Scientists visualise quantum behaviour of hot electrons for first time
30 September 2016

Such was the title of the University of Birmingham’s Press Release on Wednesday (28 Sept) to accompany the publication of NPRL’s latest paper in Nature Communications, another result of our very fruitful collaboration with Bath. The paper demonstrates coherent expansion of the wavefunction, over a diameter of 15nm at room temperature, when hot electrons are injected into the Si(111)-7x7 surface from an STM tip. Beyond that range the transport is diffusive, as shown in last year’s Nature Comms. The transport of the charge carriers was visualised by the desorption of probe toluene molecules from the surface (which occurs due to electron capture/scattering). As Richard explained in the Press Release: “When an electron is captured by a molecule of toluene, we see the molecule lift off from the surface – imagine the Apollo lander leaving the moon’s surface. By comparing before and after images of the surface we measure the pattern of these molecular launch sites and reveal the behaviour of electrons in a manner not possible before. These findings are, crucially, undertaken at room temperature. They show that the quantum behaviour of electrons which is easily accessible at close to absolute zero temperature (-273°C!) persist under the more balmy conditions of room temperature and over a “large” 15 nanometre scale. T hese findings suggest future atomic-scale quantum devices could work without the need for a tank of liquid helium coolant.” The video shown is a computer simulation of the expansion of the wavefunction. The original paper is here. Richard likes to compare the mechanism with the inflation model of the Big Bang… quantum inflation on the Nanoscale?