TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.15.6.251
TI  - Beyond Fermi's golden rule with the statistical Jacobi approximation
PY  - 2023/12/22
UR  - https://www.scipost.org/SciPostPhys.15.6.251
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 15
IS  - 6
SP  - 251
A1  - Long, David M.
AU  - Hahn, Dominik
AU  - Bukov, Marin
AU  - Chandran, Anushya
AB  - Many problems in quantum dynamics can be cast as the decay of a single quantum state into a continuum. The time-dependent overlap with the initial state, called the fidelity, characterizes this decay. We derive an analytic expression for the fidelity after a quench to an ergodic Hamiltonian. The expression is valid for both weak and strong quenches, and timescales before finiteness of the Hilbert space limits the fidelity. It reproduces initial quadratic decay and asymptotic exponential decay with a rate which, for strong quenches, differs from Fermi's golden rule. The analysis relies on the statistical Jacobi approximation (SJA), which was originally applied in nearly localized systems, and which we here adapt to well-thermalizing systems. Our results demonstrate that the SJA is predictive in disparate regimes of quantum dynamics.
ER  -

@Article{10.21468/SciPostPhys.15.6.251,
	title={{Beyond Fermi's golden rule with the statistical Jacobi approximation}},
	author={David M. Long and Dominik Hahn and Marin Bukov and Anushya Chandran},
	journal={SciPost Phys.},
	volume={15},
	pages={251},
	year={2023},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.15.6.251},
	url={https://scipost.org/10.21468/SciPostPhys.15.6.251},
}