Time-domain quantum optics

Inspired by recent breakthrough measurements of the quantum vacuum fluctuations of the electric field [1], we are developing a new theoretical framework for time-dependent quantum optics [2-4]. This theory enables a description of the formation and dynamics of the squeezed quantum vacuum of the electromagnetic field on ultrashort timescales that span only a few or approximately one optical cycle [5] (Figure 1). Introducing the concept of conformal time into quantum optics, our formalism builds on analogies with general relativity. Our theory framework also applies to quantum correlation measurements in the terahertz frequency regime [6].

Figure (a) Setup illustrating the time-flow perspective of sub-cycle squeezing, showing the generation and detection of the quantum field ε(z,t) inside the nonlinear crystal [5].
(b) Horizontal plane: grey lines depict the world lines for ε(z,t) determined by τz,t=const. for the case of a half-cycle driving field. Vertical plane: field enhancement at the crystal exit is shown together with the final spacing between the world lines.

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[2] A. S. Moskalenko, C. Riek, D. V. Seletskiy, G. Burkard, and A. Leitenstorfer, Phys. Rev. Lett. 115, 263601 (2015)
[3] C. Riek, P. Sulzer, M. Seeger, A.S. Moskalenko, G. Burkard, D.V. Seletskiy, and A. Leitenstorfer, Nature 541, 376 (2017)
[4] T. Lucena de M. Guedes, M. Kizmann, D.V. Seletskiy, A. Leitenstorfer, G. Burkard, and A. S. Moskalenko, Phys. Rev. Lett. 122, 053604 (2019)
[5] M. Kizmann, T. Lucena de M. Guedes, D. V. Seletskiy, A. S. Moskalenko, A. Leitenstorfer, and G. Burkard, Nature Phys. 15, 960 (2019)
[6] I.-C. Benea-Chelmus, F. F. Settembrini, G. Scalari, and J. Faist, Nature 568, 202 (2019)