Items tagged with "quantum hall effect"
When it comes to quantum physics, light and matter are not so different. Under certain circumstances, negatively charged electrons can fall into a coordinated dance that allows them to carry a current through a material laced with imperfections. That motion, which can only occur if electrons are confined to a two-dimensional plane, arises due to a phenomenon known as the quantum Hall effect.
From NIST-PML--JQI scientists have achieved a major milestone in simulating the dynamics of condensed-matter systems – such as the behavior of charged particles in semiconductors and other materials – through manipulation of carefully controlled quantum-mechanical models.
JQI researchers led by Mohammad Hafezi report detailed measurements of the transmission (how much energy is lost) and delay for edge-state light and for bulk-route light on a photonic chip.
In this week’s issue of Nature Photonics scientists at the Joint Quantum Institute (*) report the first observation of topological effects for light in two dimensions, analogous to the quantum Hall effect for electrons. To accomplish this, they built a structure to guide infrared light over the surface of a room temperature, silicon-on-insulator chip.
All materials are composed of the same basic stuff--atoms and their electrons. Atoms come in 118 different types, giving rise to enormous variation in material properties. For example, aluminum conducts electricity; add some oxygen and you get insulating aluminum oxide. One is shiny; the latter is whitish and dull.
An old material gets a new name, and with it, topological insulators have another chance to shine. Samarium hexaboride (SmB6) has been around since the late 1960s--but understanding its low temperature behavior has remained a mystery until recently. Experimentalists* have recently confirmed that this material is the first true 3D topological insulator—as originally predicted by JQI/CMTC☨ theorists in 2010.