Long-time saturation of the Loschmidt echo in quantum chaotic billiards

Abstract

The Loschmidt echo (LE) (or fidelity) quantifies the sensitivity of the time evolution of a quantum system with respect to a perturbation of the Hamiltonian. In a typical chaotic system the LE has been previously argued to exhibit a long-time saturation at a value inversely proportional to the effective size of the Hilbert space of the system. However, until now no quantitative results have been known and, in particular, no explicit expression for the proportionality constant has been proposed. In this paper we perform a quantitative analysis of the phenomenon of the LE saturation and provide the analytical expression for its long-time saturation value for a semiclassical particle in a two-dimensional chaotic billiard. We further perform extensive (fully quantum mechanical) numerical calculations of the LE saturation value and find the numerical results to support the semiclassical theory.

5 pages, 2 figures

References in corpus (2)

• Dynamics of Loschmidt echoes and fidelity decay
• Classical basis for quantum spectral fluctuations in hyperbolic systems

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• Semiclassical approach to fidelity amplitude
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• Equilibration of Non-interacting Photons and Quantum Signatures of Chaos