PreprintCC BY 4.0arXiv
Quantum Data Ruler
Abstract
A ruler reads an unknown length against a calibrated scale. The quantum data ruler reads a matrix element of an unknown state against the signal of a known reference, from their ratio. It is exact for any Hamiltonian and any time, since transition operators change by a state-dependent constant times one function of time, removing the vanishing-signal limit. The readout is unbiased under dephasing and amplitude damping, and recovers the coherent ergotropy of a quantum battery that two-point measurement erases. The structure survives the classical limit as action--angle Fourier modes.
Related
- Charging of a quantum battery by a two-photon quantum pulse
- Quantum computing and quantum optics with recoiled free electrons
- Resource-efficient quantum-walker quantum random access memory
- Bosonic quantum error correction with microwave cavities for quantum repeaters
- Reflections on quantum Reflectometry: Quantum and tunneling capacitances as well as sisyphus and hermes resistances
BibTeX
@misc{lu2026quantum,
title = {{Quantum Data Ruler}},
author = {Wangjun Lu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.07827},
eprint = {2610.07827},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.07827},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Quantum Data Ruler
AU - Wangjun Lu
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2610.07827
UR - https://arxiv.org/abs/2610.07827
AB - A ruler reads an unknown length against a calibrated scale. The quantum data ruler reads a matrix element of an unknown state against the signal of a known reference, from their ratio. It is exact for any Hamiltonian and any time, since transition operators change by a state-dependent constant times one function of time, removing the vanishing-signal limit. The readout is unbiased under dephasing and amplitude damping, and recovers the coherent ergotropy of a quantum battery that two-point measurement erases. The structure survives the classical limit as action--angle Fourier modes.
ER -