Quantum reading of digital memory with non-Gaussian entangled light

TL;DR

This paper demonstrates that non-Gaussian entangled light can outperform classical light in reading digital memory, especially at low signal intensities, by discriminating between ideal and thermal noise channels.

Contribution

It introduces a quantum readout model using non-Gaussian entangled states for binary memory discrimination, focusing on ideal and thermal noise channels, and shows improved performance over classical sources.

Findings

Entangled light outperforms classical light in memory reading at low signal levels.

Non-Gaussian entangled states are effective for discriminating between identity and thermal noise channels.

Quantum advantage is demonstrated in a simplified model with ideal and thermal noise channels.

Abstract

It has been shown recently (Phys. Rev. Lett. 106, 090504 (2011)) that entangled light with Einstein-Podolsky-Rosen (EPR) correlations retrieves information from digital memory better than any classical light. In identifying this, a model of digital memory with each cell consisting of reflecting medium with two reflectivities (each memory cell encoding the binary numbers 0 or 1) is employed. The readout of binary memory essentially corresponds to discrimination of two Bosonic attenuator channels characterized by different reflectivities. The model requires an entire mathematical paraphernalia of continuous variable Gaussian setting for its analysis, when arbitrary values of reflectivities are considered. Here we restrict to a basic quantum read-out mechanism with non-Gaussian entangled states of light, with the binary channels to be discriminated being ideal memory characterized by reflectivity one i.e., an identity channel and thermal noise channel, where the signal light illuminating the memory location gets completely lost (zero reflectivity) and only a white thermal noise hitting the upper side of the memory reaches the decoder. We compare the quantum reading efficiency of entangled light with any classical source of light in this model. We show that entangled transmitters offer better reading performance than any classical transmitters of light in the regime of low signal intensity.