Sequential random access codes and self-testing of quantum measurement instruments. (20th August 2019)

• Record Type: Journal Article
• Authors: Mohan, Karthik; Tavakoli, Armin; Brunner, Nicolas
• Is Part Of: New journal of physics. Volume 21:Number 8(2019:Aug.)
• Publication Date: 2019-08-20
• Subjects: random access code -- quantum correlations -- self-testing; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/ab3773
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: Quantum random access codes (QRACs) are key tools for a variety of protocols in quantum information theory. These are commonly studied in prepare-and-measure scenarios in which a sender prepares states and a receiver measures them. Here, we consider a three-party prepare-transform-measure scenario in which the simplest QRAC is implemented twice in sequence based on the same physical system. We derive optimal trade-off relations between the two QRACs. We apply our results to construct semi-device independent self-tests of quantum instruments, i.e. measurement channels with both a classical and quantum output. Finally, we show how sequential QRACs enable inference of upper and lower bounds on the sharpness parameter of a quantum instrument.