Variational fast forwarding for quantum simulation beyond the coherence time

Trotterization-based, iterative approaches to quantum simulation (QS) are restricted to simulation times less than the coherence time of the quantum computer (QC), which limits their utility in the near term. Here, we present a hybrid quantum-classical algorithm, called variational fast forwarding (...

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Bibliographic Details
Published in:npj quantum information 2020-09, Vol.6 (1), Article 82
Main Authors: Cîrstoiu, Cristina, Holmes, Zoë, Iosue, Joseph, Cincio, Lukasz, Coles, Patrick J., Sornborger, Andrew
Format: Article
Language:English
Subjects:
639/766/259
639/766/483/3926
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Classical and Quantum Gravitation
computer science
mathematics
MATHEMATICS AND COMPUTING
Physics
Physics and Astronomy
Quantum Computing
quantum computing, quantum machine learning
Quantum Field Theories
Quantum Information Technology
quantum machine learning
Quantum Physics
quantum simulation
Relativity Theory
Spintronics
String Theory
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Summary:Trotterization-based, iterative approaches to quantum simulation (QS) are restricted to simulation times less than the coherence time of the quantum computer (QC), which limits their utility in the near term. Here, we present a hybrid quantum-classical algorithm, called variational fast forwarding (VFF), for decreasing the quantum circuit depth of QSs. VFF seeks an approximate diagonalization of a short-time simulation to enable longer-time simulations using a constant number of gates. Our error analysis provides two results: (1) the simulation error of VFF scales at worst linearly in the fast-forwarded simulation time, and (2) our cost function’s operational meaning as an upper bound on average-case simulation error provides a natural termination condition for VFF. We implement VFF for the Hubbard, Ising, and Heisenberg models on a simulator. In addition, we implement VFF on Rigetti’s QC to demonstrate simulation beyond the coherence time. Finally, we show how to estimate energy eigenvalues using VFF.
ISSN:2056-6387
2056-6387
DOI:10.1038/s41534-020-00302-0