Rating the performance of noisy teleportation using fluctuations in fidelity

Abstract

Quantum teleportation is one of the most pioneering features of the quantum world. Typically, the quality of a teleportation protocol is solely judged by its average fidelity. In this work, we analyze the performance of teleportation in terms of both fidelity and the deviation in fidelity. Specifically, we define a quantity called teleportability score, which incorporates contributions from both the fidelity and its deviation. It also takes into account the sensitivity one requires for a protocol in which the teleportation of a quantum state is required in one or many intermediate steps. We compute the teleportability score in the noiseless scenario and find that it increases monotonically with the entanglement content of the resource state. The result remains same even if we consider an n-chain repeater-like configuration. However, in the presence of noise, the teleportability score, can sometime display a nonmonotonic behaviour with respect to the entanglement content of the initially shared resource state. Specifically, under local bit-flip and bit-phase-flip noise, lesser entangled states can have higher teleportability score for certain choice of system parameters. In the presence of global depolarizing noise, for low entangled resource states and high sensitivity requirements, the noisy states can have better a teleportability score in comparison to the noiseless scenario.