Phonon spectrum and correlations in a transonic flow of an atomic Bose gas
Phonon spectrum and correlations in a transonic flow of an atomic Bose gas
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DOI：
10.1103/physrevd.94.084027
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发表时间：
2016-05
影响因子：
5
通讯作者：
F. Michel;J.-F. Coupechoux;R. Parentani
中科院分区：
文献类型：
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作者：
F. Michel;J.-F. Coupechoux;R. Parentani
受J.Steinhauer最近的一项实验的启发，我们重新考虑了定常跨音速流动中自发发射的声子的光谱和关联。后者用“瀑布”构型来描述，它形成了一个稳定流量族。对于接近实验值的参数，尽管在声速视界附近有很高的梯度，但在相应的频域内，谱是精确的普朗克谱，那里的温度与相对论预测的温度相差不到10%。然后，我们研究了横跨视界的密度关联和终态的不可分性质。我们表明，当初始温度不太高时，相对论表达式提供了精确的近似。我们还表明，散射系数的相位引入了关联位置的有限移动，这一点到目前为止被忽略了。这种变化是由于横跨地平线的气流的不对称性造成的，并持续在无弥散的区域。最后，我们展示了声速视界的形成如何改变局域和非局域密度关联。
Motivated by a recent experiment of J. Steinhauer, we reconsider the spectrum and the correlations of the phonons spontaneously emitted in stationary transonic flows. The latter are described by “waterfall” configurations which form a one-parameter family of stable flows. For parameters close to their experimental values, in spite of high gradients near the sonic horizon, the spectrum is accurately Planckian in the relevant frequency domain, where the temperature differs from the relativistic prediction by less than 10%. We then study the density correlations across the horizon and the nonseparable character of the final state. We show that the relativistic expressions provide accurate approximations when the initial temperature is not too high. We also show that the phases of the scattering coefficients introduce a finite shift of the location of the correlations which has so far been overlooked. This shift is due to the asymmetry of the flow across the horizon, and persists in the dispersionless regime. Finally we show how the formation of the sonic horizon modifies both local and nonlocal density correlations.