High Resolution Laser Spectroscopy of Atomic Hydrogen and Deuterium

Discrepancies between theory and experiments have been fueling the development of physics.

Today, Quantum Electrodynamics (QED) is the most accurate theory and served as a blueprint for all subsequent field theories. Physics beyond the Standard Model must exist as we know from observations of the cosmos.

It is likely to be found where no one has looked before, i.e., at very large energies, high sensitivity, or high precision.

To progress with the so-called precision frontier, high resolution spectroscopy of atomic hydrogen and hydrogen-like systems continues to play a decisive role because their simplicity.

Testing QED means to verify the consistency of parameters that enter this theory as they are obtained from as many different measurements as possible. Spectroscopic data also provides the input for the determination of the best values for the fundamental constants.

The largest leverage for the determination of the Rydberg constant is currently due to the 1S-3S transition frequency that we want to improve in the framework of this proposal. A second apparatus provides a cold metastable 2S beam of atomic hydrogen and deuterium.

This will be used in a series of measurements between the 2S and nP states as well as two-photon transitions between 2S and nS/nD states (with n=3…10).

The same apparatus can be used to remeasure the 1S-2S transition frequency as an improved result from anti-hydrogen is expected. The work with the spectrometers builds on proven technologies.

To go further we are proposing a method to trap atomic hydrogen in an optical dipole trap that operates at the magic wavelength. The proposed scheme avoids a cooling laser and will not be more complex than existing optical lattice clocks. It could eliminate all leading systematics for the above-mentioned transitions.

Moreover, it could be employed as a computable clock to redefine the SI by fixing the value of the Rydberg constant. The new SI system would then be based exclusively on defined constants.