Characterizing quantum processors using discrete time crystals
We present a method for characterizing the performance of noisy quantum
processors using discrete time crystals. Deviations from ideal persistent
oscillatory behavior give rise to numerical scores by which relative quantum
processor capabilities can be measured. We construct small sets of qubit
layouts that cover the full topology of a target system, and execute our metric
over these sets on a wide range of IBM Quantum processors. We show that there
is a large variability in scores, not only across multiple processors, but
between different circuit layouts over individual devices. The stability of
results is also examined. Our results suggest that capturing the true
performance characteristics of a quantum system requires interrogation over the
full device, rather than isolated subgraphs. Moreover, the disagreement between
our results and other metrics indicates that benchmarks computed infrequently
are not indicative of the real-world performance of a quantum processor. This
method is platform agnostic, simple to implement, and scalable to any number of
qubits forming a linear-chain, while simultaneously allowing for identifying
ill-performing regions of a device at the individual qubit level.
Victoria Zhang Paul D. Nation