共查询到20条相似文献,搜索用时 31 毫秒
1.
We study the influence of multi-photon processes on the geometric quantum computation in the systems of superconducting qubits based on the displacement-like and the general squeezed operator methods. As an example, we focus on the question about how to implement a two-qubit geometric phase gate using superconducting circuit quantum electrodynamics with both single- and two-photon interaction between the qubits and the cavity modes. We find that the multiphoton processes are not only controllable but also improve the gating speed. The comparison with other physical systems and experimental feasibility are discussed in detail. 相似文献
2.
CHEN Chang-Yong 《理论物理通讯》2012,(5):649-652
We study the influence of multi-photon processes on the geometric quantum computation in the systems of superconducting qubits based on the displacement-like and the general squeezed operator methods. As an example, we focus on the question about how to implement a two-qubit geometric phase gate using superconducting circuit quantum electrodynamics with both single- and two-photon interaction between the qubits and the cavity modes. We find that the multiphoton processes are not only controllable but also improve the gating speed. The comparison with other physical systems and experimental feasibility are discussed in detail. 相似文献
3.
Ju-ju Hu Shi-hua Cai Ying-hua Ji 《International Journal of Theoretical Physics》2006,45(11):1983-1992
We study the dynamic evolution of a mesoscopic coupled circuit with alternating source and solve its time-dependent Schrödinger equation with the help of the time dependent invariant of the Hermitian operator. It indicates that the state of the system can evolve a generalized squeezed state. The results show that in certain circumstance, compared to the initial vacuum state, either the charges or the currents in two meshes are squeezed simultaneously in the same extent. The expression of the nonadiabatic geometric phase in the circuit is also obtained. 相似文献
4.
本文用量子力学方法研究在一腔中的等离子体与电磁场的相互作用,求得系统的哈密顿量的本征值和本征态,这本征态是一种广义压缩相干态。还求得在广义压缩相干态,场的压缩、反聚束、亚泊松统计等效应以及测量相算符的有关公式,这些效应均为时间守恒的。
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5.
In this paper, we derive the time dependent solution of the effective master equation for the reduced density matrix operator of a two level atom driven by a coherent laser field and damped by a finite bandwidth squeezed vacuum. The results show that the initial state setting, detuning parameter and Rabi frequency play important roles in the evolution of the system dynamics and geometric phase. We present a useful way for controlling the geometric phase variation for the system under consideration. 相似文献
6.
Creating unconventional geometric phase gate using squeeze-like operator assisted by strong driving field 下载免费PDF全文
Based on the idea that a squeezing process can be thought of as a
total cumulative effect of a large number of tiny squeezing
processes, we define a squeeze-like operator with a time-dependent
squeeze parameter. Applying this operator to and combining with a
system which includes a two-photon interaction between two atoms and
an initial vacuum cavity field, and resorting to a resonant strong
driving classical field, we obtain an unconventional geometric phase
gate with a shorter gating time. 相似文献
7.
The paper investigates the dynamic evolution behaviors of entanglement and quantum discord of coupled superconducting qubits in circuit QED system. We put emphasis on the effects of cavity field quantum state on quantum entanglement and quantum correlations dynamic behaviors of coupling superconducting qubits. The results show that, (1) generally speaking, the entanglement will appear the death and new birth because of the interaction between qubits and cavity field, on the contrary, this phenomenon will not appear in quantum discord. (2) When the cavity field is in coherent state, the entanglement survival time is controlled by the average photon number. The more the average photon number is, the longer survival time of entanglement is prolonged. Thus it has the benefit of keeping quantum correlations. (3) When the cavity field is in squeezed state, the squeezed amplitude parameters have controlling effects on quantum correlations including entanglement and quantum discord. On the one hand, the increase of squeezed amplitude parameters can prolong the survival time of entanglement, on the other hand, with the increase of squeezed amplitude parameters, the robustness of quantum discord is more and more superior to concurrence and is more advantage to keep the system quantum correlations. The further study results show that the increase of the initial relative phase of coupling superconducting qubits can also keep the quantum correlations. 相似文献
8.
9.
WANG Zhong-Jie 《理论物理通讯》2010,54(6):1109-1111
Several schemes have been proposed to prepare two-mode squeezed state and entanglement state between motional states of a single trapped ion and light. Preparation of two-mode squeezed state is based on interaction of a trapped ion located in light cavity with cavity field. Preparation of entanglement state is based on interaction of a trapped ion located in light cavity with cavity field and a traveling wave light field. 相似文献
10.
We propose a new way to generate an observable geometric phase by means of a completely incoherent phenomenon. We show how to imprint a geometric phase to a system by adiabatically manipulating the environment with which it interacts. As a specific scheme, we analyze a multilevel atom interacting with a broadband squeezed vacuum bosonic bath. As the squeezing parameters are smoothly changed in time along a closed loop, the ground state of the system acquires a geometric phase. We also propose a scheme to measure such a geometric phase by means of a suitable polarization detection. 相似文献
11.
We show how to generate bilinear (quadratic) Hamiltonians in cavity quantum
electrodynamics (QED) through the interaction of a single driven three-level
atom with two (one) cavity modes. With this scheme it is possible to
generate one-mode mesoscopic squeezed superpositions, two-mode
entanglements, and two-mode squeezed vacuum states (such the original EPR
state), without the need for Ramsey zones and external parametric
amplification. The degree of squeezing achieved is up to 99% with currently
feasible experimental parameters and the errors due to dissipative
mechanisms become practically negligible. 相似文献
12.
Shuai Wang 《International Journal of Theoretical Physics》2009,48(5):1459-1465
For L-C circuit, a new quantized scheme has been proposed in the context of number-phase quantization. In this quantization
scheme, the number n of the electric charge q(q=en) is quantized as the charge number operator and the phase difference θ across the capacity is quantized as phase operator. Based on the scheme of number-phase quantization and the thermo field
dynamics (TFD), the quantum fluctuations of the charge number and phase difference of a mesoscopic L-C circuit in the thermal
vacuum state, the thermal coherent state and the thermal squeezed state have been studied. It is shown that these quantum
fluctuations of the charge number and phase difference are related to not only the parameters of circuit, the squeezing parameter,
but also the temperature in these quantum states. It is proven that the number-phase quantization scheme is very useful to
tackle with quantization of some mesoscopic electric circuits and the quantum effects. 相似文献
13.
根据大失谐条件下原子-腔场相互作用的特点,讨论了一个制备纠缠压缩态的方法,提出了一个利用两能级原子与腔场相互作用实现纠缠压缩态纠缠浓缩的方案。在这个方案中,两束具有相同振幅但有着 相位差的压缩光 和 构成的纠缠态光场被用来作为量子信道。通过利用两能级原子与腔场的相互作用以及两模正交态测量实现了这个纠缠浓缩的过程。结果表明:对于纠缠压缩态,无论其初始的纠缠是多么微弱,利用这种方法总有一定的几率可以从部分纠缠态中提取出最大纠缠态。 相似文献
14.
15.
YANG Wen-Xing CHEN Ai-Xi 《理论物理通讯》2008,49(4):913-918
In the system with superconducting quantum interference devices (SQUID) in cavity, a scheme for constructing two-qubit quantum phase gate via a conventional geometric phase-shift is proposed by using a quantized cavity field and classical microwave pulses. In this scheme, the gate operation is realized in the subspace spanned by the two lower flux states of the SQUID system mud the population operator of the excited state has no effect on it. Thus the effect of decoherence caused from the levels of the SQUID system is possible to minimize. Under cavity decay, our strictly numerical simulation shows that it is also possible to realize the unconventional geometric phase gate. The experimental feasibility is discussed in detail. 相似文献
16.
Chang-Yong Chen 《International Journal of Theoretical Physics》2008,47(5):1397-1408
A scheme has been proposed for generating the macroscopic superpositions and the entanglement between the mesoscopic squeezed
vacuum states by considering the two-photon interaction of N two-level atoms in a dissipative cavity with high quality factor assisted by a strong driving field. A number of multiparty
entangled states between the atoms and the squeezed vacuum states, among the atoms, and among the squeezed vacuum states,
can be prepared by virtue of a specific choice of the cavity detuning and the detuning of applied coherent field under the
dissipation condition. The corresponding analytical expressions of the influence can be given. Moreover, we can also give
a series of macroscopic entangled states between the usual coherent states and the squeezed vacuum states using the combination
of the dissipative one-photon interaction Hamiltonian with the dissipative two-photon interaction Hamiltonian. We also discuss
the experimental feasibility. Our scheme can be realized in the current techniques on the cavity QED. 相似文献
17.
From the normally ordered form of the density operator of a squeezed coherent state(SCS),we directly derive the compact expression of the SCS’s photon-number distribution(PND).Besides the known oscillation characteristics,we find that the PND is a periodic function with a period of π and extremely sensitive to phase.If the squeezing is strong enough,and the compound phase which is relevant to the complex squeezing and displacement parameters are assigned appropriate values,different oscillation behaviours in PND for even and odd photon numbers appear,respectively. 相似文献
18.
We propose a scheme to implement an unconventional geometric phase gate in circuit QED, i.e. two superconducting charge qubits inside a superconducting transmission line resonator. The quantum operation depends only on global geometric features, and thus is insensitive to the state of the cavity mode. 相似文献
19.