论文标题
非平衡声子凝结和相变的完整量子理论
Full quantum theory of nonequilibrium phonon condensation and phase transition
论文作者
论文摘要
Frölich凝结是一种室温非平衡现象，预计在许多物理和生物系统中都会发生。尽管从一个半个世纪前的理论上预测，这种冷凝的性质仍然难以捉摸。在这封信中，我们从Wu-Austin Hamiltonian中得出了Fröhlich凝结的完整量子理论，并首次出现了分析证明，即在大的限制和没有脱离近似近似的情况下，由非质量和非线性引起的二阶相变引起的二阶相变。如果对外部来源进行经典处理，则无法见证这种批判行为。我们表明，相变伴随着冷凝水声子的统计分布的大波动，并且表征波动的曼德尔Q因子在过度外部能量输入的极限下变为负。与冷原子平衡BEC相反，Fröhlich冷凝物是泵的非平衡驱动器的结果，该泵在设定颗粒的数量方面起着作用，并且培养基在设置温度方面起着作用。因此，BEC可以通过在固定泵（平衡情况）下降低中等温度或在固定中等温度（非平衡情况）下增加泵来引起BEC。
Frölich condensation is a room-temperature nonequilibrium phenomenon which is expected to occur in many physical and biological systems. Though predicted theoretically a half century ago, the nature of such condensation remains elusive. In this Letter, we derive a full quantum theory of Fröhlich condensation from the Wu-Austin Hamiltonian and present for the first time an analytical proof that a second-order phase transition induced by nonequilibrium and nonlinearity emerges in the large-$D$ limit with and without decorrelation approximation. This critical behavior cannot be witnessed if external sources are treated classically. We show that the phase transition is accompanied by large fluctuations in the statistical distribution of condensate phonons and that the Mandel-Q factor which characterizes fluctuations becomes negative in the limit of excessive external energy input. In contrast with the cold atom equilibrium BEC, the Fröhlich condensate is a result of the nonequilibrium driving where the pump plays a role of setting the number of particles, and the medium plays a role of setting the temperature. Hence, BEC can either arise by reducing the medium temperature at fixed pump (equilibrium case), or by increasing the pump at fixed medium temperature (nonequilibrium case).
