Energy Inference of Black-Box Quantum Computers Using Quantum Speed Limit

Fuente: arXiv
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Autori principali: Ishida, Nobumasa, Hasegawa, Yoshihiko
Natura: Preprint
Pubblicazione: 2025
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author Ishida, Nobumasa
Hasegawa, Yoshihiko
author_facet Ishida, Nobumasa
Hasegawa, Yoshihiko
contents Cloud-based quantum computers do not provide users with access to hardware-level information such as the underlying Hamiltonians, which obstructs the characterization of their physical properties. We propose a method to infer the energy scales of gate Hamiltonians in such black-box quantum processors using only user-accessible data, by exploiting quantum speed limits. Specifically, we reinterpret the Margolus-Levitin and Mandelstam-Tamm bounds as estimators of the energy expectation value and variance, respectively, and relate them to the shortest time for the processor to orthogonalize a quantum state. This shortest gate time, expected to lie on the nanosecond scale, is inferred from job execution times measured in seconds by employing gate-time amplification. We apply the method to IBM's superconducting quantum processor and estimate the energy scales associated with single-, two-, and three-qubit gates. The order of estimated energy is consistent with typical drive energies in superconducting qubit systems, suggesting that current gate operations approach the quantum speed limit. Our results demonstrate that fundamental energetic properties of black-box quantum computers can be quantitatively accessed through operational time measurements, reflecting the conjugate relationship between time and energy imposed by the uncertainty principle.
format Preprint
id arxiv_https___arxiv_org_abs_2512_15472
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Energy Inference of Black-Box Quantum Computers Using Quantum Speed Limit
Ishida, Nobumasa
Hasegawa, Yoshihiko
Quantum Physics
Computational Physics
Cloud-based quantum computers do not provide users with access to hardware-level information such as the underlying Hamiltonians, which obstructs the characterization of their physical properties. We propose a method to infer the energy scales of gate Hamiltonians in such black-box quantum processors using only user-accessible data, by exploiting quantum speed limits. Specifically, we reinterpret the Margolus-Levitin and Mandelstam-Tamm bounds as estimators of the energy expectation value and variance, respectively, and relate them to the shortest time for the processor to orthogonalize a quantum state. This shortest gate time, expected to lie on the nanosecond scale, is inferred from job execution times measured in seconds by employing gate-time amplification. We apply the method to IBM's superconducting quantum processor and estimate the energy scales associated with single-, two-, and three-qubit gates. The order of estimated energy is consistent with typical drive energies in superconducting qubit systems, suggesting that current gate operations approach the quantum speed limit. Our results demonstrate that fundamental energetic properties of black-box quantum computers can be quantitatively accessed through operational time measurements, reflecting the conjugate relationship between time and energy imposed by the uncertainty principle.
title Energy Inference of Black-Box Quantum Computers Using Quantum Speed Limit
topic Quantum Physics
Computational Physics
url https://arxiv.org/abs/2512.15472