Special Relativity and Quantum Cloning
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Special Relativity and Quantum Cloning
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Z. Gedik

Sabanci University

TIme/Place: Mar. 28 Wednesday @ 10:40 (Coffee/Tea @ 10:20 in SUNUM Hall)

Special relativity forbids superluminal influences. No-signalling principle is necessary for consistency of the theory of relativity and quantum mechanics. Impossibility of faster than light communication based on quantum correlations  led to the discovery of the no-cloning theorem. However, the no-signalling principle leaves room for an approximate cloning. Imperfect or approximate optimal quantum cloners have been shown to exist.  In this talk, we present a pseudo-spin representation for universal symmetric 1-to-M cloning of qubits, including both linear and nonlinear evolutions. We derive a set of equations to be satisfied by the cloning transformation under the no-signalling condition, and find an expression for the fidelity. We further introduce the linearity constraint, and obtain the unique universal symmetric quantum cloning machine for an arbitrary fidelity. No-signalling condition alone leads to fidelities higher than those of the quantum machines, and the maximum value converges to 3/4 rather than the optimal quantum limit of 2/3. We introduce the prime cloners whose fidelities have multiplicative property and show that the infinite copy limit of the prime cloners is 1/2.
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Contact: İnanç Adagideli, adagideli@sabanciuniv.edu

 and/or Cem Çelebi, cemcelebi@sabanciuniv.edu