Error Mitigation for IBM Quantum Devices via Online Testing and Post-selection*

Online testing is essential to verify the functionality of a classical chip during operation. 

Online testing detects disruptive errors in real-time while leaving non-disruptive errors undetected.

Therefore, real-time quantum error detection via online testing is promising.

By assuming the occurrence of error is related to initialization, we execute a single shot online test before the original quantum circuit.

We aim to distinguish faulty and fault-free circuits with a high confidence level in a single shot.

To verify our assumption, we execute the online test twice in a single shot and analyze the consequent failure rate. 

We demonstrate the effectiveness of this idea by executing quantum characterization, calibration, and verification experiments with our error mitigation technique. 

The standard randomized benchmarking results show that our method significantly improved the two-qubit Error Per Clifford (EPC).