Tunable Non-Gaussian Mechanical States in a Strongly Coupled Hybrid Quantum System

Abstract: Quantum states of motion are critical components in the second quantum revolution. We investigate the generation and control of non-Gaussian motional states in a tripartite hybrid quantum system consisting of a collection of qubits coupled to a mechanical resonator, which in turn interacts with an externally driven photonic cavity. This hybrid architecture provides a versatile platform for quantum control by integrating nonlinear interactions and multiple control parameters. Operating in the strong coupling regime, we study the transient dynamics resulting from a time-dependent external drive that has a boxcar profile. Starting from coherent states in both the mechanical and cavity subsystems, we show that this drive protocol, combined with time-independent interaction and frequency configurations, leads to the emergence of highly non-Gaussian quantum states in the intermediary mechanical degree of freedom. These states are characterized by a pronounced negative volume in the Wigner quasi-probability distribution and enhanced quantum Fisher information, indicative of their quantum utility. We systematically analyze the impact of the qubit phase, interaction strengths, and drive parameters on the degree of non-Gaussianity. Our findings underscore the tunability and richness of this hybrid platform, paving the way for advanced quantum state engineering and applications in quantum sensing, metrology, and information processing.