Active Qubit Reset: Measurement Feedback vs. Passive Decay

Getting a qubit back to |0⟩ between circuits is a real engineering bottleneck: wait for T1 relaxation and you burn tens of microseconds of dead time, or close a quantum-classical control loop — measure the qubit dispersively, let classical logic decide, and fire a conditional π-pulse if it read out excited. This simulator renders a single qubit as a 3D Bloch-sphere arrow coupled to a readout resonator and lets you race the two strategies side by side: toggle between passive and active reset, tune the natural relaxation time T₁, the readout fidelity of the measurement, and the residual error rate of the correction pulse, then watch live population, elapsed time and feedback-round counters as the quantum-classical loop iterates until it confirms the ground state twice in a row.