Signs of a Quantum Dynamical Phase Transition in a steady state observable.

FERNANDEZ, LUCAS JONATAN; BENDERSKY, DENISE; PASTAWSKI, HORACIO MIGUEL

Bariloche

Congreso; Reunión Nacional de Física 2013 - AFA; 2013

Asociación de Física Argentina, Centro Atómico Bariloche

In recent years, there has been great interest in dynamical phase transitions both in classical and quantum systems [1]. These transitions manifest as a non-analyticity in the observables and bifurcations in the spectrum as a function of some control parameter.  In systems with few degrees of freedom, such as nanoscale devices and molecules [2], environmentally induced decoherence may produce such Quantum Dynamical Phase Transition (QDPT) [3] and it can be observed experimentally [4]. Nevertheless, it is still unclear whether the QDPT show up in steady state observables. In this work we present an analytical and numerical study of steady state transport on systems that are know to show the QDPT [5]. The observable considered is the Fermi energy dependent conductance (with and without charge conservation), while the control parameter is the system-environment interaction strength. In a Landauer-Büttiker picture of transport, decoherence is included using a linearization of the Keldysh evolution equation known as D´Amato and Pastawski model [6]. We find that  the conductance reflects quite well the QDPT that take place as bifurcations in eigenenergy spectrum of the effective Hamiltonian. However, conductance does not reflect the PT when it occurs only in the eigenfrequency spectrum of the Keldysh/DP/Lindblad evolution equations.