Open AccessExperimental direct estimation of nonlinear functionals of photonic quantum states via interferometry with a controlled-swap operation
Author(s) -
Sang Min Lee,
Sang Kyung Choi,
Hee Su Park
Publication year - 2013
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.21.017824
Subject(s) - interferometry , photonics , physics , swap (finance) , optics , nonlinear system , photon , qubit , visibility , interference (communication) , quantum , refractive index , quantum mechanics , computer science , telecommunications , channel (broadcasting) , finance , economics
We propose a multi-photon interferometer with a generalized C-SWAP operation that can estimate Tr[ρ(1)ρ(2)···ρ(n)], a nonlinear functional of n photonic density matrices. The scheme is demonstrated for three single-photon states whose overlap is experimentally measured as the interference visibility of a control qubit encoded into photonic paths. The validity of this method is verified by comparing the visibility with the results of Hong-Ou-Mandel experiments.