Dual-state purification for practical quantum error mitigation

Understand

Quantum error mitigation is essential for computing on the noisy quantum computer with a limited number of qubits.

• In this paper, we propose a practical protocol of error mitigation by virtually purifying the quantum state without qubit overhead or requiring only one ancillary qubit.
• In dual-state purification, we effectively generate a purified state with increased fidelity using the erroneous state and its dual state, respectively, prepared with the noisy quantum circuit and the dual map of its inverse circuit.
• Combined with tomography purification, we can make sure that the final estimate of an observable is obtained from a pure state.