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Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography 被引量:2
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作者 尹君 于凌尧 +3 位作者 刘星 万辉 林子扬 牛憨笨 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第1期385-391,共7页
In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of variou... In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of various molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactions in the fields of biology, chemistry and material science. 展开更多
关键词 coherent anti-Stokes Raman scattering photonic crystal fibre SUPERCONTINUUM molecular vibrational spectrum dephasing time time-resolved measurement
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Robust Quantum Secure Direct Communication and Deterministic Secure Quantum Communication over Collective Dephasing Noisy Channel 被引量:2
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作者 YUAN Hao SONG Jun +4 位作者 HE Qin HAN Lian-Fang HOU Kui HU Xiao-Yuan SHI Shou-Hua 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第9期627-632,共6页
We propose two schemes for quantum secure direct communication (QSDC) and deterministic securequantum communication (DSQC) over collective dephasing noisy channel.In our schemes,four special two-qubit statesare used a... We propose two schemes for quantum secure direct communication (QSDC) and deterministic securequantum communication (DSQC) over collective dephasing noisy channel.In our schemes,four special two-qubit statesare used as the quantum channel.Since these states are unchanged through the collective dephasing noisy channel,the effect of the channel noise can be perfectly overcome.Simultaneously,the security against some usual attacks canbe ensured by utilizing the various checking procedures.Furthermore,these two schemes are feasible with present-daytechnique. 展开更多
关键词 quantum secure direct communication deterministic secure quantum communication collective dephasing noisy channel special two-qubit states
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Robustness of Genuine Tripartite Entanglement under Collective Dephasing 被引量:1
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作者 MAZHAR Ali 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第6期6-9,共4页
We study the robustness of genuine multipartite entanglement for a system of three qubits under collective dephasing. Using a computable entanglement monotone for multipartite systems, we find that almost every state ... We study the robustness of genuine multipartite entanglement for a system of three qubits under collective dephasing. Using a computable entanglement monotone for multipartite systems, we find that almost every state is quite robust under this type of decoherence. We analyze random states and weighted graph states at infinity and find all of them to be genuinely entangled. 展开更多
关键词 Robustness of Genuine Tripartite Entanglement under Collective dephasing
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Entanglement and non-Markovianity of a spin-S system in a dephasing environment
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作者 范子龙 田晶 曾浩生 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第6期30-36,共7页
We study the entanglement (measured by negativity) evolution and the non-Markovianity for the dynamical process of a spin-S system embedded in dephasing environments. The exact analytical solution is presented, whic... We study the entanglement (measured by negativity) evolution and the non-Markovianity for the dynamical process of a spin-S system embedded in dephasing environments. The exact analytical solution is presented, which shows that the decoherence function governs the evolutions of coherence, entanglement, and the non-Markovianity of the correspond- ing dynamical processes. For Ohmic and sub-Ohmic reservoirs, the negativity decreases monotonically in time and the corresponding dynamics is Markovian. While for super-Ohmic reservoirs with non-monotonic decoherence function, the negativity appears as the phenomenon of revival and the corresponding dynamics is non-Markovian. The relation between non-Markovianity and the system dimension is studied. 展开更多
关键词 ENTANGLEMENT non-Markovianity spin-S system dephasing
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Optical Bloch Equations Modified with Phonon-Induced Intensity-Dependent Dephasing
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作者 ZHOU Guang-Hua LI Yao-Yi +2 位作者 CHENG Mu-Tian LIU Shao-Ding WANG Qu-Quan 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第2X期335-338,共4页
We extend the exciton population equations of a two-level quantum dot system with weak excitation to the ones with strong excitations, in which, the phonon-induced intensity-dependent dephasing time and decay rate are... We extend the exciton population equations of a two-level quantum dot system with weak excitation to the ones with strong excitations, in which, the phonon-induced intensity-dependent dephasing time and decay rate are involved. The straightforward calculated populations from the modified population equations demonstrate the damping behavior of Rabi oscillation as the external field increasing. The effect of the intensity-dependent dephasing time and the intensity-dependent decay rate are also discussed. 展开更多
关键词 DECOHERENCE dephasing optical Bloch equation quantum dot
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Role of phase fluctuation and dephasing in the enhancing continuous variable entanglement of a two-photon coherent beat laser
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作者 Sintayehu Tesfa 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第1期210-221,共12页
A steady state analysis of the nonclassical features and statistical properties of the cavity radiation of a two- photon coherent beat laser is presented. Results show that the degree of two-mode squeezing, detectable... A steady state analysis of the nonclassical features and statistical properties of the cavity radiation of a two- photon coherent beat laser is presented. Results show that the degree of two-mode squeezing, detectable entanglement and intensity of the cavity radiation can increase with the deviation of the phase fluctuations of the laser employed in preparing the atoms, but decrease with the increasing rate at which the induced coherence superposition decays. Although it is found that varying the phase fluctuations and dephasing can lead to modification in the quantum features and statistical properties of the radiation, it does not alter the similarity in the nature of the degree of entanglement detectable by the criteria following from Duan-Giedke-Cirac Zoller and logarithmic negativity in a perceivable manner. Since the intensity and quantum features can be readily enhanced, this system is expected to be a viable source of a strong robust entangled (squeezed) light under various conditions. Moreover, comparison of the mean number of photon pairs with intensity difference shows that the chance of inciting a two-photon process can be enhanced by changing the rate of dephasing and phase fluctuations. 展开更多
关键词 coherent beat laser phase fluctuations dephasing ENTANGLEMENT
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Quantum speed limit of the double quantum dot in pure dephasing environment under measurement
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作者 Zhenyu Lin Tian Liu +2 位作者 Zongliang Li Yanhui Zhang Kang Lan 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第7期146-151,共6页
The quantum speed limit(QSL)of the double quantum dot(DQD)system has been theoretically investigated by adopting the detection of the quantum point contact(QPC)in the pure dephasing environment.The Mandelstam–Tamm(MT... The quantum speed limit(QSL)of the double quantum dot(DQD)system has been theoretically investigated by adopting the detection of the quantum point contact(QPC)in the pure dephasing environment.The Mandelstam–Tamm(MT)type of the QSL bound which is based on the trace distance has been extended to the DQD system for calculating the shortest evolving time.The increase of decoherence rate can weaken the capacity for potential speedup(CPS)and delay the evolving process due to the frequently measurement localizing the electron in the DQD system.The system needs longer time to evolve to the target state as the enhancement of dephasing rate,because the strong interaction between pure dephasing environment and the DQD system could vary the oscillation of the electron.Increasing the dephasing rate can sharp the QSL bound,but the decoherence rate would weaken the former effect and vice versa.Moreover,the CPS would be raised by increasing the energy displacement,while the enhancement of the coupling strength between two quantum dots can diminish it.It is interesting that there has an inflection point,when the coupling strength is less than the value of the point,the increasing effect of the CPS from the energy displacement is dominant,otherwise the decreasing tendency of the CPS is determined by the coupling strength and suppress the action of the energy displacement if the coupling strength is greater than the point.Our results provide theoretical reference for studying the QSL time in a semiconductor device affected by numerous factors. 展开更多
关键词 quantum speed limits the DQD system the pure dephasing environment quantum measurement
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Quantum parameter estimation in a spin-boson dephasing quantum system by periodical projective measurements
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作者 Le Yang Hong-Yi Dai Ming Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第4期242-249,共8页
In this paper,we explore how to estimate the phase damping parameter γ and the tunneling amplitude parameter ?from a spin-boson dephasing quantum model by periodical projective measurements.The preparation of initia... In this paper,we explore how to estimate the phase damping parameter γ and the tunneling amplitude parameter ?from a spin-boson dephasing quantum model by periodical projective measurements.The preparation of initial states is accomplished by performing the period measurements in our scheme.The parameter γ can be always estimated when projective measurement bases are chosen as θ = π/2 and φ = 0.Based on the estimated value of γ and the interval information of ?,we can select another measurement bases(θ = π/4 and φ = π/2) to obtain the estimated value of ?.A coherent control is indispensable to estimate ? if γ is in the interval of ?;whereas the control is not necessary if γ is out of the known interval of ?.We establish the relation between the optimal period time and the parameter γ or ? in terms of Fisher information.Although the optimal measurement period cannot be selected beforehand,the aforementioned relation can be utilized to adjust the measurement period to approach the optimal one. 展开更多
关键词 parameter estimation periodical projective measurement spin-boson model dephasing quantum system
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Dynamics of Entanglement of Qutrit-Qutrit States with Stochastic Dephasing
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作者 马小三 任明凡 +1 位作者 赵光兴 王安民 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第8期258-262,共5页
The effect of stochastic dephasing on the dynamics of entanglement of qutrit-qutrit states is investigated by using negativity and bound entanglement defined with realignment criterion, From the analysis, we, find tha... The effect of stochastic dephasing on the dynamics of entanglement of qutrit-qutrit states is investigated by using negativity and bound entanglement defined with realignment criterion, From the analysis, we, find that the time evolution of quantum free entanglement and bound entanglement depends on the fluctuations of the stochastic variables and the parameters of the particular initial states of concern. Our results imply that some qutrits states display both distillability sudden death and entanglement sudden death, while some states do not display distillability sudden death but only entanglement sudden death. 展开更多
关键词 bound entanglement free entanglement stochastic dephasing
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Dephasing of quantum tunnelling in molecular nanomagnets
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作者 张树群 陈芝得 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第4期1436-1442,共7页
Dephasing mechanism of quantum tunnelling in molecular magnets has been studied by means of the spin-coherentstate path integral in a mean field approximation. It is found that the fluctuating uncompensated transverse... Dephasing mechanism of quantum tunnelling in molecular magnets has been studied by means of the spin-coherentstate path integral in a mean field approximation. It is found that the fluctuating uncompensated transverse field from the dipolar-dipolar interaction between molecular magnets contributes a random phase to the quantum interference phase. The resulting transition rate is determined by the average tunnel splitting over the random phase. Such a dephasing process leads to the suppression of quenching due to the quantum phase interference, and to the steps due to odd resonances in hysteresis loop survived, which is in good agreement with experimental observations in molecular nanomagnets Fes and Mn12. 展开更多
关键词 single molecule magnet quantum tunnelling dephasing
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Geometric Phases Corrected by Stochastic Dephasing
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作者 MA Xiao-San WANG An-Min 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第5期1179-1181,共3页
We analyze the effect of stochastic dephasing on geometric phases. The result implies that the correction of geometric phases relies on not only the fluctuation of the random variable in the stochastic process, but al... We analyze the effect of stochastic dephasing on geometric phases. The result implies that the correction of geometric phases relies on not only the fluctuation of the random variable in the stochastic process, but also the frequency of the system. 展开更多
关键词 stochastic dephasing geometric phase
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Disentanglement of Qubit in Dephasing Model
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作者 YANG Qing YANG Ming CAO Zhuo-Liang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第4期627-630,共4页
We investigate the entanglement evolution of two qubits that are initially in Werner state under the classical phase noise. We discuss the influence of mixture degree on disentanglement. It is showed that the more mix... We investigate the entanglement evolution of two qubits that are initially in Werner state under the classical phase noise. We discuss the influence of mixture degree on disentanglement. It is showed that the more mixed the state, the shorter is the time of disentanglement. 展开更多
关键词 DISENTANGLEMENT dephase
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Traveling-wave parametric amplifiere-induced qubit dephasing:analysis and mitigation
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作者 Yingshan Zhang Huikai Xu +8 位作者 Yu Song Yuqun Xu Shuang Yang Ziyue Hua Shoukuan Zhao Weiyang Liu Guangming Xue Yirong Jin Haifeng Yu 《Chip》 EI 2023年第4期97-104,共8页
The mitigation of dephasing poses a significant challenge toimproving the performance of error-prone superconducting quantum computing systems.Here,the dephasing of a transmon qubit ina dispersive readout regime was i... The mitigation of dephasing poses a significant challenge toimproving the performance of error-prone superconducting quantum computing systems.Here,the dephasing of a transmon qubit ina dispersive readout regime was investigated by adopting aJosephson traveling-wave parametric amplifier as the preamplifier.Our findings reveal that the potent pump leakage from the preamplifier may lead to severe dephasing.This could be attributed to amixture of measurement-induced dephasing,ac Stark effect,andheating.It is showed that pulse-mode readout is a promising measurement scheme to mitigate qubit dephasing while minimizing theneed for bulky circulators.Our work provides key insights intomitigating decoherence from microwave-pumped preamplifiers,which will be critical for advancing large-scale quantum computers. 展开更多
关键词 TWPA Microwave pump dephasing Pulse mode
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Tunneling Electrons Triggered Energy Transfer between Coherently Coupled Donor-Acceptor Molecules
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作者 Huifang Wang 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2024年第4期497-504,I0093,I0094,共10页
Energy transfer is ubiquitous in natural and artificial lightharvesting systems,and coherent energy transfer,a highly efficient energy transfer process,has been accepted to play a vital role in such systems.However,th... Energy transfer is ubiquitous in natural and artificial lightharvesting systems,and coherent energy transfer,a highly efficient energy transfer process,has been accepted to play a vital role in such systems.However,the energy oscillation of coherent energy transfer is exceedingly difficult to capture because of its evanescence due to the interaction with a thermal environment.Here a microscopic quantum model is used to study the time evolution of electrons triggered energy transfer between coherently coupled donoracceptor molecules in scanning tunneling microscope(STM).A series of topics in the plasmonic nanocavity(PNC)coupled donor-acceptor molecules system are discussed,including resonant and nonresonant coherent energy transfer,dephasing assisted energy transfer,PNC coupling strength dependent energy transfer,Fano resonance of coherently coupled donor-acceptor molecules,and polariton-mediated energy transfer. 展开更多
关键词 Energy transfer Coherent energy transfer Scanning tunneling microcopy induced luminescence Plasmonic nanocavity Quantum master equation dephasing Fano resonance Polariton-mediated energy transfer
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Dephasing eflfects in topological insulators 被引量:1
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作者 Junjie Qi Haiwen Liu +1 位作者 Hua Jiang X.C.Xie 《Frontiers of physics》 SCIE CSCD 2019年第4期47-61,共15页
Topological insulators,a class of typical topological materials in both two dimensions and three dimensions,are insulating in bulk and metallic at surface.The spin-momentum locked surface states and peculiar transport... Topological insulators,a class of typical topological materials in both two dimensions and three dimensions,are insulating in bulk and metallic at surface.The spin-momentum locked surface states and peculiar transport properties exhibit promising potential applications on quantum devices,which generate extensive interest in the last decade.Dephasing is the process of the loss of phase coherence,which inevitably exists in a realistic sample.In this review,we focus on recent progress in dephasing effects on the topological insulators.In general,there are two types of dephasing processes:normal dephasing and spin dephasing.In two-dimensional topological insulators,the phenomenologically numerical investigation shows that the longitudinal resistance plateaus is robust against normal dephasing but fragile with spin dephasing.Several microscopic mechanisms of spin dephasing are then discussed.In three-dimensional topological insulators,the helical surface states exhibit a helical spin texture due to the spin-momentum locking mechanism.Thus,normal dephasing has close connection to spin dephasing in this case,and gives rise to anomalous "gap-like" feature.Dephasing effects on properties of helical surface states are investigated. 展开更多
关键词 dephasing EFFECTS TOPOLOGICAL insulators BACKSCATTERING
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Experimental demonstration of suppressing residual geometric dephasing 被引量:1
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作者 Jin-Ming Cui Ming-Zhong Ai +7 位作者 Ran He Zhong-Hua Qian Xiao-Ke Qin Yun-Feng Huang Zheng-Wei Zhou Chuan-Feng Li Tao Tu Guang-Can Guo 《Science Bulletin》 SCIE EI CAS CSCD 2019年第23期1757-1763,共7页
The geometric phase is regarded as a promising strategy in fault tolerance quantum information processing(QIP) domain due to its phase only depending on the geometry of the path executed. However, decoherence caused b... The geometric phase is regarded as a promising strategy in fault tolerance quantum information processing(QIP) domain due to its phase only depending on the geometry of the path executed. However, decoherence caused by environmental noise will destroy the geometric phase. Traditional dynamic decoupling sequences can eliminate dynamic dephasing but can not reduce residual geometric dephasing, which is still vital for high-precision quantum manipulation. In this work, we experimentally demonstrate effective suppression of residual geometric dephasing with modified dynamic decoupling schemes,using a single trapped171 Ybtion. The experimental results show that the modified schemes can reduce dephasing rate up to more than one order of magnitude compared with traditional dynamic decoupling schemes, where residual geometric dephasing dominates. Besides, we also investigate the impact of intensity and correlation time of the low-frequency noise on coherence of the quantum system. And we confirm these methods can be used in many cases. 展开更多
关键词 Geometric dephasing Berry phase Dynamic decoupling Ion trap
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Investigation of the correlation between internal gradients and dephasing effect in inhomogeneous field 被引量:1
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作者 AN TianLin XIAO LiZhi +2 位作者 LI Xin LIU HuaBing ZHANG ZongFu 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2014年第9期1676-1683,共8页
Internal magnetic gradient plays a significant role in Nuclear Magnetic Resonance(NMR)measurements of fluid saturated porous media.The quantitative characterization and application of this physical phenomenon could ef... Internal magnetic gradient plays a significant role in Nuclear Magnetic Resonance(NMR)measurements of fluid saturated porous media.The quantitative characterization and application of this physical phenomenon could effectively improve the accuracy of NMR measurements and interpretations.In this paper,by using the equivalent magnetic dipole method,the three-dimensional distribution of internal induced magnetic field and its gradients in the randomly packed water saturated glass beads are quantitatively characterized.By simulating the diffusive motion of water molecules in porous media with random walk method,the computational dephasing effects equation related to internal gradients is deduced.Thereafter,the echo amplitudes are obtained and the corresponding T2-G spectrum is also inverted.For the sake of verifying the simulation results,an experiment is carried out using the Halbach core analyzing system(B0=0.18 T,G=2.3 T/m)to detect the induced internal field and gradients.The simulation results indicate the equivalent internal gradient is a distribution of 0.1-0.3 T/m,which matched well with the experimental results. 展开更多
关键词 porous media NMR internal gradients dephasing effect inhomogeneous field
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Rotational dephasing of the molecular alignment by centrifugal distortion [Invited] 被引量:1
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作者 Yunxia Huang Guizhen Liu Shuwu Xu 《Chinese Optics Letters》 SCIE EI CAS CSCD 2022年第10期20-24,共5页
The dephasing of molecular alignment can lead to the deformation of the alignment signal during its periodic revivals.Most studies are concentrated on the first few rotational revival periods of the molecular alignmen... The dephasing of molecular alignment can lead to the deformation of the alignment signal during its periodic revivals.Most studies are concentrated on the first few rotational revival periods of the molecular alignment and neglect the dephasing effect.However,study of the alignment dephasing is still of great significance for both the long-term dynamics of the molecular alignment and the dephasing itself.In this work,we theoretically demonstrate that the dephasing effect is correlated with both the rotational temperature and the rotational revival period of the molecules.The results present that the dephasing is especially significant for those molecules with long rotational revival period at high rotational temperatures.The physics behind it is explored by taking advantage of the coherence of the rotational quantum state population.This work deepens our understanding of rotational dynamics and rotational spectroscopy in molecular alignment. 展开更多
关键词 dephasing molecular alignment centrifugal distortion rotational state population
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Ultrafast dephasing of interband transitions in semiconductors 被引量:1
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作者 张海潮 邓莉 +3 位作者 文锦辉 廖睿 赖天树 林位株 《Science China Mathematics》 SCIE 2001年第10期1340-1348,共9页
Two basic types of dephasing mechanisms, carrier-carrier and carrier-phonon scattering including hole-hole and hole-phonon scattering are proposed in the theory of ultrafast polarization dephasing of continuum transit... Two basic types of dephasing mechanisms, carrier-carrier and carrier-phonon scattering including hole-hole and hole-phonon scattering are proposed in the theory of ultrafast polarization dephasing of continuum transitions in bulk semiconductors. The contribution of optical phonon scattering to the dephasing rate is the average of the scattering rates for electrons and holes. A weighting factor that reflects the change in the momentum of the particle in a collision is introduced into the usual integral of the carrier-carrier scattering rate to describe the contribution of carrier-carrier scattering to the dephasing rate for the case of static screening interaction. The theoretical calculations are in quantitative agreement with the reported experimental results. 展开更多
关键词 femtosecond spectroscopy optical polarization dephasing
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^(13)C NMR SPECTROSCOPY OF KEROGEN——APPLICATION OF DIPOLAR DEPHASING TECHNIQUE
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作者 秦匡宗 李振广 N.V.BODOEV 《Chinese Science Bulletin》 SCIE EI CAS 1992年第17期1457-1460,共4页
Solid state <sup>13</sup>C nuclear magnetic resonance (NMR)with cross polarization (CP)and magic angle spinning (MAS) techniques have made possible a direct measurement of organic carbon distribution... Solid state <sup>13</sup>C nuclear magnetic resonance (NMR)with cross polarization (CP)and magic angle spinning (MAS) techniques have made possible a direct measurement of organic carbon distribution in kerogens, which is helpful to characterization of the kerogen types, ma- 展开更多
关键词 KEROGEN 13C NMR DIPOLAR dephasing.
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