A mid-circuit erasure check on a dual-rail cavity qubit using the joint-photon number-splitting regime of circuit QED

Hardware-efficient mid-circuit erasure check for a dual-rail qubit in two superconducting cavities. A strong parametric beamsplitter makes the ancilla spectrum depend on joint photon number, allowing total-excitation information to be measured without resolving the logical rail.

Key Results

• Missed-erasure fraction: $(9.0\pm 0.5)\times 10^{-4}$
• Erasure rate per check: $2.92\pm 0.01\%$
• Pauli error rate per check: $0.31\pm 0.01\%$

Links

• Journal: npj Quantum Information

Zoo Links

• dual-rail-superconducting-qubit
• qubit-readout