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.