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arXiv · 2409.03473

Purification of Gaussian States by Photon Subtraction

Kun Zhang·Huijun Li·Jietai Jing·Nicolas Treps·Mattia Walschaers
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Abstract

Photon subtraction can enhance entanglement, which for pure states induces a decrease in the purity of reduced states. In contrast, by analyzing the purities of Gaussian states before and after subtracting a single photon, we prove that the purity of a Gaussian state can also be increased by less than 20%. On the one hand, it reveals that photon subtraction can reduce entanglement, and on the other hand, it reveals that it can achieve a limited amount of Gaussian state purification. Through the analysis of some examples, we demonstrate the inherent mechanism and applicable scope of photon-subtraction-based purification. In a multimode system, we find that photon subtraction can increase entanglement and purify some of the reduced states simultaneously. We thus present purification through the suppression of Gaussian noise as a new application for photon subtraction in continuous-variable quantum information processing.

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Kun Zhang, Huijun Li, Jietai Jing, Nicolas Treps, Mattia Walschaers. 2024-09-05. Purification of Gaussian States by Photon Subtraction. https://arxiv.org/abs/2409.03473

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