Measurements of nanoresonator-qubit interactions in a hybrid quantum electromechanical system

TL;DR

This study demonstrates a hybrid quantum system with a nanoresonator and superconducting qubit, achieving strong coupling and low thermal occupation, paving the way for advanced quantum information and thermodynamics experiments.

Contribution

First measurement of a nanoresonator-qubit system with high coherence and strong coupling, aligning experimental results with simulations and highlighting potential for quantum applications.

Findings

Nanoresonator and transmon energies are commensurate

Transmon coherence times are significantly longer than previous systems

Nanoresonator operates near its ground state with low thermal occupation

Abstract

Experiments to probe the basic quantum properties of motional degrees of freedom of mechanical systems have developed rapidly over the last decade. One promising approach is to use hybrid electromechanical systems incorporating superconducting qubits and microwave circuitry. However, a critical challenge facing the development of these systems is to achieve strong coupling between mechanics and qubits while simultaneously reducing coupling of both the qubit and mechanical mode to the environment. Here we report measurements of a qubit-coupled mechanical resonator system consisting of an ultra-high-frequency nanoresonator and a long coherence-time superconducting transmon qubit, embedded in superconducting coplanar waveguide cavity. It is demonstrated that the nanoresonator and transmon have commensurate energies and transmon coherence times are one order of magnitude larger than for all previously reported qubit-coupled nanoresonators. Moreover, we show that numerical simulations of this new hybrid quantum system are in good agreement with spectroscopic measurements and suggest that the nanoresonator in our device resides at low thermal occupation number, near its ground state, acting as a dissipative bath seen by the qubit. We also outline how this system could soon be developed as a platform for implementing more advanced experiments with direct relevance to quantum information processing and quantum thermodynamics, including the study of nanoresonator quantum noise properties, reservoir engineering, and nanomechanical quantum state generation and detection.