共查询到20条相似文献,搜索用时 31 毫秒
1.
A scheme for approximate generation of an N-qubit phase gate is proposed in cavity QED based on nonidentical coupling between the atoms and the cavity. The atoms interact with a highly detuned cavity-field mode, but quantum information does not transfer between the atoms and cavity field, and thus the cavity decay is negligible. The gate time does not rise with an increase in the number of qubits. With the choice of a smaller odd number l (related to atom-cavity coupling constants), the phase gate can be generated with a higher fidelity and a higher success probability in a shorter time (the gate time is much shorter than the atomic radiative lifetime and photon lifetime). When the number of qubits N exceeds certain small values, the fidelity and success probability rise slowly with an increase in the number of qubits N. When N→∞, the fidelity and success probability infinitely approach 1, but never exceed 1. 相似文献
2.
This paper proposes a scheme for realization of a three-qubit
Toffoli gate operation using three four-level atoms by a selective
atom--field interaction in a cavity quantum electrodynamics system. In
the proposed protocol, the quantum information is encoded on the
stable ground states of atoms, and atomic spontaneous emission is
negligible as the large atom--cavity detuning effectively suppresses
the spontaneous decay of the atoms. The influence of the dissipation
on fidelity and success probability of the three-qubit Toffoli gate
is also discussed. The scheme can also be applied to realize an
N-qubit Toffoli gate and the interaction time required does not
rise with increasing the number of qubits. 相似文献
3.
In this paper, we investigate perfect quantum teleportation and dense coding by using an 2N-qubit W state channel. In the quantum teleportation scheme, an unknown N-qubit entangled state can be perfectly teleported. One ebit of entanglement and two bits of classical communication are consumed in the teleportation process, just like when using the Bell state channel. While N+1 bits of classical information can be transmitted by only sending N particles in the dense coding protocol. 相似文献
4.
Chui-Ping Yang 《Physics letters. A》2008,372(16):2782-2786
We present a new scheme for realizing a n-qubit controlled-phase gate with atoms in cavity QED. The present scheme operates essentially by exchanging a single photon between the control atoms and the cavity mode before and after a phase shift performed on the target atom. It is interesting to note that the gate can be implemented in a very simple way and by employing resonant interaction with one cavity only. 相似文献
5.
Realizing the teleportation of quantum state, especially the teleportation of N-qubit quantum state, is of great importance in quantum information. In this paper, Raman-interaction of the V-type degenerate
three-level atom and single-mode cavity field is studied by utilizing complete quantum theory. Then a new scheme for teleporting
N-qubit unknown atomic state via Raman-interaction of the V-type degenerate three-level atom with a single-mode cavity field
is proposed, which is based upon the complete quantum theory mentioned above. 相似文献
6.
We explore the possibility of an N-qubit (N>3) Grover
search in cavity QED, based on a fast operation of an N-qubit
controlled phase-flip with atoms in resonance with the cavity mode.
We demonstrate both analytically and numerically that our scheme
can be achieved efficiently to find a marked state with high
fidelity and high success probability. As an example, a ten-qubit
Grover search is simulated specifically under the discussion of
experimental feasibility and challenge. We argue that our scheme is
applicable to the case involving an arbitrary number of qubits. As
cavity decay is involved in our quantum trajectory treatment, we
can analytically understand the implementation of a Grover search
subject to dissipation, which will be very helpful for relevant
experiments. 相似文献
7.
Implementation of quantum controlled phase gate and preparation of multiparticle entanglement in cavity QED 下载免费PDF全文
Schemes are presented for realizing quantum controlled phase gate and preparing an N-qubit W-like state, which are based on the large-detuned interaction among three-state atoms, dual-mode cavity and a classical pulse. In particular, a class of W states that can be used for perfect teleportation and superdense coding is generated by only one step. Compared with the previous schemes, cavity decay is largely suppressed because the cavity is only virtually excited and always in the vacuum state and the atomic spontaneous emission is strongly restrained due to a large atom-field detuning. 相似文献
8.
M. Bina F. Casagrande A. Lulli 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(2):257-264
We solve the dynamics of an open quantum system where N strongly driven two-level atoms are equally coupled on resonance to a dissipative cavity mode. Analytical results are derived
on decoherence, entanglement, purity, atomic correlations and cavity field mean photon number. We predict decoherencefree
subspaces for the whole system and the N-qubit subsystem, the monitoring of quantum coherence and purity decay by atomic populations measurements, the conditional
generation of atomic multi-partite entangled states and of cavity cat-like states. We show that the dynamics of atoms prepared
in states invariant under permutation of any two components remains restricted within the subspace spanned by the completely
symmetric Dicke states. We discuss examples and applications in the cases N = 3, 4.
An erratum to this article can be found at 相似文献
9.
A nearly deterministic scheme for generation of multiphoton GHZ states with weak cross-Kerr nonlinearity 下载免费PDF全文
We propose a scheme to generate polarization-entangled multiphoton Greenberger-Horne-Zeilinger (GHZ) states based on weak cross-Kerr nonlinearity and subsequent homodyne measurement. It can also be generalized to produce maximally N-qubit entangled states. The success probabilities of our schemes are almost equal to 1. 相似文献
10.
Run-hua Shi Liu-sheng Huang Wei Yang Hong Zhong 《International Journal of Theoretical Physics》2011,50(11):3329-3336
We present an efficient symmetric scheme for five-party quantum state sharing of an arbitrary m-qubit state with 2m three-particle entangled states. The implementations of this scheme only need to exploit the CNOT gate operations and the
single-particle measurements, instead of the three-particle GHZ-state measurements, which makes it more convenient in a practical
application than some previous schemes. In addition, its total efficiency can approach the maximal value in theory. 相似文献
11.
Qing-Jun Xu 《International Journal of Theoretical Physics》2009,48(5):1415-1421
We propose a scheme to deterministically realize N-qubit GHZ state measurement and discrimination. The scheme is simple and efficient in the senses that only controlled-not
operations and single-qubit measurement are needed. 相似文献
12.
Xiu-Lao Tian Xiao-Qiang Xi Guo-Fang Shi Ming-Liang Hu Guo-Guang Yao 《Optics Communications》2009,282(24):4815-4818
We propose the tensor representation of teleportation and controlled teleportation. By using this representation, it is easy to describe the process of teleporting an unknown N-qubit state via a genuine 2N-qubit channel, and to find the necessary and sufficient condition of realizing a successful teleportation (which is determined by the measurement matrix Tα and the quantum channel parameter matrix X). For controlled teleportation, if composing tensor representation with graph, one can easily design any kind of controlled teleportation. As examples, we give a scheme of symmetrically controlled teleportation of two-qubit states and a scheme of representative network controlled of three-qubit states. This method can also be generalized to the controlled teleportation of N-qubit states. 相似文献
13.
Quantum controlled phase gate and cluster states
generation via two superconducting quantum interference devices in a
cavity 总被引:3,自引:0,他引:3
Z.-Y. Xue G. Zhang P. Dong Y.-M. Yi Z.-L. Cao 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(3):333-336
A scheme for implementing 2-qubit quantum controlled phase gate (QCPG) is proposed with two superconducting quantum interference
devices (SQUIDs) in a cavity. The gate operations are
realized within the two lower flux states of the SQUIDs by using a quantized cavity field and classical microwave pulses.
Our scheme is achieved without any type of measurement, does not use the cavity mode as the data bus and only requires a very
short resonant interaction of the SQUID-cavity system. As an application of the QCPG operation, we also propose a scheme for
generating the cluster
states of many SQUIDs. 相似文献
14.
Yi-you Nie Yuan-hua Li Cui-ping Jin Jun-chang Liu Ming-huang Sang 《International Journal of Theoretical Physics》2011,50(9):2799-2804
A new application of the four-qubit cluster state is investigated for quantum information splitting (QIS) of an arbitrary
N-qubit GHZ-type state among three parties. We demonstrate that a four-qubit cluster state can be used to realize the deterministic
QIS of an arbitrary N-qubit GHZ-type state by introducing N−1 ancillary qubits and performing N−1 controlled-NOT operations. The presented protocols considered here are secure against certain eavesdropping attacks. 相似文献
15.
提出一种任意两粒子纠缠态1→2普适远程克隆方案. 此方案仅需一个特殊的四粒子纠缠态作为量子信道, 就可使处于空间不同位置的两个接收者分别以5/6的保真度得到任意输入态的近似拷贝, 该保真度远高于已有方案中的保真度. 将方案推广到任意两粒子纠缠态1→N(N>2)普适远程克隆的情况, 可使处于不同地点的N个接收者分别以(2N+1)/(3N)的保真度得到输入态的近似拷贝. 另外, 提出一种以上述单个特殊四粒子纠缠态作为量子信道, 在多目标量子比特受控非门和
关键词:
量子纠缠态
普适远程克隆
保真度 相似文献
16.
Quantum logic operations on two distant atoms trapped in two optical-fibre-connected cavities 下载免费PDF全文
Based on the coupling of two distant three-level atoms in two separate optical cavities connected with two optical fibres, schemes on the generation of several two-qubit logic gates are discussed under the conditions of Δ = δ - 2ν cos πk/2 >> g/2 and ν ~ g. Discussion and analysis of the fidelity, gate time and experimental setups show that our schemes are feasible with current optical cavity, atomic trap and optical fibre techniques. Moreover, the atom-cavity- fibre coupling can be used to generate an N-qubit nonlocal entanglement and transfer quantum information among N distant atoms by arranging N atom-cavity assemblages in a line and connecting each two adjacent cavities with two optical fibres. 相似文献
17.
Yao Jin 《Annalen der Physik》2018,530(8)
Transmission of quantum Fisher information (QFI) of initially disentangled parties is studied and the results show that the indirect correlations generated by the environment, which is considered as a bath of fluctuating quantum fields, will help transmit the quantum information. Specifically, using N initially disentangled atoms—one in an excited state carried by one party (the sender, Alice) and the other in the ground state carried by the other parties (the receivers: Bob1, Bob2,…, Bob(N?1)), the phase factor of the state of another atom held by Alice can be transmitted from Alice to Bob with proper time. The transmitted QFI of the phase factor for each receiver has been calculated as a function of the transmitted distance as well as the measurement time and is found to be in relation with the concurrence of the pair of atoms that the sender and the receiver carry. For each transmitted distance, there exists an optimal measurement time to obtain the maximal transmitted QFI, which is in relation with the total number of receivers. 相似文献
18.
Jin Zhi-Xiang Fei Shao-Ming Li-Jost Xianqing 《International Journal of Theoretical Physics》2019,58(5):1576-1589
We investigate the generalized monogamy and polygamy relations N-qubit systems. We give a general upper bound of the αth (0 ≤ α ≤ 2) power of concurrence for N-qubit states. The monogamy relations satisfied by the αth (0 ≤ α ≤ 2) power of concurrence are presented for N-qubit pure states under the partition AB and C1...CN− 2, as well as under the partition ABC1 and C2⋯CN− 2. These inequalities give rise to the restrictions on entanglement distribution and the trade off of entanglement among the subsystems. Similar results are also derived for negativity.
相似文献19.
提出基于腔QED技术的多用户间的多原子W态和GHZ态量子信道的建立方案.在量子网络的空闲时段,各个用户和量子交换机共享EPR对.量子交换机通过原子和腔场的相互作用将两个EPR对制备成W态,再与另一个EPR对进行纠缠交换,经过直接测量后为用户建立三原子W态量子信道;同时讨论了四用户间的W态量子信道的建立方案.量子交换机对三个EPR对进行纠缠交换,将三个原子同时与腔场作用,经过直接测量后为用户建立三原子GHZ态量子信道;并将此方法推广到N个用户间的GHZ态量子信道的建立.
关键词:
腔QED
量子信道
量子交换机
纠缠交换 相似文献
20.
Implementation of quantum search scheme by adiabatic passage in a cavity--laser--atom system 下载免费PDF全文
This paper proposes a scheme for implementing the adiabatic quantum
search algorithm of different marked items in an unsorted list of
N items with atoms in a cavity driven by lasers. N identical
three-level atoms are trapped in a single-mode cavity. Each atom is
driven by a set of three pulsed laser fields. In each atom, the same
level represents a database entry. Two of the atoms are marked
differently. The marked atom has an energy gap between its two
ground states. The two different marked states can be sought out
respectively starting from an initial entangled state by controlling
the ratio of three pulse amplitudes. Moreover, the mechanism, based
on adiabatic passage, constitutes a decoherence-free method in the
sense that spontaneous emission and cavity damping are avoided since
the dynamics follows the dark state. Furthermore, this paper extends
the algorithm with m (m>2) atoms marked in an ideal situation.
Any different marked state can be sought out. 相似文献