We were recently awarded a $12.6M Energy Frontier Research Center by the U.S. Department of Energy. With our partner, SLAC National Accelerator Laboratory, we will pioneer several new quantum sensing techniques for studying elementary phenomena in quantum materials. These will include a scanning qubit microscope, a time-of-flight instrument for detecting Einstein-Podolsky-Rosen pairs of electrons, and an x-ray instrument for studying nonlinear optical response of materials at nonzero momentum.
We just finished a study demonstrating a way to use time-resolved RIXS to measure the collective exctiations of quantum materials, in this instance CDW-ordered La2-xBaxCuO4 (LBCO). The idea is to weakly perturb the system with a pump pulse and then measure the time evolution of the order parameter, which encodes the collective excitations of the system. The advantage of this technique is that the energy information comes from the time dynamics in a Fourier sense, allowing one to achieve extraordinarily high, sub-meV resolution. We found that the excitations in LBCO are overdamped and propagate diffusively, exhibiting dynamic critical scaling analogous to that observed in Oswald ripening in metal alloys in the 1980’s. The study, which was a collaboration with Nigel Goldenfeld’s group done at the new LCLS free electron laser facility at SLAC, was published in Science Advances.
Our paper on density fluctuations in Bi2Sr2CaCu2O8+x appeared in the Proceedings of the National Academy of Sciences. This study shows that, unlike conventional metals, this so-called “strange metal” does not exhibit propagating plasmons. Instead, it shows a continuum of fluctuations exhibiting “local scale invariance”–a phase in which time and space axes become decoupled. The origin of these fluctuations is still a mystery.
unlike conventional metals, this so-called “strange metal” does not exhibit propagating plasmons. Instead, it shows a continuum of fluctuations exhibiting “local scale invariance”–a phase in which time and space axes become decoupled. The origin of these fluctuations is still a mystery.