|Ph.D Student||Paz London|
|Subject||Coherent Interactions of Spins and Photons in the|
Nitrogen-Vacancy Center in Diamond
|Department||Department of Physics||Supervisor||Full Professor Gershoni David|
|Full Thesis text|
The nitrogen-vacancy (NV) color-center in diamond is considered one of the promising candidates for realizing a quantum bit (qubit) - the basic building block of a quantum computer. It allows room-temperature all-optical initialization and readout of the qubit state, high fidelity manipulation using resonant microwave (MW) radiation, and unprecedented coherence times for a solid-state system at room-temperature. Moreover, the precise and controlled interaction of the NV center’s spin with its surroundings, allows using the surroundings as a quantum resource as well. In addition to quantum information processing, these properties of the NV-center mark its qubit as a nanometer-scale sensor for minute magnetic and electric fields, and for its local temperature.
This study presents two examples for the coherent interaction of a single NV-center’s electronic spin with (I) polarized MW photons (II) surrounding nuclear spins. These interactions are used for fundamental study and for applications.
In the first study, we developed a wide-band polarized MW field source, and investigated its effect on a single NV-center. We showed that using circular polarized fields, one can manipulate the spin of the NV-center faster than its natural frequency scale (in the so called “strong-driving regime”). Usually in the strong driving regime the rotating wave approximation is not valid, leading to a time-dependent system Hamiltonian and complex dynamics. As we show experimentally in our study, with circular polarized fields the approximation is exact regardless of the driving field’s strength. We further investigated the polarized MW source for manipulating the spin 1 system in the NV-center’s ground-state. These demonstrations are specifically important when operating the NV-center at zero magnetic field. There, the only scheme allowing a full control of the quantum state of the system relays on the polarization of the MW, since two of the three states become degenerate and cannot be distinguish spectrally. We demonstrated how to selectively excite specific superpositions with a single MW pulse, and investigated the relation between the MW source’s parameters and the excited superpositions.
In the second study, we investigated the coherent interactions of the electronic spin with its surrounding nuclear spins. We showed that a well-known technique from the nuclear magnetic resonance field - the “Hartmann and Hahn double resonance” - suppresses parasitic noise and facilitates imaging capability of the NV-center as a nanometric sensor for nuclear spins. We experimentally show how to use both the MW strength, and the coherent dynamics of the spins as a 2D imaging technique. In addition, we studied the effect of pulsed and continuous dynamical decoupling schemes on an NV-center surrounded by a bath of polarized nuclear spins. We developed novel techniques for using the central electronic spin to interact with these weakly coupled nuclear spins, and to measure their polarization quantitatively.