Quantum simulator finds a ‘pseudogap’ in a model material

Researchers at Harvard University, Cambridge, MA, USA; JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado, USA have observed a transition between normal metallic behavior and a pseudogapped metal within a model material using a cold atom quantum simulator. This observation was made possible by a recent several-fold reduction in experimentally achievable temperatures, overcoming a key barrier to studying these complex states of matter. Measurements of the compressibility show a maximum versus doping that develops upon cooling, signaling an inflection point in the equation of state; lattice modulation spectroscopy then showed a non-uniform loss of spectral weight at low energies in the underdoped regime, indicating the formation of the pseudogap. The work demonstrates the utility of quantum simulation in addressing frontier problems in correlated electron physics and offers…