摘要:
Light scattered by a regular structure of atoms can exhibit interference signatures, similar to the classical double-slit. These first-order interferences, however, vanish for strong light intensities, restricting potential applications. Here, we show how to overcome these limitations to quantum interference in strong fields. First, we recover the first-order interference in strong fields via a tailored electromagnetic bath with a suitable frequency dependence. At strong driving, the optical properties for different spectral bands are distinct, thus extending the set of observables. We further show that for a two-photon detector as, e.g., in lithography, increasing the field intensity leads to twice the spatial resolution of the second-order interference pattern compared to the weak-field case.
摘要:
We investigate the generation of a strongly entangled electromagnetic field through laser pumping a collection of N two-level atoms in a two-mode optical resonator. The vacuum-multiparticle interactions enhance the coupling of the atomic sample to the cavity modes facilitating the creation of entangled photons at higher frequencies. In the dispersive atom-cavity limit, one can obtain a steady-state output field consisting of tens of such photons per mode.
摘要:
We analyze the quantum correlations between side modes of a quantum beat laser when a two-level atomic medium is driven strongly by a classical field. The squeezing and the entanglement generation of the cavity radiation are investigated. It turns out that there is neither squeezing nor entanglement when the strong driving field is resonant with the atomic transition but the generated light exhibits both two-mode squeezing and entanglement when the driving field is tuned away from the atomic transition.
作者机构:
[Tan Rong; Tan, R; Li Gao-Xiang] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构:
[Tan Rong] H;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
关键词:
Spontaneous Decay;Infinitely Permeable
摘要:
We present the explicit expression of the spontaneous decay rate of a quadrupole placed between two parallel plates (one or both the plates have infinite permeability, i.e. μ→∞). It is found that the spontaneous decay rate displays oscillations with the position of the quadrupole, and the oscillations exhibit a symmetric profile with respect to the central plane of the plates for the symmetric models and lack the symmetry for the asymmetric model.
作者机构:
[Yang, Yaping] Tongji Univ, Dept Phys, Shanghai 200092, Peoples R China.;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.;Hong Kong Baptist Coll, Dept Phys, Hong Kong, Hong Kong, Peoples R China.
摘要:
The spontaneous emission properties of a Lambda type atom embedded in a three-dimensional anisotropic photonic crystal are investigated. Only one of the two atomic transition frequencies is considered near the photonic band edge. The atomic decay properties such as the time-evolution of the excited-state population and the instant and effective decay rates are studied in detail. It is found that there exists a wide region for the difference of the transition frequency from the band edge, in which only diffusion fields with frequencies being near or far away from the band edge appear in the emitted field. The spontaneous emitted field and its spectrum depend not only on the detuning of the transition frequency from the band edge, but also on the distance from the atom. Therefore, during the propagating process, the propagating field is partially transferred into the diffusion field. (c) 2006 Elsevier B.V. All rights reserved.
通讯机构:
[Li, Gao-xiang] H;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要:
Two different schemes are proposed for deterministically generating a pure motion-entangled state for two well-separated ions trapped in a cavity. The first one is that through adjusting the amplitudes and the frequencies of transverse lasers, the two ions trapped in a bimodal cavity can unconditionally evolve into a two-mode squeezed vacuum state with the aid of the cavity dissipation. The second one is based on the interactions of two appropriate series of the driving laser pulses with the two ions trapped in a single-mode cavity, it allows us to produce a two-mode squeezed vacuum state for the trapped ions’ center-of-mass motion.
作者机构:
[Li, Gao-xiang] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.;Hong Kong Baptist Univ, Dept Phys, Hong Kong, Hong Kong, Peoples R China.
通讯机构:
[Li, Gao-xiang] H;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要:
We investigate the enhancement of the intracavity entanglement of a self-phase-locked type-II nondegenerate optical parameter oscillator (SPL NOPO) via homodyne-mediated quantum feedback. It is found that the feedback can effectively enhance the squeezing, entanglement, and purity of the two-mode field in the SPL NOPO. Especially for an ordinary NOPO, our feedback scheme can simulate a standard two-mode squeezed vacuum environment and a pure steady two-mode squeezed vacuum cavity field can be generated, different from the scheme proposed by Mancini [Phys. Rev. A 73, 010304(R) (2006)] in which only a mixed two-mode entangled state is generated.
作者机构:
[Li, Gao-xiang; Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构:
[Li, Gao-xiang] H;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要:
We propose schemes for the deterministic preparation of pure multipartite entangled vibrational states for N ions trapped in a single-mode cavity. Through sequentially sending lasers with appropriate phases and amplitudes to drive the ions, two kinds of pure multipartite entangled continuous variable entangled states respectively suggested by van Loock and Braunstein [Phys. Rev. Lett. 84, 3482 (2000)] and Pfister et al. [Phys. Rev. A 70, 020302(R) (2004)] can be unconditionally prepared with the help of cavity dissipation.
期刊:
Journal of Modern Optics,2005年52(18):2743-2758 ISSN:0950-0340
通讯作者:
Li, GX
作者机构:
[Ke, SS; Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构:
[Li, GX] H;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要:
The entanglement property between two two-level atoms interacting with a stochastic field is studied. We analytically prove that when the correlation time κ −1 of the stochastic field is very short compared to the radiative lifetime γ −1 of the atom, the steady-state entanglement between the two atoms can appear. The concurrence characterizing the entanglement degree has also been calculated by using Monte Carlo simulation. It is shown that the correlation time has a strong effect on the entanglement. We also discuss the influence of strength of the stochastic process on the entanglement. The validity of the decorrelation approximation is also investigated.
作者机构:
[Wu, SP; Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构:
[Li, GX] H;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要:
The influence of the vibrational heating of a single cold ion trapped in a bimodal cavity under continuous excitation on the generation of two-mode squeezing and entanglement of the cavity field from the ion is discussed. It is found that the vibrational heating gives a strong limitation for the appearance of the two-mode squeezing, but the two cavity modes can develop into a robust entangled Gaussian state.
期刊:
Journal of Modern Optics,2005年52(12):1729-1742 ISSN:0950-0340
通讯作者:
Tan, R
作者机构:
[Tan, R; Li, GX] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构:
[Tan, R] H;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
会议名称:
Conference on Lasers and Electro Optics/International Conference on Quantum Electronics (CLEO/IQEC 2004)
会议时间:
MAY 17, 2004
会议地点:
San Francisco, CA
会议主办单位:
Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要:
The spontaneous emission of a four-level atom embedded in a one-dimensional photonic crystal is investigated. The atom has two upper levels coupled by the same vacuum modes to a common lower level and is driven by a coherent field to an auxiliary level. Spontaneous emission can be suppressed significantly due to the combinational influences of the interference effect and the band edge effect. The radiation field emitted by the atom is also studied. Spontaneous emission can be modified by controlling the Rabi frequency of the driving.