The NISQ Era: Computing in the Presence of Noise
Coined by John Preskill, NISQ refers to the current generation of noisy, mid-sized quantum devices lacking error correction.
QWiki Team 1 min read
#research#nisq#noise#algorithms
Explore LabsCoining the Term
In 2018, physicist John Preskill coined the term NISQ to describe the current state of quantum hardware:
- Noisy: Qubits are prone to environmental errors and gate inaccuracies.
- Intermediate-Scale: Qubit counts range from 50 to a few hundred physical qubits.
Why Error Correction is Not Yet Viable
True Fault-Tolerant Quantum Computing (FTQC) requires thousands of physical qubits to build a single error-corrected logical qubit. Modern devices do not have enough qubits or low enough error rates to support this overhead.
Algorithm Strategies for NISQ
Because gates fail after a short depth, algorithms in the NISQ era must be short and resilient:
- Hybrid Quantum-Classical Algorithms: Algorithms like VQE or QAOA run short quantum circuits, measure results, and optimize classical parameters.
- Error Mitigation: Statistical techniques that run multiple circuit variations to estimate and subtract noise effects from the final data.