[2954] in cryptography@c2.net mail archive
Quantum error correction for communication with linear optics
daemon@ATHENA.MIT.EDU (Paul Pomes)
Tue Jul 14 13:23:18 1998
From: Paul Pomes <ppomes@Qualcomm.com>
To: cryptography@c2.net
Date: Tue, 14 Jul 1998 07:57:18 -0700
Samuel L. Braunstein, "Quantum error correction for communication with
linear optics", Nature 394, 47-49 (1998) Letters to Nature
<http://second.nature.com/server-java/Propub/nature/394047A0.pdf>
Improving the signal-to-noise ratio in optical communication systems is a
fundamental requirement for cost-effective data transmission. This is
particularly important for the transmission of noise-intolerant quantum
states: excess noise at the quantum level destroys the coherence of the
states, rendering classical error correction or amplifier-based schemes
useless for quantum communication. Only quantum error correction can remove
the effects of noise without corrupting the fragile superpositions of
quantum states. But difficulties arise in the practical implementation of
such a correction process because nonlinear operations have been thought to
be required, greatly reducing the efficiency of any optical scheme. Here I
report an efficient, compact scheme involving only linear optical elements
and feedback, which performs error correction for both quantum and
classical noise. In the classical case, the noise penalty incurred is no
worse than for ideal amplification. But for low-noise quantum optical
communication, this penalty may be eliminated entirely. This quantum
error-correction scheme may thus find application in quantum cryptographic
networks (where low noise is equivalent to high security), possibly
extending their range far beyond limits imposed by system losses.
