3D Bloch Sphere Decoherence Simulation

Three.js simulation of a qubit's state vector genuinely shrinking toward the center of the Bloch sphere over time — real decoherence, not an idealized noiseless gate demo. The vector's xy-plane component decays as exp(−t/T2) (dephasing) while its z-component relaxes toward the ground pole with time constant T1 (energy relaxation), following the standard single-qubit Bloch relaxation equations, with T2 ≤ 2×T1 enforced as a real physical constraint. Tune T1 and T2 to represent better or worse real hardware, set a gate-operation duration, and watch a genuine circuit-depth budget count down: the number of gate operations that survive before coherence drops below a usable 50% threshold, computed directly from T2 and the gate time.