Decoherence limiting the cost to simulate an anharmonic oscillator

Tzula B. Propp, Sayonee Ray, John B. Debrota, Tameem Albash, Ivan H. Deutsch

Research output: Contribution to journalArticleScientificpeer-review


We study how decoherence increases the efficiency with which we can simulate the quantum dynamics of an anharmonic oscillator governed by the Kerr effect. As decoherence washes out the fine-grained sub-Planck structure associated with phase-space quantum interference in the closed quantum system, open quantum dynamics can be more efficiently simulated using a coarse-grained finite-difference numerical integration. We tie this to the way in which decoherence recovers the semiclassical truncated Wigner approximation, which strongly differs from the exact closed-system dynamics at times when quantum interference leads to cat states and more general superpositions of coherent states. The regression in quadrature measurement statistics to semiclassical dynamics becomes more pronounced as the initial amplitude of the oscillator grows, with implications for the quantum advantage that might be accessible as system size grows in noisy quantum devices. Lastly, we show that this regression does not have the form of a convex noise model, such as for a depolarizing noise channel. Instead, closed quantum system effects interact with the open-system effects, giving rise to distinct open-system behavior.

Original languageEnglish
Article number062219
Number of pages21
JournalPhysical Review A
Issue number6
Publication statusPublished - 2023
Externally publishedYes


This material is based upon work supported by the Air Force Office of Scientific Research under award number FA9550-22-1-0498. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the United States Air Force.

We gratefully acknowledges helpful conversations with Jun Takahashi, Changhao Yi, and Chris Jackson. We acknowledge the indigenous peoples of the Pueblo of Sandia as the original inhabitants, stewards, and protectors of the lands on which the University of New Mexico now sits. The authors would like to thank the UNM Center for Advanced Research Computing, supported in part by the National Science Foundation, for providing the high-performance computing resources used in this work. This work was supported by National Science Foundation Grants No. PHY-2116246 and No. 2037755 and is based upon work partially supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Quantum Systems Accelerator.


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