Fujiwara Mikio, Takeoka Masahiro, Mizuno Jun, Sasaki Masahide
Communications Research Laboratory, Koganei, Tokyo 184-8795, Japan.
Phys Rev Lett. 2003 Apr 25;90(16):167906. doi: 10.1103/PhysRevLett.90.167906. Epub 2003 Apr 24.
The amount of information transmissible through a communications channel is determined by the noise characteristics of the channel and by the quantities of available transmission resources. In classical information theory, the amount of transmissible information can be increased twice at most when the transmission resource is doubled for fixed noise characteristics. In quantum information theory, however, the amount of information transmitted can increase even more than twice. We present a proof-of-principle demonstration of this superadditivity of classical capacity of a quantum channel by using the ternary symmetric states of a single photon, and by event selection from a weak coherent light source. We also show how the superadditive coding gain, even in a small code length, can boost the communication performance of the conventional coding technique.
通过通信信道可传输的信息量由信道的噪声特性和可用传输资源的数量决定。在经典信息论中，对于固定的噪声特性，当传输资源翻倍时，可传输信息量最多可增加两倍。然而，在量子信息论中，传输的信息量增加甚至可以超过两倍。我们通过使用单光子的三进制对称态以及从弱相干光源进行事件选择，对量子信道经典容量的这种超可加性进行了原理验证演示。我们还展示了即使在短码长情况下，超可加编码增益如何提高传统编码技术的通信性能。
