Jeremy Tanlimco: A matter-wave Fabry-Pérot cavity in the ultrastrong driving regime

Abstract:

The optical cavity is a foundational technology in quantum optics and laser science that structures the vacuum into a mode structure defined by the cavity geometry. If the length of a cavity is periodically driven, fixed point trajectories emerge and energy exponentially concentrates around the stable fixed points. Consequently, photons in such a cavity troboscopically propagate as if in a curved spacetime with white and black hole event horizons that correspond to thi table and unstable fixed points. However, this ultrastrong driving regime eludes direct experimental verification because it requires relativistic mirror acceleration. We report the results of an experiment that circumvents this difficulty by reflecting a matter-wave analog of photons between optical barriers. By exchanging the roles of matter and light in this way, we achieve an experimentally accessible effective speed of light, modulate the position of massless mirrors at equivalently relativistic speeds, and thereby observe the predicted bright and dark fixed point trajectories. Varying the modulation scheme introduces additional fixed points and can even exchange their stability character, highlighting the flexibility of this platform. Finally, we identify departures from the perfectly photonic theory and attribute them to nonlinearities in the matter wave dispersion. These results not only realize for the first time the elusive regime of ultrastrong cavity modulation but also demonstrate its utility in signal compression and pulse generation.