Reexamination of quantum bit commitment: The possible and the impossible

Journal Article · Sat Sep 15 04:00:00 EDT 2007 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.76.032328· OSTI ID:21015959

D'Ariano, Giacomo Mauro ^[1]; Kretschmann, Dennis ^[2]; Schlingemann, Dirk ^[3]; Werner, Reinhard F ^[3]

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1. Quantum Information Theory Group, Dipartimento di Fisica A. Volta, Universita di Pavia, via Bassi 6, 27100 Pavia (Italy)
2. Centre for Quantum Computation, DAMTP, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)
3. Institut fuer Mathematische Physik, Technische Universitaet Braunschweig, Mendelssohnstrasse 3, 38106 Braunschweig (Germany)

Bit commitment protocols whose security is based on the laws of quantum mechanics alone are generally held to be impossible. We give a strengthened and explicit proof of this result. We extend its scope to a much larger variety of protocols, which may have an arbitrary number of rounds, in which both classical and quantum information is exchanged, and which may include aborts and resets. Moreover, we do not consider the receiver to be bound to a fixed 'honest' strategy, so that 'anonymous state protocols', which were recently suggested as a possible way to beat the known no-go results, are also covered. We show that any concealing protocol allows the sender to find a cheating strategy, which is universal in the sense that it works against any strategy of the receiver. Moreover, if the concealing property holds only approximately, the cheat goes undetected with a high probability, which we explicitly estimate. The proof uses an explicit formalization of general two-party protocols, which is applicable to more general situations, and an estimate about the continuity of the Stinespring dilation of a general quantum channel. The result also provides a natural characterization of protocols that fall outside the standard setting of unlimited available technology and thus may allow secure bit commitment. We present such a protocol whose security, perhaps surprisingly, relies on decoherence in the receiver's laboratory.

• OSTI ID: 21015959
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 3 Vol. 76; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
PROBABILITY
QUANTUM CRYPTOGRAPHY
QUANTUM DECOHERENCE
QUANTUM MECHANICS
QUBITS
SECURITY