Quantum dynamical phase transition in a system with many-body interactions

ERNESTO P. DANIELI; GONZALO A. ÁLVAREZ; PATRICIA R. LEVSTEIN; HORACIO M. PASTAWSKI

SOLID STATE COMMUNICATIONS

Elsevier

Lugar: Las Mavinas son Argentinas; Año: 2006 vol. 141 p. 422 - 426

0038-1098

We introduce a microscopic Hamiltonian model of a two level system with many-body interactions with an environment whose excitation dynamics is fully solved within the Keldysh formalism. If a particle starts in one of the states of the isolated system, the return probability oscillates with the Rabi frequency $omega_{0}$. For weak interactions with the environment $1/ au_{mathrm{SE}}<2omega_{0},$ we find a slower oscillation whose amplitude decays with a decoherence rate $1/ au_{phi}=1/(2 au_{mathrm{SE}% })$. However, beyond a finite critical interaction with the environment, $1/ au_{mathrm{SE}}>2omega_{0}$, the decoherence rate becomes $1/ au_{phi}propto(omega_{0}^{2}) au_{mathrm{SE}}$. The oscillation period diverges showing a emph{quantum dynamical phase transition}to a Quantum Zeno phase.