Tunable superradiance and quantum phase gate based on graphene wrapped nanowire

Abstract

In the past few years there has been a great deal of interest in studying the efficient control of the interaction between quantum emitters (QEs) and nanostructures [1, 2]. Recently, we have investigated the interaction between quantum emitters and graphene wrapped nanowire (see Fig. 1(a)) by using a Green's function technique. The eigenmodes for the graphene wrapped nanowire at various Fermi levels in graphene have been solved exactly and the sensitivity of the fundamental mode to the Fermi level or the external voltage in graphene has been demonstrated. The plasmon-mediated coupling between two QEs has also been discussed. The Dicke subradiance and superradiance resulting from the graphene-mediated interaction have been observed, as shown in Fig. 1(b). It has also been confirmed that there is an optimum emitter-graphene distance yielding the maximal coupling between the QEs due to the finite material losses. Based on these phenomena, we have proposed a scheme for a deterministic tunable two-qubit quantum phase gate. The “switching” effect for the quantum phase gate has been realized theoretically by changing an external voltage. The advantage of such a phase gate is that it can be not only controlled by the external voltage, switching speed is also fast because graphene can exhibit ultrafast carrier dynamics. These are very beneficial for the quantum-information processing.