Secure continuous variable quantum teleportation and   Einstein-Podolsky-Rosen steering
  We investigate the resources needed for secure teleportation of coherent states. We extend continuous variable teleportation to include quantum tele-amplification protocols, that allow non-unity classical gains and a pre-amplification or post-attenuation of the coherent state. We show that, for arbitrary Gaussian protocols and a significant class of Gaussian resources, two-way steering is required to achieve a teleportation fidelity beyond the no-cloning threshold. This provides an operational connection between Gaussian steerability and secure teleportation. We present practical recipes suggesting that heralded noiseless pre-amplification may enable high-fidelity heralded teleportation, using minimally entangled yet steerable resources. 
Qiongyi He, Laura Rosales-Zarate, Gerardo Adesso and Margaret Reid
quant-ph