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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