肋片型太阳能集热器热量通道传热效果仿真

对肋片型太阳能集热器热量通道传热特性效果进行分析,能够高效提高集热器的使用质量。对太阳能集热器热量通道传热效果进行仿真,需要建立集热器热量通道的湍流模型,分析计算流体动力学方法。传统方法建立集热器单侧吸收高热流密度的传热数学模型,但忽略了对流体动力学的分析,导致传热效果分析的准确度低,提出一种肋片型太阳能集热器热量通道传热效果分析方法,通过建立集热器热量通道的湍流模型,对集热器热量的湍流进行分析,确定集热器的湍流性能,并通过分析近壁区空气湍流特性,提高集热器热量通道传热特性效果的分析的准确性;对计算流体动力学方法进行分析,对影响肋片型太阳能集热器热量通道传热效果的参数进行求解,从而实现传热效果分析。实验结果表明,所提方法能够准确描述各参数对肋片型太阳能集热器热量通道传热效果的影响,传热效果分析的准确度较高。

Efficient Scheme for One-Way Quantum Computing with Radiofrequency SQUID Qubits by Adiabatic Passage

We proposed an efficient scheme for constructing a quantum controlled phase-shift gate and generating thecluster states with rf superconducting quantum interference devices (SQUIDs)coupled to a microwave cavity throughadiabatic evolution of dark eigenstates.During the operation,the spontaneous emission is suppressed since the rf SQUIDsare always in the three lowest flux states.Considering the influence from the cavity decay with achievable experimentalparameters,we numerically analyze the success probability and the fidelity for generating the two-SQUID maximallyentangled state and the controlled phase-shift gate by adiabatic passage.

Three-Dimensional Quantum State Transferring Between Two Remote Atoms by Adiabatic Passage under Dissipation

Recently, Zhou et al. [Phys. Rev. A 79 （2009） 044304] proposed a scheme for transferring three-dimensional quantum states between remote atomic qubits confined in cavities connected by fibers through adiabatic passage. In order to avoid the decoherence due to spontaneous emission, Zhou et al. utilized the large detuning atom-field interaction. In the present paper, we discuss the influence of dissipation on the scheme in both the resonant atom-field interaction case and the large detuning case. We numerically analyze the success probability and the transferring fidelity. It is shown that the resonant case is a preferable choice for the technique of the stimulated Raman adiabatic passage （STIRAP） due to the shorter operation time and the smaller probability of dissipation.

Generating W State with Qubits of Superconducting Quantum Interference Devices via Adiabatic Passage

A scheme is proposed to generate W state with qubits of superconducting quantum interference devices （SQUIDs）, based on adiabatic passage along dark state. Taking advantages of adiabatic passage, the scheme is very robust against decoherence, and it does not need to control the classical field and the interaction time accurately. Because of the achievable strong coupling between SQUID qubits and cavity, W state can be generated with high successful probability.

Entangled W State Generation via Adiabatic Passage in Cavity QED

A scheme is proposed to generate W state of N atoms trapped in a cavity,based on adiabatic passage alongdark state.Taking advantage of adiabatic passage,the atoms have no probability of being excited and thus the atomicspontaneous emission is suppressed.The scheme is simple.It does not need to adjust the interaction time accurately,anddoes not need to prepare the cavity field in one-photon state.Numerical simulation shows that the successful probabilityof the scheme increases with the increasing of the atom number.

Implementation of Controlled Geometric Phase Gate for Two Trapped Neutral Atoms

We propose a scheme for realizing a controlled geometric phase gate for two neutral atoms.We apply thestimulated Raman adiabatic passage to transfer atoms from their ground states into Rydberg excited states, and use theRydberg interaction induced energy shifts to generate geometric phase and construct quantum gates.

Long-range adiabatic quantum state transfer through a linear array of quantum dots

We introduce an adiabatic long-range quantum communication proposal based on a quantum dot array.By adiabatically varying the external gate voltage applied on the system,the quantum information encoded in the electron can be transported from one end dot to another.We numerically solve the schr dinger equation for a system with a given number of quantum dots.It is shown that this scheme is a simple and efficient protocol to coherently manipulate the population transfer under suitable gate pulses.The dependence of the energy gap and the transfer time on system parameters is analyzed and shown numerically.We also investigate the adiabatic passage in a more realistic system in the presence of inevitable fabrication imperfections.This method provides guidance for future realizations of adiabatic quantum state transfer in experiments.

Stark-Chirped Rapid Adiabatic Passage in Presence of Dissipation for Quantum Computation

Stark-chirped rapid adiabatic passage(SCRAP) is an important technique used for coherent quantum controls. In this paper we investigate how the practically-existing dissipation of the system influences on the efficiency of the passage, and thus the fidelities of the SCRAP-based quantum gates. With flux-biased Josephson qubits as a specifical example, our results show clearly that the efficiency of the logic gates implemented by SCRAP are robust against the weak dissipation. The influence due to the non-adiabtic transitions between the adiabatic passages is comparatively significantly small. Therefore, the SCRAP-based logic gates should be feasible for the realistic physical systems with noises.

Heat and Momentum Transport in Micro-Channels

Effect of velocity jump and temperature jump on the heat and momentum transfer in micro-domains is discussed in detail. A simulation aided by locally fully developed assumption is developed to ex-plain the experimental results different from those predicted by conventional theory. Heat transfer in microrchannels under the uniform heat flux is also analyzed. It is found that velocity-jump and temperature-jump have an opposite innuence and Nusselt number has a greater ralue when the Knud-sen number is very small. With the increasing of Knudsen Number, Nusselt number became smaller than 8.24.