Experimental investigation of heralded Gaussification of phase-randomized coherent states of light

TL;DR

This paper experimentally investigates the convergence behavior of heralded Gaussification of phase-randomized coherent states, demonstrating the process with multiple iterations and analyzing the resulting quantum states.

Contribution

It provides the first experimental implementation of iterative heralded Gaussification with phase-randomized coherent states, offering new insights into its convergence properties.

Findings

Experimental verification of Gaussification convergence.

Good agreement between experimental results and theoretical predictions.

Enhanced understanding of iterative quantum state processing.

Abstract

Probabilistic heralded Gaussification of quantum states of light is an important ingredient of protocols for distillation of continuous variable entanglement and squeezing. An elementary step of heralded Gaussification protocol consists of interference of two copies of the state at a balanced beam splitter, followed by conditioning on outcome of a suitable Gaussian quantum measurement on one output mode. When iterated, the protocol either converges to a Gaussian state, or diverges. Here we report on experimental investigation of the convergence properties of iterative heralded Gaussification. We experimentally implement two iterations of the protocol, which requires simultaneous processing of four copies of the input state. We utilize the phase-randomized coherent states as the input states, which greatly facilitates the experiment, because these states can be generated deterministically and their mean photon number can easily be tuned. We comprehensively characterize the input and partially Gaussified states by balanced homodyne detection and quantum state tomography. Our experimental results are in good agreement with theoretical predictions and they provide new insights into the convergence properties of heralded quantum Gaussification.