Towards the cold atom analog false vacuum
Towards the cold atom analog false vacuum
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DOI：
10.1007/jhep07(2018)014
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发表时间：
2018-07-02
影响因子：
5.4
通讯作者：
Weinfurtner, Silke
中科院分区：
文献类型：
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作者：
Braden, Jonathan;Johnson, Matthew C.;Weinfurtner, Silke
模拟凝聚态物质系统为在桌面实验中模拟早期宇宙模型提供了令人兴奋的机会。我们考虑最近提出的模拟凝聚态物质实验来模拟假真空的相对论量子衰变。在所提出的实验中，两种超冷冷凝物通过时变射频场耦合。该系统中两种凝聚体的相对相位近似地由相对论标量场来描述，该标量场具有具有一系列假和真真空局部最小值的势。如果系统建立在假真空中，它就会通过量子力学隧道效应衰减到真真空。如果这样的实验得以实现，就有可能回答有关量子场论和早期宇宙宇宙学中非微扰现象的许多悬而未决的问题。在本文中，我们说明了一个可能的障碍：为凝聚态的长波长模式创建假真空而调用的时变耦合，通过参数共振导致系统内较短波长模式的不稳定。我们专注于理想化的设置，其中两种冷凝物具有相同的属性和相同的背景密度。通过耦合 Gross-Pitaevskii 方程 (GPE) 描述系统，我们使用 Floquet 理论机制进行线性稳定性分析，计算与各种实验参数的第一不稳定带相关的波数。然而，我们证明，通过调整时变耦合的频率，有可能将第一个不稳定带推到 GPE 的有效性之外，其中耗散效应预计会抑制任何不稳定性。这提供了可行的实验参数范围来执行假真空衰变的模拟实验。
Analog condensed matter systems present an exciting opportunity to simulate early Universe models in table-top experiments. We consider a recent proposal for an analog condensed matter experiment to simulate the relativistic quantum decay of the false vacuum. In the proposed experiment, two ultra-cold condensates are coupled via a time-varying radio-frequency field. The relative phase of the two condensates in this system is approximately described by a relativistic scalar field with a potential possessing a series of false and true vacuum local minima. If the system is set up in a false vacuum, it would then decay to a true vacuum via quantum mechanical tunnelling. Should such an experiment be realized, it would be possible to answer a number of open questions regarding non-perturbative phenomena in quantum field theory and early Universe cosmology. In this paper, we illustrate a possible obstruction: the time-varying coupling that is invoked to create a false vacuum for the long-wavelength modes of the condensate leads to a destabilization of shorter wavelength modes within the system via parametric resonance. We focus on an idealized setup in which the two condensates have identical properties and identical background densities. Describing the system by the coupled Gross-Pitaevskii equations (GPE), we use the machinery of Floquet theory to perform a linear stability analysis, calculating the wavenumber associated with the first instability band for a variety of experimental parameters. However, we demonstrate that, by tuning the frequency of the time-varying coupling, it may be possible to push the first instability band outside the validity of the GPE, where dissipative effects are expected to damp any instabilities. This provides a viable range of experimental parameters to perform analog experiments of false vacuum decay.