From Non-Hermitian Linear Response to Dynamical Correlations and
Fluctuation-Dissipation Relations in Quantum Many-Body Systems
- URL: http://arxiv.org/abs/2104.03983v2
- Date: Wed, 28 Sep 2022 18:00:03 GMT
- Title: From Non-Hermitian Linear Response to Dynamical Correlations and
Fluctuation-Dissipation Relations in Quantum Many-Body Systems
- Authors: Kevin T. Geier and Philipp Hauke
- Abstract summary: We propose a technique for measuring unequal-time anti-commutators using the linear response of a system to a non-Hermitian perturbation.
We relate the scheme to the quantum Zeno effect and weak measurements, and illustrate possible implementations.
- Score: 0.0
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: Quantum many-body systems are characterized by their correlations. While
equal-time correlators and unequal-time commutators between operators are
standard observables, the direct access to unequal-time anti-commutators poses
a formidable experimental challenge. Here, we propose a general technique for
measuring unequal-time anti-commutators using the linear response of a system
to a non-Hermitian perturbation. We illustrate the protocol at the example of a
Bose-Hubbard model, where the approach to thermal equilibrium in a closed
quantum system can be tracked by measuring both sides of the
fluctuation-dissipation relation. We relate the scheme to the quantum Zeno
effect and weak measurements, and illustrate possible implementations at the
example of a cold-atom system. Our proposal provides a way of characterizing
dynamical correlations in quantum many-body systems with potential applications
in understanding strongly correlated matter as well as for novel quantum
technologies.
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