Near optimal discrimination of binary coherent signals via atom–light interaction. (12th April 2018)

• Record Type: Journal Article
• Authors: Han, Rui; Bergou, János A; Leuchs, Gerd
• Is Part Of: New journal of physics. Volume 20:Number 4(2018:Apr.)
• Publication Date: 2018-04-12
• Subjects: coherent state -- quantum communication -- atom–light interaction -- Helstrom bound -- nondestructive measurement -- state discrimination; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/aab2c5
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: We study the discrimination of weak coherent states of light with significant overlaps by nondestructive measurements on the light states through measuring atomic states that are entangled to the coherent states via dipole coupling. In this way, the problem of measuring and discriminating coherent light states is shifted to finding the appropriate atom–light interaction and atomic measurements. We show that this scheme allows us to attain a probability of error extremely close to the Helstrom bound, the ultimate quantum limit for discriminating binary quantum states, through the simple Jaynes–Cummings interaction between the field and ancilla with optimized light–atom coupling and projective measurements on the atomic states. Moreover, since the measurement is nondestructive on the light state, information that is not detected by one measurement can be extracted from the post-measurement light states through subsequent measurements.