Summary
The sixth and final lesson reviewed experiments on the control of isolated quantum systems, reminiscent in many respects of the cavity quantum electrodynamics experiments at ENS. The lesson began by describing trapped ion experiments, with particular emphasis on those carried out by David Wineland and his group. It then briefly recalled the electrodynamics of circuits (QED circuits) that couple artificial atoms (Josephson qubits) to radio-frequency resonators. The latter experiments had been described in detail in the 2010-2011 lecture as well as in Andreas Wallraff's April 9, 2013 seminar.
The description of the trapped-ion experiments first analyzed how the detection of single-ion quantum jumps has become the method of choice for non-destructively measuring the internal state of ions. The analogy between the coupling of photons to atoms in QED cavities and the coupling, by laser excitation, of the internal states of ions and their external vibrational states was then recalled. This was followed by a brief description of laser cooling experiments on ions in their fundamental vibrational state. Experiments involving Rabi oscillations of an ion whose external motion is a coherent vibrational state, realizations of quantum logic gates with ions, and quantum entanglement of two ions were then described. The reconstruction of the vibrational state of a trapped ion by tomography concluded this first part of the lesson.
