Principles of coherent communication

Y. Yamamoto, N. Imoto, S. MACHIDA +1 more

The Heisenberg uncertainty principle dictates the standard quantum limit (SQL) in preparation, measurement, and amplification of optical quantum states. The best performance of coherent communication and photon counting communication is already close to the quantum limit. This paper discusses the new strategies that beat optimally the SQL in optical communication.

Michel Le Bellac

Subhash C. Kak

This paper presents an epistemological perspective on quantum communication between parties that highlights the choices that must be made in order to send and obtain information. The notion of information obtained in such a communication is a property associated with the observers and while dependent on the nature of the physical system its fundamental basis is epistemic. We argue that the observation process is in accord with the principle of psychophysical parallelism that was used by Bohr, von Neumann, Schrodinger and others to establish the philosophical basis of complementarity but has since fallen out of fashion. This principle gave coherence to the original Copenhagen Interpretation without which the latter has come to have some sort of an ad hoc character.

Chao Liu, Jinhong Liu, Junxiang Zhang +1 more

We present an interaction-free measurement with quantum Zeno effect and a high efficiency η = 74.6% ± 0.15%. As a proof-of-principle demonstration, this measurement can be used to implement a quantum counterfactual-like communication protocol. Instead of a single photon state, we use a coherent light as the input source and show that the output agrees with the proposed quantum counterfactual communication protocol according to Salih et al. Although the counterfactuality is not achieved due to the presence of a few photons in the public channel, we show that the signal light is nearly absent in the public channel, which exhibits a proof-of-principle quantum counterfactual-like property of communication.

Nicolas Gisin, Rob Thew