It expresses the maximum size of square quantum circuits that can be implemented successfully by the computer.
The allowable circuit depth decreases when more qubits with the same effective error rate are added.
In 2019, IBM's researchers modified the quantum volume definition to be an exponential of the circuit size, stating that it corresponds to the complexity of simulating the circuit on a classical computer:[4][13] The world record, as of September 2024[update], for the highest quantum volume is 221.
Volumetric benchmarks can be generalized not only to account for uncoupled N and d dimensions, but also to test different types of quantum circuits.
While these data can be analyzed in many ways, a simple method of visualization is illustrating the Pareto front of the N versus d trade-off for the processor being benchmarked.