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.