Friction depends on speed A team of researchers from the SNI network has recent- ly shown that, on the nanometer scale, frictional forces depend on speed. The scientists from the Department of Physics (University of Basel) moved the tip of an atomic force microscope (AFM) over a monolayer of molybdenum disul昀椀de on a gold surface. They found that the friction between the AFM tip and the surface decreases over a broad speed range of 10 to 100 nanometers per second. SNI post: https://nanoscience.unibas.ch/en/news/details/reibung-haengt-von-geschwindigkeit-ab/ Original publication: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.133.136201 Researchers use an AFM to investigate friction on the nanometer scale over a monolayer of molybdenum disul昀椀de on a gold surface. (Image: Department of Physics, University of Basel) Strong coupling between Andreev qubits mediated by a microwave resonator Physicists from the University of Basel have succeeded in coupling two Andreev qubits coherently over a macro- scopic distance for the 昀椀rst time. They achieved this with the help of microwave photons generated in a narrow su- perconducting resonator. The results of the experiments and accompanying calculations were recently published in Nature Physics, laying the foundation for the use of coupled Andreev qubits in quantum communication and Andreev qubit coupler: The long microwave resonator (a) couples two quantum computing. Andreev qubits (left (b), right (c)). The port in the center of image (a) is the readout port. The magni昀椀cation of a single nanowire (d) gives an idea of the SNI post: tiny size of a single qubit. The nanowire is coated with a superconductor https://nanoscience.unibas.ch/en/news/details/starke-kopplung-zwischen-andreev-qu- bits-ueber-einen-mikrowellenresonator/ (cyan). The actual Andreev bound state, which forms the qubit states, is located in the central white section marked by the red arrow. There is also Original publication: a similar nanowire on the left quantum device. (Image: C. Schönenberger, https://www.nature.com/articles/s41567-024-02630-w Department of Physics, University of Basel) New method for determining the exchange energy of 2D materials Researchers from the University of Basel have looked at how the ferromagnetic properties of electrons in the two-dimensional semiconductor molybdenum disul昀椀de can be better understood. They revealed a surprisingly simple way of measuring the energy needed to 昀氀ip an electron spin. SNI post: https://nanoscience.unibas.ch/en/news/details/neue-methode-zur-bestimmung-der-aus- tauschenergie-bei-2d-materialien/ The two-dimensional semiconductor material molybdenum disul昀椀de Original publication: is 昀椀lled with electrons (red spheres). The electron-electron interaction https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.133.026501 causes the spins of all electrons (red arrows) to align in the same direc- tion. The exchange energy required to 昀氀ip a single electron spin in the ferromagnetic state can be determined by the separation between two speci昀椀c spectral lines. (Image: N. Leisgang, Harvard University, formerly Department of Physics, University of Basel/Scixel) SNI INSight December 2024 28