Noise excess free record/upload of non-classical states to continuous-variable quantum memory

TL;DR

This paper proposes a deterministic, noise excess free method for recording unknown non-classical quantum states into a continuous-variable quantum memory, enhancing fidelity through pre-squeezing and post-correction techniques.

Contribution

It introduces a novel approach for noise-free, deterministic storage of non-classical states in quantum memory, including methods for pre-squeezing and post-correction, and probabilistic upload of complex states.

Findings

Deterministic noise excess free recording of unknown quantum states.

Enhanced fidelity with pre-squeezing and post-correction.

Probabilistic upload of non-classical states approaching lossless transfer.

Abstract

In a recent continuous-variable quantum memory experiment, one quadrature of light pulse is directly uploaded by the light-atom coupling whereas complementary quadrature is obtained by homodyne measurement of the out-coupled light. Subsequently, information from homodyne mea- surement is written into the memory by feed-back electro-optical control of the atomic state. Using the same experimental set-up, a deterministic noise excess free record of unknown quantum states to continuous-variable quantum atomic memory is proposed. Further, the memory experiment is extended by the pre-squeezing of the recorded state of light and squeezing post-correction of the recorded state. To upload a resource to the memory, as single-photon state or superposition of co- herent states, the post-selection of the measurement results from homodyne detection is suggested. Then such the probabilistic upload approaches even a lossless transfer of these highly nonclassical states into the quantum memory.