Output state in multiple entanglement swapping

Abstract

The technique of quantum repeaters is a promising candidate for sending quantum states over long distances through a lossy channel. The usual discussions of this technique deals with only a finite dimensional Hilbert space. However the qubits with which one implements this procedure will "ride" on continuous degrees of freedom of the carrier particles. Here we analyze the action of quantum repeaters using a model based on pulsed parametric down conversion entanglement swapping. Our model contains some basic traits of a real experiment. We show that the state created, after the use of any number of parametric down converters in a series of entanglement swappings, is always an entangled (actually distillable) state, although of a different form than the one that is usually assumed. Furthermore, the output state always violates a Bell inequality.

11 pages, 6 figures, RevTeX4

References in corpus (4)

• Bell's theorem for general N-qubit states
• Additivity of the Classical Capacity of Entanglement-Breaking Quantum Channels
• Entanglement cost of mixed states
• Rates of asymptotic entanglement transformations for bipartite mixed states: Maximally entangled states are not special

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• Isolating noise and amplifying signal with quantum Cheshire cat
• How efficient is transport of quantum cargo through multiple highways?
• Testing Quantum Dynamics using Signaling
• Quantum entanglement percolation under a realistic restriction