arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1809.03708cond-mat.supr-concond-mat.quant-gascond-mat.stat-mech
收藏

孤立超导体中的数相涨落

Number-Phase Fluctuations in Isolated Superconductors

Xiaotian Si, Wataru Kohno, Takafumi Kita

摘要:

我们改进了Bardeen-Cooper-Schrieffer波函数,使其具有固定的粒子数,从而包含了超出平均场处理的多体关联。结果表明,在弱耦合区,关联对基态能量的降低远大于库珀对凝聚。此外,它们自然会带来凝聚粒子数量的叠加。因此,在量子力学的各种束缚态形成中,库珀对凝聚是特殊的,因为通过粒子与非凝聚库的动态交换,凝聚体中必然存在数量涨落。在此基础上,我们提出$\varDelta N_{\rm con}\cdot \varDelta ϕ\gtrsim 1$作为与超导体和超流体中的数-相涨落有关的不确定关系,其中用凝聚粒子数$N_{\rm con}$代替总粒子数$N$ .该公式意味着即使在自$\varDelta N_{\rm con}\gg 1$以来数量固定的超导体和超流体中也可以建立宏观相$ϕ$。

英文摘要:

We improve the Bardeen-Cooper-Schrieffer wave function with a fixed particle number so as to incorporate many-body correlations beyond the mean-field treatment. It is shown that the correlations lower the ground-state energy far more than Cooper-pair condensation in the weak-coupling region. Moreover, they naturally bring a superposition over the number of condensed particles. Thus, Cooper-pair condensation is special among the various bound-state formations of quantum mechanics in that number fluctuations are necessarily present in the condensate through the dynamical exchange of particles with the non-condensate reservoir. On the basis of this result, we propose $\varDelta N_{\rm con}\cdot \varDelta ϕ\gtrsim 1$ as the uncertainty relation relevant to the number-phase fluctuations in superconductors and superfluids, where the number of condensed particles $N_{\rm con}$ is used instead of the total particle number $N$. The formula implies that a macroscopic phase $ϕ$ can be established even in number-fixed superconductors and superfluids since $\varDelta N_{\rm con}\gg 1$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑