Noisy intermediate-scale quantum era

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The current state of quantum computing[1] is referred to as the noisy intermediate-scale quantum (NISQ) era,[2] characterized by quantum processors containing up to 1000 qubits which are not advanced enough yet for fault-tolerance or large enough to achieve quantum supremacy.[3][4] These processors, which are sensitive to their environment (noisy) and prone to quantum decoherence, are not yet capable of continuous quantum error correction. This intermediate-scale is defined by the quantum volume, which is based on the moderate number of qubits and gate fidelity. The term NISQ was coined by John Preskill in 2018.[5][2]


NISQ algorithms are designed for quantum processors in the NISQ era, such as the variational quantum eigensolver (VQE) and quantum approximate optimization algorithm (QAOA), which use NISQ devices but offload some calculations to classical processors.[2] These algorithms have been successful in quantum chemistry and have potential applications in various fields including physics, materials science, data science, cryptography, biology, and finance.[2] However, they often require error mitigation techniques to produce accurate results.[6][4][7]

Beyond-NISQ era[edit]

The creation of a computer with tens of thousands of qubits and enough error correction would eventually end the NISQ era.[3] These beyond-NISQ devices would be able to, for example, implement Shor's algorithm for very large numbers and break RSA encryption.[8]

See also[edit]


  1. ^ "Quantum Computing Scientists: Give Them Lemons, They'll Make Lemonade". Retrieved 2021-06-29.
  2. ^ a b c d Brooks, Michael (2019-10-03). "Beyond quantum supremacy: the hunt for useful quantum computers". Nature. 574 (7776): 19–21. Bibcode:2019Natur.574...19B. doi:10.1038/d41586-019-02936-3. ISSN 0028-0836. PMID 31578489.
  3. ^ a b "Engineers demonstrate a quantum advantage". ScienceDaily. Retrieved 2021-06-29.
  4. ^ a b "What is Quantum Computing?". TechSpot. Retrieved 2021-06-29.
  5. ^ Preskill, John (2018-08-06). "Quantum Computing in the NISQ era and beyond". Quantum. 2: 79. Bibcode:2018Quant...2...79P. doi:10.22331/q-2018-08-06-79. S2CID 44098998.
  6. ^ "Quantum computers are already detangling nature's mysteries". Wired UK. ISSN 1357-0978. Retrieved 2021-06-29.
  7. ^ Ritter, Mark B. (2019). "Near-term Quantum Algorithms for Quantum Many-body Systems". Journal of Physics: Conference Series. 1290 (1): 012003. Bibcode:2019JPhCS1290a2003R. doi:10.1088/1742-6596/1290/1/012003. ISSN 1742-6588.
  8. ^ O'Gorman, Joe; Campbell, Earl T. (2017-03-31). "Quantum computation with realistic magic-state factories". Physical Review A. 95 (3): 032338. arXiv:1605.07197. Bibcode:2017PhRvA..95c2338O. doi:10.1103/PhysRevA.95.032338. ISSN 2469-9926. S2CID 55579588.

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