Utso Bhattacharya

Mixed state dynamical quantum phase transitions

Preparing an integrable system in a mixed state described by a thermal density matrix , we subject it to a sudden quench and explore the subsequent unitary dynamics. Defining a version of the generalised Loschmidt overlap amplitude (GLOA) through the purifications of the time evolved density matrix, we claim that non-analyiticies in the corresponding “dynamical free energy density” persist and is referred to as mixed state dynamical quantum phase transitions (MSDQPTs). Furthermore, these MSDQPTs are uniquely characterised by a topological index constructed by the application of the Pancharatnam geometry on the purifications of the thermal density matrix; the quantization of this index however persists up to a critical temperature. These claims are corroborated analysing the non-equilibrium dynamics of a transverse Ising chain initially prepared in a thermal state and subjected to a sudden quench of the transverse field.

Quenching in Chern insulators with satellite Dirac points: The fate of edge states

We perform a sudden quench on the Haldane model with long range interactions, more specifically generalising to the next to next nearest neighbour hopping, referred to as the

Effects of periodic kicking on dispersion and wave packet dynamics in graphene

N3

Phase transition in the periodically pulsed Dicke model.

model in our work. Such a model possesses both isotropic and multiple anisotropic (satellite) Dirac points which lead to a rich topological phase diagram consisting of phases with higher Chern number (

Exploring chaos in the Dicke model using ground-state fidelity and Loschmidt echo.

C

Exploring the possibilities of dynamical quantum phase transitions in the presence of a Markovian bath

). Quenches between the topological and the non-topological phases of such an infinite system probe the effect of the presence of the anisotropic Dirac points on the non-equilibrium response of the topological system. Interestingly, the Chern number remains the same before and after the quench for both the quenching protocols, even when the quench of the system is carried out between two different topological phases. {However, for a finite system, we establish that the initial edge current asymptotically decays to zero when the system is quenched to the non-topological phase although the Chern number for the corresponding periodically wrapped system remains unaltered; what is remarkable is that when the Hamiltonian is quenched from

Emergent topology and dynamical quantum phase transitions in two-dimensional closed quantum systems

|C|=2

Dynamical Quantum Phase Transitions in Extended Toric-Code Models

phase to the non-topological phase the edge current associated with the inner channel decays at a faster rate than the outer channel resembling a situation in which the system passes through the phase with

Fibonacci steady states in a driven integrable quantum system

|C|=1

Critical phase boundaries of static and periodically kicked long-range Kitaev chain

before ending up in the phase