Reliable Entropy Estimation from Observed Statistics for Device-Independent Quantum Cryptography
- 1Institute for Quantum Information, RWTH Aachen University, Aachen, Germany
- 2Institut für Theoretische Physik, Leibniz Universität Hannover, Germany
Abstract
We introduce a numerical framework for reliably estimating conditional von Neumann entropies, a central quantity in device-independent quantum cryptography and randomness generation. Our method is based on semidefinite relaxations derived from the Navascués--Pironio--Acín hierarchy and provides entropy bounds directly from observed statistics, assuming only the validity of quantum mechanics. The approach builds on a recent integral representation of entropy and substantially improves efficiency: it requires about half as many support variables as existing methods, while allowing these variables to be chosen projectively, leading to a significant reduction in runtime. These advances enable the practical certification of randomness and security even in noisy conditions, while integrating seamlessly with modern entropy accumulation theorems. Consequently, our framework becomes a versatile tool for quantum cryptographic protocols, broadening the possibilities for secure communication in untrusted environments.
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BibTeX
@article{koßmann2026reliable,
title = {{Reliable Entropy Estimation from Observed Statistics for Device-Independent Quantum Cryptography}},
author = {Gereon Koßmann and René Schwonnek},
journal = {Quantum},
year = {2026},
month = oct,
doi = {10.22331/q-2026-10-20-2238},
url = {https://quantum-journal.org/papers/q-2026-10-20-2238/},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Reliable Entropy Estimation from Observed Statistics for Device-Independent Quantum Cryptography
AU - Gereon Koßmann
AU - René Schwonnek
PY - 2026
DA - 2026/10/20
JO - Quantum
DO - 10.22331/q-2026-10-20-2238
UR - https://quantum-journal.org/papers/q-2026-10-20-2238/
AB - We introduce a numerical framework for reliably estimating conditional von Neumann entropies, a central quantity in device-independent quantum cryptography and randomness generation. Our method is based on semidefinite relaxations derived from the Navascués--Pironio--Acín hierarchy and provides entropy bounds directly from observed statistics, assuming only the validity of quantum mechanics. The approach builds on a recent integral representation of entropy and substantially improves efficiency: it requires about half as many support variables as existing methods, while allowing these variables to be chosen projectively, leading to a significant reduction in runtime. These advances enable the practical certification of randomness and security even in noisy conditions, while integrating seamlessly with modern entropy accumulation theorems. Consequently, our framework becomes a versatile tool for quantum cryptographic protocols, broadening the possibilities for secure communication in untrusted environments.
SN - 2521-327X
ER -