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@ARTICLE{MontaezBarrera:1048663,
author = {Montañez-Barrera, J. A. and Beretta, G. P. and Michielsen,
Kristel and von Spakovsky, Michael R},
title = {{D}iagnosing crosstalk in large-scale {QPU}s using
zero-entropy classical shadows},
journal = {Quantum science and technology},
volume = {11},
number = {1},
issn = {2058-9565},
address = {Philadelphia, PA},
publisher = {IOP Publishing},
reportid = {FZJ-2025-04791},
pages = {17},
year = {2026},
abstract = {As quantum processing units (QPUs) scale toward hundreds of
qubits, diagnosing noise-induced correlations (crosstalk)
becomes critical for reliable quantum computation. In this
work, we introduce Zero-Entropy Classical Shadows (ZECS), a
diagnostic tool that uses information of a rank-one quantum
state tomography reconstruction from classical shadow
information to make a crosstalk diagnosis. We use ZECS on
trapped ion and superconductive QPUs including $ionq_forte$
(36 qubits), $ibm_brisbane$ (127 qubits), and $ibm_fez$ (156
qubits), using from 1000 to 6000 samples. With these
samples, we use the ZECS to characterize crosstalk among
disjoint qubit subsets across the full hardware. This
information is then used to select low-crosstalk qubit
subsets on $ibm_fez$ for executing the quantum approximate
optimization algorithm on a 20-qubit problem. Compared to
the best qubit selection via Qiskit transpilation, our
method improves solution quality by $10\%$ and increases
algorithmic coherence by $33\%.$ ZECS offers a scalable and
measurement-efficient approach to diagnosing crosstalk in
large-scale QPUs.},
cin = {JSC},
ddc = {530},
cid = {I:(DE-Juel1)JSC-20090406},
pnm = {5122 - Future Computing $\&$ Big Data Systems (POF4-512) /
5111 - Domain-Specific Simulation $\&$ Data Life Cycle Labs
(SDLs) and Research Groups (POF4-511) / BMBF 13N16149 -
QSolid - Quantencomputer im Festkörper (BMBF-13N16149)},
pid = {G:(DE-HGF)POF4-5122 / G:(DE-HGF)POF4-5111 /
G:(DE-Juel1)BMBF-13N16149},
typ = {PUB:(DE-HGF)16},
doi = {10.1088/2058-9565/ae1e99},
url = {https://juser.fz-juelich.de/record/1048663},
}