Reaction-diffusion dynamics of the weakly dissipative Fermi gas

• Published in: New journal of physics Vol. 27; no. 8; pp. 84602 - 84628
• Main Authors: Lehr, Hannah, Lesanovsky, Igor, Perfetto, Gabriele
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.08.2025
• Subjects: Asymptotic properties; Atomic physics; Coagulation; Decay; Density; Dissipation; Fermi gas; Fermi gases; Hamiltonian functions; nonequilibrium critical dynamics; nonequilibrium many-body dissipative systems; Percolation; Phase transitions; quantum reaction-diffusion systems; Time dependence; time-dependent generalized Gibbs ensemble
• DOI: 10.1088/1367-2630/adef70
• ISSN: 1367-2630

We study the one-dimensional Fermi gas subject to dissipative reactions. The dynamics is governed by the quantum master equation, where the Hamiltonian describes coherent motion of the particles, while dissipation accounts for irreversible reactions. For lattice one-dimensional fermionic systems, emergent critical behavior has been found in the dynamics in the reaction-limited regime of weak dissipation. Here, we address the question whether such features are present also in a gas in continuum space. We do this in the weakly dissipative regime by applying the time-dependent generalized Gibbs ensemble method. We show that for two body 2 A → ∅ and three 3 A → ∅ body annihilation, as well as for coagulation A + A → A , the density features an asymptotic algebraic decay in time akin to the lattice problem. In all the cases, we find that upon increasing the temperature of the initial state the density decay accelerates, but the asymptotic algebraic decay exponents are not affected. We eventually consider the competition between branching A → A + A and the decay processes A → ∅ and 2 A → ∅ . We find a second-order absorbing-state phase transition in the mean-field directed percolation universality class. This analysis shows that emergent behavior observed in lattice quantum reaction-diffusion systems is present also in continuum space, where it may be probed using ultra-cold atomic physics.