Thursday, August 1, 2013

1307.8219 (Swathi S. Hegde et al.)

Freezing a Quantum Magnet by Repeated Quantum Interference: An
Experimental Realization

Swathi S. Hegde, Hemant Katiyar, T. S. Mahesh, Arnab Das
We experimentally demonstrate the phenomenon of dynamical many-body freezing in a periodically driven quantum Ising magnet within an NMR simulation scheme. The phenomenon is essentially a result of repeated quantum interference between the amplitudes of the fundamental excitations of the many-body system. The degree of freezing exhibits surprising non-monotonic behavior with respect to the driving frequency. At the points of maximal freezing, the population dynamics of all the quasi-particle modes are frozen very strongly for all time, which renders the freezing occurring independent of initial state and visible for almost all system sizes. Magnetization measured for our finite spin system gives direct access to the time-evolution of the underlying fermionic excitations in momentum space.
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