Real-world quantum computations need to be verified to rule out errors. But most useful computations cannot be efficiently verified by classical simulations. Our method enables verification, by efficiently quantifying how accurately a given computer can implement a given algorithm’s quantum circuits.

We introduced a simple and efficient technique for measuring the fidelity with which an as-built quantum computer can execute an algorithm.

Our technique converts the algorithm’s quantum circuits into a set of closely related circuits whose success rates can be efficiently measured, and it enables measuring the fidelity of quantum algorithm executions, for any number of qubits. We applied our technique, in simulations, to the Quantum Approximate Optimization Algorithm (QAOA).

For details see

“Establishing trust in quantum computations”, Timothy Proctor, Stefan Seritan, Erik Nielsen, Kenneth Rudinger, Kevin Young, Robin Blume-Kohout, Mohan Sarovar. arXiv:2204.07568.