Novel Phases and Dynamics of Optical Lattice gases under continuous quantum measurement

利用量子科学实现新材料或量子计算的努力通常取决于创建与耗散和退相干源隔离的鲁棒量子系统的能力。然而，在现实中，所有的量子系统都是“开放的”，也就是说，它们不断地与环境相互作用。在大多数情况下，这种相互作用会导致量子效应的破坏。然而，越来越多的人认识到量子动力学和耗散之间的相互作用有时会导致开放量子系统中新颖而稳健的非平衡量子行为。本项目将检验这种行为。有趣的是，这些开放系统可以表现出与基于对称、尺度不变性和普适性等中心范式的传统描述不同的特性。因此，这种开放系统的涌现相和动力学目前知之甚少，并且在原子物理学，凝聚态物理学和信息科学的界面上提出了挑战。目前，这一领域的理论活动与开放系统严格实验研究的缺乏形成鲜明对比。该项目将对一个由原子与光子相互作用的超冷气体组成的清洁、可调开放量子系统的相变和涌现阶段进行一系列实验。这些研究将揭示开放量子系统的普遍方面，并有助于量子系统的发展，将在量子计量和量子计算中得到应用。参与该项目的学生将获得研究方法和量子技术方面的经验，这将有助于他们参与高科技行业或学术事业。这个实验项目旨在阐明在超冷晶格气体的特定背景下开放的、相互作用的量子系统的本质。基于该小组最近使用双光子成像技术控制光学晶格气体动力学的工作，该项目将探索在可调耗散和光散射形式的连续量子测量存在下的玻色-哈伯德模型的非平衡动力学和相位。首先，该团队将通过研究多体相互作用、量子干涉和粒子不可分辨对晶格气体中弱耗散存在的量子到经典跃迁的影响，扩展他们对晶格气体中量子到经典跃迁的研究。接下来，他们的目标是实现和探索晶格气体中由于量子相干性、多体相互作用和耗散之间的相互作用而产生的驱动、耗散跃迁和涌现的动力学相。特别是，他们提出了实现金属到绝缘体的转变和由可调耗散驱动的多体局部转变。这些跃迁和由此产生的涌现相与迄今未知的临界行为的各种量子渗透和磁挫折模型密切相关。该项目支持的实验研究有望阐明这些模型，并作为实验试金石，为更广泛、更普遍地描述开放量子系统的现象学。

Efforts to harness quantum science for the realization of novel materials or quantum computation generally hinge on the ability to create robust quantum systems that are isolated from sources of dissipation and decoherence. In reality, however, all quantum systems are 'open', i.e. they interact constantly with their environment. In most cases, this interaction leads to the destruction of quantum effects. However, there is growing appreciation of how the interplay between quantum dynamics and dissipation can sometimes result in novel and robust nonequilibrium quantum behavior in open quantum systems. This project will examine such behavior. Interestingly, these open systems can exhibit properties that defy conventional descriptions based on central paradigms of symmetry, scale invariance and universality. As a result, the emergent phases and dynamics of such open systems are currently poorly understood and present a challenge that lies at the interface of atomic physics, condensed matter physics and information science. At present, the theoretical activity in this arena stands in stark contrast to the dearth of rigorous experimental studies on open systems. This project will conduct a series of experiments on the phase transitions and emergent phases of a clean, tunable open quantum system consisting of an ultracold gas of atoms interacting with photons. These studies will shed light on universal aspects of open quantum systems and aid in the development of quantum systems that will have applications in quantum metrology and quantum computation. Students that participate in this project will gain experience with research methods and quantum technologies that will help them participate in high tech industry or academic careers.This experimental program aims to shed light on the nature of open, interacting quantum systems in the specific context of an ultracold lattice gas. Building upon this group's recent work controlling the dynamics of optical lattice gases using two-photon imaging techniques, this project will explore the nonequilibrium dynamics and phases of the Bose-Hubbard model in the presence of tunable dissipation and continuous quantum measurements in the form of light scattering. First, this team will extend their studies on the quantum-to-classical transition in a lattice gas in the presence of weak dissipation by studying the influence of many-body interactions, quantum interference and particle indistinguishability on this transition. Next, they aim to realize and explore driven, dissipative transitions and emergent dynamical phases in the lattice gas due to the interplay between quantum coherence, many-body interactions and dissipation. In particular, they propose to realize a metal-to-insulator transition and a many-body localized transition driven by tunable dissipation. These transitions and the resulting emergent phases have close correspondences to various models of quantum percolation and magnetic frustration with hitherto unknown critical behavior. The experimental studies supported by this project promise to shed light on these models and serve as experimental touchstones for broader, more universal descriptions of the phenomenology of open quantum systems.