions showing improvement per case correlated with the number of VT sessions completed. Convergence changes were statistically significant when pre-/post-VT data were compared for these cases as a group. Conclusion: Patients complaining of distance blur following refractive surgery may have undiagnosed binocular vision problems. VT incorporating an internet orthoptics component improved convergence ability in the cases reported here, and most patients reported symptomatic relief.
Infrared non-planar plasmonic perfect absorber for enhanced sensitive refractive index sensing
Cheng, Yongzhi; Mao, Xue Song; Wu, Chenjun; Wu, Lin; Gong, RongZhou
2016-03-01
We present a non-planar all-metal plasmonic perfect absorber (PA) with response polarization independent in infrared region, which can be served as a sensor for enhanced refractive index sensing. Distinct from previous designs, the proposed PA consisted of all metal structured film constructed with an assembly of four-tined rod resonators (FRRs). The PA with a high quality-factor (Q-factor) of 41.2 and an absorbance of 99.9% at 142.6 THz has been demonstrated numerically. The resonance behavior occurs in the space between the rods of the FRRs, which is remarkable different conventional sandwiched structural PAs. Based on equivalent LC circuit theory, the absorption peak can be finely tuned by varying the geometrical dimensions of the FRRs. Furthermore, the resonance frequency shows highly sensitive response to the change of refractive index in the surrounding medium. A careful design for refractive index sensor can yield a sensitivity of 1445 nm/refractive index unit (RIU) and a figure of merit (FOM) of 28.8. The demonstrated design of the plasmonic PA for sensing provides great potential application in enhancing refractive index sensors and the enhanced infrared spectroscopy.
Effects of Atmospheric Refraction on an Airborne Weather Radar Detection and Correction Method
Lei Wang
2015-01-01
Full Text Available This study investigates the effect of atmospheric refraction, affected by temperature, atmospheric pressure, and humidity, on airborne weather radar beam paths. Using three types of typical atmospheric background sounding data, we established a simulation model for an actual transmission path and a fitted correction path of an airborne weather radar beam during airplane take-offs and landings based on initial flight parameters and X-band airborne phased-array weather radar parameters. Errors in an ideal electromagnetic beam propagation path are much greater than those of a fitted path when atmospheric refraction is not considered. The rates of change in the atmospheric refraction index differ with weather conditions and the radar detection angles differ during airplane take-off and landing. Therefore, the airborne radar detection path must be revised in real time according to the specific sounding data and flight parameters. However, an error analysis indicates that a direct linear-fitting method produces significant errors in a negatively refractive atmosphere; a piecewise-fitting method can be adopted to revise the paths according to the actual atmospheric structure. This study provides researchers and practitioners in the aeronautics and astronautics field with updated information regarding the effect of atmospheric refraction on airborne weather radar detection and correction methods.
Effects of short-term wear of silicone hydrogel contact lenses on refractive behaviour
W. D. H. Gillan
2012-12-01
Full Text Available Contact lens wear is known to induce change in both the cornea and refractive state. Often a shift towards increased myopia is noted. Historically investigations into the effects of contact lenses onrefractive state have often been incomplete in terms of statistical analysis whereby nearest equivalent sphere is used or the spherical, cylindrical and axis components are analyzed in isolation. The aim ofthis study was to investigate the short-term effects of silicone hydrogel contact lenses on refractive behaviour. Seven volunteers agreed to wear a silicone hydrogel lens on one eye for a period of thirty minutes. Prior to lens wear, after ten minutes of lens wear and after thirty minutes of lens wear 50 autorefractor measurements were taken of refractive state from each subject. Data were analyzed using multivariate statistical methods. Scatter plots and other multivariate statistics are used to show how lens wear influences refractive behaviour. The results of this study show that silicone hydrogel contact lenses do influence refractive behaviour in both a spherical as well as an antistigmatic (astigmatism fashion. (S Afr Optom 2012 71(2 78-85
Optomecatronic system to estimate the index of refraction of a Compound Chromic
The paper presents an optomechatronic system, which it can detect the displacement of laser beam refracted by Lophine layer deposited in a slider. The displacement was estimated by mean of image processing. The displacement of the laser beam is a function of the refractive index of the Lophine layer as function of temperature change. The system uses a Graphical User Interface (GUI), where it is possible to control the incidence angle of the laser beam, and the same time, the temperature of the lophine layer can be sensed. (Author)
A wide-range temperature immune ultra-sensitive refractive index sensor using concatenated LPGs
Tripathi, Saurabh Mani; Kumar, Arun; Bock, Wojtek J.; Mikulic, Predrag
2013-01-01
Compensating the temperature induced phase-changes of concatenated dual-resonance long-period-gratings by a suitably chosen inter-grating material and space we report wide-range temperature insensitivity along with extremely high refractive-index sensitivity, on either side of turn-around wavelength.
Nanofocusing refractive X-ray lenses
Boye, Pit
2010-02-05
This thesis is concerned with the optimization and development of the production of nanofocusing refractive X-ray lenses. These optics made of either silicon or diamond are well-suited for high resolution X-ray microscopy. The goal of this work is the design of a reproducible manufacturing process which allows the production of silicon lenses with high precision, high quality and high piece number. Furthermore a process for the production of diamond lenses is to be developed and established. In this work, the theoretical basics of X-rays and their interaction with matter are described. Especially, aspects of synchrotron radiation are emphasized. Important in X-ray microscopy are the different optics. The details, advantages and disadvantages, in particular those of refractive lenses are given. To achieve small X-ray beams well beyond the 100 nm range a small focal length is required. This is achieved in refractive lenses by moving to a compact lens design where several single lenses are stacked behind each other. The, so-called nanofocusing refractive lenses (NFLs) have a parabolic cylindrical shape with lateral structure sizes in the micrometer range. NFLs are produced by using micro-machining techniques. These micro-fabrication processes and technologies are introduced. The results of the optimization and the final fabrication process for silicon lenses are presented. Subsequently, two experiments that are exemplary for the use of NFLs, are introduced. The rst one employs a high-resolution scanning fluorescence mapping of a geological sample, and the second one is a coherent x-ray diffraction imaging (CXDI) experiment. CXDI is able to reconstruct the illuminated object from recorded coherent diffraction patterns. In a scanning mode, referred to as ptychography, this method is even able to reconstruct the illumination and the object simultaneously. Especially the reconstructed illumination and the possibility of computed propagation of the wave field along the
Nanofocusing refractive X-ray lenses
This thesis is concerned with the optimization and development of the production of nanofocusing refractive X-ray lenses. These optics made of either silicon or diamond are well-suited for high resolution X-ray microscopy. The goal of this work is the design of a reproducible manufacturing process which allows the production of silicon lenses with high precision, high quality and high piece number. Furthermore a process for the production of diamond lenses is to be developed and established. In this work, the theoretical basics of X-rays and their interaction with matter are described. Especially, aspects of synchrotron radiation are emphasized. Important in X-ray microscopy are the different optics. The details, advantages and disadvantages, in particular those of refractive lenses are given. To achieve small X-ray beams well beyond the 100 nm range a small focal length is required. This is achieved in refractive lenses by moving to a compact lens design where several single lenses are stacked behind each other. The, so-called nanofocusing refractive lenses (NFLs) have a parabolic cylindrical shape with lateral structure sizes in the micrometer range. NFLs are produced by using micro-machining techniques. These micro-fabrication processes and technologies are introduced. The results of the optimization and the final fabrication process for silicon lenses are presented. Subsequently, two experiments that are exemplary for the use of NFLs, are introduced. The rst one employs a high-resolution scanning fluorescence mapping of a geological sample, and the second one is a coherent x-ray diffraction imaging (CXDI) experiment. CXDI is able to reconstruct the illuminated object from recorded coherent diffraction patterns. In a scanning mode, referred to as ptychography, this method is even able to reconstruct the illumination and the object simultaneously. Especially the reconstructed illumination and the possibility of computed propagation of the wave field along the
A Simple Model for Measuring Refractive Index of a Liquid Based upon Fresnel Equations
ZHANG Zhi-Wei; WU Zhi-Fang; WEN Ting-Dun
2007-01-01
Due to many experimental data required and a lot of calculations involved, it is very complex and cumbersome to model prism-based liquid-refractive-index-measuring methods. We develop a new method of mathematical modelling for measuring refractive index of a liquid based upon the Fresnel formula and prism internal reflection at an incident angle less than the critical angle. With this method, only two different concentrations measurements for a kind of solution can lead to the determination of computational model. Measurements are performed to examine the validity of the theoretical model. Experimental results indicate the feasibility of the theoretical model with an error of 1%. The method is also capable of measuring even smaller changes in the optical refractive index of the material on a metal surface by the surface plasma resonance sensing techniques.
Martin, Jacob A.; Gross, Kevin C.
2016-05-01
As off-nadir viewing platforms become increasingly prevalent in remote sensing, material identification techniques must be robust to changing viewing geometries. Current identification strategies generally rely on estimating reflectivity or emissivity, both of which vary with viewing angle. Presented here is a technique, leveraging polarimetric and hyperspectral imaging (P-HSI), to estimate index of refraction which is invariant to viewing geometry. Results from a quartz window show that index of refraction can be retrieved to within 0.08 rms error from 875-1250 cm-1 for an amorphous material. Results from a silicon carbide (SiC) wafer, which has much sharper features than quartz glass, show the index of refraction can be retrieved to within 0.07 rms error. The results from each of these datasets show an improvement when compared with a maximum smoothness TES algorithm.
Occupation times of refracted L\\'evy processes
Kyprianou, Andreas E; Pérez, J L
2012-01-01
A refracted L\\'evy process is a L\\'evy process whose dynamics change by subtracting off a fixed linear drift (of suitable size) whenever the aggregate process is above a pre-specified level. More precisely, whenever it exists, a refracted L\\'evy process is described by the unique strong solution to the stochastic differential equation \\[ \\ud U_t=-\\delta\\mathbf{1}_{\\{U_t>b\\}}\\ud t +\\ud X_t, \\] where $X=(X_t, t\\ge 0)$ is a L\\'evy process with law $\\p$ and $b,\\delta\\in \\R$ such that the resulting process $U$ may visit the half line $(b,\\infty)$ with positive probability. In this paper, we consider the case that $X$ is spectrally negative and establish a number of identities for the following functionals \\[ \\int_0^\\infty\\mathbf{1}_{\\{U_t a\\}$ and $\\rho^-_c=\\inf\\{t\\ge 0: U_t< c\\}$ for $c
Size dependence of complex refractive index function of growing nanoparticles
Eremin, A.; Gurentsov, E.; Popova, E.; Priemchenko, K.
2011-08-01
The evidence of the change of the complex refractive index function E( m) of carbon and iron nanoparticles as a function of their size was found from two-color time-resolved laser-induced incandescence (TiRe-LII) measurements. Growing carbon particles were observed from acetylene pyrolysis behind a shock wave and iron particles were synthesized by pulse Kr-F excimer laser photo-dissociation of Fe(CO)5. The magnitudes of refractive index function were found through the fitting of two independently measured values of particle heat up temperature, determined by two-color pyrometry and from the known energy of the laser pulse and the E( m) variation. Small carbon particles of about 1-14 nm in diameter had a low value of E( m)˜0.05-0.07, which tends to increase up to a value of 0.2-0.25 during particle growth up to 20 nm. Similar behavior for iron particles resulted in E( m) rise from ˜0.1 for particles 1-3 nm in diameter up to ˜0.2 for particles >12 nm in diameter.
Prevalence of amblyopia and refractive errors among primary school children
Zhale Rajavi
2015-01-01
Results: Amblyopia was present in 2.3% (95% CI: 1.8% to 2.9% of participants with no difference between the genders. Amblyopic subjects were significantly younger than non-amblyopic children (P=0.004. Overall, 15.9% of hyperopic and 5.9% of myopic cases had amblyopia. The prevalence of hyperopia ≥+2.00D, myopia ≤-0.50D, astigmatism ≥0.75D, and anisometropia (≥1.00D was 3.5%, 4.9%, 22.6%, and 3.9%, respectively. With increasing age, the prevalence of myopia increased (P<0.001, that of hyperopia decreased (P=0.007, but astigmatism showed no change. Strabismus was found in 2.3% of cases. Strabismus (OR=17.9 and refractive errors, especially anisometropia (OR=12.87 and hyperopia (OR=11.87, were important amblyogenic risk factors. Conclusion: The high prevalence of amblyopia in our subjects in comparison to developed countries reveals the necessity of timely and sensitive screening methods. Due to the high prevalence of amblyopia among children with refractive errors, particularly high hyperopia and anisometropia, provision of glasses should be specifically attended by parents and supported by the Ministry of Health and insurance organizations.
Alteration in refractive index profile during accommodation based on mechanical modelling
Bahrami, Mehdi; Heidari, Ali; Pierscionek, Barbara K.
2015-01-01
The lens of the eye has a gradient refractive index (GRIN). Ocular accommodation, which alters the shape of the lens in response to visual demand, causes a redistribution of the internal structure of the lens leading to a change in the GRIN profile. The nature of this redistribution and the consequence of change in the GRIN profile are not understood. A modelling approach that considers how the GRIN profile may change with accommodation needs to take into account optical and mecha...
Piezoelectric control of the mobility of a domain wall driven by adiabatic and non-adiabatic torques
de Ranieri, E.; Roy, P. E.; Fang, D.; Vehsthedt, E. K.; Irvine, A. C.; Heiss, D.; Casiraghi, A.; Campion, R. P.; Gallagher, B. L.; Jungwirth, T.; Wunderlich, J.
2013-09-01
The rich internal degrees of freedom of magnetic domain walls make them an attractive complement to electron charge for exploring new concepts of storage, transport and processing of information. Here we use the tunable internal structure of a domain wall in a perpendicularly magnetized GaMnAsP/GaAs ferromagnetic semiconductor and demonstrate devices in which piezoelectrically controlled magnetic anisotropy yields up to 500% mobility variations for an electrical-current-driven domain wall. We observe current-induced domain wall motion over a wide range of current-pulse amplitudes and report a direct observation and the piezoelectric control of the Walker breakdown separating two regimes with different mobilities. Our work demonstrates that in spin-orbit-coupled ferromagnets with weak extrinsic domain wall pinning, the piezoelectric control allows one to experimentally assess the upper and lower boundaries of the characteristic ratio of adiabatic and non-adiabatic spin-transfer torques in the current-driven domain wall motion.
Yarkony, David
2015-03-01
The construction of fit single state potential energy surfaces (PESs), analytic representations of ab initio electronic energies and energy gradients, is now well established. These single state PESs, which are essential for accurate quantum dynamics and have found wide application in more approximate quasi-classical treatments, have revolutionized adiabatic dynamics. The situation for nonadiabatic processes involving dissociative and large amplitude motion is less sanguine. In these cases, compared to single electronic state dynamics, both the electronic structure data and the representation are more challenging to determine. We describe the recent development and applications of algorithms that enable description of multiple adiabatic electronic potential energy surfaces coupled by conical intersections in their full dimensionality using coupled quasi-diabatic states. These representations are demonstrably quasi-diabatic, provide accurate representations of conical intersection seams and can smooth out the discontinuities in electronic structure energies due to changing active orbital spaces that routinely afflict global multistate representations.
Rajinder Pal
2016-01-01
Entropy generation, and hence exergy destruction, in adiabatic flow of unstable and surfactant-stabilized emulsions was investigated experimentally in different diameter pipes. Four types of emulsion systems are investigated covering a broad range of the dispersed-phase concentration: (a) unstable oil-in-water (O/W) emulsions without surfactant; (b) surfactant-stabilized O/W emulsions; (c) unstable water-in-oil (W/O) emulsions without surfactant; and (d) surfactant-stabilized W/O emulsions. T...
Numerical study on lithium titanate battery thermal response under adiabatic condition
Highlights: • The thermal behavior of lithium titanate battery during cycling was investigated. • The temperature rate in charging was less than that of discharging in the cycling. • The temperature difference was less than 0.02 °C at 0.5 C in adiabatic condition. • The temperature distribution and thermal runaway of the battery were predicted. - Abstract: To analyze the thermal behavior of 945 mA h lithium titanate battery during charging and discharging processes, the experimental and numerical studies are performed in this work. The cathode and anode of the 945 mA h lithium titanate soft package battery are the lithium nickel–cobalt–manganese-oxide and lithium titanate, respectively. In the experiment, an Accelerating Rate Calorimeter combined with battery cycler is employed to investigate the electrochemical–thermal behavior during charge–discharge cycling under the adiabatic condition. In numerical simulation, one electrochemical-thermal model is adopted to predict the thermal response and validated with the experimental results. From both experimental and simulated results, the profile of potential and current, the heat generation, the temperature, the temperature changing rate and the temperature distribution in the cell are obtained and thermal runaway is predicted. The analysis of the electrochemical and thermal behavior is beneficial for the commercial application of lithium titanate battery in the fields of electric vehicles and hybrid electric vehicles
A two-dimensional space-time kinetics model using the adiabatic approach
A two-dimensional space-time kinetics code, based on the adiabatic method is described. In this approach, the space, energy and time dependent flux is factorized into an amplitude factor and a shape function, the latter being assumed to be slowly varying in time as compared to the former. Further, one does not distinguish between the shapes of delayed and prompt neutron sources. The shape function is calculated at selected times by solving numerically a multigroup static eigen-value diffusion equation by the finite difference method. Between two consecutive time-steps, the point kinetics equations are solved by Cohen's method. Feedback is introduced through changes in cross-sections. With the changed cross-sections, the static calculation is repeated. The cycle is repeated till convergence is achieved in reactivity and temperatures. The code was tested against a typical fast reactor benchmark. The results agree well with those obtained elsewhere. (auth.)
The refractive index of human hemoglobin in the visible range
Because the refractive index of hemoglobin in the visible range is sensitive to the hemoglobin concentration, optical investigations of hemoglobin are important for medical diagnostics and treatment. Direct measurements of the refractive index are, however, challenging; few such measurements have previously been reported, especially in a wide wavelength range. We directly measured the refractive index of human deoxygenated and oxygenated hemoglobin for nine wavelengths between 400 and 700 nm for the hemoglobin concentrations up to 140 g l-1. This paper analyzes the results and suggests a set of model functions to calculate the refractive index depending on the concentration. At all wavelengths, the measured values of the refractive index depended on the concentration linearly. Analyzing the slope of the lines, we determined the specific refraction increments, derived a set of model functions for the refractive index depending on the concentration, and compared our results with those available in the literature. Based on the model functions, we further calculated the refractive index at the physiological concentration within the erythrocytes of 320 g l-1. The results can be used to calculate the refractive index in the visible range for arbitrary concentrations provided that the refractive indices depend on the concentration linearly.
The refractive index of human hemoglobin in the visible range
Zhernovaya, O; Tuchin, V [International Research-Educational Center of Optical Technologies for Industry and Medicine ' Photonics' , Saratov State University, 83 Astrakhanskaya str., 410012 Saratov (Russian Federation); Sydoruk, O [Optical and Semiconductor Devices Group, Department of Electrical and Electronic Engineering, South Kensington Campus, Imperial College London, London SW7 2AZ (United Kingdom); Douplik, A, E-mail: alexandre.douplik@aot.uni-erlangen.de [Medical Photonics Engineering Group, Chair of Photonic Technologies, Friedrich-Alexander University Erlangen-Nuremberg, Paul-Gordan-Strasse 3, 91052 Erlangen (Germany)
2011-07-07
Because the refractive index of hemoglobin in the visible range is sensitive to the hemoglobin concentration, optical investigations of hemoglobin are important for medical diagnostics and treatment. Direct measurements of the refractive index are, however, challenging; few such measurements have previously been reported, especially in a wide wavelength range. We directly measured the refractive index of human deoxygenated and oxygenated hemoglobin for nine wavelengths between 400 and 700 nm for the hemoglobin concentrations up to 140 g l{sup -1}. This paper analyzes the results and suggests a set of model functions to calculate the refractive index depending on the concentration. At all wavelengths, the measured values of the refractive index depended on the concentration linearly. Analyzing the slope of the lines, we determined the specific refraction increments, derived a set of model functions for the refractive index depending on the concentration, and compared our results with those available in the literature. Based on the model functions, we further calculated the refractive index at the physiological concentration within the erythrocytes of 320 g l{sup -1}. The results can be used to calculate the refractive index in the visible range for arbitrary concentrations provided that the refractive indices depend on the concentration linearly.
Super-virtual refraction interferometry: Theory
Bharadwaj, Pawan
2011-01-01
Inverting for the subsurface velocity distribution by refraction traveltime tomography is a well-accepted imaging method by both the exploration and earthquake seismology communities. A significant drawback, however, is that the recorded traces become noisier with increasing offset from the source position, and so prevents accurate picking of traveltimes in far-offset traces. To enhance the signal-to-noise ratio of the far-offset traces, we present the theory of super-virtual refraction interferometry where the signal-to-noise ratio (SNR) of far-offset head-wave arrivals can be theoretically increased by a factor proportional to N; here, N is the number of receiver and source positions associated with the recording and generation of the head-wave arrival. There are two steps to this methodology: correlation and summation of the data to generate traces with virtual head-wave arrivals, followed by the convolution of the data with the virtual traces to create traces with super-virtual head-wave arrivals. This method is valid for any medium that generates head-wave arrivals. There are at least three significant benefits to this methodology: 1). enhanced SNR of far-offset traces so the first-arrival traveltimes of the noisy far-offset traces can be more reliably picked to extend the useful aperture of data, 2). the SNR of head waves in a trace that arrive after the first arrival can be enhanced for accurate traveltime picking and subsequent inversion by traveltime tomography, and 3). common receiver-pair gathers can be analyzed to detect the presence of diving waves in the first arrivals, which can be used to assess the nature of the refracting boundary. © 2011 Society of Exploration Geophysicists.
Lehtikangas, O., E-mail: Ossi.Lehtikangas@uef.fi [Department of Applied Physics, University of Eastern Finland, PO Box 1627, 70211 Kuopio (Finland); Tarvainen, T. [Department of Applied Physics, University of Eastern Finland, PO Box 1627, 70211 Kuopio (Finland); Department of Computer Science, University College London, Gower Street, London WC1E 6BT (United Kingdom); Kim, A.D. [Applied Mathematics Unit, School of Natural Sciences, University of California, Merced, CA 95343 (United States); Arridge, S.R. [Department of Computer Science, University College London, Gower Street, London WC1E 6BT (United Kingdom)
2015-02-01
The radiative transport equation can be used as a light transport model in a medium with scattering particles, such as biological tissues. In the radiative transport equation, the refractive index is assumed to be constant within the medium. However, in biomedical media, changes in the refractive index can occur between different tissue types. In this work, light propagation in a medium with piece-wise constant refractive index is considered. Light propagation in each sub-domain with a constant refractive index is modeled using the radiative transport equation and the equations are coupled using boundary conditions describing Fresnel reflection and refraction phenomena on the interfaces between the sub-domains. The resulting coupled system of radiative transport equations is numerically solved using a finite element method. The approach is tested with simulations. The results show that this coupled system describes light propagation accurately through comparison with the Monte Carlo method. It is also shown that neglecting the internal changes of the refractive index can lead to erroneous boundary measurements of scattered light.
The radiative transport equation can be used as a light transport model in a medium with scattering particles, such as biological tissues. In the radiative transport equation, the refractive index is assumed to be constant within the medium. However, in biomedical media, changes in the refractive index can occur between different tissue types. In this work, light propagation in a medium with piece-wise constant refractive index is considered. Light propagation in each sub-domain with a constant refractive index is modeled using the radiative transport equation and the equations are coupled using boundary conditions describing Fresnel reflection and refraction phenomena on the interfaces between the sub-domains. The resulting coupled system of radiative transport equations is numerically solved using a finite element method. The approach is tested with simulations. The results show that this coupled system describes light propagation accurately through comparison with the Monte Carlo method. It is also shown that neglecting the internal changes of the refractive index can lead to erroneous boundary measurements of scattered light
Gupta, D R C
2004-01-01
Many of the general-relativity-tests such as bending of light near a star and gravitational red/blue shift are explained without general-relativity and without Newtonian-approach. The author first casts doubts on both, the Newtonian and the relativistic approach; and proposes a novel alternative-explanation. The new alternative-explanation is based on refraction-phenomenon of optics. It predicts that as the ray passes through/near the stars atmospheric-medium, it bends due to refraction-phenomenon towards star-core, like a ray bends while passing through a prism or water-drop. A semi-empirical estimation of the atmospheric-height and its refractive-index are made to find the refraction-results. The refraction-based theory also suggests new explanation for gravitational red/blue shift; it tells that frequency remains constant (as it is so in refraction-phenomenon) and the red/blue shift is due to change in wavelength due to change in velocity of light in the medium . Estimated results for bending of light and ...
Diffraction tomography for plasma refractive index measurements
Measurement of the properties of probing beams of coherent electromagnetic radiation yields essential information about the line of sight integrated plasma refractive index. Presented is a scalar diffraction treatment of forward angle scattering plasma diagnostics based on the diffraction projection theorem first presented by E. Wolf in 1969. New results are obtained for near field scattering from probing Gaussian beams and it is demonstrated that the effects of diffraction need to be addressed for tomographic inversion of near field scattering and interferometry data. 33 refs., 10 figs
Super-Gaussian conical refraction beam
Turpin, A; Kalkandkiev, T K; Tomizawa, H; Mompart, J
2014-01-01
We demonstrate the transformation of Gaussian input beams into super-Gaussian beams with a quasi flat-top transverse profile by means of the conical refraction phenomenon by adjusting the ratio between the ring radius and the waist radius of the input beam to 0.445. We discuss the beam propagation of the super-Gaussian beam and show that it has a confocal parameter three times larger than the one that would be obtained from a Gaussian beam. The experiments performed with a KGd(WO4)2 biaxial crystal are in good agreement with the theoretical predictions.
Femtosecond laser in refractive and cataract surgeries
Han-Han; Liu; Ying; Hu; Hong-Ping; Cui
2015-01-01
In the past few years, 9 unique laser platforms have been brought to the market. As femtosecond(FS) laserassisted ophthalmic surgery potentially improves patient safety and visual outcomes, this new technology indeed provides ophthalmologists a reliable new option. But this new technology also poses a range of new clinical and financial challenges for surgeons. We provide an overview of the evolution of FS laser technology for use in refractive and cataract surgeries. This review describes the available laser platforms and mainly focuses on discussing the development of ophthalmic surgery technologies.
Cataract: refractive error, diabetes, and morphology.
Perkins, E. S.
1984-01-01
A retrospective analysis of 388 records of patients undergoing surgery for cataract between the years 1968 and 1978 showed that more women than men were admitted. About 13.7% of the patients were diabetic, and there was a striking excess of women over men with diabetes and cataract. The diabetic patients required surgery at an earlier age than the non-diabetics. Patients who had been refracted at least 5 years before surgery showed an incidence of myopia of -1.00 D or more of 25.4%. In 34% of...
Ye Cao; Yinfei Yang; Xiufeng Yang; Zhengrong Tong
2012-01-01
An alternative solution for the simultaneous measurement of temperature and refractive index is presented. A local micro-structured fiber Bragg grating (LMSFBG) is formed as the sensing head, in which a standard grating is etched by HF. According to the phase shift theory, the main spectral change of the LMSFBG is the formation of a narrow allowed band, which is strongly dependent on the etching features and the surrounding refractive index. As such, the temperature and refractive index measurements can be achieved by the shifts of the double peaks and narrow allowed band, and their fitting linearity coefficients are 0.996 and 0.994, respectively. Thus, the reflection and transmission peaks of the LMSFBG have a good linear relationship with temperature and refractive index.%An alternative solution for the simultaneous measurement of temperature and refractive index is presented.A local micro-structured fiber Bragg grating (LMSFBG) is formed as the sensing head,in which a standard grating is etched by HF.According to the phase shift theory,the main spectral change of the LMSFBG is the formation of a narrow allowed band,which is strongly dependent on the etching features and the surrounding refractive index.As such,the temperature and refractive index measurements can be achieved by the shifts of the double peaks and narrow allowed band,and their fitting linearity coefficients are 0.996 and 0.994,respectively.Thus,the reflection and transmission peaks of the LMSFBG have a good linear relationship with temperature and refractive index.
Hu, Shuai; Gao, Tai-chang; Li, Hao; Liu, Lei; Liu, Xi-chuan; Zhang, Ting; Cheng, Tian-ji; Li, Wan-tong; Dai, Zhong-hua; Su, Xiaojian
2016-03-01
Refraction is an important factor influencing radiative transfer since it can modify the propagation trajectory and polarization states of lights; therefore, it is necessary to quantitively evaluate the effect of atmospheric refraction on radiative transfer process. To this end, a new atmospheric radiative transfer model including refraction process is proposed. The model accuracy is validated against benchmark results, literature results, and well-tested radiative transfer models such as discrete coordinate method and RT3/PolRadtran. The impact of atmospheric refraction on both polarized radiance and fluxes is discussed for pure Rayleigh scattering atmosphere, atmosphere with aerosol, and cloud. The results show that atmospheric refraction has a significant influence on both the radiance and polarization states of diffuse light, where the relative change of the radiance of reflected light and transmitted light due to refraction can achieve 6.3% and 7.4% for Rayleigh scattering atmosphere, 7.2% and 7.8% for atmosphere with aerosol, and 6.2% and 6.8% for cloudy atmosphere, respectively. The relative change of the degree of polarization ranges from near zero in the horizon to 9.5% near neutral points. The angular distribution pattern of the relative change of the radiance for atmosphere with aerosol and cloud is very similar to that for pure Rayleigh scattering case, where its magnitude decreases gradually with the increasing of zenith angle for reflected light; but for transmitted light, the variation characteristics is opposite. The impact of refraction is gradually enhanced with the increasing of solar zenith angles and the optical depth of aerosol and cloud. As the wavelength of incident light increases, the impact declines rapidly for Rayleigh scattering medium. The relative change of the fluxes due to refraction is most notable for Middle Latitude Winter profile (about 8.2043% and 7.3225% for the transmitted and reflected light, respectively, at 0.35 µm). With
Nonlinear Absorption and Refraction in Multilevel Organic Molecular System
LI Chun-Fei; DENG Xiao-Xu; WANG Yu-Xiao
2000-01-01
The nonlinear absorption and refraction in a multilevel organic molecular system is described by using the density matrix theory. The total absorptive coefficient of the system in the low-density case is equal to a linear sum of contributions from each energy level. Similarly, the total refractive index is equal to a linear sum of contributions from each energy level plus the refractive index of the vacuum. The absorption coefficient or refractive index due to each level is proportional to the population of that level, where the constant of proportionality is called the absorption cross-section or the refraction volume, respectively. The relation between the absorption cross-section and the refraction volume for each level is also given.
Negative refractive index of layered nonmagnetic/magnetic composites
We investigate the possibility of preparing left-handed material in a layered alternated nonmagnetic/magnetic composite under different direction of incident electromagnetic wave at the microwave region. We calculate the effective refractive index of the layered composites and find that the effective refractive index varies as a function of the volume fraction of one component of the composite. Especially, within the certain volume fraction of component 1 (or 2) the effective refractive index can be negative at a finite frequency region. Moreover, we find that the direction of the incident electromagnetic wave affects the effective refractive index greatly. When the incident electric field is parallel to the laminations and the magnetic field is perpendicular to the laminations, the volume fraction of component 1 (or 2) range, which causes the effective refractive index to be negative, is relatively wider than that of the opposite case, but the absolute values of the negative refractive index are smaller than that of the opposite case
Applications of Adiabatic Approximation to One- and Two-electron Phenomena in Strong Laser Fields
Bondar, Denys
2010-01-01
The adiabatic approximation is a natural approach for the description of phenomena induced by low frequency laser radiation because the ratio of the laser frequency to the characteristic frequency of an atom or a molecule is a small parameter. Since the main aim of this work is the study of ionization phenomena, the version of the adiabatic approximation that can account for the transition from a bound state to the continuum must be employed. Despite much work in this topic, a universally accepted adiabatic approach of bound-free transitions is lacking. Hence, based on Savichev's modified adiabatic approximation [Sov. Phys. JETP 73, 803 (1991)], we first of all derive the most convenient form of the adiabatic approximation for the problems at hand. Connections of the obtained result with the quasiclassical approximation and other previous investigations are discussed. Then, such an adiabatic approximation is applied to single-electron ionization and non-sequential double ionization of atoms in a strong low fr...
Shortcuts to Adiabaticity by Counterdiabatic Driving in Trapped-ion Transport
An, Shuoming; del Campo, Adolfo; Kim, Kihwan
2016-01-01
Adiabatic dynamics plays an essential role in quantum technologies. By driving a quantum system slowly, the quantum evolution can be engineered with suppressed excitation. Yet, environmentally-induced decoherence limits the implementation of adiabatic protocols. Shortcuts to adiabaticity (STA) have the potential to revolutionize quantum technologies by speeding up the time evolution while mimicking adiabatic dynamics. These nonadiabatic protocols can be engineered by means an auxiliary control field is used to tailor excitations. Here we present the first experimental realization of counterdiabatic driving in a continuous variable system, implementing a shortcut to the adiabatic transport of a trapped ion, in which nonadiabatic transitions are suppressed during all stages of the process. The resulting dynamics is equivalent to a "fast-motion video" of the adiabatic trajectory. We experimentally demonstrate the enhanced robustness of the protocol with respect to alternative approaches based on classical local ...
Nonlinear effects generation in non-adiabatically tapered fibres
Palací, Jesús; Mas, Sara; Monzón-Hernández, David; Martí, Javier
2015-12-01
Nonlinear effects are observed in a non-adiabatically tapered optical fibre. The designed structure allows for the introduction of self-phase modulation, which is observed through pulse breaking and spectral broadening, in approximately a centimetre of propagation using a commercial telecom laser. These devices are simple to fabricate and suitable to generate and control a variety of nonlinear effects in practical applications because they do not experience short-term degradation as previously reported approaches. Experimental and theoretical results are obtained, showing a good agreement.
Non-adiabatic study of the Kepler subgiant KIC 6442183
Grosjean M.
2015-01-01
Full Text Available Thanks to the precision of Kepler observations, [3] were able to measure the linewidth and amplitude of individual modes (including mixed modes in several subgiant power spectra. We perform a forward modelling of a Kepler subgiant based on surface properties and observed frequencies. Non-adiabatic computations including a time- dependent treatment of convection give the lifetimes of radial and non-radial modes. Next, combining the lifetimes and inertias with a stochastic excitation model gives the amplitudes of the modes. We can now directly compare theoretical and observed linewidths and amplitudes of mixed-modes to obtain new constraints on our theoretical models.
Landau-Zener Transitions in an Adiabatic Quantum Computer
Johansson, J; Amin, M. H. S.; Berkley, A. J.; Bunyk, P.; Choi, V.; Harris, R.; Johnson, M. W.; Lanting, T. M.; Lloyd, Seth; ROSE, G
2008-01-01
We report an experimental measurement of Landau-Zener transitions on an individual flux qubit within a multi-qubit superconducting chip designed for adiabatic quantum computation. The method used isolates a single qubit, tunes its tunneling amplitude Delta into the limit where Delta is much less than both the temperature T and the decoherence-induced energy level broadening, and forces it to undergo a Landau-Zener transition. We find that the behavior of the qubit agrees to a high degree of a...