Two-level Systems Coupled to Graphene plasmons: A Lindblad equation approach

TL;DR

This paper reviews the theory of open quantum systems and macroscopic quantum electrodynamics, focusing on qubits coupled to graphene surface plasmons, and demonstrates how to protect entanglement from decoherence using dissipative dynamics.

Contribution

It combines the theories of open quantum systems and quantum electrodynamics for graphene plasmons, providing a framework to analyze qubit entanglement and decoherence near graphene.

Findings

Partial protection of entangled states using graphene's dissipative properties

Comparison of zero and finite temperature dynamics via Schrödinger and Lindblad equations

Calculation of Green's function for graphene SPPs in electrostatic limit

Abstract

In this paper we review the theory of open quantum systems and macroscopic quantum electrodynamics, providing a self-contained account of many aspects of these two theories. The former is presented in the context of a qubit coupled to a electromagnetic thermal bath, the latter is presented in the context of a quantization scheme for surface-plasmon polaritons (SPPs) in graphene based on Langevin noise currents. This includes a calculation of the dyadic Green's function (in the electrostatic limit) for a Graphene sheet between two semi-infinite linear dieletric media, and its subsequent application to the construction of SPP creation and annihilation operators. We then bring the two fields together and discuss the entanglement of two qubits in the vicinity of a graphene sheet which supports SPPs. The two qubits communicate with each other via the emission and absorption of SPPs. We find that a Sch\"odinger cat state involving the two qubits can be partially protected from decoherence by taking advantage of the dissipative dynamics in graphene. A comparison is also drawn between the dynamics at zero temperature, obtained via Schrodinger's equation, and at finite temperature, obtained using the Lindblad equation.