Background Information


Charles Bennett, Wednesday November 18, 2 pm (KITP Colloquium)
Quantum information and the birth and death of complexity
Quantum information theory provides the most coherent explanation of the emergence and obliteration of correlations, even in macroscopic systems exhibiting few traditional quantum hallmarks. Turbulence is a familiar example of a process generating not only correlations but awe-inspiring complexity, and it is natural to wonder where this complexity comes from and how long it lasts. We discuss the central role of entanglement in the origin and obliteration of correlations, then attempt to apply the theory to understand the birth and death of complexity, appropriately defined.

Daniel Loss, Tuesday November 24, 4 pm (Physics Colloquium)
Spin-Qubits in Nanostructures
Electron spins in quantum dots are promising candidates for qubits and scalable quantum computers in solid state systems. I will review the current status and address a few important physics aspects in this field, the most important one being the decoherence problem due to the interaction of spins with the surrounding environment. The dominant sources are typically spin-orbit induced spin-phonon couplings and the interaction of nuclear spins with electron spins via the hyperfine interaction. The resulting spin dynamics and associated decoherence are rather complex quantum phenomena, quite often dominated by non-Markovian behavior. I will give a brief overview of various spin candidate systems, such as electrons or holes in GaAs, nanowires, nanotubes, graphene, etc. A promising strategy to deal with the nuclear spin problem is to induce a magnetic ordering in the nuclear spin system resulting from the hyperfine-induced RKKY interaction between the nuclear spins. The ordering is possible only due to strong correlation effects among the electrons such as Luttinger liquid physics in 1D and non-standard Fermi liquid behavior in 2D.