Towards quantum computing Feynman diagrams in hybrid qubit-oscillator devices
Abstract
We show that recent experiments in hybrid qubit-oscillator devices that measure the phase-space characteristic function of the oscillator via the qubit can be seen through the lens of functional calculus and path integrals, drawing a clear analogy with the generating functional of a quantum field theory. This connection suggests an expansion of the characteristic function in terms of Feynman diagrams, exposing the role of the real-time bosonic propagator, and identifying the external source functions with certain time-dependent couplings that can be controlled experimentally. By applying maximum-likelihood techniques, we show that the “measurement'' of these Feynman diagrams can be reformulated as a problem of multi-parameter point estimation that takes as input a set of Ramsey-type measurements of the qubit. By numerical simulations that consider leading imperfections in trapped-ion devices, we identify the optimal regimes in which Feynman diagrams could be reconstructed from measured data with low systematic and stochastic errors. We discuss how these ideas can be generalized to finite temperatures via the Schwinger-Keldysh formalism, contributing to a bottom-up approach to probe quantum simulators of lattice field theories by systematically increasing the qubit-oscillator number.
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BibTeX
@article{varona2026towards,
title = {{Towards quantum computing Feynman diagrams in hybrid qubit-oscillator devices}},
author = {S. Varona and S. Saner and O. BÄzÄvan and G. Araneda and G. Aarts and A. Bermudez},
journal = {Quantum},
year = {2026},
month = oct,
doi = {10.22331/q-2026-10-28-2252},
url = {https://quantum-journal.org/papers/q-2026-10-28-2252/},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Towards quantum computing Feynman diagrams in hybrid qubit-oscillator devices
AU - S. Varona
AU - S. Saner
AU - O. BÄzÄvan
AU - G. Araneda
AU - G. Aarts
AU - A. Bermudez
PY - 2026
DA - 2026/10/28
JO - Quantum
DO - 10.22331/q-2026-10-28-2252
UR - https://quantum-journal.org/papers/q-2026-10-28-2252/
AB - We show that recent experiments in hybrid qubit-oscillator devices that measure the phase-space characteristic function of the oscillator via the qubit can be seen through the lens of functional calculus and path integrals, drawing a clear analogy with the generating functional of a quantum field theory. This connection suggests an expansion of the characteristic function in terms of Feynman diagrams, exposing the role of the real-time bosonic propagator, and identifying the external source functions with certain time-dependent couplings that can be controlled experimentally. By applying maximum-likelihood techniques, we show that the “measurement'' of these Feynman diagrams can be reformulated as a problem of multi-parameter point estimation that takes as input a set of Ramsey-type measurements of the qubit. By numerical simulations that consider leading imperfections in trapped-ion devices, we identify the optimal regimes in which Feynman diagrams could be reconstructed from measured data with low systematic and stochastic errors. We discuss how these ideas can be generalized to finite temperatures via the Schwinger-Keldysh formalism, contributing to a bottom-up approach to probe quantum simulators of lattice field theories by systematically increasing the qubit-oscillator number.
SN - 2521-327X
ER -