Quantum Volume Benchmark 2D: Heavy Output Generation

Quantum Volume is the industry standard IBM introduced to grade real quantum processors with one number: run a random "square" circuit of n qubits and depth n, and check whether the machine still reproduces more probability mass in the upper half of the output distribution — the heavy outputs — than an untrained coin flip would. This simulator runs an actual complex-amplitude statevector simulation of that circuit (random SU(4) two-qubit gates over a random pairing, layer by layer), draws the circuit lattice as a pannable/zoomable 2D diagram alongside the resulting output-probability histogram and a live HOP-convergence trace, and then fires simulated measurement shots whose noise is driven by a gate-error slider, so you can watch the empirical heavy-output probability converge toward its theoretical value and see exactly where a device would pass or fail certification at QV = 2ⁿ.