Title: 

Self-testing of a single quantum device under computational assumptions

Abstract:

Self-testing is a method to characterise an arbitrary quantum device based only on its classical input-output correlations. Prior works on self-testing require the assumption that the quantum device is composed of two non-communicating subsystems. Here, we replace this non-communication assumption by a computational assumption. Specifically, we give a protocol that allows a classical verifier to robustly certify that a single computationally bounded quantum device must have prepared a Bell pair and performed single-qubit measurements on it, up to a change of basis applied to both the device's state and measurements. This means that under computational assumptions, the verifier is able to certify the presence of entanglement inside a single quantum device. To achieve this, we employ techniques introduced by Brakerski et al. (2018) and Mahadev (2018) which allow a classical verifier to constrain the actions of a quantum device assuming the device does not break post-quantum cryptography.