Microwave Andreev bound state spectroscopy of a nanowire Josephson junction in magnetic fields*

Microwave spectroscopy of Andreev bound states (ABS) in hybrid superconducting circuit-QED has so far been limited to magnetic fields of a few tens of mT. In contrast to ABS transitions involving pairs of quasiparticles, transitions involving a single spin-carrying quasiparticle to higher lying ABS have been observed and manipulated recently. Here, we expand on these results by performing microwave spectroscopy of a gate-tunable InAs-Al hybrid weak link in presence of spin-orbit coupling and Zeeman fields. In parallel fields up to 250 mT we track both even and odd fermion parity branches of the spectrum. Additionally, in junctions with broken chiral and time-reversal symmetry, through spin-orbit coupling and magnetic field respectively, an anomalous Josephson current is expected to appear. In contrast to measurements of this aggregate effect, we show a field induced anomalous phase shift in transitions between individual Andreev bound states. Finally, the ability to perform microwave spectroscopy of ABS in magnetic fields is requisite for probing signatures of the 4-pi periodic Josephson effect directly in the ABS spectrum and can serve as a platform for Andreev spin based qubits.