Ivanov Denis A, Ivanova Tatiana Yu, Caballero-Benitez Santiago F, Mekhov Igor B
St. Petersburg State University, Ulianovskaya 3, Petrodvorets, St. Petersburg, 198504, Russia.
Instituto de Física, Universidad Nacional Autónoma de México, Ciudad de Mexico, 04510, Mexico.
Sci Rep. 2020 Jun 29;10(1):10550. doi: 10.1038/s41598-020-67280-3.
Feedback is a general idea of modifying system behavior depending on the measurement outcomes. It spreads from natural sciences, engineering, and artificial intelligence to contemporary classical and rock music. Recently, feedback has been suggested as a tool to induce phase transitions beyond the dissipative ones and tune their universality class. Here, we propose and theoretically investigate a system possessing such a feedback-induced phase transition. The system contains a Bose-Einstein condensate placed in an optical potential with the depth that is feedback-controlled according to the intensity of the Bragg-reflected probe light. We show that there is a critical value of the feedback gain where the uniform gas distribution loses its stability and the ordered periodic density distribution emerges. Due to the external feedback, the presence of a cavity is not necessary for this type of atomic self-organization. We analyze the dynamics after a sudden change of the feedback control parameter. The feedback time constant is shown to determine the relaxation above the critical point. We show as well that the control algorithm with the derivative of the measured signal dramatically decreases the transient time.
反馈是一种根据测量结果修改系统行为的总体概念。它从自然科学、工程学和人工智能领域延伸到当代古典音乐和摇滚音乐。最近，反馈被提议作为一种工具，用于诱导超越耗散相变的相变，并调整其普适类。在此，我们提出并从理论上研究一个具有这种反馈诱导相变的系统。该系统包含一个置于光学势中的玻色 - 爱因斯坦凝聚体，其光学势的深度根据布拉格反射探测光的强度进行反馈控制。我们表明，存在一个反馈增益的临界值，在该值处均匀气体分布失去稳定性，有序的周期性密度分布出现。由于外部反馈，对于这种类型的原子自组织，腔的存在并非必要。我们分析了反馈控制参数突然变化后的动力学。结果表明，反馈时间常数决定了临界点以上的弛豫过程。我们还表明，带有测量信号导数的控制算法显著减少了瞬态时间。
