We present a weak-coupling theory of semiclassical periodically driven two-level systems. The explicit analytical approximating solution is shown to reproduce highly accurately the exact results well beyond the regime...We present a weak-coupling theory of semiclassical periodically driven two-level systems. The explicit analytical approximating solution is shown to reproduce highly accurately the exact results well beyond the regime of the rotating-wave approximation.展开更多
We study the long-time average of the reduced density matrix(RDM)of a two-level system as the central system,which is locally coupled to a many-body quantum chaotic system as the environment,under an overall Schr?ding...We study the long-time average of the reduced density matrix(RDM)of a two-level system as the central system,which is locally coupled to a many-body quantum chaotic system as the environment,under an overall Schr?dinger evolution.A phenomenological relation among elements of the RDM is proposed for a dissipative interaction in the strong coupling regime and is tested numerically with the environment as a defect Ising chain,as well as a mixed-field Ising chain.展开更多
We present a feasible scheme that realizes quantum computation using the two-level systems （TLSs） in Current-biased Josephson junction （CBJJ） under the present experimental technology. Effective manipulation of th...We present a feasible scheme that realizes quantum computation using the two-level systems （TLSs） in Current-biased Josephson junction （CBJJ） under the present experimental technology. Effective manipulation of the TLSs by CBJJ serving as register qubit can be obtained, such as initialization, single-qubit rotations, two-qubit gates, entanglement generation, and read out, etc. In addition, we also discuss the experimental feasibility and efficiency of the scheme.展开更多
We generalize the Wu-Yang strong-coupling theory to solve analytically periodically driven two-level systems in the weak-coupling and low-frequency regimes for single- and multi-period periodic driving of continuous-w...We generalize the Wu-Yang strong-coupling theory to solve analytically periodically driven two-level systems in the weak-coupling and low-frequency regimes for single- and multi-period periodic driving of continuous-wave-type and pulse-type including ultrashort pulses of a few cycles.We also derive a general formula of the AC Stark shift suitable for such diverse situations.展开更多
We present a scheme with the multiple-induced transparency windows in a hybrid optomechanical device.By studying the transmission of a probe field through the hybrid device,we show the successive generations of three ...We present a scheme with the multiple-induced transparency windows in a hybrid optomechanical device.By studying the transmission of a probe field through the hybrid device,we show the successive generations of three transparent windows induced by multiple factors including tunneling,optomechanical and qubit-phonon coupling interactions,and analyze the physical mechanism of the induced transparency based on a simplified energy-level diagram of the system.Moreover,the effects of the transition frequency and decay rate of the two-level system on the multiple-induced transparency windows are discussed.We find that the transparency windows can be modulated by the coupling interaction between the qubit and NMR,the decay of qubit and the power of the control field.Therefore,the transmission of the probe field can be coherently adjusted in the hybrid cavity optomechanical device with a two-level system.展开更多
We study theoretically the nonadiabatic geometric phase of a doubly driven two-level system with an additional relative phase between the two driving modes introduced in. It is shown that the time evolution of the sys...We study theoretically the nonadiabatic geometric phase of a doubly driven two-level system with an additional relative phase between the two driving modes introduced in. It is shown that the time evolution of the system strongly depends on this relative phase. The condition for the system returning to its initial state after a single period is given by the means of the Landau–Zener–Stückelberg–Majorana destructive interference. The nonadiabatic geometric phase accompanying a cyclic evolution is shown to be related to the Stokes phase as well as this relative phase. By controlling the relative phase, the geometric phase can characterize two distinct phases in the adiabatic limit.展开更多
We present an approximate analytical solution to periodically driven two-level system in the weak-coupling regime. The analytical solution is in good agreement with the exact numerical solution in resonance and near r...We present an approximate analytical solution to periodically driven two-level system in the weak-coupling regime. The analytical solution is in good agreement with the exact numerical solution in resonance and near resonance cases when Ω 〈 0.3ωa with Ω and ωa denoting the Rabi and transition frequencies respectively.展开更多
The investigation on quantum radar requires accurate computation of the state vectors of the single-photon processes of the two-level system in free space. However, the traditional Weisskopf-Wigner(W-W) theory fails t...The investigation on quantum radar requires accurate computation of the state vectors of the single-photon processes of the two-level system in free space. However, the traditional Weisskopf-Wigner(W-W) theory fails to deal with those processes other than spontaneous emission. To solve this problem, we provide a new method based on the renormalization theory. We evaluate the renormalized time-ordered Green functions associated with the single-photon processes, and relate them to the corresponding state vectors. It is found that the ultraviolet divergences generated by the Lamb shift and higher-order interactions can be systematically subtracted in the state vectors. The discussions on spontaneous emission and single-photon absorption are then presented to illustrate the proposed method. For spontaneous emission, we obtain the same results of the W-W theory. For single-photon absorption where W-W theory fails, we find that the two-level electric dipole first gets excited rapidly and then decays exponentially, and that the efficiency of the single-photon absorption declines as the bandwidth of the incident photon becomes narrow. The proposed method can improve the investigation on quantum radar.展开更多
We investigate the dynamics of parity-and time-reversal（PT） symmetric two-energy-level atoms in the presence of two optical and one radio-frequency fields. The strength and relative phase of fields can drive the sys...We investigate the dynamics of parity-and time-reversal（PT） symmetric two-energy-level atoms in the presence of two optical and one radio-frequency fields. The strength and relative phase of fields can drive the system from the unbroken to the broken PT symmetric regions. Compared with the Hermitian model, Rabi-type oscillation is still observed, and the oscillation characteristics are also adjusted by the strength and relative phase in the region of the unbroken symmetry. At the exception point, the oscillation breaks down. To better understand the underlying properties we study the effective Bloch dynamics and find that the emergence of the PT components of the fixed points is the feature of the PT symmetry breaking and the projections in the x–y plane can be controlled with high flexibility compared with the standard two-level system with the PT symmetry. It helps to study the dynamic behavior of the complex PT symmetric model.展开更多
This paper is devoted to theoretical investigation of characteristic features arising during excitation by short nonresonance laser pulses. The treatment is made within the applicability of perturbation is given to th...This paper is devoted to theoretical investigation of characteristic features arising during excitation by short nonresonance laser pulses. The treatment is made within the applicability of perturbation is given to the dependence of total excitation probability from eigenfrequency of TLS. Various laser pulse shapes of TLS on the pulse duration for different detuning are considered. two-level system （TLS） approach. Main attention of carrier laser frequency展开更多
We investigate a two-level quantum system driven by a Lorentzian-shaped pulse field.An analytical solution is presented in terms of the confluent Heun functions.It is shown that for specially chosen parameter conditio...We investigate a two-level quantum system driven by a Lorentzian-shaped pulse field.An analytical solution is presented in terms of the confluent Heun functions.It is shown that for specially chosen parameter conditions,there are a number of the exact analytical solutions in an explicit form.The dependence of the final transition probabilities in the two levels on the system parameters is derived analytically and confirmed numerically.展开更多
We investigate the optical bistabiiity （OB） in a duplicated two-level system contained in a ring cavity. The atoms are driven by two orthogonally polarized fields with a relative phase. The OB behavior of such a sys...We investigate the optical bistabiiity （OB） in a duplicated two-level system contained in a ring cavity. The atoms are driven by two orthogonally polarized fields with a relative phase. The OB behavior of such a system can be controlled by the amplitude and the relative phase of the coupling field, and it is possible to switch between bistabilitv and multistability by adjusting the relative phase.展开更多
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10575040, 90503010, 60478029, and 10634060, and by the State Key Basic Research Program under Grant No. 2005CB724508
文摘We present a weak-coupling theory of semiclassical periodically driven two-level systems. The explicit analytical approximating solution is shown to reproduce highly accurately the exact results well beyond the regime of the rotating-wave approximation.
基金the Natural Science Foundation of China under Grant Nos.11275179,11535011 and 11775210the Deutsche Forschungsgemeinschaft(DFG)within the Research Unit FOR 2692 under Grant No.397107022(GE 1657/3-2)
文摘We study the long-time average of the reduced density matrix(RDM)of a two-level system as the central system,which is locally coupled to a many-body quantum chaotic system as the environment,under an overall Schr?dinger evolution.A phenomenological relation among elements of the RDM is proposed for a dissipative interaction in the strong coupling regime and is tested numerically with the environment as a defect Ising chain,as well as a mixed-field Ising chain.
基金supported by National Natural Science Foundation of China under Grant No. 10905024Doctoral Startup Natural Science Foundation of Guangdong Province
文摘We present a feasible scheme that realizes quantum computation using the two-level systems （TLSs） in Current-biased Josephson junction （CBJJ） under the present experimental technology. Effective manipulation of the TLSs by CBJJ serving as register qubit can be obtained, such as initialization, single-qubit rotations, two-qubit gates, entanglement generation, and read out, etc. In addition, we also discuss the experimental feasibility and efficiency of the scheme.
基金supported by the Natural Science Foundation of Jiangxi Province under Grant Nos.0612006 and 2007GZW0819the Scientific Research Foundation of the Education Department of Jiangxi Province under Grant No.[2007]191Funds from East China Jiaotong University
文摘We generalize the Wu-Yang strong-coupling theory to solve analytically periodically driven two-level systems in the weak-coupling and low-frequency regimes for single- and multi-period periodic driving of continuous-wave-type and pulse-type including ultrashort pulses of a few cycles.We also derive a general formula of the AC Stark shift suitable for such diverse situations.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61605225 and 11704238)the Natural Science Foundation of Shanghai,China(Grant No.16ZR1448400).
文摘We present a scheme with the multiple-induced transparency windows in a hybrid optomechanical device.By studying the transmission of a probe field through the hybrid device,we show the successive generations of three transparent windows induced by multiple factors including tunneling,optomechanical and qubit-phonon coupling interactions,and analyze the physical mechanism of the induced transparency based on a simplified energy-level diagram of the system.Moreover,the effects of the transition frequency and decay rate of the two-level system on the multiple-induced transparency windows are discussed.We find that the transparency windows can be modulated by the coupling interaction between the qubit and NMR,the decay of qubit and the power of the control field.Therefore,the transmission of the probe field can be coherently adjusted in the hybrid cavity optomechanical device with a two-level system.
基金the Special Foundation for theoretical physics Research Program of China (Grant No. 11647165)the China Postdoctoral Science Foundation Funded Project (Project No. 2020M673118)+3 种基金the funding from the National Natural Science Foundation of China (Grant No. 11874247)the National Key Research and Development Program of China (Grant No. 2017YFA0304500)the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices, China (Grant No. KF201703)the support from Guangdong Provincial Key Laboratory (Grant No. 2019B121203002)。
文摘We study theoretically the nonadiabatic geometric phase of a doubly driven two-level system with an additional relative phase between the two driving modes introduced in. It is shown that the time evolution of the system strongly depends on this relative phase. The condition for the system returning to its initial state after a single period is given by the means of the Landau–Zener–Stückelberg–Majorana destructive interference. The nonadiabatic geometric phase accompanying a cyclic evolution is shown to be related to the Stokes phase as well as this relative phase. By controlling the relative phase, the geometric phase can characterize two distinct phases in the adiabatic limit.
基金The project supported by the Postdoctoral Science Foundation of China under Grant Nos.20060408878 and 2007RS4015Key Science Research Foundation of the Education Ministry of China,Natural Science Foundation of Hunan Province of China under Grant No.05JJ40007Key Science Research Foundation of the Education Department of Hunan Province under Grant No.07A057
文摘We present an approximate analytical solution to periodically driven two-level system in the weak-coupling regime. The analytical solution is in good agreement with the exact numerical solution in resonance and near resonance cases when Ω 〈 0.3ωa with Ω and ωa denoting the Rabi and transition frequencies respectively.
基金supported by the National Natural Science Foundation of China (6149690025)。
文摘The investigation on quantum radar requires accurate computation of the state vectors of the single-photon processes of the two-level system in free space. However, the traditional Weisskopf-Wigner(W-W) theory fails to deal with those processes other than spontaneous emission. To solve this problem, we provide a new method based on the renormalization theory. We evaluate the renormalized time-ordered Green functions associated with the single-photon processes, and relate them to the corresponding state vectors. It is found that the ultraviolet divergences generated by the Lamb shift and higher-order interactions can be systematically subtracted in the state vectors. The discussions on spontaneous emission and single-photon absorption are then presented to illustrate the proposed method. For spontaneous emission, we obtain the same results of the W-W theory. For single-photon absorption where W-W theory fails, we find that the two-level electric dipole first gets excited rapidly and then decays exponentially, and that the efficiency of the single-photon absorption declines as the bandwidth of the incident photon becomes narrow. The proposed method can improve the investigation on quantum radar.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11104171,11404199,11574187 and 11604188the Youth Science Foundation of Shanxi Province of China under Grant No 2012021003-1the Natural Science Foundation for Youths of Shanxi Province under Grant Nos 201601D201027 and 1331KSC
文摘We investigate the dynamics of parity-and time-reversal（PT） symmetric two-energy-level atoms in the presence of two optical and one radio-frequency fields. The strength and relative phase of fields can drive the system from the unbroken to the broken PT symmetric regions. Compared with the Hermitian model, Rabi-type oscillation is still observed, and the oscillation characteristics are also adjusted by the strength and relative phase in the region of the unbroken symmetry. At the exception point, the oscillation breaks down. To better understand the underlying properties we study the effective Bloch dynamics and find that the emergence of the PT components of the fixed points is the feature of the PT symmetry breaking and the projections in the x–y plane can be controlled with high flexibility compared with the standard two-level system with the PT symmetry. It helps to study the dynamic behavior of the complex PT symmetric model.
文摘This paper is devoted to theoretical investigation of characteristic features arising during excitation by short nonresonance laser pulses. The treatment is made within the applicability of perturbation is given to the dependence of total excitation probability from eigenfrequency of TLS. Various laser pulse shapes of TLS on the pulse duration for different detuning are considered. two-level system （TLS） approach. Main attention of carrier laser frequency
基金Natural Science Foundation of Hainan Province,China(Grant No.2019RC179).
文摘We investigate a two-level quantum system driven by a Lorentzian-shaped pulse field.An analytical solution is presented in terms of the confluent Heun functions.It is shown that for specially chosen parameter conditions,there are a number of the exact analytical solutions in an explicit form.The dependence of the final transition probabilities in the two levels on the system parameters is derived analytically and confirmed numerically.
基金supported by the National Natural Science Foundation of China(Nos.61108006 and 11104221)the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.11JK0529)+2 种基金the Natural Science Basis Research Plan in Shaanxi Province of China(No.2010JQ1002)the Doctoral Program Foundation of Institutions of Higher Education of China(No.20106101120020)the support from the Science Foundation of Northwest University(No.10NW14)
文摘We investigate the optical bistabiiity （OB） in a duplicated two-level system contained in a ring cavity. The atoms are driven by two orthogonally polarized fields with a relative phase. The OB behavior of such a system can be controlled by the amplitude and the relative phase of the coupling field, and it is possible to switch between bistabilitv and multistability by adjusting the relative phase.
