Quantum conditional cloning of continuous variable entangled states

K Liu,J R Gao

doi:10.2971/jeos.2014.14057

Abstract

We extend the technique of conditional preparation to a quantum cloning machine, and present a protocol of 1 → 2 conditional cloning of squeezed state and entanglement states. It is shown that the entanglement degree of the cloned entangled states can be well preserved even when the fidelity between the input and output states is beyond the limit of 4/9. This scheme is practicable since only the linear elements of beam splitters, homodyne detections, optical modulations and electrical trigger system, are involved.

Highlights

Quantum cloning is a fundamental issue in quantum information processing and the topic of quantum cloning is concerned with devising a quantum cloning machine to make optimal approximate copies [1]–[3]
A continuous variables (CV) entanglement cloning machine can be used in quantum information processing, such as error correction in the quantum computation [18] and quantum eavesdropping [19] in quantum cryptography
We extend the technique of conditional preparation to a quantum cloning machine, and present a protocol of 1 → 2 conditional cloning of squeezed state and entangled states

Summary

INTRODUCTION

Quantum cloning is a fundamental issue in quantum information processing and the topic of quantum cloning is concerned with devising a quantum cloning machine to make optimal approximate copies [1]–[3]. Conditional preparation is an important technique in quantum information experiments Recent developments in both theory and experiment demonstrate that a nonclassical quantum state of light can be conditional prepared in the continuous variable regime [21, 22]. With this technique of conditional preparation, the purification of squeezed and entangled states for CV was experimentally accomplished [23, 24]. We extend the technique of conditional preparation to a quantum cloning machine, and present a protocol of 1 → 2 conditional cloning of squeezed state and entangled states. The conditional quantum cloning machine can be applied into quantum information processing

CONDITIONAL CLONING OF SINGLE-MODE SQUEEZED STATE

Vx1Vp1Vx2Vp2Vx5Vp5Vx9Vp9

CONDITIONAL CLONING OF ENTANGLED STATES

CONCLUSIONS