Optimal secure quantum teleportation of coherent states of light
Abstract
We investigate quantum teleportation of ensembles of coherent states of light with a Gaussian distributed displacement in phase space. Recently, the following general question has been addressed in [P. LiuzzoScorpo et al., arXiv:1705.03017]: Given a limited amount of entanglement and mean energy available as resources, what is the maximal fidelity that can be achieved on average in the teleportation of such an alphabet of states? Here, we consider a variation of this question, where EinsteinPodolskyRosen steering is used as a resource rather than plain entanglement. We provide a solution by means of an optimisation within the space of Gaussian quantum channels, which allows for an intuitive visualisation of the problem. We first show that not all channels are accessible with a finite degree of steering, and then prove that practical schemes relying on asymmetric twomode Gaussian states enable one to reach the maximal fidelity at the border with the inaccessible region. Our results provide a rigorous quantitative assessment of steering as a resource for secure quantum teleportation beyond the socalled nocloning threshold. The schemes we propose can be readily implemented experimentally by a conventional BraunsteinKimble continuous variable teleportation protocol involving homodyne detections and corrective displacements with an optimally tuned gain. These protocols can be integrated as elementary building blocks in quantum networks, for reliable storage and transmission of quantum optical states.
 Publication:

Society of PhotoOptical Instrumentation Engineers (SPIE) Conference Series
 Pub Date:
 August 2017
 DOI:
 10.1117/12.2272993
 arXiv:
 arXiv:1708.08548
 Bibcode:
 2017SPIE10358E..0VL
 Keywords:

 Quantum Physics;
 Condensed Matter  Statistical Mechanics;
 Mathematical Physics;
 Physics  Optics
 EPrint:
 10 pages, 2 figures. Published in Proceedings of SPIE Optics + Photonics 2017. Update: Eq. (24) corrected and some statements rectified