Microwave photon-mediated interactions between semiconductor qubits

TL;DR

This paper demonstrates photon-mediated coherent interactions between distant semiconductor quantum dot charge qubits, providing a promising pathway for scalable quantum information processing with strong, controllable qubit coupling.

Contribution

It reports the first experimental realization of both resonant and non-resonant photon-mediated interactions between distant semiconductor qubits, with strong coupling strengths exceeding system linewidths.

Findings

Spectroscopic evidence of collective qubit coupling

Observation of exchange coupling via virtual photons

Agreement with master-equation simulations

Abstract

The realization of a coherent interface between distant charge or spin qubits in semiconductor quantum dots is an open challenge for quantum information processing. Here we demonstrate both resonant and non-resonant photon-mediated coherent interactions between double quantum dot charge qubits separated by several tens of micrometers. We present clear spectroscopic evidence of the collective enhancement of the resonant coupling of two qubits. With both qubits detuned from the resonator we observe exchange coupling between the qubits mediated by virtual photons. In both instances pronounced bright and dark states governed by the symmetry of the qubit-field interaction are found. Our observations are in excellent quantitative agreement with master-equation simulations. The extracted two-qubit coupling strengths significantly exceed the linewidths of the combined resonator-qubit system. This indicates that this approach is viable for creating photon-mediated two-qubit gates in quantum dot based systems.