Introduction to Nanomechanics Starts
On Wednesday the 18th, the Master-level lecture “Introduction to Nanomechanics” started. The lecture will take place every Wednesday from 10:00 to 12:00 in 1.22 until the 18th of December. The course (not surprisingly) focuses on the mechanics of very small objects. In particular, we will discuss the regime of nanometer-scale objects where classical theory begins to break down and quantum mechanical behavior emerges. In order to do so, we will touch on continuum mechanics, statistical mechanics, opto-mechanics, and quantum mechanics. After covering the fundamentals of the field, we will study its most important results up to and including contemporary work. We will discuss efforts to bring nanomechanical resonators into the quantum mechanical regime. We will also emphasize the most practical and successful applications of these devices, i.e. as sensors of force, mass, and displacement.
Masters Student Joins Group
Lukas Schneider joined our group as a Masters student in mid-September. Lukas received his Bachelor of Science in Nanoscience from the University of Basel in 2018. He carried out one of his two short Masters projects in our lab on magnetic nanowire (NW) sensors. He will continue work in this direction during his full Masters project, working on NW as scanning probe sensors.
Paper on Imaging Superconducting Vortices Published
On Thursday the 5th, Physical Review B, published our article entitled, Imaging pinning and expulsion of individual superconducting vortices in amorphous MoSi thin films. The manuscript reports the first images of individual superconducting vortices in thin films used in the production of sensitive photon detectors. Superconducting vortices are tiny whirl-like configurations of supercurrent, which flow around a non-superconducting core and allow a quantum of magnetic flux to penetrate a superconductor. Newly developed superconducting nanowire single photon detectors (SNSPDs) are fast, efficient, and extremely sensitive, making them attractive for many cutting-edge applications. How exactly they work, however, remains poorly understood. Recently, evidence has emerged that superconducting vortices are crucial both in the mechanism used for the detection of photons and in the generation of dark counts. For this reason, we used an ultra-sensitive nanometer-scale superconducting quantum interference device (SQUID) fabricated on the end of a sharp scanning probe – a so-called SQUID-on-tip – to investigate vortices in MoSi, one of the materials used in SNSPDs. The tiny scanning probe made images showing where the vortices appear, how they move, and how they get trapped – or ‘pinned’ – on defects in the material. The work suggests that control of the density and strength of these pinning sites is important for the optimization of SNSPD devices based on amorphous thin films. Given that vortex motion contributes to loss in many superconducting circuits – including those used as qubits in quantum computers – such experiments may prove useful on a variety of other superconducting circuits.
Ph.D. student Lorenzo Ceccarelli carried out the experiments, analyzed the data, and led the work. Early contributions were made by former post-doc Dr. Denis Vasyukov. Post-docs Dr. Marcus Wyss, Dr. Nicola Rossi, and Ph.D student Giulio Romagnoli made various contributions to the experiments with Nicola also contributing to the figures for the manscript. Post-doc Dr. Lucas Moser of the Meyer group carried out X-ray photoelectron spectroscopy of the MoSi samples.
New Department Chair
Effective on the 1st, Prof. Poggio took over from Prof. Dominik Zumbühl as the new Chair of the Department of Physics.