Proposal for a quantum traveling Brillouin resonator

TL;DR

This paper proposes a novel on-chip liquid-based Brillouin system using superfluid helium-filled silicon waveguides, aiming to achieve ultra-high coherent phonon-photon coupling for quantum information and sensing applications.

Contribution

It introduces a new liquid-based silicon waveguide design supporting strong traveling wave interactions with low dissipation, enabling quantum regime exploration.

Findings

Predicted single photon optomechanical coupling rate exceeds 240 kHz

Supports ultra-high coherent phonon-photon interactions

Potential for quantum sensing and fluid dynamics studies

Abstract

Brillouin systems operating in the quantum regime have recently been identified as a valuable tool for quantum information technologies and fundamental science. However, reaching the quantum regime is extraordinarily challenging, owing to the stringent requirements of combining low thermal occupation with low optical and mechanical dissipation, and large coherent phonon-photon interactions. Here, we propose an on-chip liquid based Brillouin system that is predicted to exhibit ultra-high coherent phonon-photon coupling with exceptionally low acoustic dissipation. The system is comprised of a silicon-based "slot" waveguide filled with superfluid helium. This type of waveguide supports optical and acoustical traveling waves, strongly confining both fields into a subwavelength-scale mode volume. It serves as the foundation of an on-chip traveling wave Brillouin resonator with a single photon optomechanical coupling rate exceeding $240$kHz. Such devices may enable applications ranging from ultra-sensitive superfluid-based gyroscopes, to non-reciprocal optical circuits. Furthermore, this platform opens up new possibilities to explore quantum fluid dynamics in a strongly interacting condensate.