Quantum electrodynamics with many-body states in confined systems
Angele Vasanelli1, S. Huppert1, Y. Todorov1, D. Gacemi1, G. Beaudoin2, I. Sagnes2 and C. Sirtori1
1 Université Paris-Diderot, Sorbonne Paris Cité, Laboratoire “Matériaux et phénomènes quantiques”, UMR 7162, 75013 Paris, France
2 Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, UMR9001, Université Paris-Saclay, C2N Marcoussis, F-91460, France
Elementary excitations in dense media are renormalized by their mutual interaction, giving rise to quasiparticles with new collective properties. Such renormalization occurs for instance in highly doped semiconductor layers where Coulomb interaction ties together all the single electronic excitations and gives rise to a bright collective mode [1] that carries a huge dipole perpendicular to the quantum well plane.
In the past few years we have investigated electronic many-body states in quantum wells as a valuable platform to probe some of the most fundamental phenomena of quantum electrodynamics, which are usually the realm of atomic physics. Indeed each many-body electronic state is a bosonic quasi-particle confined perpendicularly to the plane of the quantum well. While considering the first two energy levels of the harmonic ladder, the quasi particle can be regarded as a macro-atom carrying all the interaction with the electromagnetic field [2]. Identical macro-atoms located in spatially separated quantum wells, within a sub-wavelength distance, have a huge interaction with the vacuum field by exchanging real and virtual photons [3]. This results into a superradiant mode displaying a large cooperative Lamb shift [4]. Furthermore, we have demonstrated that when a macro-atom is coupled to a microcavity mode, the ultra-strong light-matter coupling regime [5] can be achieved up to room temperature, with a record value of 92% of the relative Rabi energy [6].
All these fundamental quantum effects have been investigated in optoelectronic devices [7], paving the way towards a new generation of devices in which light-matter interaction is tailored by collective phenomena.
References
[1] A. Delteil et al., Phys. Rev. Lett. 109, 246808 (2012).
[2] S. Huppert et al., Phys. Rev. B 94, 155418 (2016)
[3] M. O. Scully, Phys. Rev. Lett. 102, 143601 (2009)
[4] G. Frucci, et al. New Journal of Physics 19, 043006 (2017)
[5] C. Ciuti et al., Phys. Rev. B 72, 115303 (2005).
[6] B. Askenazi et al., New Journal of Phys. 16, 043029 (2014); B. Askenazi et al., ACS Photonics 4, 2550 (2017)
[7] T. Laurent et al., Phys. Rev. Lett. 115, 187402 (2015