Carrying an arbitrarily large amount of information using a single quantum particle

Li-Yi Hsu, Ching-Yi Lai*, You-Chia Chang, Chien Ming Wu, Ray-Kuang Lee

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Theoretically speaking, a photon can travel arbitrarily long before it enters into a detector, resulting in a click. How much information can a photon carry? We study a bipartite asymmetric "two-way signaling" protocol as an extension of that proposed by Del Santo and Dakic. Suppose that Alice and Bob are distant from each other and each of them has an n-bit string. They are tasked to exchange the information of their local n-bit strings with each other, using only a single photon during the communication. It has been shown that the superposition of different spatial locations in a Mach-Zehnder (MZ) interferometer enables bipartite local encodings. We show that, after the travel of a photon through a cascade of n-level MZ interferometers in our protocol, the one of Alice and Bob whose detector clicks can access the other's full information of the n-bit string, while the other can gain one bit of information. That is, the wave-particle duality makes two-way signaling possible, and a single photon can carry an arbitrarily large (but finite) amount of information.

Original languageEnglish
Article number022620
Number of pages6
JournalPhysical Review A
Issue number2
StatePublished - 25 Aug 2020



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