John Preskill

A theoretical physicist at Caltech who began in particle physics and cosmology and became the most influential teacher and commentator in quantum information.

In 2012 he proposed the term 'quantum supremacy' for the moment a quantum device does something no classical computer can. In 2018 he described the present as the era of 'noisy intermediate-scale quantum' (NISQ) technology: machines with tens to hundreds of qubits, too noisy for error correction, whose practical value is an open question.

Preskill is the field's clearest voice for honest expectations. His framing explains why today's machines are scientifically important but not yet practically decisive, and why error correction, not more raw qubits, is the real goal.