Reversibility of continuous-variable quantum cloning

Abstract

We analyze a reversibility of optimal Gaussian $1\to 2$ quantum cloning of a coherent state using only local operations on the clones and classical communication between them and propose a feasible experimental test of this feature. Performing Bell-type homodyne measurement on one clone and anti-clone, an arbitrary unknown input state (not only a coherent state) can be restored in the other clone by applying appropriate local unitary displacement operation. We generalize this concept to a partial LOCC reversal of the cloning and we show that this procedure converts the symmetric cloner to an asymmetric cloner. Further, we discuss a distributed LOCC reversal in optimal $1\to M$ Gaussian cloning of coherent states which transforms it to optimal $1\to M^{\prime }$ cloning for $M^{\prime }<M$. Assuming the quantum cloning as a possible eavesdropping attack on quantum communication link, the reversibility can be utilized to improve the security of the link even after the attack.

7 pages, 5 figures

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Cited by in corpus (5)

• Quantum Cloning Machines and the Applications
• Demonstration of reversible phase-insensitive optical amplifier
• Optimal multicopy asymmetric Gaussian cloning of coherent states
• Cloning and Optimal Gaussian individual attacks for continuous-variable quantum key distribution using coherent states and reverse reconciliation
• Experimental reversion of the optimal quantum cloning and flipping processes