Abstract
Optical cavity QED provides a platform with which to explore quantum many-body physics in driven-dissipative systems. Single-mode cavities provide strong, infinite-range photon-mediated interactions among intracavity atoms. However, these global all-to-all couplings are limiting from the perspective of exploring quantum many-body physics beyond the mean-field approximation. The present work demonstrates that local couplings can be created using multimode cavity QED. This is established through measurements of the threshold of a superradiant, self-organization phase transition versus atomic position. Specifically, we experimentally show that the interference of near-degenerate cavity modes leads to both a strong and tunable-range interaction between Bose-Einstein condensates (BECs) trapped within the cavity. We exploit the symmetry of a confocal cavity to measure the interaction between real BECs and their virtual images without unwanted contributions arising from the merger of real BECs. Atom-atom coupling may be tuned from short range to long range. This capability paves the way toward future explorations of exotic, strongly correlated systems such as quantum liquid crystals and driven-dissipative spin glasses.
1 More- Received 28 August 2017
- Revised 20 October 2017
DOI:https://doi.org/10.1103/PhysRevX.8.011002
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Viewpoint
A Multimode Dial for Interatomic Interactions
Published 8 January 2018
A tunable multimode optical cavity modifies interactions between atomic condensates trapped in its interior from long range to short range, paving the way towards exploring novel collective quantum phenomena.
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Popular Summary
By placing atoms in a cavity, light can be used to induce interactions between those atoms. Light scattered by one atom reflects off the cavity wall and comes back to interact with a second atom. These interactions can be used to engineer novel phases of matter. However, previous experiments using this idea have had a limitation: All the atoms interact with each other equally. This equal representation severely limits what phases of matter are possible. Our experimental work, supported by theory and simulation, provides the first demonstration of how to control which atoms interact with each other via light, potentially enabling studies of a wide range of exotic materials.
We employ a multimode cavity to mediate local interactions, where atoms only interact with those that are nearby. Moreover, our setup allows us to choose the range of this interaction. Specifically, we trap a Bose-Einstein condensate (BEC) of rubidium atoms in an adjustable-length cavity. By manipulating the position of the BEC in the cavity, we are able to measure the interaction range for a variety of tunable parameters such as cavity length.
These results show that we can use light-mediated interactions between ultracold atoms to understand exotic states of matter like high-temperature superconductors. We can also adapt our system to study spin glasses, a type of disordered magnet. Models developed to understand spin glasses have found applications in fields as diverse as protein folding, neural networks, and combinatorial optimization problems.