India, Sept. 18 -- Quantum computing has moved out of the research lab and into boardroom conversations backed by the government and venture funding worldwide. India alone has committed Rs.6,003.65 crore to its National Quantum Mission. Yet, most of what gets written about quantum computing skips past the part that will decide how impactful this turns out to be, i.e., the vast infrastructure holding it all together.

Starting with hardware. There is no single 'quantum computer' the way there is a single laptop blueprint. Superconducting circuits remain the most widely pursued architecture, but neutral atoms, trapped ions, photonics, and silicon spin qubits are all advancing in parallel, each trading off pros and cons around coherence time...