Information encoding in the spatial correlations of entangled twin beams

TL;DR

This paper demonstrates encoding information in the spatial correlations of entangled twin beams, leveraging phase matching and spatial properties to enhance quantum communication and sensing capabilities.

Contribution

It introduces a method to encode information in the spatial correlation distribution of multi-mode entangled light, controllable via the pump's angular spectrum.

Findings

Information encoded in spatial correlations can be extracted via far-field measurements.

Encoded information is inaccessible through individual beam measurements.

Temporal quantum correlations remain unaffected by the encoding process.

Abstract

The ability to use the temporal and spatial degrees of freedom of quantum states of light to encode and transmit information is crucial for the implementation of a robust and efficient quantum network. In particular, the large dimensionality of the spatial degree of freedom promises to provide significant enhancements; however, such promise has largely been unfulfilled as the necessary level of control over the spatial degree of freedom to encode information remains elusive. Here, we show that information can be encoded in the distribution of the spatial correlations of highly multi-spatial mode entangled bright twin beams. We take advantage of the dependence of the spatial correlations on the angular spectrum of the pump required for four-wave mixing, as dictated by phase matching. The encoded information can be extracted by mapping the momenta distribution of the twin beams to a position distribution in the far field and measuring the spatial cross-correlation of images acquired with a high quantum efficiency electron multiplying charge coupled device. We further show that the encoded information cannot be accessed through individual beam measurements and that the temporal quantum correlations are not modified. We anticipate that the ability to engineer the distribution of the spatial correlations will serve as a novel degree of freedom to encode information and hence provide a pathway for high capacity quantum information channels and networks. In addition, a high degree of control over the spatial properties of quantum states of light will enable real-world quantum-enhanced spatially resolved sensing and imaging applications.