University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Tuesday, July 24th 2007
12:00 pm:
Thesis Defense in Physics 435
Speaker: Roman Lutchyn
Subject: Kinetics of Superconducting Quantum Circuits

Superconducting circuits exhibit quantum properties on a
macroscopic scale, and are natural candidates for solid state
quantum computing. Their low-energy physics can be described in
terms of the phase of the order parameter, a single collective
degree of freedom associated with billions of coherently paired
electrons. In practice, however, on top of the superfluid
condensate there are single-particle excitations (quasiparticles)
with a continuous energy spectrum; the quasiparticles are coupled
to the phase degree of freedom. The presence of quasiparticles in
the system sets serious constraints on the performance of
superconducting charge qubits. In the thesis, I study the
kinetics of superconducting quantum circuits, and discuss the
fundamental limitations on the energy and phase relaxation times
in the presence of quasiparticles.

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