Information Rate Loss due to Radiation Decoherence

TL;DR

This paper compares the effects of thermal noise and decoherence on electromagnetic communication, showing that decoherence causes significant information rate loss only above certain thresholds, which vary with frequency.

Contribution

It introduces a photon gas model as an alternative to the Gaussian model for analyzing electromagnetic information rates under decoherence.

Findings

Decoherence causes up to half capacity loss above a frequency-dependent threshold.

Threshold exceeds 40 dB at radio frequencies and vanishes at optical frequencies.

Information rates are similar for both models below the threshold.

Abstract

The information rates achievable by using electromagnetic radiation affected by thermal noise and signal decoherence are studied. The standard coherent Gaussian model is compared with an alternative photon gas model which represents lack of a shared phase reference between transmitter and receiver. At any frequency, information rates over the photon gas model essentially coincide with those over the Gaussian model when the signal-to-noise ratio is below a threshold. Only above the threshold does decoherence cause a loss in information rates; the loss can amount to half of the capacity. The threshold exceeds 40 dB for radio frequencies and vanishes at optical frequencies.