Switching ultrastrong light–matter coupling on a subcycle scale

Abstract

Intersubband cavitypolaritons in a quantum wellwaveguide structure are optically generated within less than one cycle of light by a 12-femtosecond near-infrared pulse. Mid-infrared probe transients trace the nonadiabatic switch-on of ultrastrong light-matter coupling and the conversion of bare photons into cavitypolaritons directly in the time domain. Future perspectives of room-temperature subcycle control of ultrastrong electron–photon interaction are discussed.