Industry & Era
NISQ
Noisy Intermediate-Scale Quantum — the current era of quantum computing, characterized by machines with 50–1000 qubits but significant error rates.
Definition
NISQ stands for Noisy Intermediate-Scale Quantum. The term, coined by physicist John Preskill in 2018, describes the current generation of quantum computers: machines with enough qubits to be interesting and potentially useful, but with error rates too high and coherence times too short to run full quantum error correction. NISQ devices operate in a regime between simple proof-of-concept experiments and the fully fault-tolerant quantum computers of the future.
Technical Definition
A NISQ device typically has 50 to a few thousand physical qubits with gate error rates on the order of 0.1–1% per gate. At these error rates, computations are limited to relatively shallow circuits (low depth) before noise dominates. Algorithms designed for the NISQ era — like VQE (Variational Quantum Eigensolver) and QAOA (Quantum Approximate Optimization Algorithm) — are specifically designed to extract useful results within these constraints.
Visual Explanation: An Analogy
The NISQ era is like the early days of classical computing, when computers filled rooms and could only run limited programs before overheating or breaking down — powerful enough to hint at the future, but not yet the transformative technology they'd become.
Real-World Use Cases
- Running near-term quantum algorithms (VQE, QAOA) for chemistry and optimization
- Exploring quantum advantage on specific, carefully chosen problems
- Benchmarking hardware and developing the engineering needed for future fault-tolerant systems