# Multimode quantum optics

Quantum Optics, as the child of Optics and Quantum Mechanics, has inherited a double linearity: that of Maxwell equations, which use optical modes as a basis of solutions, and that of the Schrödinger equation, which uses quantum state bases. Considering these two bases on an equal footing and tailoring quantum fields not only in given modes, but also optimizing the spatio-temporal shapes of the modes in which the state is defined, opens wide perspectives for treating complex quantum states. Our aim is to explore and characterize theoretically the quantum states that span on many optical modes (from several tens to several thousands) and many Hilbert space basis states, to unravel their intrinsic properties and to find optimized witnesses of different properties such as multi-entanglement. We also investigate the use of optimized multimode states for pushing the quantum limits of the multiplexed estimation of physical parameters and for increasing the channel capacity of optical communications.

## Femtosecond Quantum Information

## Quantum Complex Networks

## Modal approach to multi-parameter estimation

**The team!**

**News**

## Two side of the same coin: EPR steering and Wigner negativity

Einstein-Podolsky-Rosen steering is the quantum correlation in the Gaussian state, shared by Alice and Bob, that allows to remotely induce Wigner negativity.

## Open post-doc position – Quantum frequency combs for multimode non-Gaussian states with application to quantum metrology

Overview Our group, the multimode quantum optics group of Laboratoire Kastler Brossel, pioneered many aspects of continuous variable (CV) approach to quantum optics. Our main objects of interest are therefore the quadratures of the electric field, which are typically...

## Open PhD position – quantum complex communication networks

ERC consolidator grant COQCOoN ( PI: Valentina Parigi - valentina.parigi@lkb.upmc.fr) Complex network theory has provided a deep insight of complex systems, assembling theoretical tools able to the describe dynamical behavior of biological, social and technological...

## Non-Gaussian quantum states of a multimode light field

Quantum computers require a range of properties. First of all, we want them to be programmable to tackle a wide range of different problems. Furthermore, we also want them to be scalable, which means that we can put fundamental building blocks together to build a...

## Internship: steering non-Gaussian quantum states

The multimode quantum optics group has an open position for a theory internship to study the connection between quantum steering and non-Gaussian effects.

## New theory results

Members of our group published several new theoretical results early on in December 2019. A first result discusses the remote preparation of Wigner-negativity by using Einstein-Podolsky-Rosen steering. The second result was obtained by Francesca Sansavini during her...

## Permanent position Mattia Walschaers

Mattia Walschaers was awarded a permanent position as junior researcher (chargé de recherche) by the CNRS. He started this position in October 2019.

## ERC COQCOoN started

The project of COQCOoN - ERC Consolidator grant recently awarded to Valentina Parigi - started last June. We will deal with Continuous Variables Quantum Complex Networks. Follow future updates on our section Quantum Complex Networks.