Research Areas - (3) Quantum Acoustics / Circuit Quantum Acousto-Dynamics (cQAD)

Full path: Physics > Quantum Optics > Optomechanics > Quantum Acoustics / Circuit Quantum Acousto-Dynamics (cQAD)

Department(s)/lab(s): Electrical Engineering / QET Labs | Balram Lab @ Bristol
Summary:

Krishna Balram (inaugural lecture May 2026) develops photonic quantum engineering at the intersection of photonics, mechanics, and quantum information. Research: (1) piezoelectric optomechanical resonators (GaAs, AlN) for microwave-optical quantum transduction; (2) photonic integrated circuits for quantum sensing; (3) on-chip phononic and photonic crystal devices. Focuses on enabling technologies for quantum repeater nodes and sensors.

Department(s)/lab(s): Physics – Laboratory for Solid State Physics | Hybrid Quantum Systems Group (Chu Group) @ ETH Zurich
Summary:

Chu leads the Hybrid Quantum Systems Group coupling mechanical resonators to superconducting circuits and diamond color centers. Research directions: (1) Circuit quantum acousto-dynamics (cQAD) — HBAR resonators coupled to transmon qubits achieve single-phonon nonlinearity (coherence/anharmonicity ratio 6.8), mechanical qubit gates demonstrated (arXiv 2406.07360, 2024); (2) Optimal control for high Fock state preparation in bulk resonators; (3) Ultra-cold mechanical quantum sensor — cryogenically cooled nanomechanical oscillators as probes for new physics beyond the standard model; (4) Coupling NV/SiV color centers in diamond to acoustic waves for hybrid quantum memory and transduction. Targets long-lived phonon storage for quantum networking and quantum sensing beyond the standard quantum limit.

Department(s)/lab(s): Quantum Nanoscience | Steele Lab @ TU Delft
Summary:

Gary Steele's lab works on quantum circuits and mechanical quantum systems, exploring quantum phenomena in nanoelectromechanical (NEMS) and superconducting circuit systems. Research includes: (1) superconducting qubit-membrane optomechanics and electromechanics; (2) circuit quantum acoustodynamics (cQAD) — coupling superconducting qubits to phonons; (3) analog quantum simulation with quantum circuits; (4) probing quantum materials (graphene, 2D materials) with superconducting circuits. The group develops novel quantum sensors for mechanical forces and electromagnetic fields.