Work

Multi-mode cooling of a Bose-Einstein condensate with linear quantum feedback

Year: 2025

Type: article

Abstract: We theoretically investigate measurement-based feedback control over the motional degrees of freedom of an oblate quasi-2D atomic Bose-Einstein condensate (BEC) subject to continuous density monitoring. We develop a linear-quadratic-Gaussian (LQG) model that describes the multi-mode dynamics of the condensate's collective excitations under continuous measurement and control. Crucially, the multi-mode cold-damping feedback control we consider uses a realistic state-estimation scheme that does not rely upon a particular model of the atomic dynamics. We present analytical results showing that collective excitations can be cooled to below single-phonon average occupation (ground-state cooling) across a broad parameter regime, and identify the conditions under which the lowest steady-state phonon occupation is asymptotically achieved. Further, we develop multi-objective optimization methods that explore the trade-off between cooling speed and the final energy of the cloud, and provide numerical simulations demonstrating the ground-state cooling of the lowest ten motional modes above the condensate ground state. Our investigation provides concrete guidance on the feedback control design and parameters needed to experimentally realize a feedback-cooled BEC.

Source: Quantum Science and Technology

DOI: 10.1088/2058-9565/ae0a7c

Authors: Zain Mehdi, Matthew L. Goh, Matthew J. Blacker, Joseph J Hope, Stuart Szigeti

Institutions: Australian National University, University of Oxford, University of Cambridge

Language: English

Topic: Cold Atom Physics and Bose-Einstein Condensates

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,895

Funders: Rhodes Scholarships, Gates Cambridge Trust, Engineering and Physical Sciences Research Council, Australian Research Council