Transient orthogonality catastrophe in a time-dependent nonequilibrium environment

Area of Science:

• Quantum Many-Body Physics
• Non-equilibrium Quantum Dynamics
• Condensed Matter Theory

Background:

• Studying the response of quantum systems to perturbations is crucial for understanding their dynamics.
• The orthogonality catastrophe describes the loss of overlap between initial and perturbed quantum states.
• Nonequilibrium environments present unique challenges for analyzing quantum state evolution.

Purpose of the Study:

• To analyze the response of excited quantum many-body states to local perturbations in a transient, nonequilibrium setting.
• To introduce and analyze a novel two-time correlator generalizing the Loschmidt echo for nonequilibrium dynamics.
• To connect theoretical findings with experimentally measurable quantities via Ramsey interferometry.

Main Methods:

• Development of a novel two-time correlator to generalize the Loschmidt echo.
• Analytical and numerical calculations for a one-dimensional interacting Fermi system.
• Investigation of scattering processes (forward and backscattering) under nonequilibrium conditions.

Main Results:

• Forward scattering preserves a power-law structure in the Loschmidt echo, influenced by the transient bath.
• Backscattering introduces nonlinearity, causing exponential decay of the Loschmidt echo, mimicking thermal behavior.
• Demonstration of distinct long-time behaviors compared to equilibrium situations.

Conclusions:

• The study provides a theoretical framework for understanding quantum many-body dynamics in nonequilibrium environments.
• Scattering processes play a critical role in shaping the response of quantum states to perturbations.
• The findings offer insights into experimental probes like Ramsey interferometry for nonequilibrium phenomena.