EFFECTS OF CLASSICAL ENVIRONMENTAL NOISE ON ENTANGLEMENT AND QUANTUM DISCORD DYNAMICS

Claudia Benedetti,Fabrizio Buscemi,Matteo G.A Paris,Paolo Bordone

doi:10.1142/s0219749912410055

Abstract

We address the effect of classical noise on the dynamics of quantum correlations, entanglement and quantum discord (QD), of two non-interacting qubits initially prepared in a Bell state. The effect of noise is modeled by randomizing the single-qubit transition amplitudes. We address both static and dynamic environmental noise corresponding to interaction with separate and common baths in either Markovian and non-Markovian regimes. In the Markov regime, a monotone decay of the quantum correlations is found, whereas for non-Markovian noise sudden death and revival phenomena may occur, depending on the characteristics of the noise. Entanglement and QD show the same qualitative behavior for all kind of noises considered. On the other hand, we find that separate and common environments may play opposite roles in preserving quantum correlations, depending on the noise regime considered.

Highlights

Quantum entanglement is a fundamental resource for quantum information processing, communication and exponential speed-up of some computational tasks 1,2.2 C
We address the effect of classical noise on the dynamics of quantum correlations, entanglement and quantum discord, of two non-interacting qubits initially prepared in a Bell state
Static and slow random telegraph noise (RTN) are classified as non-Markovian noises, while the fast RTN mimics a Markovian environment

Summary

Introduction

Quantum entanglement is a fundamental resource for quantum information processing, communication and exponential speed-up of some computational tasks 1,2. Recent works showed that the non-monotonic time dependence of the amount of quantum correlations may occur in two-qubit systems under the local action of a system-unaffected environment, such as classical random external potentials 20,21. The occurrence of entanglement revival in a non-Markovian classical environment is in contrast to the well-established interpretation of revivals in terms of system-environment quantum back action, and rises the fundamental question of how one could explain the effect of classical noise on quantum correlations dynamics in bipartite systems. A dynamic disorder can model both a non-Markov environment, expressed by a slow RTN, and a Markovian noise, in the limit of fast RTN In both cases single-qubits transition amplitudes are timedependent and are assumed to stochastically switch between two values.

The Physical Model

Static noise

Random telegraph noise

Estimators of quantum correlations

Results

Conclusions