Friday, March 29, 2013

1303.7169 (B. Dóra et al.)

Loschmidt echo and the many-body orthogonality catastrophe in a
qubit-coupled Luttinger liquid

B. Dóra, F. Pollmann, G. Zaránd
We investigate the many-body generalization of the orthogonality catastrophe by studying the Loschmidt echo of Luttinger liquids (LLs) after a global interaction quench or ramp. It decays exponentially with system size and exhibits universal behaviour: the steady state exponent after quenching back and forth n-times between 2 LLs (bang-bang protocol) is 2n-times bigger than that of the adiabatic overlap, and depends only on the initial and final LL parameters. These are corroborated numerically by matrix-product state based methods of the XXZ Heisenberg model. An experimental setup consisting of a hybrid system containing cold atoms and a flux qubit is proposed to measure the Loschmidt echo using rf spectroscopy or Ramsey interferometry.
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