Exploring Excited-State 1D Dipolar Quantum Matter with Dysprosium Gases

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General audience abstract:This research program is built on the machine the PI and his students assembled under prior NSF support---this apparatus has inspired research groups worldwide to develop their own similar experiments. With this apparatus, the PI is exploring new types of excited quantum gases constrained by light to move in only one dimension. These gases---of dysprosium---are the most magnetic of any element. That allows the team to exploit the large, bar-magnet-like interaction between the dysprosium atoms to reveal exotic quantum physics. Constraining the gas to move in one dimension results in bizarre phenomena. For example, atoms are normally either bosons (with integer spin) or fermions (with half-integer spin), but in one dimension, bosons can act like fermions and vice versa. Moreover, inherently large quantum effects prevent phases from emerging that possess order at long length scales, like perfect crystals do. Exciting such gases to higher energy states should yield even stranger effects, but these are largely unexplored. The PI and his team aim to create such gases because they suspect these quantum systems will not thermalize---i.e., unlike how coffee and milk mix to form a brown liquid, the excited gas will not come into any “mixed-like” thermal equilibrium. Such systems may teach us how to protect stored quantum information in quantum gases or materials by inhibiting all information-destroying thermalization processes. More generally, this research project explores uncharted regimes of strongly correlated matter by pushing the experimental state-of-the-art in atomic physics, quantum optics, and condensed matter physics. As such, this research program provides an exceptional training ground for graduate and undergraduate students in the formative scientific environment provided by Stanford University and the PI’s state-of-the-art laser lab. The research concerns physics and technical skills that find application in a variety of significant areas of technology, most notably lasers and photonics for telecommunications and advanced novel solid-state materials for electronic devices. Technical audience abstract:A diversity of exotic quantum many-body phases and nonequilibrium dynamics may arise from the unusual properties of dysprosium confined to one dimension. The PI and his students are extending the frontier of quantum simulation by using their unique experimental system to address novel aspects of the physics of out-of-equilibrium 1D dipolar gases. These systems allow the PI’s team to touch on poorly understood aspects of thermalization in quantum physics. For example, much remains to be learned about both the breakdown of quantum integrability and the stabilization of highly excited quantum many-body systems. The present program funds two new activities based on 1D dipolar gases; the PI and students are: 1) studying how dipolar interactions modify Luttinger-liquid-like ground and excited states, possibly stabilizing the latter against collapse to yield novel `quantum many-body scar'-like states; 2) extending their work on bosonic dipolar quantum Newton's cradles to fermions to ask how quantum thermalization depends on quantum exchange statistics; and 3) exploring the possible breakdown of many-body localization in the presence of long-range dipolar interactions in 1D.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.