A quantum state readout method based on a single ancilla qubit

Quantum state measurement is essential for reading-out a quantum computing outcome. Meanwhile, the readout results are always affected by the large noise of quantum measurements in physical implementation, which also hinders the large-scale expansion of quantum computing. In light of this, we present an indirect quantum state readout method based on a single ancilla qubit that can avoid the large noise of multiple-qubit measurements. The theoretical analysis and simulations indicate that our method is more robust against the measurement noise and promises to become a method of large-scale quantum error correction and high-fidelity quantum state readout.