Self-Consistent Extraction of Spectroscopic Bounds on Light New Physics.

Fundamental physical constants are determined from a collection of precision measurements of elementary particles, atoms, and molecules. This is usually done under the assumption of the standard model (SM) of particle physics. Allowing for light new physics (NP) beyond the SM modifies the extraction of fundamental physical constants.

A hybrid optical-wireless network for decimetre-level terrestrial positioning.

Global navigation satellite systems (GNSS) are widely used for navigation and time distribution, features that are indispensable for critical infrastructure such as mobile communication networks, as well as emerging technologies such as automated driving and sustainable energy grids. Although GNSS can provide centimetre-level precision, GNSS receivers are prone to many-metre errors owing to multipath propagation and an obstructed view of the sky, which occur particularly in urban areas where accurate positioning is most needed. Moreover, the vulnerabilities of GNSS, combined with the lack of a back-up system, pose a severe risk to GNSS-dependent technologies.

White Rabbit Precision Time Protocol on Long-Distance Fiber Links.

The application of White Rabbit precision time protocol (WR-PTP) in long-distance optical fiber links has been investigated. WR-PTP is an implementation of PTP in synchronous Ethernet optical fiber networks, originally intended for synchronization of equipment within a range of 10 km. This paper discusses the results and limitations of two implementations of WR-PTP in the existing communication fiber networks.

Direct frequency-comb spectroscopy of a dipole-forbidden clock transition in trapped 40Ca+ ions.

We demonstrate direct frequency-comb (FC) spectroscopy of the dipole-forbidden 4s(2)S(1/2)-3d(2)D(5/2) transition in trapped (40)Ca(+) ions using an unamplified FC laser. The excitation is detected with nearly 100% efficiency using a shelving scheme in combination with single-ion imaging. The method demonstrated here has the potential to reach hertz-level accuracy, if a hertz-level linewidth FC is used in combination with confinement in the Lamb-Dicke regime.

Determination of the ionization and dissociation energies of the hydrogen molecule.

The transition wave number from the EF (1)Sigma(g)(+)(v = 0, N = 1) energy level of ortho-H(2) to the 54p1(1)(0) Rydberg state below the X(+) (2)Sigma(g)(+)(v(+) = 0, N(+) = 1) ground state of ortho-H(2)(+) has been measured to be 25,209.99756 +/- (0.00022)(statistical) +/- (0.