Two-body loss dynamics as a probe of dynamical bulk viscosity in ultracold atomic gases
Abstract
We show that the equilibrium connected correlation of the two-body loss rate provides access to the dynamical bulk viscosity in weakly dissipative quantum gases. Starting from the Lindblad equation for weak inelastic losses, we derive the loss-current operator and, using a counting-field formulation of the loss statistics, the relation between the statistics of detected losses and the equilibrium loss-rate correlator. The connected correlation of the two-body loss rate is found to be proportional to the equilibrium contact correlation and hence to the bulk-viscosity spectrum. We show that the measured loss-counting covariance contains, besides the Poissonian self-correlation, a quantum-jump backaction term of the same order as the target correlator, which is fixed by the transient of the mean loss rate after the loss is switched on. The bulk-viscosity spectrum can therefore be reconstructed from the combination of the loss-counting covariance and the mean loss dynamics. Our result identifies weak two-body loss dynamics as a probe of dynamical bulk viscosity, whose measurement has remained elusive in experiments.
Versions
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BibTeX
@misc{zhang2026twobody,
title = {{Two-body loss dynamics as a probe of dynamical bulk viscosity in ultracold atomic gases}},
author = {Tingyu Zhang and Hiroyuki Tajima and Takeo Kato},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.01835},
eprint = {2606.01835},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.01835},
}
RIS
TY - UNPB
TI - Two-body loss dynamics as a probe of dynamical bulk viscosity in ultracold atomic gases
AU - Tingyu Zhang
AU - Hiroyuki Tajima
AU - Takeo Kato
PY - 2026
DA - 2026/09/11
PB - arXiv
DO - 10.48550/arxiv.2606.01835
UR - https://arxiv.org/abs/2606.01835
AB - We show that the equilibrium connected correlation of the two-body loss rate provides access to the dynamical bulk viscosity in weakly dissipative quantum gases. Starting from the Lindblad equation for weak inelastic losses, we derive the loss-current operator and, using a counting-field formulation of the loss statistics, the relation between the statistics of detected losses and the equilibrium loss-rate correlator. The connected correlation of the two-body loss rate is found to be proportional to the equilibrium contact correlation and hence to the bulk-viscosity spectrum. We show that the measured loss-counting covariance contains, besides the Poissonian self-correlation, a quantum-jump backaction term of the same order as the target correlator, which is fixed by the transient of the mean loss rate after the loss is switched on. The bulk-viscosity spectrum can therefore be reconstructed from the combination of the loss-counting covariance and the mean loss dynamics. Our result identifies weak two-body loss dynamics as a probe of dynamical bulk viscosity, whose measurement has remained elusive in experiments.
ER -