Quantum Optimal Control for Mitigating Bit-Flip, Phase-Flip, and Depolarizing Noise in Quantum Systems

Quantum computing is highly vulnerable to noise, with bit-flip, phase-flip, and depolarizing errors arising from imperfections in classical control pulses that manage qubits. While Quantum Error Correction (QEC) addresses these errors post-occurrence, Quantum Optimal Control (QOC) provides a proactive strategy by designing control pulses to prevent errors at the hardware level. This research article traces the historical evolution of quantum computing through three distinct acts—theoretical foundations, algorithm development, and the race to scale—while proposing and implementing a GRAPE-like QOC algorithm to mitigate multi-channel noise. Executed using Qiskit on IBM’s ibm_torino backend, the optimized X-gate pulse achieved a fidelity of 1.0000, validated through extensive simulations, histograms, and Bloch sphere visualizations. This study bridges the Noisy Intermediate-Scale Quantum (NISQ) to fault-tolerant gap, enhancing gate reliability and reducing QEC overhead, with significant implications for scalable quantum technologies in fields such as cryptography, optimization, and quantum simulation.