New Delhi, June 28 -- For decades, quantum computing promised revolutionary breakthroughs while remaining stubbornly out of reach. Researchers struggled with unstable qubits, high error rates and daunting engineering challenges. The running joke in technology circles was that quantum computing, much like nuclear fusion, was always 20 years away.

However, recent advances in error correction, qubit stability and system architecture, led by companies such as Google, Microsoft and IBM, have challenged this long-held assumption. The effect is that governments are now scrambling to secure an early advantage in what is increasingly being viewed as the next major technology race.

This month, US President Donald Trump signed executive orders see...