The interaction between a single confined spin Even though recent experiments have established this system as a new paradigm for solid-state quantum optics, all of the striking experimental observations to date could be understood within the framework of single-or few-particle physics enriched by perturbative coupling to reservoirs involving either phonons, a degenerate electron gas [7,8], or nuclear spins [9,10]).We present differential transmission (DT)

Light-matter interaction has played a central role in understanding as well as engineering new states of matter. Reversible coupling of excitons and photons enabled groundbreaking results in condensation and superfluidity of nonequilibrium quasiparticles with a photonic component. We investigated such cavity-polaritons in the presence of a high-mobility two-dimensional electron gas, exhibiting strongly correlated phases. When the cavity was on resonance with the Fermi level, we observed previously unknown many-body physics associated with a dynamical hole-scattering potential. In finite magnetic fields, polaritons show distinct signatures of integer and fractional quantum Hall ground states. Our results lay the groundwork for probing nonequilibrium dynamics of quantum Hall states and exploiting the electron density dependence of polariton splitting so as to obtain ultrastrong optical nonlinearities.

We demonstrate dispersion compensation in mid-infrared quantum cascade laser frequency combs (FCs) emitting at 7.8 μm using the coupling of a dielectric waveguide to a plasmonic resonance in the top cladding layer of the latter. Devices with group velocity dispersion lower than 110  fs²/mm were fabricated, and narrow beatnotes with FWHM linewidths below 1 kHz were measured on the entire operation range. At -20°C, the optical output power reaches 275 mW, and the optical spectrum spans 60  cm^-1. The multi-heterodyne beating spectrum of two devices was measured and spans 46  cm^-1, demonstrating the potential of dispersion-engineered waveguides for the fabrication of highly stable and reliable quantum cascade laser FCs with high output power across the mid-infrared.

No abstract