QSCL-24h

Quantum computing desperately needs a benchmark that normal people can understand.

Not physical qubits. Not logical qubits. Not quantum volume. Not CLOPS. Not “algorithmic qubits”. Those are all internal engineering metrics.

A better metric would be;

“What is the largest RSA key you can crack exactly within 24 hours?”

Call it QSCL-24h: Quantum Shor Crack Length, 24 hour limit. And don’t worry about the cost for now

Because a “logical qubit” by itself tells you very little. A machine may technically possess logical qubits while still being unable to execute useful fault-tolerant computation at meaningful scale. Some systems rely on postselection. Some demonstrate protected quantum memory rather than practical computation. Some cannot sustain sufficiently deep circuits. Some scale badly.

The public hears: “94 logical qubits”

But the more meaningful translation may be: “approximately RSA-15 capability under very generous assumptions.”

That is still toy-scale cryptography.

Meanwhile, classical computing quietly continues to dominate actual demonstrated factoring capability. The public RSA-250 factorisation in 2020 cracked an 829-bit RSA number using classical algorithms and enormous compute resources. Under a 24-hour benchmark, extrapolation suggests it would require roughly one million modern CPU cores to reproduce that result in a day.

So today’s rough picture looks something like this:

Classical QSCL-24h: approximately RSA-829

Quantum QSCL-24h: approximately RSA-15.

At present Shor’s algorithm is effectively the only quantum algorithm with a clear, widely understood, economically valuable application. There are many other proposed quantum algorithms for chemistry, optimisation, simulation, and sampling, but none have the same combination of: clear advantage, clear benchmark, clear commercial impact, and deterministic verification.

That is why RSA cracking makes such a useful benchmark. A factorisation either works or it does not. There is no “close enough”, no subjective scoring, no benchmark gaming through approximations. If p × q equals N, success. Otherwise failure.

The beauty of the benchmark is that it collapses many hidden variables into one externally meaningful number: logical fidelity, gate depth, decoder performance, connectivity, runtime, architectural efficiency, and scaling behaviour.

The most honest quantum computing leaderboard would simply read:

QSCL-24h: Largest RSA modulus factored exactly within 24 hours.