Strong-Driving-Assisted Probabilistic State Preparation in Cavity QED

An alternative scheme is proposed for preparing the superpositions of coherent states with controllable weighting factors along a straight line for a cavity field. The scheme is based on the interaction of a single-mode cavity field with a resonant two-level atom driven by a strong classical field. It is in contrast to the previous methods used in cavity QED of injecting a coherent state into a cavity via a microwave source. In the scheme, the interaction between the cavity mode and atoms is fully resonant, thus the required interaction time is greatly shortened. Moreover, the present scheme requires smaller numbers of operations. In view of decoherence, a reduction of interaction time and numbers of operations for the state preparation is very important for experimental implementation of quantum state engineering.     

Alternative Scheme for Teleportation of Two-Atom Entangled State in Cavity QED

We have proposed an alternative scheme for teleportation of two-atom entangled state in cavity QED. It is based on the degenerate Raman interaction of a single-mode cavity field with a A-type three-level atom. The prominent feature of the scheme is that only one cavity is required, which is prior to the previous one. Moreover, the atoms need to be detected are reduced compared with the previous scheme. The experimental feasibility of the scheme is discussed. The scheme can easily be generalized for teleportation of N-atom GHZ entangled states. The number of the atoms needed to be detected does not increase as the number of the atoms in GHZ state increases.     

Generation of Entangled States of Multiple Superconducting Quantum Interference Devices in Cavity

We propose a scheme for generating the maximally entangled states of many superconducting quantum interference devices (SQUIDs) by using a quantized cavity field and classicalmicrowave pulses in cavity. In the scheme,the maximally entangled states can be generated without requiring the measurement and individual addressing of the SQUIDs.     

Entangled Fields in Multiple Cavities by Interaction with One Three-Level Atom

We present a scheme to entangle fields in multiple cavities. Our scheme is based on the resonant interaction of a Ξ-type three-level atom with the cavity fields for precalculated interaction time, which enables us to generate a quantum entangled Greenberger-Horn-Zeilinger (GHZ) state of fields in multiple cavities. In principle, the scheme can be also generalized to generate N-party GHZ state. The required experimental techniques are within the scope of what can be obtained in the microwave cavity QED set up.     

Production of Entanglement of Multiple Three-Level Atoms with a Two-Mode Cavity

A scheme is proposed for generating maximally entangled states for two or more three-level atoms. In the scheme the atoms are sent through a two-mode cavity one by one and interact with the two-cavity modes sequentially. The required experimental techniques are within the scope of what can be obtained in the microwave cavity QED setup.     

Entanglement swapping with atoms separated by long distance

This paper proposes a scheme for entanglement swapping based on cavity QED. The two atoms to be entanglement-swapped can be separated over long distance. The scheme is a non-post-selection one with the success probability of 1/2.     

多模短波长激光在圆形球面腔中的传输

用数值积分方法求解了在圆柱坐标中的横向多模菲涅尔(Fresnel)积分方程.在初始复数光场振幅取均匀分布和随机分布的条件下对圆形球面共焦腔、稳定腔和平面腔的TEM_n0模进行了计算分析.计算结果表明,球面腔单一模的数值结果同解析解的结果符合较好,多种模同时存在时的结果不仅符合多模空间分布特性而且其基模是主要的.     

Quantum Statistical Properties of the Exciton in a Leaky Quasi-Mode Cavity

We have studied quantum statistical properties of the exciton in a leaky quasi-mode cavity. It is shown that when the exciton is initially in a squeezed coherent state whereas cavity initially in a vacuum state, there is energy exchange between the exciton and cavity. Both the exciton and cavity may exhibit sub-Poissonian distribution and exist quadrature squeezing. Calculation shows that correlation between the exciton and cavity is classical, which implies that there is not the violation of the Cauchy-Schwartz inequality.     

Teleportation of an Unknown Atomic State via Adiabatic Passage

We propose a scheme for teleporting an unknown atomic state via adiabatic passage. Taking advantage of adiabatic passage, the atom has no probability of being excited and thus the atomic spontaneous emission is suppressed. We also show that the fidelity can reach 1 under certain condition.     

Cavity QED Scheme for Realizing Entanglement Swapping

A new scheme is proposed for realizing entanglement swapping in cavity QED. The scheme is based on the resonant interaction of two-mode cavity with ∧-type three-level atom, and it involves only a single measurement. In the scheme, the output state after swapping is exactly the maximally entangled state in principle, thus it is prior to the previous one, in which the output state is just approximate. Calculations indicate that our scheme is less influenced by an error.