Holography of the Dirac Fluid in Graphene with Two Currents

January 18, 2017

Recent experiments have uncovered evidence of the strongly coupled nature of graphene: the Wiedemann-Franz law is violated by up to a factor of 20 near the charge neutral point. Profs. Philip Kim and Subir Sachdev and colleagues from Hanyang University, Seoul, described this strongly coupled plasma in a recent article in PRL. Their description uses a holographic model in which there are two distinct conserved U(1) currents.


Using Quantum Defects in Diamond to Sense the Magnetic Fields of Firing Neurons

November 30, 2016

Magnetic fields from neuronal action potentials (APs) pass largely unperturbed through biological tissue, allowing magnetic measurements of AP dynamics to be performed extracellularly or even outside intact organisms. To date, however, magnetic techniques for sensing neuronal activity have either operated at the macroscale with coarse spatial and/or temporal resolution - e.g., magnetic resonance imaging methods and magnetoencephalography - or been restricted to biophysics studies of excised neurons probed with cryogenic or bulky detectors that do not provide single-neuron spatial resolution and are not scalable to functional networks or intact organisms.


The Future of Primordial Features with Large-Scale Structure Surveys

November 16, 2016

Primordial features are one of the most important extensions of the Standard Model of cosmology, providing a wealth of information on the primordial Universe, ranging from discrimination between inflation and alternative scenarios, new particle detection, to fine structures in the inflationary potential. Prof. Cora Dvorkin and colleagues from Harvard-Smithsonian CfA, Sun Yat-Sen University, and University of Barcelona published an article in Journal of Cosmology and Astroparticle Physics in which they examine the prospects of future large-scale structure (LSS) surveys on the detection and constraints of these features.


Atom-by-Atom Assembly of Defect-Free One-Dimensional Cold Atom Arrays

November 7, 2016

This image shows the basic setup that enables researchers to use lasers as optical “tweezers” to pick individual atoms out from a cloud and hold them in place. The atoms are imaged onto a camera, and the traps are generated by a laser that is split into many different focused laser beams. This allows a single atom to be trapped at each focus. [Image reprinted with permission from AAAS ©2016]