A high-gain and high-fidelity coherent statecomparison amplifier

Donaldson, Ross J. and Mazzarella, Luca and Collins, Robert J. and Jeffers, John and Buller, Gerald S. (2018) A high-gain and high-fidelity coherent statecomparison amplifier. Communications Physics, 1. 54. ISSN 2399-3650 (https://doi.org/10.1038/s42005-018-0054-z)

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Optical signals are subject to a distance-dependent loss as they propagate through trans-mission media. High-intensity, classical, optical signals can routinely be amplified to over-come the degradation caused by this loss. However, quantum optical states cannot bedeterministically amplified and any attempt to do so will introduce intrinsic noise that spoilsthe desired quantum properties. Non-deterministic optical amplification, based on post-selection of the output depending on certain conditioning detection outcomes, is an emergingenabling technology in quantum measurement and quantum communications. Here wepresent an investigation into the properties of a simple, modular optical state comparisonamplifier operating on weak coherent states. This amplifier requires no complex quantumresources and is based on linear optical components allowing for a high amplification rate athigh gain andfidelity. We examine the amplifier’s performance in different configurations anddevelop an accurate analytical model that accounts for typical experimental scenarios.


Donaldson, Ross J., Mazzarella, Luca ORCID logoORCID: https://orcid.org/0000-0001-9173-3477, Collins, Robert J., Jeffers, John ORCID logoORCID: https://orcid.org/0000-0002-8573-1675 and Buller, Gerald S.;