共查询到17条相似文献,搜索用时 203 毫秒
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在有效质量近似条件下研究了由两个垂直耦合自组织InAs量子点组成的双电子量子点分子的电子结构,在此基础上利用系统的总自旋提出了一种磁场方向调制的量子比特方案.电子的相关效应可以导致系统的总自旋在0和1之间转换,值得注意的是,通过调节外部磁场的方向来实现这种转换,而不是像以往那样通过改变外部磁场的大小.结果支持利用系统的总自旋作为磁场方向调制的量子比特的可能性,而且因为高质量的垂直耦合量子点分子的制作工艺已经成熟,所以这是一个非常现实的量子比特设计方案.
关键词:
量子点分子
磁场方向调制
量子比特 相似文献
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以理想费米气体为工质的量子制冷循环 总被引:2,自引:0,他引:2
本文基于理想费米气体的状态方程,分析了以理想费米气体为工质的量子Ericsson制冷循环中的回热特征,推导出其制冷循环的制冷系数表达式。并在高温和低温条件下对制冷系数进行了讨论。这将对低温制冷机的研究提供理论依据。 相似文献
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建立了蒸气压缩/喷射制冷循环稳定运行时两相喷射器的热力学模型,以常压沸点相差较大的制冷剂为工质,比较了两相喷射器引射室压降最优范围的差异,并在同一工况下,研究了不同工质压缩/喷射制冷循环的性能。结果表明:喷射器引射室压降存在最佳范围使压缩/喷射制冷循环性能接近最优值;在相同工况下不同制冷工质这个最佳范围不相同;在同一工况下,当采用压缩/喷射制冷循环时,不同工质的循环性能系数和单位容积制冷能力相比基本循环均增强了。研究结果为压缩/喷射制冷循环制冷工质的选择及两相喷射器结构的优化设计提供理论参考。 相似文献
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A new model of a quantum refrigeration cycle composed of two adiabatic and
two isomagnetic field processes is established. The working substance in the
cycle consists of many non-interacting spin-1/2 systems. The performance of
the cycle is investigated, based on the quantum master equation and
semi-group approach. The general expressions of several important
performance parameters, such as the coefficient of performance, cooling
rate, and power input, are given. It is found that the coefficient of
performance of this cycle is in the closest analogy to that of the classical
Carnot cycle. Furthermore, at high temperatures the optimal relations of the
cooling rate and the maximum cooling rate are analysed in detail. Some
performance characteristic curves of the cycle are plotted, such as the
cooling rate versus the maximum ratio between high and low ``temperatures'
of the working substances, the maximum cooling rate versus the ratio between
high and low ``magnetic fields' and the ``temperature' ratio between high
and low reservoirs. The obtained results are further generalized and
discussed, so that they may be directly applied to describing the performance
of the quantum refrigerator using spin-$J$ systems as the working substance.
Finally, the optimum characteristics of the quantum Carnot and Ericsson
refrigeration cycles are derived by analogy. 相似文献
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An irreversible model of an Ericsson cryogenic refrigeration cycle working with an ideal Fermi gas is established, which is
composed of two isothermal and two isobaric processes. The influence of both the quantum degeneracy and the finite-rate heat
transfer between the working fluid and the heat reservoirs on the performance of the cycle is investigated, based on the theory
of statistical mechanics and thermodynamic properties of an ideal Fermi gas. The inherent regeneration losses of the cycle
are analyzed. Expressions for several important performance parameters such as the coefficient of performance, cooling rate
and power input are derived. By using numerical solutions, the cooling rate of the cycle is optimized for a given power input.
The maximum cooling rate and the corresponding parameters are calculated numerically. The optimal regions of the coefficient
of performance and power input are determined. Especially, the optimal performance of the cycle in the strong and weak gas
degeneracy cases and the high temperature limit is discussed in detail. The analytic expressions of some optimized parameters
are derived. Some optimum criteria are given. The distinctions and connections between the Ericsson refrigeration cycles working
with the Fermi and classical gases are revealed.
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In this paper, an irreversible quantum Otto refrigeration cycle working with harmonic systems is established. Base on Heisenberg
quantum master equation, the equations of motion for the set of harmonic systems thermodynamic observables are derived. The
simulated diagrams of the quantum Otto refrigeration cycle are plotted. The relationship between average power of friction,
cooling rate, power input, and the time of adiabatic process is analyzed by using numerical calculation. Moreover, the influence
of the heat conductance and the time of iso-frequency process on the performance of the cycle is discussed. 相似文献
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An irreversible Ericsson refrigeration cycle model is established, in which multi-irreversibilities such as finite-rate heat transfer, regenerative loss, heat leakage, and the efficiency of the regenerator are taken into account. Expressions for several important performance parameters, such as the cooling rate, coefficient of performance (COP), power input, exergy output rate, entropy generation rate, and ecological function are derived. The influences of the heat leakage and the time of the regenerative processes on the ecological performance of the refrigerator are analyzed. The optimal regions of the ecological function, cooling rate, and COP are determined and evaluated. Furthermore, some important parameter relations of the refrigerator are revealed and discussed in detail. The results obtained here have general significance and will be helpful in gaining a deep understanding of the magnetic Ericsson refrigeration cycle. 相似文献
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铁磁质斯特林制冷循环的优化分析 总被引:10,自引:0,他引:10
铁磁质斯特林制冷循环的优化分析林国星,严子浚(厦门大学物理系厦门361005)关键词:铁磁质,制冷循环,优化分析一、引言磁制冷机在制冷效率和可靠性方面都优于传统的气体制冷机,且可减少环境污染,得到了世界各国普遍重视。而磁斯特林制冷循环是磁制冷机研制中... 相似文献