Engineering Hamiltonians in the Laboratory: Many-body Physics in Semiconductor Nanostructures David Golhaber-Gordon, Assistant Professor of Physics, Experimental Condensed Matter, Stanford University

In principle, every electron in a solid can feel every other electron through the long-range Coulomb interaction. The complexity of this many-body system prohibits brute force prediction of the diverse behavior of real materials, from superconductors to magnets. However, simplified theoretical models with phenomenological parameters have successfully explained many properties of solids. Recent developments in nanotechnology allow experimentalists to rigorously test such theoretical models: we build a realization of a model and measure and tune its most important parameters in situ. In this talk, I will present transport measurements on a novel semiconductor nanostructure designed to display many-body phenomena, including a quantum phase transition and an associated quantum critical point.  A quantum dot (acting as an artificial magnetic impurity) attached to conducting reservoirs displays a many-body screening effect known as the Kondo effect. Coupling the small quantum dot to an additional, finite-sized reservoir dramatically modifies transport through the dot, providing evidence for a quantum phase transition.