共查询到20条相似文献,搜索用时 15 毫秒
1.
In this paper, we study the control problem of adiabatic decoherence in a three-level atom. We will find the decoupling bang-bang group for various configurations, including the V configuration and the cascade type of three-levelatom subjected to adiabatic decoherence. We also give the programs to design a sequence of periodic twinborn pulses to suppress the decoherence. 相似文献
2.
WANG Yan-Hui LIU Xiao-Shu RUAN Dong LONG Gui-Lu 《理论物理通讯》2008,49(4):881-886
In this paper, we present the decoupling bang-bang (BB) twin-born pulses to suppress the genera/deco- herence, both amplitude and phase decoherence, in a three-level atom in V- and Ξ-configurations. We give the exact sequence of periodic twinborn pulses in such systems. 相似文献
3.
我们利用腔场和激光相互作用,提出一个冗余的、对消相干不敏感的方案,来传输任意一个三能级原子的态.由于原子自发跃迁和腔延迟作用会造成信息丢失,通过用部分绝热过程和适当的原子场耦合的设计,信息丢失能够被有效的抑制,此方案传送成功的几率是0.5,保真度是1. 相似文献
4.
We study the phase probability distribution of a three-level atom interacting with a cavity field in the presence of two-photon detuning and decoherence. Anabiosis of the phase probability distribution is observed due to the presence of the Stark shift. The simulation demonstrates that there is an enhancement of the phase sensitivity as soon as the two-photon detuning is considered. The W-Wigner function is also examined and it is shown that the nonclassical effect is apparent, however, for a small value of the decoherence factor. 相似文献
5.
We present a scheme to realize the basic two-qubit logic gates such as the
quantum phase gate and SWAP gate using a detuned microwave cavity
interacting with three-level superconducting-quantum-interference-device
(SQUID) qubit(s), by placing SQUID(s) in a two-mode microwave cavity and
using adiabatic passage methods. In this scheme, the two logical states of
the qubit are represented by the two lowest levels of the SQUID, and the
cavity fields are treated as quantized. Compared with the previous method,
the complex procedures of adjusting the level spacing of the SQUID and
applying the resonant microwave pulse to the SQUID to create transformation
are not required. Based on superconducting device with relatively long
decoherence time and simplified operation procedure, the gates operate
at a high speed, which is important in view of decoherence. 相似文献
6.
Jun He Yong-Sheng Zhang Xiang-Fa Zhou Qun-Feng Chen Guang-Can Guo 《Optics Communications》2009,282(6):1167-1170
An method for adiabatic population transfer and the preparation of an arbitrary quantum superposition state using the oscillating dark states (ODS) in atomic system is presented. Quantum state of a three-level Λ configuration atomic system finally evolves into the same time-dependent state, and oscillates periodically between two ground levels under evolving adiabatic conditions when two pairs of classical detuning laser fields drive the system into the ODS forcedly, whatever the initial states of the system are. The decoherence of the ODS evolution is greatly suppressed and the oscillation is very stable, therefore adiabatic population transfer and the preparation of an arbitrary quantum superposition state of atomic system can be completed accurately and conveniently. 相似文献
7.
Two-qutrit maximally entangled states prepared via adiabatic passage in ion-trapped system 下载免费PDF全文
This paper considers a scheme for the preparation of two-qutrit entangled states via adiabatic passage in iontrapped system.In the proposal,the two three-level V-type ions are initially cooled to the ground states and need not be separately addressed.Moreover,only the ionic states act as memory and the system evolves in the dark space during the whole procedure,which makes the system robust against the decoherence and the fluctuation of the laser pulse. 相似文献
8.
A three-level system based an a three-level atom interacting with a detuned cavity is considered. Because of the fact that the three-level atom defines a total normalized state composed of superposition of three different single-level states, it is assumed that such a system implements a qutrit. In order to achieve a quantum NOT gate for a single qutrit, the respective Schrödinger equation is solved numerically within a two-photon rotating wave approximation. For small values of one-photon detuning, there appear decoherence effects. Meanwhile, for large values of one-photon detuning, an ideal quantum NOT gate for a single qutrit is achieved. An expression for the execution time of the quantum NOT gate for a single qutrit as a function of the one-photon detuning is found. 相似文献
9.
REN XueZao CONG HongLu WANG XuWen & XIA JianPing School of Science Southwest University of Science Technology Mianyang China Physics Group Beijing Jiaotong University Hai Bin College Huanghua 《中国科学:物理学 力学 天文学(英文版)》2011,(9)
In this paper, the quantum entanglement between a single mode binomial field and a cascade three-level atom is calculated mechanically without the rotating wave approximation. The numerical results indicate that the quantum entanglement at the first few periods is reduced notably due to the fact that the atom is initially in the superposition state. With increasing field parameter , the period of the entanglement evolution becomes obvious and the quantum decoherence phenomenon emerges in a short time. 相似文献
10.
Z. J. Deng L.-M. Liang W. L. Yang 《International Journal of Theoretical Physics》2010,49(8):1904-1910
We propose a simple scheme to implement multi-qubit quantum Grover search with atomic ensembles by adiabatic passage. The
scheme is immune to the atomic spontaneous emission, cavity decay and fiber decay. Furthermore, the process can be speeded
up with atomic ensemble instead of single atom, which is important in view of decoherence. With each atomic ensemble confined
in an individual cavity, our scheme is experimentally scalable to multi-qubit cases. 相似文献
11.
12.
In this talk, the interaction of a single photon injected to a single atom is studied, for which initially the photon is uncorrelated with the atom. The spontaneous emitted photon will then evolve to be entangled with the atom on their continuous kinetic variables (momentum) in the process of resonant scattering. We find the relations between the entanglement and their physical control parameters (such as the linewidth of the injected photon wave packet, and that of the atomic wave packet, etc. ), which indicates that high entanglement can be reached by broadening the scale of the atomic wave or squeezing the linewidth of the incident single-photon pulse. 相似文献
13.
探讨了阶梯形三能级原子 腔耦合系统中由绝热跟随技术引起的光子Fock态的产生 .结果发现 :对于单模腔QED系统 ,通过受激拉曼绝热跟随技术 ,在微波区域内可实现单光子Fock态的制备 ;对于双模腔QED系统 ,通过斯塔克移动的快绝热跟随技术可实现双光子对Fock态的产生.The behavior of an atom-cavity system using a three-level ladder atom was investigated. It is found that, for one-mode cavity QED, a single photon can be generated via the technique of stimulated Raman adiabatic passage; for two-mode cavity QED, a two-photon pair can be generated via Stark-shift rapid adiabatic passage. 相似文献
14.
Optical selection rules and phase-dependent adiabatic state control in a superconducting quantum circuit 总被引:1,自引:0,他引:1
We analyze the optical selection rules of the microwave-assisted transitions in a flux qubit superconducting quantum circuit (SQC). We show that the parities of the states relevant to the superconducting phase in the SQC are well defined when the external magnetic flux phi(e) = phi(0)/2; then the selection rules are the same as the ones for the electric-dipole transitions in usual atoms. When phi(e) does not = phi(0)/2, the symmetry of the potential of the artificial "atom" is broken, a so-called delta-type "cyclic" three-level atom is formed, where one- and two-photon processes can coexist. We study how the population of these three states can be selectively transferred by adiabatically controlling the electromagnetic field pulses. Different from lambda-type atoms, the adiabatic population transfer in our three-level delta atom can be controlled not only by the amplitudes but also by the phases of the pluses. 相似文献
15.
LI Chong GAO Yi-Bo 《理论物理通讯》2007,48(5):935-942
We revisit the protocols to create maximally entangled states between two Josephson junction (33) charge phase qubits coupled to a microwave field in a cavity as a quantum data bus. We analyze a novel mechanism of quantum decoherence due to the adiabatic entanglement between qubits and the data bus, the off-resonance microwave field. We show that even if the variable of the data bus can be adiabatically eliminated, the entanglement between the qubits and data bus remains and can decohere the superposition of two-particle state. Fortunately we can construct a decoherencefree subspace of two-dimension to against this adiabatic decoherence. To carry out the analytic study for this decoherence problem, we develop Frohlich transformation to re-derive the effective Hamiltonian of these systems, which is equivalent to that obtained from the adiabatic elimination approach. 相似文献
16.
17.
N. K. Solovarov 《Journal of Experimental and Theoretical Physics》2008,106(6):1033-1044
The correlated dynamics of a three-level atom resonantly coupled to an electromagnetic cavity field is calculated (Λ, V, and L models). A diagrammatic representation of quantum dynamics is proposed for these models. As an example, Λ-atom dynamics is examined to demonstrate how the use of conventional von Neumann’s reduction leads to internal decoherence (disentanglement-induced decoherence) and to the absence of atomic coherence under multiphoton excitation. The predicted absence of atomic coherence is inconsistent with characteristics of an experimentally observed atom-photon entangled state. It is shown that the correlated reduction of a composite quantum system proposed in [18] qualitatively predicts the occurrence and evolution of atomic coherence under multiphoton excitation if a seed coherence is introduced into any subsystem (the atom or a cavity mode). 相似文献
18.
We propose an implementation of the quantum search algorithm of a marked item in an unsorted list of N items by adiabatic passage in a cavity-laser-atom system. We use an ensemble of N identical three-level atoms trapped in a single-mode cavity and driven by two lasers. In each atom, the same level represents a database entry. One of the atoms is marked by having an energy gap between its two ground states. Appropriate time delays between the two laser pulses allow one to populate the marked state starting from an initial entangled state within a decoherence-free adiabatic subspace. The time to achieve such a process is shown to exhibit the square root N Grover speedup. 相似文献
19.
In this paper, we present decoupling bang-bang operations for the suppression of general decoherence, both amplitude and phase damping,
in a three-level system in Λ-configuration. We give a program
to design a sequence of periodic twinborn pulses to suppress the decoherence in such the system. 相似文献
20.
Suppression of Phase and Amplitude Damping Decoherence in a Three-Level Atom in A-Configuration Using Bang-Bang Controls 总被引:1,自引:0,他引:1
In this paper, we present decoupling bang-bang operations for the suppression of general decoherence, both amplitude and phase damping, in a three-level system in A-configuration. We give a program to design a sequence of periodic twinborn pulses to suppress the decoherence in such the system. 相似文献