# Multiphoton Quantum-State Engineering using Conditional Measurements

## TL;DR

This paper presents a method to engineer multiphoton quantum states with tunable correlations using conditional measurements on two-mode squeezed vacuum states, advancing quantum optics and potential applications in entangled lasers.

## Contribution

It introduces a novel photon subtraction technique to generate and control quantum-correlated multiphoton states with high-dimensional properties.

## Key findings

- Generated multiphoton states with tunable correlations.
- Demonstrated nearly Poissonian photon statistics.
- Paved the way for entangled laser development.

## Abstract

The quantum theory of electromagnetic radiation predicts characteristic statistical fluctuations for light sources as diverse as sunlight, laser radiation and molecule fluorescence. Indeed, these underlying statistical fluctuations of light are associated with the fundamental physical processes behind their generation. In this contribution, we demonstrate that the manipulation of the quantum electromagnetic fluctuations of a pair of vacuum states leads to a novel family of quantum-correlated multiphoton states with tunable mean photon numbers and degree of correlation. Our technique relies on the use of conditional measurements to engineer the excitation mode of the field through the simultaneous subtraction of photons from two-mode squeezed vacuum states. The experimental generation of multiphoton states with quantum correlations by means of photon subtraction unveils novel mechanisms to control fundamental properties of light. As a remarkable example, we demonstrate the engineering of a quantum correlated state of light, with nearly Poissonian photon statistics, that constitutes the first step towards the generation of entangled lasers. Our technique enables a robust protocol to prepare quantum states with multiple photons in high-dimensional spaces and, as such, it constitutes a novel platform for exploring quantum phenomena in mesoscopic systems.