Quantum methods for clock synchronization: Beating the standard quantum limit without entanglement
- School of Physical Sciences, University of Queensland, Queensland 4072 (Australia)
- School of Physics, University of Sydney, New South Wales 2006 (Australia)
We introduce methods for clock synchronization that make use of the adiabatic exchange of nondegenerate two-level quantum systems: ticking qubits. Schemes involving the exchange of N independent qubits with frequency {omega} give a synchronization accuracy that scales as ({omega}{radical}(N)){sup -1}--i.e., as the standard quantum limit. We introduce a protocol that makes use of N{sub c} coherent exchanges of a single qubit at frequency {omega}, leading to an accuracy that scales as ({omega}N{sub c}){sup -1} ln N{sub c}. This protocol beats the standard quantum limit without the use of entanglement, and we argue that this scaling is the fundamental limit for clock synchronization allowed by quantum mechanics. We analyze the performance of these protocols when used with a lossy channel.0.
- OSTI ID:
- 20718694
- Journal Information:
- Physical Review. A, Vol. 72, Issue 4; Other Information: DOI: 10.1103/PhysRevA.72.042301; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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