Quantum quench in two dimensions using the variational Baeriswyl wave function

Date
2016
Authors
Dóra, B.
Haque, M.
Pollmann, F.
Hetényi, B.
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Source Title
Physical Review B
Print ISSN
2469-9950
Electronic ISSN
2469-9969
Publisher
American Physical Society
Volume
93
Issue
11
Pages
115124-1 - 115124-6
Language
English
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Abstract

By combining the Baeriswyl wave function with equilibrium and time-dependent variational principles, we develop a nonequilibrium formalism to study quantum quenches for two-dimensional spinless fermions with nearest-neighbor hopping and repulsion. The variational ground-state energy, the charge-density wave (CDW) order parameter, and the short-time dynamics agree convincingly with the results of numerically exact simulations. We find that, depending on the initial and final interaction strength, the quenched system either exhibits oscillatory behavior or relaxes to a time-independent steady state. The time-averaged expectation value of the CDW order parameter rises sharply when crossing from the steady-state regime to the oscillating regime, indicating that the system, being nonintegrable, shows signs of thermalization with an effective temperature above or below the equilibrium critical temperature, respectively.

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