摘要：
We present a mechanism for double transparency in an optomechanical system. This mechanism is based on the coupling of a moving cavity mirror to a second mechanical oscillator. Due to the purely mechanical coupling and the radiation pressure, three pathways are established for excitations of the probe photons into the cavity photons. Destructive interference occurs at two different frequencies, leading to double transparency to the probe field. It is the coupling strength between the mechanical oscillators that determines the locations of the transparency windows. Moreover, the normal splitting appears for the generated Stokes field and the four-wave mixing process is inhibited on resonance.
作者机构：
[Hu, Xiangming] Cent China Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Hu, Xiangming] C;Cent China Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
For dark resonance, one of the most remarkable coherent effects in light-matter interactions, it has commonly been expected that squeezing and entanglement, if existent, are formed via coherent evolutions against dissipation. Contrary to the expectations, here we show that dissipation generates entanglement between two cavity fields and between two dark-state-based spins. The latter correspond also to the atomic ground-state spin squeezing in a limited parameter domain. The dissipation effects, which are hidden deeply behind the coherence-induced nonlinearities, are extracted by probing into the dressed atom-photon interactions, and are widely applicable for the coherently prepared systems in dark resonances or beyond.
作者机构：
[Wang, Fei] China Three Gorges Univ, Coll Sci, Yichang 443002, Peoples R China.;[Hu, Xiangming] Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
通讯机构：
[Wang, Fei] C;China Three Gorges Univ, Coll Sci, Yichang 443002, Peoples R China.
作者机构：
[Hu, Xiangming; Li, Xing] Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.;[Li, Xing] Jianghan Univ, Sch Phys & Informat Engn, Wuhan 430056, Peoples R China.
通讯机构：
[Li, Xing] C;Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
摘要：
We describe the effects of Raman interactions on the quantum correlations of multimode optical fields. It is shown that both quantum beats and four-wave mixing processes exist in the Raman interactions of multimode fields with atomic reservoirs. These two mechanisms combine to lead to emission in pairs into multiple cavity modes. For four fields taken as examples, we find that the four-mode squeezed state can be created at steady state. From this we can obtain the Greenberger–Horne–Zeilinger entangled state, and the linear and square cluster entangled states. This scheme does not need the preparation of the initial states of atoms and cavity modes, and is robust against atomic spontaneous decay.
作者机构：
[Hu, Xiangming; Xu, Qing] Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.;[Xu, Qing] Huanggang Normal Univ, Coll Phys & Elect Informat, Huanggang 438000, Hubei, Peoples R China.
通讯机构：
[Hu, Xiangming] C;Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
摘要：
We show that, in analogy to light fields, effective bosonic modes of atomic ensembles in the Holstein-Primakoff representation can be prepared in multimode squeezed states, and multipartite continuous-variable cluster and Greenberger-Horne-Zeilinger (GHZ) entangled states. Our scheme uses a cascade of optical cavities, in each of which one atomic ensemble is placed. Through Raman transitions between stable atomic ground states, the atomic ensembles are in the interactions with the cavity and laser fields. Because of the long-lived ground states, the atomic ensembles act as quantum network nodes, whose cluster entangled states are applicable in the one-way quantum computer, and whose GHZ entangled states have potential for quantum communication.
作者机构：
[Hu, Xiangming; He, Chang; Liang, Xiao] Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
通讯机构：
[Liang, Xiao] C;Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
摘要：
We propose a scalable scheme for a unitary multimode operator using an optical cavity with an atomic ensemble. We exemplify three-mode and four-mode cases and engineer the squeeze operators that are decoupled from the atomic degrees of freedom. The squeeze parameters can be large since they are proportional to the number of atoms. Using the input-output theory we show that ideal squeezed states and perfect squeezing could be approached at the output. At the same time, we show that it is possible to obtain tripartite and quadripartite Greenberger-Horne-Zeilinger entangled states for continuous variables. The responsible mechanism for both the multimode squeezing and the genuine multipartite entanglement is based on the atomic coherence controlled parametric interactions. The scalability of the scheme is simply obtained by including more transitions in the atomic system.
作者机构：
[Hu, Xiangming; Sun, Hong] Cent China Normal Univ, Sch Phys Sci & Technol, Wuhan 430079, Peoples R China.
通讯机构：
[Sun, Hong] C;Cent China Normal Univ, Sch Phys Sci & Technol, Wuhan 430079, Peoples R China.
摘要：
It has been known that one reservoir of driven two-level atoms can establish two-mode interactions and generate bipartite continuous-variable entangled light. Here we show that three-mode interactions can be created by combining two such reservoirs, each of which interacts with two adjacent fields in frequency. It is shown that the van Loock–Furusawa criteria [Phys. Rev. A 67, 052315 (2003)] are well satisfied for a wide range of the relevant parameters. This determines that tripartite continuous-variable Greenberger-Horne-Zeilinger entanglement is obtainable. The scalability to more fields is straightforward, allowing an alternative implementation of a multipartite quantum networks with continuous variables.
作者机构：
[Hu, Xiang-ming; Xu, Jun] Cent China Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.;[Zubairy, M. Suhail; Xu, Jun; Yang, Shuai] Texas A&M Univ, IQSE, College Stn, TX 77843 USA.;[Zubairy, M. Suhail; Xu, Jun; Yang, Shuai] Texas A&M Univ, Dept Phys & Astron, College Stn, TX 77843 USA.;[Xu, Jun] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.
通讯机构：
[Xu, Jun] C;Cent China Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
关键词：
Energy shifts;Quantum interference effects;Spontaneous emission spectrum
摘要：
We study the coherent control of spontaneous emission in a driven three-level atomic system. In particular we consider the quantum interference effects including energy shifts due to the counter-rotating terms. We show that the quantum interference resulting from the energy shifts has great influence on the evolution of the atomic population and the spontaneous emission spectrum. This makes it feasible to observe the effect of the counter-rotating terms in the long time limit. (C) 2011 Elsevier B.V. All rights reserved.
作者机构：
[Hu, Xiangming] Cent China Normal Univ, Sch Phys Sci & Technol, Wuhan 430079, Peoples R China.;[Oh, C. H.] Natl Univ Singapore, Dept Phys, Singapore 117543, Singapore.;[Oh, C. H.] Natl Univ Singapore, Ctr Quantum Technol, Singapore 117543, Singapore.
通讯机构：
[Hu, Xiangming] C;Cent China Normal Univ, Sch Phys Sci & Technol, Wuhan 430079, Peoples R China.
摘要：
We analyze the nonadiabatic effects on the propagation of a two-mode squeezed field inside a medium of three-level Λ atoms that display the dark resonance. We identify the different effects for the two-mode quantum properties: (i) unconditional transparency for the sum squeezing and (ii) induced transparency or spectral narrowing for the difference squeezing depending on the relative widths of the initial correlation spectrum to the transparency window. These effects combine to induce transparency or spectrum narrowing for the bipartite entanglement. The potential applications range from quantum information to laser spectroscopy and frequency standards.
