Sami amasha thesis

The corresponding values of. Since spin relaxation involves the orbital states of the lot via the spin-orbit interaction, we can achieve electrical control over WI by using the surface gates to manipulate the orbital states. Figure 2A shows the evolution of the differential conductance Gd with for a peak with a relatively large kBTK.

This Week's Colloquium: Sami Amasha, Feb. 2, 2012

The charge sensor is a quantum point contact QPC adjacent to the dot and the sensitivity is comparable to other QPC-based systems. In addition, the small size of our quantum dot makes non-Kondo excitations of the dot less likely.

Moreover, a given voltage on a gate has less influence on the dot than does the same voltage on the source or drain because of the respective capacitances.

The horizontal direction is a schematic cross section of the device, showing the drain lead, the SET island central regionand the source lead.

In a parallel magnetic field B the spin states are split by the Zeeman energy and we measure the ratio of the rates for tunneling into the excited and ground spin states of an empty dot.

One can then predict the response from the dc characteristics, and this also allows us to calibrate versus microwave power P We demonstrate that we can vary Wt by over an order of magnitude at fixed Zeeman splitting, and we extract the spin-orbit length, which describes the strength of the spin-orbit interaction in GaAs.

We develop an automated feedback system to position the energies of the states in the dot with respect to the Fermi energy of the leads. The effect appears to be quite delicate, which may be why it has not been previously seen.

The microwave signals are probably induced in all the leads simultaneously. We show that this dependence is consistent with a model that assumes elastic tunneling and accounts for the changes in the energies of the states in the dot relative to the heights of the tunnel barriers.

Further details of our method are given in An intuitive way to describe this is that electrons are excited by energy hf in one lead and then tunnel to the Fermi energy in the other lead. Massachusetts Institute of Technology Year: We therefore assume that microwave excitation by the gate is negligible.

However, theory 14 suggests that the Kondo effect is less sensitive to microwave gate voltage than toespecially midway between the Coulomb charging peaks. We also develop a triggering system to identify electron tunneling events in real-time data.

Using real-time charge sensing, we measure the rate at which an electron tunnels onto or off of the dot.

The dependence of W on magnetic field is a power-law, and the exponent is consistent with the prediction for the spin relaxation mechanism of spin-orbit mediated coup ling to piezoelectric phonons.Please include the seminar type (e.g.

Colloquia), date, name of the speaker, title of talk, and an abstract (if available). Reda Hassan Amasha MSc., King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia MPhil., University of Sheffield, England Thesis submitted in partial fulfillment for the requirements of the Degree of Doctor of Philosophy Department of Molecular Biology and Biotechnology.

model, depends on the details and complexity of the system.

This thesis investigates two cases: the Fermi liquid behavior in a system with exchange interactions (the spin 1 2 Kondo model) and effect of Coulomb interactions on the phase coherence of electrons in a quantum dot with single mode leads.

By Andrei Kogan, Sami Amasha, M. A. Kastner Science 28 May A single-electron transistor exposed to microwaves develops high-energy quantum states near its leads, confirming a theoretical prediction.

The work in this thesis could not have been completed without the constant instruction, advice, creativity, and excitement from graduate.

We demonstrate that we can vary Wt by over an order of magnitude at fixed Zeeman splitting, and we extract the spin-orbit length, which describes the strength of the spin-orbit interaction in Sami (Ph. D.)--Massachusetts Institute of Technology, Dept.

of Physics, Includes bibliographical references (p.


Sami amasha thesis
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