Abstract
The phenomenon of many-body localized (MBL) systems has attracted significant interest in recent years, for its intriguing implications from a perspective of both condensed-matter and statistical physics: they are insulators even at non-zero temperature and fail to thermalize, violating expectations from quantum statistical mechanics. What is more, recent seminal experimental developments with ultra-cold atoms in optical lattices constituting analog quantum simulators have pushed many-body localized systems into the realm of physical systems that can be measured with high accuracy. In this work, we introduce experimentally accessible witnesses that directly probe distinct features of MBL, distinguishing it from its Anderson counterpart. We insist on building our toolbox from techniques available in the laboratory, including on-site addressing, super-lattices, and time-of-flight measurements, identifying witnesses based on fluctuations, density–density correlators, densities, and entanglement. We build upon the theory of out of equilibrium quantum systems, in conjunction with tensor network and exact simulations, showing the effectiveness of the tools for realistic models.
Highlights
Many-body localization provides a puzzling and exciting paradigm within quantum many-body physics and is for good reasons attracting significant attention in recent years
The setting we focus on is that of interacting fermions placed into a one-dimensional optical lattice, a setting that prominently allows to probe the physics under consideration [21,24]
We proposed an operational procedure for distinguishing many-body localized (MBL) phases building upon realistic measurements, which can be performed in the realm of optical lattices with present technology
Summary
Many-body localization provides a puzzling and exciting paradigm within quantum many-body physics and is for good reasons attracting significant attention in recent years. Maybe more strikingly from the perspective of statistical physics, these many-body localized models would fail to thermalize following out of equilibrium dynamics [3,4,5], challenging common expectations how systems “form their own heat bath” and tend to be locally well described by the familiar canonical Gibbs ensemble [6,7,8] Following these fundamental observations, a “gold rush” of theoretical work followed, identifying a plethora of phenomenology of such many-body localized models. Rather than seeing localization and taking the presence of interactions for granted, it seems highly desirable to make use of these novel exciting possibilities to directly see the above features, distinctly separating the observations from those expected from non-interacting Anderson insulators Such a mindset is that of “witnessing” a property, somewhat inspired by how properties such as entanglement are witnessed [25,26,27] in quantum information.
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