A panoramic shot of the Advanced Cold Molecule Electron EDM, a device in the laboratory of Silsbee professor of physics John Doyle that is designed to make measurements of the quantum physical behavior of electrons so precise that the results could change understanding of the Standard Model of quantum physics. [Photograph courtesy of John Doyle/Harvard Research Center for Quantum Optics.]
Researchers excited and detected spin waves in a quantum Hall ferromagnet, spending them through the insulating material like waves in a pond. (Image courtesy of Second Bay Studios/Harvard SEAS)
Quantum Hall ferromagnets are among the purest magnets in the world — and one of the most difficult to study. These 2D magnets can only be made in temperatures less than a degree above absolute zero and in high magnetic fields, about the scale of an MRI.
Fig. 5. Localization of the other set of constructed Wannier functions.*
In the last few months, researchers have discovered that twisted bilayer graphene—two sheets of graphene layered at a slight angle to one another—can behave as either a superconductor or a type of insulator. An exciting aspect of this realization is that the behavior is selectable: By simply changing an applied voltage, it is possible to go from insulator to superconductor and back.
The spin state of a diamond defect known as a nitrogen-vacancy (NV) center is highly sensitive to a magnetic field. As such, NV centers can be used as tiny magnetometers. However, sequential measurements are needed to detect each spatial component of a magnetic field, limiting the use of these devices. Now, Dr. Ronald Walsworth and colleagues from Harvard Center for Brain Science have created an NV-center magnetometer that simultaneously measures all three spatial components of a magnetic field. The new device is 4 times faster than existing diamond-defect magnetometers and can measure fields that are 2 times smaller in strength...
Fig. 1 from J. Perczel et al., Phys. Rev. A (2018)
Nearly 150 years ago, the physicist James Maxwell proposed that a circular lens that is thickest at its center, and that gradually thins out at its edges, should exhibit some fascinating optical behavior. Namely, when light is shone through such a lens, it should travel around in perfect circles, creating highly unusual, curved paths of light.