NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
M-ary state phase-shift keying discrimination below the homodyne limit
Published
Author(s)
Francisco E. Becerra Chavez, Jingyun Fan, Gerald Baumgartner, Sergey V. Polyakov, Julius Goldhar, Jonathan Kosloski, Alan L. Migdall
Abstract
We investigate a strategy for M-ary discrimination of nonorthogonal phase states with error rates below the homodyne limit. This strategy uses feed forward to update a reference field and Signal nulling for the state discrimination. We experimentally analyze the receiver performance using postprocessing and a Bayesian strategy to emulate the feed-forward process. This analysis demonstrates that for a moderate system detection efficiency, it is possible to surpass the homodyne error limit for quadrature phase-shift keying (QPSK) signals using feed forward.
Becerra, F.
, Fan, J.
, Baumgartner, G.
, Polyakov, S.
, Goldhar, J.
, Kosloski, J.
and Migdall, A.
(2011),
M-ary state phase-shift keying discrimination below the homodyne limit, Physical Review A, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=908874
(Accessed October 11, 2025)