  Discrimination of coherent states beyond the standard quantum limit (SQL) is
an important tasknot only for quantum information processing but also for
optical coherent communication. In orderto optimize long distance optical fiber
networks, it is of practical importance to develop a quantumreceiver beating
the SQL and approaching the quantum bound at telecom wavelength. In this
paper,we experimentally demonstrate a receiver beating the conventional SQL at
telecom wavelength. Ourreceiver is composed of a displacement operation, a
single photon counter and a real time adaptivefeedback operation. By using a
high performance single photon detector operating at the telecomwavelength, we
achieve a discrimination error beyond the SQL. The demonstration in the
telecomband provides the first step important towards quantum and classical
communication beyond theSQL using a coherent state alphabet, and we envision
that the technology can be used for long-distance quantum key distribution,
effective quantum state preparation and quantum estimation.
