Closed time like curves enable perfect state distinguishability

Journal Article · Tue Jan 01 04:00:00 EST 2008 · Physical Review Letters

OSTI ID:960930

Harrington, James William ^[1]; Wilde, Mark M ^[2]; Brun, Todd A ^[2]

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1. Los Alamos National Laboratory
2. USC

The causal self-consistency condition for closed timelike curves can give rise to nonlinear interactions on chronology-respecting qubits. We demonstrate that particular unitary interactions between closed timelike curve qubits and chronology-respecting qubits allow perfect distinguishability of nonorthogonal states, and provide a constructive proof for an arbitrary number of nonorthogonal states. This has a number of highly significant consequences. For example, an adversary with access to closed timelike curves can break the B92, BB84, and SARG04 quantum key distribution protocols, or any prepare-and-measure quantum key distribution scheme. Our result also implies that a party with access to closed timelike curves can violate the Holevo bound by accessing more than log(N) bits of information from an N-dimensional quantum state. In principle, he can transmit an arbitrarily large amount of classical information with a quantum system of fixed size. We discuss the implications of this for quantum cloning.

• Research Organization: Los Alamos National Laboratory (LANL)
• Sponsoring Organization: DOE
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 960930
• Report Number(s): LA-UR-08-06563; LA-UR-08-6563
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CLONING
DIAGRAMS
DISTRIBUTION
INFORMATION
INTERACTIONS
QUBITS