作者机构：
[Li, GX] Hong Kong Baptist Univ, Dept Phys, Hong Kong, Hong Kong, Peoples R China.;[Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 43007
通讯机构：
[Li, GX] Hong Kong Baptist Univ, Dept Phys, Hong Kong, Hong Kong, Peoples R China.
摘要：
A cavity-modified master equation is derived for a coherently driven V-type three-level atom coupled to a single-mode cavity in the bad cavity limit. The influences of the cavity-induced quantum interference on the steady-state populations are analyzed. We show that population inversion can occur in atomic bare state representation. The probe absorption spectrum is also investigated. Various line shapes and probe gain with and without population inversion can appear in the Autler-Townes doublet due to the effects of the cavity-induced quantum interference. (C) 2000 Elsevier Science B.V. All rights reserved.
作者机构：
[Tan, Huatang; Li, Gaoxiang; Wei, Yanghua] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Hubei, Peoples R China.
通讯机构：
[Wei, YH] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Hubei, Peoples R China.
摘要：
Greenberger-Horne-Zeilinger (GHZ) and cluster states are two typical kinds of multipartite entangled states and can respectively be used for realizing quantum networks and one-way computation. We propose a feasible scheme for generating Gaussian GHZ and cluster states of multiple mechanical oscillators by pulsed cavity optomechanics. In our scheme, each optomechanical cavity is driven by a blue-detuned pulse to establish quantum steerable correlations between the cavity output field and the mechanical oscillator, and the cavity outputs are combined at a beam-splitter array with given transmissivity and reflectivity for each beam splitter. We show that by harnessing the light-mechanical steerable correlations, the mechanical GHZ and cluster states can be realized via homodyne detection on the amplitude and phase quadratures of the output fields from the beam-splitter array. These achieved mechanical entangled states can be viewed as the output states of an effective mechanical beam-splitter array with the mechanical inputs prepared in squeezed states with the light-mechanical steering. The effects of detection efficiency and thermal noise on the achieved mechanical states are investigated. The present scheme does not require externally injected squeezing and it can also be applicable to other systems such as light-atomic-ensemble interface, apart from optomechanical systems.
通讯机构：
[Tan, HT] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
Einstein-Podolsky-Rosen (EPR) steering is a quantum nonlocal effect which is intrinsically distinct from Bell nonlocality and quantum entanglement. In this paper, we investigate in detail the properties of steady-state light-mechanical Gaussian steerable correlations in a generic cavity optomechanical system. When considering the steering between the intracavity field and the mechanical oscillator, we find that under blue-detuned driving, the steady-state steering via optomechanical parametric downconversion is present in only one direction and, moreover, the steering direction is determined merely by the relative dissipation strength of the cavity to the mechanics. Furthermore, when considering the steering between the cavity output field and the mechanical oscillator, we reveal that under red-detuned driving, strong steering can be achieved in the sideband-unresolved regime for a filtered output field with given central frequency and bandwidth. This steering with the output field can also be present in one way by adjusting the driving strength and exists up to the environment temperature T approximate to 10 K for the parameters close to those in the recent experiments. Finally, we show that the achieved strong light-mechanical correlations can be explored to realize macroscopic EPR steering of two distant optomechanical oscillators in the regime of unresolved sidebands via entanglement swapping.
作者机构：
[Ficek, Zbigniew] KACST, Natl Ctr Appl Phys, POB 6086, Riyadh 11442, Saudi Arabia.;[Gao, Bo; Li, Gao-xiang] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
We demonstrate how an acoustic phonon bath when coupled to a quantum dot with the help of a bichromatic laser field may effectively form a quantum squeezed reservoir. This approach allows one to achieve an arbitrary degree of squeezing of the effective reservoir and it incorporates the properties of the reservoir into two parameters, which can be controlled by varying the ratio of the Rabi frequencies of the bichromatic field. It is found that for unequal Rabi frequencies, the effective reservoir may appear as a quantum squeezed field of ordinary or inverted harmonic oscillators. When the Rabi frequencies are equal the effective reservoir appears as a perfectly squeezed field in which the decay of one of the polarization quadratures of the quantum dot dipole moment is inhibited. The decay of the quantum dot to a stationary state which depends on the initial coherence is predicted. This unusual result is shown to be a consequence of a quantum-nondemolition-type coupling of the quantum dot to the engineered squeezed reservoir. The effect of the initial coherence on the steady-state dressed-state population distribution and the fluorescence spectrum is discussed in detail. The complete polarization of the dressed state population and asymmetric spectra composed of only a single Rabi sideband peak are obtained under strictly resonant excitation.
作者：
Zhu, Fengzheng;Zhao, Teng;Zhang, Hebin;Li, Gao-xiang;Ficek, Zbigniew
期刊：
PHYSICAL REVIEW A,2017年95(2) ISSN：2469-9926
通讯作者：
Li, GX
作者机构：
[Zhang, Hebin; Zhao, Teng; Zhu, Fengzheng; Li, Gao-xiang] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.;[Ficek, Zbigniew] KACST, Natl Ctr Appl Phys, POB 6086, Riyadh 11442, Saudi Arabia.
通讯机构：
[Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
We examine conditions under which an open quantum system composed of a driven degenerated parametric oscillator cavity and a driven two-level atom coupled to a waveguide could decay to a pure dark state rather than the expected mixed state. The calculations are carried out analytically in a low-dimensional Hilbert space truncated at the double-excitation states of the combined system. The validity of the truncation is confirmed by the exact numerical analysis. It is found that one way to produce the pure state is to chirally couple the cavity and the atom to the waveguide. Another way to produce the pure state is to drive the cavity and the atom with unequal detunings. In both cases, if the driving fields are weak, the produced state is a coherent superposition of only the single-excitation and ground states of the combined system. In addition, we have found a direct correspondence between the generation of the dark state and the photon blockade effect. In other words, the generation of the dark state acts as a blockade to the number of photons so that only a single photon can be present in the cavity. We investigate the normalized second-order correlation function of the cavity field and find that the conditions under which the correlation function vanishes coincide with the conditions for the creation of the pure dark state. This system is, therefore, suggested as an alternative scheme for the generation of single-photon states.
作者机构：
[Li, Gao-xiang ; Huang, Guang-ming ; Peng, Jin-sheng ] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
We have investigated the atomic coherent population trapping in a multilevel laser-induced continuum structure system including cascade two-photon processes, in which two sets of quasicontinua of excited levels to be modeled as the Bixon-Jortner quasicontinuum are laser-embedded into a previously structureless atomic continuum. The condition leading to the atomic coherent population trapping and the coherent population trapping state are given explicitly. And the effects of the Fano factors, the laser intensities and the detunings on the amount of population trapped in the atomic bound states and the populations distributed in the two sets of quasicontinua are also examined.
期刊：
CHINESE PHYSICS LETTERS,2001年18(1):48-50 ISSN：0256-307X
通讯作者：
Li, GX
作者机构：
[Li, GX; Huang, GM; Wu, SP; Peng, JS] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
A cavity-modified master equation is derived for a coherently driven V-type three-level atom coupled to a single-mode cavity in the bad cavity limit. The influences of the cavity-induced quantum interference on the steady-state populations are analysed. We show that the population inversion can occur due to the effect of cavity-induced quantum interference.
通讯机构：
[Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Hubei, Peoples R China.
摘要：
Coherent perfect absorption (CPA) is investigated in the quantum nonlinear regime of cavity quantum electrodynamics (CQED), in which a single two-level atom couples to a single-mode cavity weakly driven by two identical laser fields. In the strong-coupling regime and due to the photon blockade effect, the weakly driven CQED system can be described as a quantum system with three polariton states. CPA is achieved at a critical input field strength when the frequency of the input fields matches the polariton transition frequency. In the quantum nonlinear regime, the incoherent dissipation processes such as atomic and photon decays place a lower bound for the purity of the intracavity quantum field. Our results show that under the CPA condition, the intracavity field always exhibits the quadrature squeezing property manifested by the quantum nonlinearity, and the outgoing photon flux displays the super-Poissonian distribution.
期刊：
CHINESE PHYSICS LETTERS,2000年17(7):501-503 ISSN：0256-307X
通讯作者：
Li, GX
作者机构：
[Li, GX; Huang, GM; Peng, JS] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
The absorption spectrum of a driven two-level atom in a frequency tunable cavity with injected squeezed vacuum is investigated. The line shape of the spectra depends on the relative phase between the driving field and the squeezed vacuum, and the frequency detuning between the driving field and the cavity mode. Line narrowing and probe gain can occur and be enhanced by adjusting the phase and detuning.
作者机构：
[Li, GX; Guo, H; Peng, JS] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Guo, H] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
An analytical expression of emission spectrum for A-type three-level atom interacted with two-mode cavity field is given. The characters of the emission spectrum for the field in photon number state, coherent state and SU(2) coherent state are exhibited. The effects of the atomic initial state, the field property on the time-dependent physical spectrum are analyzed. (C) 2002 Elsevier Science B.V. All rights reserved.
作者机构：
[Li, GX; Huang, GM; Wu, SP] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
A scheme for generating two-mode photon-added SU(2) coherent state by means of conditional measurement is proposed. Feeding three uncorrelated Fock states into three input ports of two cascade placed lossless beam splitters respectively and counting photons in one of the output channels, the conditional state in the other two output channels is a two-mode photon-added SU(2) coherent state. The quantum nonlocality property for this state is investigated using parity measurement. (C) 2002 Elsevier Science B.V. All rights reserved.
通讯机构：
[Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
The time evolution of nonlocality for atom-field entangled state in the system of a two-level atom interacting dispersively C with a single-mode field in a dissipative cavity is investigated. It is found that, if the cavity dissipation is very weak, the atom-field state can exhibits nonlocality periodically. The rapidity of the loss of the initial quantum nonlocality depends on the amplitude of the two coherent states and the cavity damping constant K. The stronger the field is and the larger the constant K, the more rapidly the nonlocality decreases. (C) 2001 Elsevier Science B.V. All rights reserved.
摘要：
In this paper, we have investigated the influence of the counter-rotating terms on the squeezing of light in the two-photon Jaynes-Cummings model by means of the nonrelativistic quantum electrodynamics. We verified that the effect of the virtual-photon field increases the squeezing. The relations between the degree of squeezing and the frequency of the field, the mean photon number, and the atom-field coupling constant have also been analyzed.
作者机构：
[Zhou, P; Peng, JS; Li, GX] Huazhong Normal Univ, Wuhan, China
通讯机构：
[Li, GX] CHINA CTR ADV SCI & TECHNOL,WORLD LAB,POB 8730,BEIJING 100080,PEOPLES R CHINA.
关键词：
Laser cooling - Laser induced continuum structure - Raman transition processes - Raman type photoionization system - Semiclassical theory - Two mode quantized field
摘要：
We have studied the properties of coherent population trapping in a Raman-type photoionization system driven by a two-mode quantized field. The influence of the parameters describing the atom-field coupling character on the states of the field trapping the atom is analyzed. Under certain conditions, the atom driven by an appropriate two-mode SU (2) coherent field can be completely trapped in its two bound states.
摘要：
We have investigated atomic coherent population trapping in a multilevel model of laser-induced continuum structure, in which a quasicontinuum of excited levels to be modeled as the Bixon-Jortner quasicontinuum is laser-embedded into a previously structureless atomic continuum. The condition leading to atomic coherent population trapping and the coherent population trapping state are given explicitly. The effects of nondegenerate detuning, the Fano factors and the laser intensities on the amount of population trapped in the atomic bound states and the populations distributed in the quasicontinuum are also examined.
通讯机构：
[Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
The modification of the Autler-Townes spectrum of a V-type three-level atom driven by a strong coherent field and a weak stochastic field with a wide bandwidth is studied. It is found that the lineshape of the probe absorption spectrum varies drastically with the changing of the frequency difference between the coherent field and the stochastic one. The probe beam can be amplified due to the effect of the stochastic field and this amplification can be enhanced due to the quantum interference induced by the stochastic field. (C) 2002 Elsevier Science B.V. All rights reserved.
期刊：
Zeitschrift für Physik B Condensed Matter,1996年100(01):91-93 ISSN：0722-3277
通讯作者：
Li, GX
作者机构：
[Li, GX; Peng, JS] HUAZHONG NORMAL UNIV, DEPT PHYS, WUHAN 430070, PEOPLES R CHINA.
通讯机构：
[Li, GX] CCAST, WORLD LAB, POB 8730, BEIJING 100080, PEOPLES R CHINA.
摘要：
The generation of two-mode pure states in a lossless nondegenerate two-photon micromaser has been analyzed. The results show that under appropriate conditions, the field may evolve to pure states which can exhibit two-mode squeezing, or evolve to two-mode number states.
作者机构：
[Li, Gao-xiang] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
关键词：
Entangled States;Coherence;Cavity QED;Squeezed States
摘要：
We study the problem of creation of multi-mode continuous variable entangled states in an atomic ensemble located inside a high-Q ring cavity composed of two degenerate mutually counter-propagating modes. We show that multi-mode squeezed (entangled) states can be constructed from the vacuum by a unitary transformation associated with the collective dynamics of the atomic ensemble subjected to external lasers pulses of suitably adjusted amplitudes and phases.
