NISQ (Noisy Intermediate-Scale Quantum)
The current era of quantum computing: systems with 50-1000+ qubits that are too error-prone for fault-tolerant computation but large enough to be potentially useful for some tasks.
NISQ stands for Noisy Intermediate-Scale Quantum, a term coined by physicist John Preskill in 2018 to describe the current generation of quantum computers. NISQ devices have enough qubits to perform computations that are hard to simulate classically, but too many errors to run most error-corrected quantum algorithms.
NISQ-era quantum computers are essentially the transistor radios of quantum computing, useful, but not yet performing the sophisticated computations the field ultimately targets. The challenge is finding problems where NISQ devices can provide value despite their errors.
The NISQ era is expected to end as quantum error correction matures and fault-tolerant quantum computing becomes possible. When that happens, systems will be capable of running algorithms like Shor's (breaking encryption) and Grover's (database search) at scale.