Ultrastrong coupling in the near field of complementary split-ring resonators

Abstract

The ultrastrong light-matter interaction regime was investigated in metallic and superconducting complementary split ring resonators coupled to the cyclotron transition of two dimensional electron gases. The sub-wavelength light confinement and the large optical dipole moment of the cyclotron transition yield record high normalized coupling rates of up to Ω R ωc = 0.87. We observed a blue-shift of both polaritons due to the diamagnetic term of the interaction Hamiltonian. arXiv:1408.3547v1 [cond-mat.mes-hall]

Continuously tunable ultrastrong light-matter interaction

“…We employ complementary SRR [2,10] which are formed by a 255 nm thin metal film composed of a 5 nm thin Titanium adhesion layer followed by 230 nm Copper and 20 nm Gold to avoid oxidation of the Copper. Figure 3 a) shows the microscope picture of four resonators together with its dimensions.…”

“…where is the electric field associated to vacuum fluctuations of the electromagnetic mode, is the dipole moment of the matter excitation, and denotes the number of electric transitions coupled to the same electromagnetic mode [2]. The THz frequency range is predestined for experiments in this ultrastrong coupling regime due to the large dipole moments of the matter excitations and high density of electrons with the same transition energy which can be achieved.…”

Magneto-optic transmittance modulation observed in a hybrid graphene–split ring resonator terahertz metasurface

“…Indeed, the electric actuation can be achieved in an integrated fashion: the electrostatic biasing needed to tune the Fermi energy of graphene can be applied in metamaterial surfaces exploiting the patterned metal itself, provided that it is arranged in a connected geometry (thanks to the complementary metasurface approach, this is not an issue even for SRR structures 30,31 ). This effect, in conjunction with the non-diagonal conductivity response of magnetostatically biased graphene, could lead to functional devices working towards the quantum regime where certain figures of merit like the Faraday rotation angle may reach anomalously large values.…”

Perspectives for gapped bilayer graphene polaritonics

“…The boundary between the two, that is conventionally fixed at ΩR ωx = 0.1, was in fact the coupling value that allowed for the first observation of ultrastrong coupling effects [57]. The ultrastrong coupling regime has been since then observed in a variety of different systems [58][59][60][61][62][63][64][65], with an actual record of ΩR ωx = 0.87 [66]. Excitons in GBG could be very interesting in this regards, a priori allowing to reach or even improve such a record.…”