Lower bounds for communication capacities of two-qudit unitary operations
- Centre for Quantum Computer Technology, Macquarie University, Sydney, New South Wales 2109 (Australia) and Department of Physics, University of Queensland, St. Lucia, Queensland 4072 (Australia)
It is known that entangling capacities of bipartite unitary operations may be used to place upper bounds on communication capacities. Here we present alternative definitions of entangling capacities for unitary operations and use them to place lower bounds on the communication capacities of arbitrary bipartite unitaries. Thus entangling capacities may be used to place both upper and lower bounds on the communication capacities for arbitrary bipartite unitaries, allowing them to be more easily estimated. We elucidate the connection between these results and the standard formula for the entanglement assisted capacity of channels. In addition, we present more general methods for producing ensembles for communication from initial states for entanglement creation, and thereby derive sufficient conditions such that the usual forms of entangling capacity provide lower bounds on communication capacities.
- OSTI ID:
- 21140617
- Journal Information:
- Physical Review. A, Vol. 76, Issue 6; Other Information: DOI: 10.1103/PhysRevA.76.062302; (c) 2007 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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