Events at Physics |
Events on Monday, August 11th, 2014
- R. G. Herb Condensed Matter Seminar
- Detection and Coherent Control of Rydberg States in Silicon
- Time: 10:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Dr. Byron Villis, London Centre for Nanotechnology
- Abstract: Over recent years there has been much focus on the QIP potential of donor atoms in silicon, including several studies to demonstrate the measurement of the electron and nuclear spin states of single donors. However, to date, there has only been a small effort to explore the quantum nature of orbital states (Rydberg states) of donor-bound electrons; in part this is due to their extremely short lifetimes. Nevertheless, the excited orbital states provide great potential for QIP, for example controlling the exchange interaction of neighbouring donor atoms. These states are addressable using free space optics and, unlike the electronic and nuclear spin states, they are present without the application of an external magnetic field. In this presentation I explore the quantum nature and detection mechanisms of the Rydberg states in bulk phosphorus doped wafers as well as lithographically defined silicon-on-insulator field-effect-transistor devices. The excitation is done using Fourier transform infrared spectroscopy and terahertz time domain measurements via picosecond free electron laser pulses. The results demonstrate coherent control and ‘detector free’ measurement of Rydberg state transitions and pave the way to achieving reliable readout of orbital states of single donors.<br>
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- Host: Mark Eriksson
- Atomic Physics Seminar
- RF Spectroscopy of Optically Trapped Lithium : Magic Polarization.
- Time: 2:00 pm
- Place: 5310 Chamberlin Hall
- Speaker: Huidong Kim, Korea University
- Abstract: An optical dipole trap for alkali metal atoms is one of the most useful ways for a precision spectroscopy and a quantum information processing (QIP). We are interested in eliminating differential ac-Stark shift of atoms in the optical trap between the two ground hyperfine levels to obtain narrow line width and long coherence time. We study the polarization dependence of the Stark shift via vector polarizability and controlled the polarization of the trapping field. We carry out a hyperfine spectroscopy between two ground hyperfine states . We expect that the magic polarization brings breakthroughs in precision measurement and quantum information processing.<br><br>
- Host: Mark Saffman