Xu leads the Experimental Quantum Engineering group with a joint ETH–PSI appointment. Research directions: (1) Superconducting circuit quantum sensing — using qubits-as-sensors for detecting weak microwave signals beyond standard quantum limits, quantum non-demolition readout of photon fields; (2) Quantum error correction enabled sensing — integrating bosonic codes (cat qubits, binomial codes) into sensing protocols; (3) Quantum acoustics — coupling superconducting qubits to surface acoustic wave (SAW) resonators for hybrid quantum sensing; (4) Novel quantum hardware at PSI — leveraging PSI's infrastructure for cryogenic device fabrication and testing. Connected to the ETH–PSI Quantum Computing Hub.

Emil Zeuthen works on theoretical quantum optomechanics and quantum transduction. Research focuses on (1) figures of merit and protocols for quantum transducers (mechanical interfaces between microwave and optical domains); (2) back-action-evading measurements using optomechanical systems; (3) quantum limits for gravitational wave detection with mechanical systems in a negative-mass spin reference frame. Key QUANTOP theory collaborator bridging optomechanics and quantum sensing.