New Research from Physics Faculty: Jensen, Doret, Majumder, Strauch

Recent research from the department:

Assistant Professor Kate Jensen co-authored a perspective article: “The contact mechanics challenge: tribology meets soft matter”, Robert W. Style, Brandon A. Krick, Katharine E. Jensen, and W. Gregory Sawyer, Soft Matter 2018.  Paper here.

Also from Prof. Jensen: “Strain-Dependent Solid Surface Stress and the Stiffness of Soft Contacts” by
Katharine E. Jensen, Robert W. Style, Qin Xu, and Eric R. Dufresne, Phys. Rev. X 7, 041031.  Paper here.

Summary:  Sticky notes, adhesive bandages, product labels, and packing tape are all examples of everyday objects that rely on soft adhesives. Despite their ubiquitous application, much remains unknown about the physics of soft contact. Meanwhile, it is often assumed that classic theories developed for much stiffer materials can be used to interpret experiments with soft materials. We present experiments that demonstrate that soft solids stick differently than their stiffer counterparts.

Key ImageOur experiment looks at the pull-off of small glass spheres from silicone gel substrates. We stick the spheres (ranging in diameter from about 16  μm to 64  μm) to the silicone gel and then slowly pull them back off. By measuring force and imaging the shape of the contact zone at the same time, we find that the surface of the gel contributes significantly to its stiffness. The role of the surface also becomes more pronounced as we pull more.  These findings change the way we think about soft contacts. In the future, a complete theory of soft adhesion will need to account for both elastic mechanics and strain-dependent solid surface stresses.

Assistant Professor Charlie Doret wrote “Simple, low-noise piezo driver with feed-forward for broad tuning of external cavity diode lasers”, Review of Scientific Instruments 89, 023102 (2018).  Paper here.

Professor Tiku Majumder and Dr. Dan Maser wrote “High-precision measurements and theoretical calculations of indium excited-state polarizabilities”, N. B. Vilas, B.-Y. Wang, P. M. Rupasinghe, D. L. Maser, M. S. Safronova, U. I. Safronova, and P. K. Majumder, Phys. Rev. A 97, 022507 (2018).  Paper here.  This includes the thesis work of Nathaniel Vilas ’17 (currently studying at the University of Cambridge) and Bing-Yi Wang ’18 (currently studying at Stanford University).

Associate Professor Fred Strauch and Will Kirby ’17 (currently studying at Tufts University) wrote “A practical quantum algorithm for the Schur transform”, Quantum Information and Computation 18, 0721-0742 (2018).  Preprint here.