The Lorentz transformation — a central component of our understanding of special relativity — is visualized for electromagnetic potentials in experiments with a highly energetic electron beam. This provides another test of special relativity and confirms its predictions.

See Ota et al.

Contact-electrification can lead to heterogeneous surface charge distributions called charge mosaics. Experiments and theory show that these arise from electrostatic discharges between the charged surface and the charger.

See Sobolev et al.

In active solids, work is performed by elastically coupled units. By studying a minimal experimental model of an active solid, actuation mechanisms resulting in a collectively oscillating displacement field that drives work cycles are identified.

See Baconnier et al. and Binysh and Souslov

Wrinkling happens because of mechanical instabilities arising from length mismatches. A theory now describes wrinkling in confined elastic shells, and is expected to be relevant for the controlled design of complex wrinkle patterns.

See Tobasco et al.

Measurements of the gravitational interaction between two parallel beams vibrating in bending motion enable the quantitative investigation of dynamic gravitation in the hertz regime and allow the determination of the gravitational constant.

See Brack et al. and Rothleitner

Mechanical resonators combined with superconducting circuits are a promising platform for controlling non-classical mechanical states. Here, this platform is used to directly measure the parity of a motional quantum state.

See von Lüpke et al. and Navarathna and Bowen

The change in a band structure when a magnetic field is applied should depend on the momentum of the electronic state, but this is hard to measure. Now, this effect is demonstrated in a topological magnet.

See Li et al.

Dark states of quantum systems do not absorb or emit light, removing a major source of decoherence. Four superconducting qubits in a waveguide can be combined to make a coherently controlled dark-state qubit with a long lifetime.

See Zanner et al. and Masson and Asenjo-Garcia

The dynamic relaxation spectrum of a supercooled liquid is asymmetric near the glass transition. Overcoming the difficulties of accessing low temperatures and long time scales, simulations now attribute this feature to dynamic facilitation.

See Guiselin et al. and Zorn

The beating of motile cilia arises from the collective action of hundreds of proteins. A study of the dynamics of cilia under different environmental and genetic conditions shows that the space of beating variations is low-dimensional.

See Geyer et al. and Wan

In its second measurement campaign, the Karlsruhe Tritium Neutrino experiment achieved a sub-eV sensitivity on the effective electron antineutrino mass.

See The KATRIN Collaboration and Nucciotti

Despite their relevance for quantum technology, photon-pair sources are difficult to control. A theoretical proposal shows how photon pairs can be created from vacuum fluctuations in time-dependent systems, potentially enabling heralded single-photon frequency combs.

See Sloan et al. and Talebi