Engineered entropic forces allow ultrastrong dynamical backaction

Abstract

When confined within an optical cavity, light can exert strong radiation pressure forces. Combined with dynamical backaction, this enables important processes such as laser cooling, and applications ranging from precision sensors to quantum memories and interfaces. However, the magnitude of radiation pressure forces is constrained by the energy mismatch between photons and phonons. Here, we overcome this barrier using entropic forces arising from the absorption of light. We show that entropic forces can exceed the radiation pressure force by eight orders of magnitude, and demonstrate this using a superfluid helium third-sound resonator. We develop a framework to engineer the dynamical backaction from entropic forces, applying it to achieve phonon lasing with a threshold three orders of magnitude lower than previous work. Our results present a pathway to exploit entropic forces in quantum devices, and to study nonlinear fluid phenomena such as turbulence and solitons.

Main text is 10 pages, 5 figures. Supplements is 21 pages, 11 figures

References in corpus (6)

• Ultrasensitive optical magnetometry at the microscale
• Opto-Mechanics of deformable Fabry-Perot Cavities
• Quantum limit of photothermal cooling
• Thin film superfluid optomechanics
• Cryogenic and hermetically sealed packaging of photonic chips for optomechanics
• Proposal for a quantum traveling Brillouin resonator

Cited by in corpus (2)

• A cryogenic chamber setup for superfluid helium experiments with optical fiber and electrical access
• Entropic magnetic interlayer coupling