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arXiv 2503.03396quant-phcond-mat.quant-gas
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大原子数下Dicke型模型中的真量子效应

Genuine Quantum effects in Dicke-type Models at large atom numbers

Kai Müller, Walter T. Strunz

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AI总结：

针对大原子数开放Dicke模型，本文采用新型开放系统动力学方法计算介观尺度N≈1000的精确量子动力学，发现非平衡Dicke模型存在可在介观N下持续的真量子效应，根源是两个极限不对易。

摘要：

我们研究了原子数N较大但有限的平衡与非平衡开放Dicke模型中真量子效应及超越平均场物理的出现情况。这类驱动耗散量子多体系统近期已在光学腔内超冷气体相关实验中实现，已知其在热力学极限N→∞下符合平均场预测。本文采用一种新型开放系统动力学方法，可获得原子数高达介观尺度N≈1000时的数值精确量子动力学结果，借此证明了在大但有限N下仍存在的量子效应。我们发现平衡Dicke模型中的超越平均场效应随N增大快速消失，而在非平衡Dicke模型中可识别出允许真量子效应即使在介观N下仍持续存在的参数区间。这些效应表现为稳态的强压缩以及平均场描述无法观测到的稳态相图修正，其成因是稳态极限t→∞与热力学极限N→∞不对易。

英文摘要：

We investigate the occurrence of genuine quantum effects and beyond mean-field physics in the balanced and unbalanced open Dicke model with a large, yet finite number of atoms $N$. Such driven and dissipative quantum many-body systems have recently been realized in experiments involving ultracold gases inside optical cavities and are known to obey mean-field predictions in the thermodynamic limit $N\to\infty$. Here we show quantum effects that survive for large but finite $N$, by employing a novel open-system dynamics method that allows us to obtain numerically exact quantum dynamical results for atom numbers up to a mesoscopic $N\approx 1000$. While we find that beyond-mean-field effects vanish quickly with increasing $N$ in the balanced Dicke model, we are able to identify parameter regimes in the unbalanced Dicke model that allow genuine quantum effects to persist even for mesoscopic $N$. They manifest themselves in a strong squeezing of the steady state and a modification of the steady-state phase diagram that cannot be seen in a mean-field description. This is due to the fact that the steady-state limit $t\rightarrow \infty$ and thermodynamic limit $N\rightarrow \infty$ do not commute.

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。

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