Time-domain approach to quantum optics

Quantum optics is traditionally described in the frequency domain yet the time-domain perspective arguably can offer some advantages for technological implementation, from quantum computing to communication and sensing. In this talk, I will review a special realization of time-domain quantum optics where the temporal resolution of the state under study is obtained on intervals shorter than the oscillation cycle of light. I will review the experimental results of subcycle sampling of the variance of the amplitude quadrature of a bare vacuum state at mid-infrared frequencies. A route toward subcycle quantum state tomography as well as a sampling of high-order statistical moments will be also reviewed. I will conclude with a brief discussion of fundamental applications and give an overview of the mid-infrared sensing technologies where subcycle quantum optics is poised to uncover new opportunities.