Experimental preparation of multiphoton-added coherent states of light

TL;DR

This paper reports the experimental creation of multiphoton-added coherent states, demonstrating their nonclassical properties and potential for noiseless quantum amplification, advancing optical quantum state engineering.

Contribution

It presents the first experimental implementation of adding multiple photons to coherent states and characterizes the resulting non-Gaussian quantum states.

Findings

Successfully added one, two, and three photons to coherent states.

Confirmed nonclassicality via Wigner function negativity.

Showed potential for noiseless quantum amplification.

Abstract

Conditional addition of photons represents a crucial tool for optical quantum state engineering and it forms a fundamental building block of advanced quantum photonic devices. Here we report on experimental implementation of the conditional addition of several photons. We demonstrate the addition of one, two, and three photons to input coherent states with various amplitudes. The resulting highly nonclassical photon-added states are completely characterized with time-domain homodyne tomography, and the nonclassicality of the prepared states is witnessed by the negativity of their Wigner functions. We experimentally demonstrate that the conditional addition of photons realizes approximate noiseless quantum amplification of coherent states with sufficiently large amplitude. We also investigate certification of the stellar rank of the generated multiphoton-added coherent states, which quantifies the non-Gaussian resources required for their preparation. Our results pave the way towards the experimental realization of complex optical quantum operations based on combination of multiple photon additions and subtractions.