Cavity optomechanics in a fiber cavity: the role of stimulated Brillouin scattering

New Journal of Physics IOP Publishing (2022)

Authors:

Abel Beregi, Antonio Pontin, Peter F Barker

Abstract:

Abstract We study the role of stimulated Brillouin scattering in a fiber cavity by numerical simulations and a simple theoretical model and find good agreement between experiment, simulation and theory. We also investigate an optomechanical system based on a fiber cavity in the presence on the nonlinear Brillouin scattering. Using simulation and theory, we show that this hybrid optomechanical system increases optomechanical damping for low mechanical resonance frequencies in the unresolved sideband regime. Furthermore, optimal damping occurs for blue detuning in stark contrast to standard optomechanics. We investigate whether this hybrid optomechanical system is capable cooling a mechanical oscillator to the quantum ground state.

Observation of the Berezinskii-Kosterlitz-Thouless transition in a two-dimensional Bose gas via matter-wave interferometry

Physical Review Letters American Physical Society 128:25 (2022) 250402

Authors:

S Sunami, Vp Singh, D Garrick, A Beregi, Aj Barker, K Luksch, E Bentine, L Mathey, Cj Foot

Abstract:

We probe local phase fluctuations of trapped two-dimensional (2D) Bose gases using matter-wave interferometry. This enables us to measure the phase correlation function, which changes from an algebraic to an exponential decay when the system crosses the Berezinskii-Kosterlitz-Thouless (BKT) transition. We determine the temperature dependence of the BKT exponent η and find the critical value ηc = 0.17(3) for our trapped system. Furthermore, we measure the local vortex density as a function of the local phase-space density, which shows a scale-invariant behaviour across the transition. Our experimental investigation is supported by Monte Carlo simulations and provides a comprehensive understanding of the BKT transition in a trapped system.

Quench dynamics of 2D Bose gases across the BKT critical point

(2022)

Authors:

SHINICHI SUNAMI, David Garrick, ABEL BEREGI, ELLIOT BENTINE, CHRISTOPHER FOOT

Abstract:

APS March Meeting 2022 focus session talk

Faraday-imaging-induced squeezing of a double-well Bose-Einstein condensate

PHYSICAL REVIEW A 104:5 (2021) ARTN 053324

Authors:

Ebubechukwu O Ilo-Okeke, Shinichi Sunami, Christopher J Foot, Tim Byrnes

Demonstration of an atomic frequency comb quantum memory using velocity-selective pumping in warm alkali vapour

Conference on Lasers and Electro-Optics, OSA Technical Digest (Optical Society of America, 2020) OSA Publishing (2021)

Authors:

Thomas Hird, Dougal Main, S Gao, E Oguz, Dylan Saunders, Ian Walmsley, Patrick Ledingham

Abstract:

We present the first demonstration of velocity-selective pumping in an atomic vapour to preserve light-matter coherence. Control is illustrated by a subsequent demonstration of an atomic frequency comb quantum memory realised in the vapour.