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，通常取决于创造与耗散和消相干源头隔离的强大量子系统的能力。然而，在现实中，所有的量子系统都是“开放的”，即它们与环境不断地相互作用。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，人们越来越认识到，量子动力学和耗散之间的相互作用有时可以导致开放量子系统中新颖而稳健的非平衡量子行为。这个项目将研究这种行为。有趣的是，这些开放系统可以表现出与基于对称性、标度不变性和普适性的中心范式的传统描述不符的性质。因此，目前对这种开放系统的涌现相和动力学了解得很少，这是原子物理、凝聚态物理和信息科学之间的一个挑战。目前，这一领域的理论活动与缺乏对开放系统的严格实验研究形成鲜明对比。该项目将对一个干净的、可调谐的开放量子系统的相变和出射相进行一系列实验，该系统由原子与光子相互作用的超冷气体组成。这些研究将阐明开放量子系统的普遍方面，并有助于开发将在量子计量学和量子计算中应用的量子系统。参与这个项目的学生将获得研究方法和量子技术的经验，这将有助于他们参与高科技行业或学术生涯。这个实验项目旨在揭示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性质。在这个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的基础上，这个项目将探索存在可调耗散和以光散射形式进行连续量子测量的玻色-哈伯德模型的非平衡动力学和相。首先，这个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这种转变的影响来扩展他们对存在弱耗散的格子气体中量子到经典转变的研究。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、多体相互作用和耗散之间的相互作用而产生的驱动、耗散跃迁和浮现动力学相。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域转变。这些转变和由此产生的涌现相与迄今为止未知的临界行为的量子渗流和磁场受挫的各种模型有密切的对应。该项目支持的实验研究有望阐明这些模型，并为更广泛、更普遍地描述开放量子系统的现象学提供实验试金石。

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.