Coherent manipulation of an Andreev spin qubit

First demonstration of coherent manipulation of an Andreev spin qubit: a qubit encoded in the spin degree of freedom of a single Andreev bound state in a semiconductor-superconductor Josephson junction. Distinct from the gatemon (which uses the charge/parity degree of freedom).

Key Results

• Qubit states: the odd-parity spin doublet of a single Andreev bound state
• Coherent control via Raman transitions through an auxiliary Andreev state, with Ramsey and Hahn-echo measurements
• Best reported spin lifetime: $T_s=17\pm 1\mu$s
• Coherence times: $T_{2R}=18\pm 1$ ns and $T_{2E}=52\pm 3$ ns
• Single-shot readout via the dispersive shift of a coupled microwave resonator
• Platform: InAs/Al nanowire Josephson junction

Links

• Journal: Science
• arXiv: 2101.06701

Zoo Links

• andreev-spin-qubit
• gatemon