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arXiv · 2509.03567

Two-Body Contact Dynamics in a Bose Gas near a Fano-Feshbach Resonance

Alexandre Journeaux·Julie Veschambre·Maxime Lecomte·Ethan Uzan·Jean Dalibard·Félix Werner·Dmitry S. Petrov·Raphael Lopes
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Abstract

We investigate the real-time buildup of short-range correlations in a nondegenerate ultracold Bose gas near a narrow Fano-Feshbach resonance. Using rapid optical control, we quench the closed-channel molecular energy to resonance on submicrosecond timescales and track the evolution of the two-body contact through photodissociation losses. Repeated pulse sequences enhance sensitivity to early-time two-body losses and reveal long-lived coherence between atom pairs and molecular states. The observed dynamics are accurately reproduced by our dynamical two-channel zero-range theory, which explicitly accounts for the resonance's narrow width and finite closed-channel decay, establishing a predictive framework for correlation dynamics in quantum gases near Fano-Feshbach resonances.

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Alexandre Journeaux, Julie Veschambre, Maxime Lecomte, Ethan Uzan, Jean Dalibard, Félix Werner, Dmitry S. Petrov, Raphael Lopes. 2025-09-03. Two-Body Contact Dynamics in a Bose Gas near a Fano-Feshbach Resonance. https://doi.org/10.1103/prf8-3q27

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