Implementation of n-qubit Deutsch-Jozsa algorithm using resonant interaction in cavity QED

We propose a scheme to implement the n-qubit Deutsch-Jozsa algorithm based on resonant interaction between the atoms and a single-mode cavity. In the scheme, the resonant transitions between two ground states and one excited state of an atom are changed alternately by adjusting the cavity frequency appropriately, and the operations required to complete the algorithm can be significantly simplified following the increment of the number of qubits. The implementation of the scheme in experiment would show the full power of quantum algorithm and would be significative and important for more complicated quantum algorithm in cavity quantum electrodynamics.

Approximate Toffoli Gate Originated from a Single Resonant Interaction of Cavity Dissipation and Atomic Spontaneous Emission

We propose a potentially practical scheme to implement an approximate three-qubit Toffoli gate by a single resonant interaction in dissipative cavity QED in which the cavity mode decay and atomic spontaneous emission are considered. The scheme does not require two-qubit controlled-NOT gates but uses a three-qubit phase gate and two Hadamard gates, where the approximate phase gate can be implemented by only a single dissipative resonant interaction of atoms with the cavity mode. Discussions are made for the advantages and the experimental feasibility of our scheme.

Generation of various multiatom entangled graph states via resonant interactions

In this paper, a scheme for generating various multiatom entangled graph states via resonant interactions is proposed. We investigate the generation of various four-atom graph states first in the ideal case and then in the case in which the cavity decay and atomic spontaneous emission are taken into consideration in the process of interaction. More importantly, we improve the possible distortion of the graph states coming from cavity decay and atomic spontaneous emission by performing appropriate unitary transforms on atoms. The generation of multiatom entangled graph states is very important for constructing quantum one-way computer in a fault-tolerant manner. The resonant interaction time is very short, which is important in the sense of decoherence. Our scheme is easy and feasible within the reach of current experimental technology.

Transferring of a Two-Mode Entangled State Between Two Cavities via Cavity QED

We propose a scheme for transferring of a two-mode entanglement of zero- or one-photon entangled states between two cavities via atom-cavity field resonant interaction. In our proposal, in order to transfer the entangled state, we only need two identical two-level atoms and a two-mode cavity for receiving the teleported state. This scheme does not require Bell-state measurement and performing any transformations to reconstruct the initial state. And the transfer can occur with 100% success probability in a simple manner. And a network for transferring of a two-mode entangled state between cavities is suggested. This scheme can also be extended to transfer N-mode entangled state of cavity.

Scheme for Preparation of Macroscopic Multi-component Entanglement in Cavity QED

We propose a scheme of generating multi-component entangled coherent states of cavity fields. In this scheme, the atoms pass through cavities one by one, simultaneously driven by a strong classical field in each cavity. Then the detection of the atomic states collapses the cavity fields onto multi-component entangled coherent states. It is shown that, with a judicious choice of the parameters of the classical field, we can conditionally produce macroscopic multi-dimensional maximal entanglement for the cavity modes.

Quantum State Transfer for Two Atoms with a Single Resonant Interaction

We present a scheme for transferring an unknown atomic entangled state with a single resonant interaction. This scheme only requires a single resonant interaction of two atoms with a cavity mode and does not use the cavity mode as the memory. Thus the scheme is very simple and the interaction time is very short, which is important, in view of decoherence. Quantum state can be directly transferred from two atoms to another two at, oms with a successful probability of 100 percent.

Implementing Deutsch-Jozsa Algorithm in Cavity QED

We propose a simple scheme for implementing Deutsch-Jozsa algorithm in cavity QED. Our scheme is insensitive to both the cavity decay and thermal field because we use the large-detuned interaction. The scheme would be important to constructing practical computer in cavity QED system.

Entangling Mesoscopic Squeezed Vacuum States and Mesoscopic Coherent States in Dissipative Cavity QED System

A scheme has been proposed for generating the macroscopic entanglement between the mesoscopic squeezed vacuum states and mesoscopic coherent states by considering both the two-photon interaction and the single photon interaction of N two-level atoms in cavities with high quality factor assisted by a strong driving field. Moreover, we derive the dissipative interaction models for single photon interaction and two-photon interaction, respectively. The corresponding analytical expressions of the fidelities can be given. Our scheme can be realized in the current techniques on the cavity QED.

Efficient Scheme for Macroscopic Superpositions and Entanglement of High-Order Squeezed Vacuum States in Cavity QED

We propose an etticient scheme for generating the macroscopic superpositions and the entanglement between the high-order squeezed vacuum states by considering the multi-photon interaction of N two-level atoms in a cavity with high quality factor, assisted by a strong driving field. Through specific choices of the cavity detuning, a number of multi-party entangled states between the atoms and the high-order squeezed vacuum states and among the high-order squeezed vacuum states of the cavities can be prepared, including also the macroscopic ＂Schrodinger cats＂ of the high- order squeezed vacuum states, the entangled states of the macroscopic ＂Schrodinger cats＂, and so on. Possible extension and application of our scheme are discussed. Our scheme is reachable within the current techniques in the cavity QED.

Generation of any superposition of coherent states along a straight line via resonant atom-cavity interaction

This paper proposes a scheme for generating arbitrary superpositions of several coherent states along a straight line for a cavity mode. In the scheme, several atoms are sent through a cavity initially in a strong coherent state. The superposition of several coherent states with desired coefficients may be generated if each atom is detected in the excited state after it exits the cavity. The scheme is based on resonant atom-cavity interaction and no classical field is required during and after the atom cavity interaction. Thus, the scheme is very simple and the interaction time is very short, which is important in view of decoherence.

Teleportation of two-atom entangled state in resonant cavity quantum electrodynamics

An alternative scheme is presented for teleportation of a two-atom entangled state in cavity quantum electrodynamics （QED）. It is based on the resonant atom-cavity field interaction. In the scheme, only one cavity is involved, and the number of the atoms needed to be detected is decreased compared with the previous scheme. Since the resonant atom-cavity field interaction greatly reduces the interaction time, the decoherence effect can be effectively suppressed during the teleportation process. The experimental feasibility of the scheme is discussed. The scheme can easily be generalized to the teleportation of N-atom Greeninger-Horne-Zeilinger （GHZ） entangled states. The number of atoms needed to be detected does not increase as the number of the atoms in the GHZ state increases.

Preparation of W state in resonant bimodal cavity quantum electrodynamics

A scheme is proposed for generating entangled W states with four cavity modes. In this scheme, we send a V-type three-level atom through two identical two-mode cavities in succession. After the atom exits from the second cavity, the four cavity modes are prepared in the W state. On the other hand we can obtain three-atom W states by sending three V-type three-level atoms through a two-mode cavity in turn. The present scheme does not require conditional measurement, and it is easily generalized to preparing 2n-mode W states and n-atom W states.

Vibration induced transparency:Simulating an optomechanical system via the cavity QED setup with a movable atom

We simulate an optomechanical system via a cavity QED scenario with a movable atom and investigate its application in the tiny mass sensing.We find that the steady-state solution of the system exhibits a multiple stability behavior,which is similar to that in the optomechanical system.We explain this phenomenon by the opto-mechanical interaction term in the effective Hamiltonian.Due to the dressed states formed by the effective coupling between the vibration degree of the atom and the optical mode in the cavity,we observe a narrow transparent window in the output field.We utilize this vibration induced transparency phenomenon to perform the tiny mass sensing.We hope our study will broaden the application of the cavity QED system to quantum technologies.

基于两原子同时和腔场共振作用制备两原子纠缠态的腔QED方案(英文)

我们提出了一个将两个远离的原子制备成纠缠态的腔QED方案,该方案基于两个原子同时和一个腔场发生共振作用.在这个方案里,我们利用一个事先制备好的纠缠态将另外两个分离的原子制备成纠缠态.该方案仅包含两个原子和腔场的共振相互作用,不需要用腔场存储量子信息,并且原子和腔场作用时间极短.因此,我们的方案基于目前的腔QED技术是可以实现的.

用腔场QED技术隐形传送未知原子态(英文)

提出一种方案用于隐形传送未知原子态,方案基于两个耦合双能级原子与一个单模腔场的非共振相互作用。方案要求腔场处于相干态,这使得方案容易实现。原子与相干腔场相互作用以后,腔场仍然处于相干态,通过探测原子的状态,即可将一个未知原子态隐形传送。方案也可以用于隐形传送未知原子纠缠态。

利用腔QED技术传送纠缠相干态

提出了一种基于腔QED技术实现纠缠相干态隐形传态的方案 ;方案中仅用到对单原子态和场态的局域测量 .

基于腔QED的任意相干叠加态远程制备方案

运用Λ型三能级原子与相干态光场大失谐作用,在腔量子电动力学体系中制备原子与相干态光场的最大纠缠态,并以此作为量子通道在经典场辅助作用下远程制备可随意操控的相干态光场任意叠加态。经过计算,得出对于叠加系数为实数的相干态光场的叠加态,通过适当旋转操作,远程制备成功的概率是100%。最后讨论了实验上实现此方案的可行性和所具备的应用优势。

应用腔QED制备多比特纠缠态

提出一个应用圆极化双模腔制备多比特纠缠态的方案.该方案基于1个原子和多个腔以及多个原子和1个腔的共振相互作用,制备过程简单,相互作用时间短,并能有效地抑制退相干,具有实验可行性.

Approximate and Conditional Teleportation of an Unknown Atomic State Without Bell-State Measurement with Two-Photon Interaction

A scheme for approximately and conditionally teleporting an unknown atomic state via two-photon interaction in cavity QED is proposed. It is the extension of the scheme of Ref. [11] [Phys. Rev. A 69 （2004） 064302], which is based on Jaynes-Cummings model in QED and where only a time point of system evolution and the corresponding fidelity implementing the teleportation are given. In our scheme, the two-photon interaction Jaynes-Cummings model is used to realize the approximate and conditional teleportation. Our scheme does not involve the Bell-state measurement and an additional atom, only requiring two atoms and one single-mode cavity. The fidelity of the scheme is higher than that of Ref. [11]. The scheme may be generalized to not only the teleportation of the state of a cavity mode to another mode by means of a single atom but also the teleportation of the state of a trapped ion.

Comment on “Approximate and Conditional Teleportation of an Unknown Atomic State Without Bell-State Measurement with Two-Photon Interaction”

In a previous work [Commun. Theor. Phys. 45 （2006） 79] a scheme was presented for approximate and conditional teleportation of an unknown atomic state in a QED-cavity without Bell-state measurement via two-photon Jaynes-Cummings model in the effective Hamiltonian approach. This comment presents an alternative method, based on the so called ＂full two-photon Jaynes-Cummings Hamiltonian approach＂. Accordingly, it describes the evolution of the two-photon degenerate process for arbitrary average photon number inside the cavity, as the correct way to implement teleportation in this scenario.