Fundamental physics

B.1.1 | Detecting Radiation From Strong Electron Acceleration In High-Intensity Laser Fields

B.1.2 | Towards optical access to the lowest nuclear excitation in ²²⁹Th

B.1.3 | Laser frequency combs and new frontiers of precision spectroscopy

B.1.4 | Precise laser spectroscopy of antimatter atoms, and metrological determination of the proton-to-electron mass ratio

B.1.5 | Frequency Comb based Fourier Transform Spectroscopy

Exploiting novel light sources and technologies for fundamental physics studies represents an important part of MAP's research spectrum. The ultra-high fields of high-power short-pulse lasers may - for the first time - grant experimental access to understanding fundamental properties of the quantum vacuum and quantum theory in non-inertial frames.
Gamma radiation components originating from the ultrastrong laser-driven acceleration of electrons are investigated, comprising classical Larmor radiation as well as entangled photon pairs expected from the Unruh effect (i.e. an analogy to Hawking radiation of a black hole) where laser-accelerated electrons experience the vacuum as a thermal bath
characterised by the Unruh temperature.

Moreover, the isotope ²²⁹Th is studied, which exhibits the lowest nuclear excited state (7.6(5) eV). Aiming at an optical control of its ground state decay (relative width 10^-20) could enable an all-optical nuclear clock with unprecedented accuracy and enhance the sensitivity to search for a potential time variation of fundamental constants by orders of magnitude. Further projects exploit the unprecedented frequency precision achievable with the laser frequency comb technique to explore and push the limits of precision laser spectroscopy.
Investigating the interference between two independent frequency comb sources and applying the novel comb-based Fourier Transform Spectroscopy technique (FTS) allows for an improvement of about 6 orders of magnitude in resolution, sensitivity and data acquisition time over conventional techniques.
Laser spectroscopy of anti-matter atoms, especially of the determined the ratio between the 'antiprotonic helium', i.e. the 3-body system formed of an anti-proton, an electron and a He nucleus has been used to determine the ratio between the antiproton and electron mass to a precision of better than 1 part in 100 million, while still working towards a further
improvement.

Major goals:

• First experiments aiming at the identification of gamma radiation components from extremely strong acceleration originating from the ultra-strong fields of high-intensity, short-pulse lasers, e.g. linear Larmor radiation, radiation damping components, photon pairs from the Unruh effect.

• Experiments towards bridging the gap between laser and nuclear physics by the first optical control of a nuclear transition in the lowest excited nuclear state in the isotope ²²⁹Th. This uniquely sharp transition bears the potential to built an all-optical nuclear clock or to search for potential time variations of fundamental constants (e.g. fine structure constant alpha).

• Exploring the limits of precision laser spectroscopy using laser frequency combs by characterizing the spectral properties and limits of high-harmonic frequency combs. Novel spectroscopic techniques will be explored that can extend the present ones into new spectral territory.

• Synthesize artificial atoms made of antimatter particles, and study their properties at the highest possible precision using the most advanced laser spectroscopic techniques.

• Explore the intriguing potential of frequency comb based Fourier Transform Spectroscopy for vibrational and electronic spectroscopy.