Classical simulations of noisy variational quantum circuits
Abstract Noise detrimentally affects quantum computations so that they not only become less accurate but also easier to simulate classically as systems scale up. We construct a classical simulation algorithm, lowesa (low weight efficient simulation algorithm), for estimating expectation values of no...
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2025-05-01
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| Series: | npj Quantum Information |
| Online Access: | https://doi.org/10.1038/s41534-024-00955-1 |
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| _version_ | 1849730927451701248 |
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| author | Enrico Fontana Manuel S. Rudolph Ross Duncan Ivan Rungger Cristina Cîrstoiu |
| author_facet | Enrico Fontana Manuel S. Rudolph Ross Duncan Ivan Rungger Cristina Cîrstoiu |
| author_sort | Enrico Fontana |
| collection | DOAJ |
| description | Abstract Noise detrimentally affects quantum computations so that they not only become less accurate but also easier to simulate classically as systems scale up. We construct a classical simulation algorithm, lowesa (low weight efficient simulation algorithm), for estimating expectation values of noisy parameterised quantum circuits with a fixed observable. It combines previous results on spectral analysis of parameterised circuits with Pauli back-propagation and recent ideas for simulations of noisy random circuits. We show, under some conditions on the circuits and mild assumptions on noise, that lowesa gives an efficient, polynomial algorithm in the number of qubits (and depth), with approximation error that vanishes exponentially in the physical error rate and a controllable cutoff parameter. This is valid for any expectation value that may be efficiently evaluated on a quantum computer. We discuss the practical limitations of the method for circuit classes with correlated parameters and its scaling with decreasing error rates. |
| format | Article |
| id | doaj-art-e901e17443c841afb29f3544ccdb382e |
| institution | DOAJ |
| issn | 2056-6387 |
| language | English |
| publishDate | 2025-05-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | npj Quantum Information |
| spelling | doaj-art-e901e17443c841afb29f3544ccdb382e2025-08-20T03:08:43ZengNature Portfolionpj Quantum Information2056-63872025-05-0111111210.1038/s41534-024-00955-1Classical simulations of noisy variational quantum circuitsEnrico Fontana0Manuel S. Rudolph1Ross Duncan2Ivan Rungger3Cristina Cîrstoiu4Department of Computer and Information Sciences, University of StrathclydeInstitute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL)QuantinuumNational Physical LaboratoryQuantinuumAbstract Noise detrimentally affects quantum computations so that they not only become less accurate but also easier to simulate classically as systems scale up. We construct a classical simulation algorithm, lowesa (low weight efficient simulation algorithm), for estimating expectation values of noisy parameterised quantum circuits with a fixed observable. It combines previous results on spectral analysis of parameterised circuits with Pauli back-propagation and recent ideas for simulations of noisy random circuits. We show, under some conditions on the circuits and mild assumptions on noise, that lowesa gives an efficient, polynomial algorithm in the number of qubits (and depth), with approximation error that vanishes exponentially in the physical error rate and a controllable cutoff parameter. This is valid for any expectation value that may be efficiently evaluated on a quantum computer. We discuss the practical limitations of the method for circuit classes with correlated parameters and its scaling with decreasing error rates.https://doi.org/10.1038/s41534-024-00955-1 |
| spellingShingle | Enrico Fontana Manuel S. Rudolph Ross Duncan Ivan Rungger Cristina Cîrstoiu Classical simulations of noisy variational quantum circuits npj Quantum Information |
| title | Classical simulations of noisy variational quantum circuits |
| title_full | Classical simulations of noisy variational quantum circuits |
| title_fullStr | Classical simulations of noisy variational quantum circuits |
| title_full_unstemmed | Classical simulations of noisy variational quantum circuits |
| title_short | Classical simulations of noisy variational quantum circuits |
| title_sort | classical simulations of noisy variational quantum circuits |
| url | https://doi.org/10.1038/s41534-024-00955-1 |
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