Information capacity of a single photon

Peter P. Rohde*, Joseph F. Fitzsimons, Alexei Gilchrist

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
17 Downloads (Pure)


Quantum states of light are the obvious choice for communicating quantum information. To date, encoding information into the polarization states of single photons has been widely used as these states form a natural closed two-state qubit. However, photons are able to encode much more - in principle, infinite - information via the continuous spatiotemporal degrees of freedom. Here we consider the information capacity of an optical quantum channel, such as an optical fiber, where a spectrally encoded single photon is the means of communication. We use the Holevo bound to calculate an upper bound on the channel capacity, and relate this to the spectral encoding basis and the spectral properties of the channel. Further, we derive analytic bounds on the capacity of such channels, and, in the case of a symmetric two-state encoding, calculate the exact capacity of the corresponding channel.

Original languageEnglish
Article number022310
Pages (from-to)1-6
Number of pages6
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number2
Publication statusPublished - 9 Aug 2013

Bibliographical note

Rohde, P. P., Fitzsimons, J. F., & Gilchrist, A. (2013). Information capacity of a single photon. Physical Review A, 88(2), 022310. Copyright (2013) by the American Physical Society. The original article can be found at


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