8

As a start, you might want to look at https://arxiv.org/abs/1605.03590, which lays out conservative (i.e., high) qubit and gate requirements for a meaningful quantum chemistry calculation under some pretty reasonable assumptions. The estimates there are on the order of $10^{15}$ total logical gates (not gate depth) over roughly 100 logical qubits, which ...


7

Quantum volume is likely only useful as a metric for small noisy computers. It’s impossible to invent any single-number metric that’s ideal for all tasks. Even with classical computers, metrics such as Dhrystone or Windows Performance Index are at best suggestive at predicting performance on real-world tasks. Conversely, giving more than one number can ...


3

Here is an example of using Qiskit to benchmark quantum devices using the Quantum Volume metric. It generates the quantum volume model circuits, compiles them, runs them, and fits the result to find the volume. The source code for how the fitting is done is here: https://github.com/Qiskit/qiskit-ignis/blob/master/qiskit/ignis/verification/quantum_volume/...


2

The Quantum Volume is a benchmark for near term, noisy quantum systems. Indeed, like other random unitary benchmarks, you need to be able to sample the ideal distribution. This distribution comes from classical simulations, so your limited to about the ~40 or so qubit limit. However, the Quantum Volume itself was designed to benchmark not only the quantum ...


2

Quantum volume is a bad metric for this purpose. For example, suppose you have a ten thousand by ten thousand grid of qubits with a gate error rate of 1 in one thousand. The quantum volume of this grid is basically 0, because if you pick two qubits at random they will on average be more than one thousand steps apart. So an error will almost certainly occur ...


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