Noise-resistant quantum state compression readout

Qubit measurement is generally the most error-prone operation that degrades the performance of near-term quantum devices, and the exponential decay of readout fidelity severely impedes the development of large-scale quantum information processing. Given these disadvantages, we present a quantum state readout method, named compression readout, that naturally avoids large multi-qubit measurement errors by compressing the quantum state into a single qubit for measurement. Our method generally outperforms direct measurements in terms of accuracy, and the advantage grows with the system size. Moreover, because only one-qubit measurements are performed, our method requires solely a fine readout calibration on one qubit and is free of correlated measurement error, which drastically diminishes the demand for device calibration. These advantages suggest that our method can immediately boost the readout performance of near-term quantum devices and will greatly benefit the development of large-scale quantum computing.

Automated summary

Compression readout is a quantum state readout method that achieves higher accuracy by compressing the quantum state into a single qubit for measurement, eliminating large multi-qubit measurement errors. It outperforms direct measurements and the advantage increases with system size. The method requires only fine readout calibration on one qubit and avoids correlated measurement error, reducing the demand for device calibration. These advantages suggest that it can immediately boost the readout performance of near-term quantum devices and greatly benefit the development of large-scale quantum computing.