Distinguishing Coherent Crosstalk from Calibration Drift via Pauli-Transfer Signatures and Quantum Edge Detection
Abstract
Multi-tenant quantum processors expose a pulse-level attack surface in which coherent crosstalk can mimic benign calibration drift at matched average gate infidelity. We present a structural verification and detection framework based on the residual Pauli transfer matrix (PTM). We prove that products of local unital, trace-preserving channels cannot mix weight-1 and weight-2 Pauli operators, even under coherent drift of arbitrary strength or axis. Building on established PTM-to-Hamiltonian relations, we prove that, for any specified qubit pair in an arbitrarily large system, the first-order map from its nine interaction coefficients to the antisymmetric cross-weight feature is an isometry up to scale. Thus, every interaction direction is locally observable near the identity. We also exhibit cancellation of this feature under large local rotations and prove that the full cross-weight norm is invariant under local unitary composition, providing a structural countermeasure. For calibrated small local rotations, shared randomized-Pauli measurements support periodic verification using the evaluated antisymmetric detector. In simulation, 16,384 randomized settings yield a detection threshold of λmin≈0.13 at a 5% calibrated false-positive target, with approximately M−1/2 scaling in the number of settings M. Further experiments characterize detection under relaxation, depolarization, native ZZ fluctuations, and time-dependent pulse dynamics. Finally, an FRQI encoding with Pauli-graph quantum Hadamard edge detection reproduces the classical structural edge score to numerical precision.
Related
- Classical simulation of coherent crosstalk in surface codes
- Flux Crosstalk Calibration from Zero Knowledge to High Precision in Fully Tunable Superconducting Circuits
- Distinguishing Quantum Capacitance Signatures of a Topological Majorana Wire from a Normal Wire Segment
- Shadow signatures and near-horizon energy accumulation in coherent quantum sine-integral black holes
- Harnessing Post-selected von Neumann Measurements to Strengthen Entanglement and Quantum Signatures in Coherent States
BibTeX
@misc{shubha2026distinguishing,
title = {{Distinguishing Coherent Crosstalk from Calibration Drift via Pauli-Transfer Signatures and Quantum Edge Detection}},
author = {Syed Emad Uddin Shubha and Tasnuva Farheen},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.40283},
eprint = {2609.40283},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.40283},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Distinguishing Coherent Crosstalk from Calibration Drift via Pauli-Transfer Signatures and Quantum Edge Detection
AU - Syed Emad Uddin Shubha
AU - Tasnuva Farheen
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.40283
UR - https://arxiv.org/abs/2609.40283
AB - Multi-tenant quantum processors expose a pulse-level attack surface in which coherent crosstalk can mimic benign calibration drift at matched average gate infidelity. We present a structural verification and detection framework based on the residual Pauli transfer matrix (PTM). We prove that products of local unital, trace-preserving channels cannot mix weight-1 and weight-2 Pauli operators, even under coherent drift of arbitrary strength or axis. Building on established PTM-to-Hamiltonian relations, we prove that, for any specified qubit pair in an arbitrarily large system, the first-order map from its nine interaction coefficients to the antisymmetric cross-weight feature is an isometry up to scale. Thus, every interaction direction is locally observable near the identity. We also exhibit cancellation of this feature under large local rotations and prove that the full cross-weight norm is invariant under local unitary composition, providing a structural countermeasure. For calibrated small local rotations, shared randomized-Pauli measurements support periodic verification using the evaluated antisymmetric detector. In simulation, 16,384 randomized settings yield a detection threshold of λ_min≈0.13 at a 5% calibrated false-positive target, with approximately M^−1/2 scaling in the number of settings M. Further experiments characterize detection under relaxation, depolarization, native ZZ fluctuations, and time-dependent pulse dynamics. Finally, an FRQI encoding with Pauli-graph quantum Hadamard edge detection reproduces the classical structural edge score to numerical precision.
ER -