https://phys.org/news/2020-08-vacuum-fluctuations-space.html An international research team from Germany and France has created structures in which light fields interact with electrons so strongly that the quantum vacuum itself is significantly altered. Using extremely short bursts of light, they interrupted this coupling much faster than the timescale of a vacuum fluctuation and observed an intriguing ringing of the emitted electromagnetic field, indicating the collapse of the vacuum state. Their key achievement could improve our understanding of the nature of nothingness—the vacuum of space itself, paving a way toward photonics exploiting vacuum fluctuations. The results are published in the current issue of Nature Photonics. One of the key insights of quantum mechanics is that absolute nothingness, a concept already discussed by Greek philosophers, is nowhere to be found in reality. Quite to the contrary, quantum field theory has shown that seemingly empty space is filled by fluctuations of light and matter fields, leading to a continuous popping into existence and disappearance of photons as well as massive particles. In the founding days of quantum mechanics, these consequences of Heisenberg's uncertainty principle were often not taken too seriously. However, modern physics is increasingly discovering how our universe is shaped by fluctuations of physical fields, which not only lead to tiny shifts of spectral lines of atoms, but moreover may cause the evaporation of black holes, and are ultimately responsible for the large-scale structure of our universe, formed during the inflationary period following the big bang. Yet controlling these fluctuations on a laboratory scale with the relevant temporal precision has remained extremely challenging to this date. more at link... the paper: https://www.nature.com/articles/s41566-020-0673-2 Non-adiabatic stripping of a cavity field from electrons in the deep-strong coupling regime: Abstract Atomically strong light pulses can drive sub-optical-cycle dynamics. When the Rabi frequency—the rate of energy exchange between light and matter—exceeds the optical carrier frequency, fascinating non-perturbative strong-field phenomena emerge, such as high-harmonic generation and lightwave transport. Here, we explore a related novel subcycle regime of ultimately strong light–matter interaction without a coherent driving field. We use the vacuum fluctuations of nanoantennas to drive cyclotron resonances of two-dimensional electron gases to vacuum Rabi frequencies exceeding the carrier frequency. Femtosecond photoactivation of a switch element inside the cavity disrupts this ‘deep-strong coupling’ more than an order of magnitude faster than the oscillation cycle of light. The abrupt modification of the vacuum ground state causes spectrally broadband polarization oscillations confirmed by our quantum model. In the future, this subcycle shaping of hybrid quantum states may trigger cavity-induced quantum chemistry, vacuum-modified transport or cavity-controlled superconductivity, opening new scenarios for non-adiabatic quantum optics.
