We build the quasiparticle picture for the tripartite mutual information (TMI) after quantum quenches in spin chains that can be mapped onto free-fermion theories. A nonzero TMI (equivalently, topological entropy) signals quantum correlations between three regions of a quantum many-body system. The TMI is sensitive to entangled multiplets of more than two quasiparticles, i.e., beyond the...

Superconducting circuits have recently emerged as a new platform to explore the physics of open many body systems using microwave photons in strongly non-linear media. In this talk, we will present some experimental results that were obtained in Orsay and in Grenoble where photons confined in a waveguide interact strongly through an impurity, here a Josephson junction. The system may be driven...

The success of Machine Learning owes to the development of neural-networks, variational approximators that can efficiently represent unknown functions living in high-dimensional spaces. Recently, those techniques have been ported to the field of numerical physics and used to approximate inherently high dimensional objects such as the Many-Body Wave-Function [1] or Density-Matrix [2] in an...

The experimental control of the coherent interaction between light and matter is one of the corner stones of the recent developments in the field of quantum technologies. In this context, cavity quantum electrodynamics has reached an important milestone in the last decade with the achievement of the ultrastrong coupling (USC) regime, where the coupling strength becomes comparable or even...

In this talk I will discuss the "entanglement" entropy growth dynamics in open spin models, comparing different matrix product representations of the many-body density matrix. Recently we discovered mechanisms behind a logarithmic growth of operator entanglement (OE) in XXZ model dynamics subjected to dephasing [1]. I will contrast this behavior to the growth of trajectory entanglement (TE),...

Superradiance of cold atoms in an optical cavity can be harvested to act as an optical frequency reference. By using an electronic transition much narrower spectrally than the cavity mode (i.e., by operating in the bad cavity limit), the frequency of the outcoming light is little affected by mirror position fluctuations – a signifiant limitation to short term stability in standard optical...

We will consider a parallel quantum dot as an example of an open quantum system that can feature a strong parity symmetry. For the dot, due to the presence of interactions, this symmetry results in the bistability characterised by distinct particle currents, while its explicit breaking leads to metastability. We will discuss when parameters of the dynamics can be estimated by continuously...