Quantum Validators: Cross-Entropy Benchmarking

Validating a noisy quantum processor doesn't mean checking whether any single measured bitstring was "right" — for a genuinely random circuit that question has no answer. Instead, cross-entropy benchmarking (XEB) compares the whole shape of the measured output distribution against the classically-precomputed ideal one. This simulator draws a fixed "speckled" ideal distribution for a random circuit, then repeatedly samples a noisy version of it — mixing the ideal distribution with a uniform one in proportion to the injected noise — and accumulates a live measured histogram alongside a running XEB fidelity estimate, so you can watch validation-without-checking-individual-outcomes happen in real time.