共查询到20条相似文献,搜索用时 0 毫秒
1.
In this paper,by employing Bogliubov backreaction method,we investigate quantum correction effects on dynamical phase transition in a single species bosonic Josephson junction induced by increasing nonlinear interaction.Compared with mean field theory results,we find that the transition point is shifted.The dynamical phase transition is accompanied by a change of the entanglement entropy,which is found to reach a maximum at the transition point of the mean field theory. 相似文献
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In this letter,the superfluid-Mott-insulator phase transition of two-species cold bosonic atoms in an optical lattices is studied.The Hamiltonian of this model is diagonalized by means of Bogliubov transformations and by the inversion symmetry of the optical lattice,the energy spectrum of this system is obtained.From the energy gap of the excitation spectrum,the quantum phase transition condition is obtained and it is determined by the competition between the interatomic repulsions and the tunnel coupling.It is found that there exists an ordinary fluid phase when taking the zero wave-vector limit. 相似文献
4.
We study a mesoscopic Josephson junction in a circular superconducting ring which encloses a magneto static flux. It is shown that with the junction being initially prepared in vacuum state, the state of the junction can evolve into a quantum superposition of two coherent states. 相似文献
5.
We investigate the self-trapping of a Bose Josephson junction, which is dispersively coupled to a driven optical cavity. The cavity-induced nonlinearity is presented analytically, and its effect results in the appearance of the self-trapping for the Bose-Einstein condensates in the Josephson oscillation regime. In addition, there exists competition between the nonlinearitiesinduced by the interatomic interaction and by the driven cavity for the emergences of self-trapping. Our results show that the driven cavity can be utilized as a possible tool to produce the self-trapping for the condensates with weak interatomic interaction. 相似文献
6.
LI Zhi-Qiang LIANG Xian-Ting 《理论物理通讯》2008,50(7):77-80
In this paper we investigate an environmental effects to Josephson charge qubit (JCQ) when the environment is taken as the Ohmic bath. At first, we derive the master equation from a JCQ-bath model. Then we investigate the coefficients of the equations that describe the shift in frequency, diffusive, decoherence, and so on. It is shown that our result on decoherence agrees with experimental one very well as the time is short enough. 相似文献
7.
We investigate the reciprocal of the mean quantum Fisher information per particle (RMQFIP) and phase sensitivity of atomic Josephson junctions with a bosonic species confined by a double-well potential. Here we are focus on the Rabi oscillation energy’s influence on RMQFIP and phase sensitivity. The better quantum entanglement and phase sensitivity may be achieved by decreasing the Rabi oscillation energy. 相似文献
8.
ZOU Jian SHAO Bin SU Wen-Yong 《理论物理通讯》2001,(10)
A mesoscopic Josephson junction with dissipation is considered. Usually the dissipation in the system is described as a consequence of its coupling to a reservoir. By solving the master equation we show that the state of the junction can evolve in a quantum superposition of two coherent states even when the dissipation is present.`` 相似文献
9.
WANG Zhong-Jie 《理论物理通讯》2004,42(10)
Dynamical control of decoherence induced by the environment in a single quantum-bit system is investigated. We choose the suitable perturbations acting on the qubit system to decrease the decoherence due to pure amplitude damping. The scheme proposed here is based on the free-Hamiltonian-elimination technique and the paritykick technique, which concludes two homogeneous classical large-blue-detuned optical fields with different frequencies added to the qubit system. By applying this scheme, the decoherence can be completely suppressed. 相似文献
10.
A mesoscopic Josephson junction with dissipation is
considered. Usually the dissipation in the system is described as a
consequence of its coupling to a reservoir.
By solving the master equation we show that the state of the junction can
evolve in a quantum superposition of two coherent states even when the
dissipation is present. 相似文献
11.
WANGZhong-Jie 《理论物理通讯》2004,42(4):539-542
Dynamical control of decoherence induced by the environment in a single quantum-bit system is investigated. We choose the suitable perturbations acting on the qubit system to decrease the decoherence due to pure amplitude damping. The scheme proposed here is based on the free-Hamiltonian-elimination technique and the paritykick technique, which concludes two homogeneous classical large-blue-detuned optical fields with different frequencies added to the qubit system. By applying this scheme, the decoherence can be completely suppressed. 相似文献
12.
The effect of quantum phase transition (QPT) on the coherence retrieval by dynamical decoupling is discussed explicitly by exemplifications. Two different cases can be identified; For QPT without variant of topology, dynamical decoupling can work better than that without QPT. Whereas the systems have nontrivial topology, it displays limited improvement of retrieval of qubit coherent. This feature can be understood by the fact that dynamical decoupling is physically to average out the effect of harmful local couplings. When nontrivial topology is involved, the local operation becomes invalid. Hence one has to find more efficient way to recover qubit coherence. 相似文献
13.
We have experimentally studied a small Josephson junction array in the presence of microwave irradiation. The array has comparable energy scales for single-charge effects and the Josephson effect, resulting in a discrete set of macroscopic eigenenergy levels. Excitation of the array by low-power microwaves is possible at frequencies where the photon energy matches the level spacing. The microwave frequency and amplitude dependence show that the excitation mechanism involves resonant quantum coherent dynamics of the array. 相似文献
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LIU Xiao-Shu LIU Yang 《理论物理通讯》2005,44(9)
In this paper, we have detailedly studied the dynamical suppression of the phase damping for the two-qubit quantum memory of Ising model by the quantum “bang-bang“ technique. We find the sequence of periodic radiofrequency pulses repetitively to flip the state of the two-qubit system and quantitatively find that these pulses can be used to effectively suppress the phase damping decoherence of the quantum memory and freeze the system state into its initial state. The general sequence of periodic radio-frequency pulses to suppress the phase damping of multi-qubit of Ising model is also given. 相似文献
16.
LIU Xiao-Shu LIU Yang 《理论物理通讯》2005,44(3):459-462
In this paper, we have detailedly studied the dynamical suppression of the phase damping for the two-qubit quantum memory of Ising model by the quantum “bang-bang” technique. We find the sequence of periodic radio-frequency pulses repetitively to flip the state of the two-qubit system and quantitatively find that these pulses can be used to effectively suppress the phase damping decoherence of the quantum memory and freeze the system state into its initial state. The general sequence of periodic radio-frequency pulses to suppress the phase damping of multi-qubit of Ising model is also given. 相似文献
17.
Quantum Phase Transition of the Bosonic Atoms near the Feshbach Resonance in an Optical Lattice 下载免费PDF全文
The quantum phase transition from the Mott insulator to the superfluid phases of the bosonic atoms trapped in an optical lattice, in which the on-site interaction carl be tuned by a Feshbach resonance, is investigated by a variational approach within mean-field theory. We derive an extended Bos~Hubbard model to describe this ultracold atomic system. By theoretical calculation and analysis, the phase diagram is shown clearly, and we find an exciting and novel phenomenon that is the appearance of the Mort insulator-sea (MI-sea). Meanwhile, the experimental feasibility of observing the MI-sea is discussed by analyzing the published data related to the Fashbaeh resonance at present. Finally, the potential application of the MI-sea for quantum information processing and quantum computation is also discussed in detail 相似文献
18.
FAN Hong-Yi WANG Ji-Suo 《理论物理通讯》2006,46(5):935-937
By making the analogy between the operator Hamiltonians of a mesoscopic ring carrying the persistent current and a Josephson junction we have introduced a phase operator and entangled state representation to establish a theoretical formalism for the ring system. 相似文献
19.
FAN Hong-Yi WANG Ji-Suo 《理论物理通讯》2006,46(11)
By making the analogy between the operator Hamiltonians of a mesoscopic ring carrying the persistent current and a Josephson junction we have introduced a phase operator and entangled state representation to establish a theoretical formalism for the ring system. 相似文献
20.
We investigate the critical behavior in tunneling dynamics of a binary mixture of Bose-Einstein condensates (BECs) trapped in a symmetric double well potential. By gradually increasing the interspecies interaction, we characterize a continuous dynamical phase transition behavior which involves power law scaling. This dynamical phase transition is a consequence of separatrix crossing as we revealed by poincaré section analysis. 相似文献