Quantum Swap Gate with Molecular Ensembles via Cavity Quantum Electrodynamics

We present a simple method to realize a swap gate at one step with two molecular ensembles in a stripline cavity. In this scheme, we can benefit from the enhancement of the coherent coupling and acquire a long coherent time with encoding qubits in different spin states of the rotational ground state in the molecular ensembles. As a by-product, a scheme to create an entangled state with one excitation stored in two ensembles is proposed.     

fficient Scheme for Implementing a Fredkin Gate via Resonant Interaction with Two-Mode Cavity Quantum Electrodynamics

A scheme for implementing a Fredkin gate with an atom sent through a microwave cavity is proposed. The scheme is based on the resonant atom-cavity interaction so that the gating time is sharply short, which is important in view of decoherence.     

Scheme for Implementing an N-Qubit Phase Gate via Selective Atom--Field Interaction with Cavity Quantum Electrodynamics

A scheme for implementing a two-qubit phase gate with atoms sent through a high-Q optical cavity is proposed by choosing nonidentical coupling constants between the atoms and cavity. The atomic spontaneous emission can be suppressed due to the large atom-field detuning. Moreover, the scheme can be generalized to implement an N-qubit phase gate and the gating time does not change with an increase of the number of qubits.     

Preparation of Six-Atom Cluster State via Cavity Quantum Electrodynamics

A cavity quantum electrodynamics scheme for preparing a six-atom cluster state is proposed. In the scheme, the atom-cavity detuning is much bigger than the atom-cavity coupling strength and the time needed to complete the whole procedure is much shorter than the Rydberg-atom lifespan. Thus the scheme is insensitive to the cavity decay and the atom radiation.     

Preparation of Genuinely Entangled Six-Atom State via Cavity Quantum Electrodynamics

A cavity quantum electrodynamics scheme for preparing a genuinely entangled state [A. Borras, et al., J. Phys. A 40 (2007) 13407] on six two-level atoms is proposed. In the scheme, the atom-cavity detuning is much bigger than the atom-cavity coupling strength and the necessary preparation time is much shorter than the Rydberg-atom lifespan. Hence the scheme has two distinct features, i.e., insensitive to the cavity decay and the atom radiation.     

腔QED中利用超导量子干涉仪实现Toffoli门

基于腔量子电动力学技术,提出了利用三能级超导量子干涉仪实现Toffoli门的理论方案.利用超导量子干涉仪与腔场发生耦合,以及与外加经典脉冲发生共振跃迁来实现量子态的演化控制.该方案可以拓展到N比特Toffoli门的实现.最后,讨论了逻辑门的实验可行性,四比特Toffoli门的作用时间约为30 nm,它远小于腔衰减时间和较高能级的能量驰豫时间,从而足以实现量子态的操控.并且随着比特数的增多,Toffoli门作用时间的增幅较慢.     

腔QED中利用超导量子干涉仪实现Toffoli门

基于腔量子电动力学技术,提出了利用三能级超导量子干涉仪实现Toffoli门的理论方案.利用超导量子干涉仪与腔场发生耦合,以及与外加经典脉冲发生共振跃迁来实现量子态的演化控制.该方案可以拓展到N比特Toffoli门的实现.最后,讨论了逻辑门的实验可行性,四比特Toffoli 门的作用时间约为30 nm,它远小于腔衰减时间...     

增光子二模纠缠相干态的纠缠特性及其通过腔量子电动力学的制备

分析了增光子二模纠缠相干态的纠缠特性,得到共生纠缠度的解析表示式.结果表明:增光子二模纠缠相干态的共生纠缠度与叠加态的相位有非常灵敏的关系.提出了一种制备增光子相干态和增光子二模纠缠相干态的方法,其制备过程为首先把增光子相干态转化为相干态与真空态一种特殊的叠加态(叠加系数与相干态振幅有关),再通过位于高Q腔内的原子与经典激光场的相互作用,从而实现增光子相干态的制备.通过一个飞行原子先后与两个光腔中光场相互作用可以实现增光子二模纠缠相干态的制备.     

Quantum Information Splitting of an Arbitrary Three-Atom State in Cavity Quantum Electrodynamics

A cavity quantum electrodynamics scheme for implementing the deterministic quantum information splitting of an arbitrary three-atom state is proposed. In the scheme, a genuine five-atom entangled state and a Bell-state can be used as the quantum channel, which does not involve Bell-state measurement and only needs to perform the single-atom measurements. Our scheme is insensitive to both the cavity decay and the atom radiation, and considered here is secure against certain eavesdropping attacks.     

增光子二模纠缠相干态的纠缠特性及其通过腔量子电动力学的制备

分析了增光子二模纠缠相干态的纠缠特性,得到共生纠缠度的解析表示式.结果表明:增光子二模纠缠相干态的共生纠缠度与叠加态的相位有非常灵敏的关系.提出了一种制备增光子相干态和增光子二模纠缠相干态的方法,其制备过程为首先把增光子相干态转化为相干态与真空态一种特殊的叠加态(叠加系数与相干态振幅有关),再通过位于高Q腔内的原子与经典激光场的相互作用,从而实现增光子相干态的制备.通过一个飞行原子先后与两个光腔中光场相互作用可以实现增光子二模纠缠相干态的制备.     

利用非Bell基测量实现两粒子纠缠态的隐形传输

研究无Bell基测量的未知两粒子纠缠态的隐形传态方案。Alice需传送未知两原子纠缠态给Bob,以她和Bob的原子组成的最大纠缠GHZ态作为量子信道,通过两原子同时在一个强经典驱动场驱动下和一个单模腔场发生相互作用,产生态的演化,从而实现隐形传态。本方案可忽略腔场热作用和腔延迟作用的影响,传送成功的总几率为1。     

Generation of Entangled Multi-atom Dicke States in Cavity Quantum Electrodynamics

We propose a scheme to generate two-atom maximally entangled state in cavity quantum electrodynamies （QED）. The scheme can 5e extended to generation of entangled multi-atom Dicke states if we control the interaction time of atoms with cavity modes. We use adiabatically state evolution under large atom-cavity detuning, so the scheme is insensitive to atomic spontaneous decay. The influence of cavity decay on fidelity and success probability is discussed.     

高精细度法布里-珀罗光学微腔及其在强耦合腔量子电动力学中的应用

强耦合腔量子电动力学(cavity quantum electrodynamics,简称C-QED)系统主要用于研究受限于空间中的光与物质相互作用的物理现象.该系统为深入认识原子与光子间相互作用的动力学行为提供了有力工具.高精细度法布里-珀罗光学微腔(Fabry-Perot cavity,F-P腔)作为强耦合C-QED...     

单原子脉塞和单原子激光——腔量子电动力学的实验平台

单原子脉塞和单原子激光是腔量子电动力学研究的重要实验平台。本文综述关于几类单原子脉塞和单原子激光的研究工作,包括德国Walther小组的单原子脉塞、超冷原子注入的单原子脉塞,法国Haroche小组的腔量子电动力学系统、注入原子的单原子激光、以及囚禁原子和囚禁离子的单原子激光。我们介绍相关的理论工作、实验系统、以及主要结果。     

Gravitational Radiation and Nonlocal Electrodynamics

A model of nonlocal response of a medium with an initially constant and homogeneous magnetic field acted upon by a planar gravitational wave is constructed on the basis of a covariant formulation of integral constitutive equations. The model is studied in detail and the problem of anomalous behavior of the response of the given electrodynamic system to a gravitational-wave action is discussed.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 27–33, April, 2005.     

Schemes of Implementing a Two-Atom Iswap Gate via Cavity QED

We propose two schemes for implementing a two-atom quantum iswap gate via cavity QED. In the first scheme, only one cavity and two classical fields are used to realizing iswap gate and thus reducing the operating time. The second scheme needs three cavities for atom-cavity interaction and single-qubit rotations without the assistant of the auxiliary level. Our schemes can effectively reduce the cavity decay owing to the reason that the cavity is only virtually excited during the interaction process between atoms and the cavity. Operator fidelity is applied to analyzing the influence when two atoms enter a cavity without accurate simultaneity.     

One-Step Implementation of Mulitqubit Quantum Phase Gate in a Cavity QED System

An alternative protocol is proposed to implement three-qubit phase gate between photon and atoms in a high-Q bimodel optical cavity. The idea can be extended to directly implement N-qubit phase gate, and the gating time that is required to implement the protocol does not rise with increasing number of qubits. The influence of cavity decay and atomic spontaneous emission on the gate fidelity is also discussed.     

Nonlocal Scalar Electrodynamics from Chern-Simons Theory

The theory of a complex scalar interacting with a pure Chern-Simons gauge field is quantized canonically. Dynamical and nondynarnical variables are separated in a gaugeindependent way. In the physical subspace of the full Hilbert space, this theory reduces to a pure scalar theory with nonlocal interaction. Several scattering processes are studied and the cross sections are calculated.     

Pre-Maxwell Quantum Electrodynamics

In the framework of off-shell quantum electrodynamics—the quantum field theory of a covariant symplectic mechanics, in which events evolve according to a Poincaré-invariant parameter —we study the low-energy scattering of identical scalar particles. It is shown that exchange of mass is permitted in the formalism, and we calculate scattering cross-sections for this case. In these cross-sections, the usual forward pole of the standard scalar QED splits into two poles and a zero, slightly offset from the forward direction. As mass exchange vanishes, a pole-zero pair cancel, the remaining pole moves to = 0, and the standard cross-section is recovered.