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Accueil > Événements > Actualités > Séminaire

Séminaire interne LPMMC

Benoît Vermersch (LPMMC)
Quantum optics with many-body systems of atoms and photons: From quantum networks to entanglement measurement
Lieu : Salle de lecture 2, maison des Magistères,
le jeudi 22 juin 2017 à 13h30
Personne à contacter : Vincent Rossetto ()

The physics of light-matter interactions plays a fundamental role for two important research areas in quantum technology: quantum information and quantum simulation. On the one hand, quantum optics theory allows to design robust protocols for the processing of quantum information in quantum networks. On the other hand, in the context of quantum simulation, light-assisted interactions between atoms provide the toolbox to prepare and probe many-body phases of complex Hamiltonians, which are related to long-standing problems in condensed matter (e.g. quantum magnetism or fractional quantum Hall states).

In this talk, I will discuss these two topics. I will present our recent results on quantum information processing in quantum networks, and on the engineering of new tools for quantum simulation. At the technical level, I will show how we combine atomic physics, quantum optical techniques and numerical methods borrowed from condensed matter physics (such as Matrix-Product-State (MPS) techniques) to study these types of complex open many-body systems.

In the first part I will discuss some of our works related to photonic quantum networks. After a general introduction, I will present a theoretical description of these systems based on the formalism of waveguide QED. This will then allow me to present recent results on the development of robust Quantum State Transfer protocols [1,2,3], and to introduce our MPS techniques for the description of the dynamics of quantum networks beyond the standard treatment of quantum optics.

The second part of the seminar will be devoted to quantum simulators. I will first explain the challenge of measuring entanglement, which is essential to characterize various phases in condensed matter physics (such as Fractional Quantum Hall effect or Haldane phase). I will then show how to measure the entanglement spectrum of ground states of generic Hamiltonians based on direct engineering of the entanglement Hamiltonian [4]. Our method, based on the Bisognano-Wichmann theorem [5], allows one to measure entanglement spectra via standard spectroscopy and can be implemented in all quantum simulation platforms. I will provide numerical examples to support this result and give examples of AMO implementations of entanglement Hamiltonians. If time allows, I will present a complementary method based on Random Matrix Theory, which would allow to measure the entanglement growth in a many-body localised (MBL) system [6].

  • [1] C Dlaska, BV and P. Zoller et al Quantum Sci. Technol. 2 015001 (2017).
  • [2] BV, PO Guimond, H. Pichler and P. Zoller et al Phys. Rev. Lett. 118, 133601 (2017).
  • [3] Berit Vogell, BV, T. Northup, B. Lanyon and C. Muschik arxiv:1704.06233.
  • [4] M. Dalmonte, BV and P. Zoller, in preparation.
  • [5] Bisognano and Wichmann, J. Math. Phys. 17, 303 (1976).
  • [6] BV, A. Elben and P. Zoller, in preparation.