Synthetic Quantum Matter under the Microscope

Ruichao Ma, Brendan Saxberg, Clai Owens +2 more

Board on Physics and Astronomy, Division on Engineering and Physical Sciences, National Academies of Sciences, Engineering, and Medicine

Tomoki Ozawa, Hannah M. Price

Chuan-Hsun Li, Yangqian Yan, Shih‐Wen Feng +4 more

The interplay between matter particles and gauge fields in physical spaces with nontrivial geometries can lead to novel topological quantum matter.However, detailed microscopic mechanisms are often obscure, and unconventional spaces are generally challenging to construct in solids.Highly controllable atomic systems can quantum simulate such physics, even those inaccessible in other platforms.Here, we realize a Bose-Einstein condensate (BEC) on a synthetic cylindrical surface subject to a net radial synthetic magnetic flux.We observe a symmetry-protected topological band structure emerging on this Hall cylinder but disappearing in the planar counterpart.BEC's transport observed as Bloch oscillations in the band structure is analogous to traveling on a Möbius strip in the momentum space, revealing topological band crossings protected by a nonsymmorphic symmetry.We demonstrate that breaking this symmetry induces a topological transition manifested as gap opening at band crossings, and further manipulate the band structure and BEC's transport by controlling the axial synthetic magnetic flux.Our work opens the door for using atomic quantum simulators to explore intriguing topological phenomena intrinsic in unconventional spaces.

Yiming Pan, Bin Zhang, Daniel K. Podolsky

We propose free-electron Rabi oscillation by creating an isolated two-level system in a synthetic energy space induced by laser. The π/2-pulse and π-pulse in synthetic Rabi dynamics can function as 'beam splitters' and 'mirrors' for free-electron interferometry, allowing us to detect local electromagnetic fields and plasmonic excitations. When the coupling field is quantized, we can observe quantum and vacuum Rabi oscillations of the two-level electron, which can be used to investigate the quantum statistics of optical excitations and electron-photon entanglement. Recent advances in laser control of electron microscopes and spectroscopes makes the experimental detection of synthetic Rabi oscillations possible. However, observing the quantum Rabi oscillation of electrons remains challenging. Our work has the potential to advance various fundamentals and applications of resonant light-matter interactions between low-energy electrons and quatum light.