Multi-step two-copy distillation of squeezed states via two photon subtraction

Abstract

Squeezed states of light have been improving the sensitivity of gravitational-wave observatories and are nonclassical resources of quantum cryptography and envisioned photonic quantum computers. The higher the squeeze factor is, the higher is the quantum advantage. Almost all applications of squeezed light require multi-path optical interference, whose unavoidable imperfections introduce optical loss, degrade the squeeze factor, as well as the quantum advantage. Here, for the first time, we experimentally demonstrate the distillation of Gaussian squeezed states that suffered from Gaussian photon loss. Our demonstration already involves two distillation steps. The first step improved the squeeze factor from 2.4 dB to 2.8 dB by the subtraction of two photons. The second step improved the value from 2.8 dB to 3.4 dB by a Gaussification protocol. It was realised on data measured at different times via an 8-port balanced homodyne detector and via data post-processing. The number of distillation steps can be increased by longer data sampling times, without additional hardware. We propose and discuss the application to quantum cryptography and photonic quantum computers.

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Cited by in corpus (8)

• Experimental preparation of multiphoton-added coherent states of light
• Extended analysis of distillation and purification of squeezed states of light
• Optimal sensing of photon addition and subtraction on nonclassical light
• Advantage of probabilistic non-Gaussian operations in the distillation of single mode squeezed vacuum state
• Nonclassical resource for continuous variable telecloning with non-Gaussian advantage
• Re-examination of the role of displacement and photon catalysis operation in continuous variable measurement device-independent quantum key distribution
• Experimental investigation of heralded Gaussification of phase-randomized coherent states of light
• Simplified scheme for continuous-variable entanglement distillation: multicopy distillation of Gaussian entanglement without heralding Gaussian measurements