Noisy Intermediate-Scale Quantum Era
NISQ is important as researchers must care about the quality of the qubits used. In particular, researchers are interested in the accuracy of the quantum gates used in their algorithms. Today, the error rate per gate for two-qubit quantum gates is above the .1% level. These errors can arise from various sources such as quantum decoherence, crosstalk, and imperfect calibration.
In the term NISQ, “noisy” is used to indicate that there is imperfect control over the qubits. Noise (or interference) places limitations on what quantum devices can achieve. Thus, "noise in quantum gates limits the size of quantum circuits that can be executed reliably."
In the term NISQ, “intermediate-scale,” refers to the size of quantum computers which will become available in the next few years. The creation of a computer with tens of thousands of qubits and enough error correction (which can reduce the noise levels) would eventually end the NISQ era. In the NISQ era, quantum computers can perform tasks that will only require 50 to a few hundred qubits.
In January 2022, it was announced that quantum computing in silicon hit 99% accuracy thus highlighting that near error-free quantum computing may be possible.
References:
- Noisy Intermediate-Scale Quantum (NISQ) era: https://en.wikipedia.org/wiki/Noisy_intermediate-scale_quantum_era
- Preskill, John, (2018) "Quantum Computing in the NISQ era and beyond", Quantum, Vol(2), p.79,
https://quantum-journal.org/papers/q-2018-08-06-79/ - University of Arizona College of Engineering, (2021) "Engineers demonstrate a quantum advantage," ScienceDaily, www.sciencedaily.com/releases/2021/06/210601155610.htm
- University of New South Wale, (2022), "Quantum computing in silicon hits 99% accuracy,"
https://phys.org/news/2022-01-quantum-silicon-accuracy.html - QuTech, (2021), "Research team takes important step in quantum computing with error correction,"
https://phys.org/news/2021-12-team-important-quantum-error.html