Decoherence effects on quantum information processing protocols

Abstract

Noisy Intermediate-Scale Quantum computers (NISQ) are fervently accelerating the capacity of Quantum Information Processing (QIP) tasks. The launch of the IBM Quantum Experience (IBM-QE) provided publicly available NISQ processors that can be accessed remotely. Apart from performing quantum computation, IBM-QE processors have been able to successfully simulate many quintessential open quantum system models. Nevertheless, decoherence is a pressing issue in QIP, as noise generated during quantum computation effectively destroys encoded quantum information. The primary objective of this work is to analyse the effects of decoherence on QIP protocols, by simulating quantum teleportation and secret sharing protocols in an open quantum systems scenario on IBM-QE processors. It is demonstrated that implementing a phase damping channel acting on the entangled quantum state utilised in the teleportation process, by means of a collisional model, results in the decay of entanglement, diminishing the state’s capability as a quantum resource. It is also shown that decoherence resulting from the inherent dephasing and thermal relaxation processes occurring during quantum computation, is indeed amplified by increasing circuit depth.