Ph.D Thesis


Ph.D StudentArtzi Yaron
SubjectDevelopment of Advanced Mwthodologies in Magnetic Resonance
for Quantum Technology
DepartmentDepartment of Chemistry
Supervisor PROF. Aharon Blank
Full Thesis textFull thesis text - English Version


Abstract

Quantum technology is an emerging field of science that employs entities possessing unique quantum mechanical properties (such as superposition and entanglement) in practical applications, such as quantum sensing, quantum computation, and quantum communication. One of the prime examples for a useful quantum entity is the spin of the electron, which can be manipulated, and read-out with magnetic resonance techniques, such as electron spin resonance (ESR). Yet, while ESR is very useful for characterizing and addressing samples with many (billions) of identical spins, it lacks the sensitivity to be useful for quantum technology, which often require the addressing and detection of single spins. In this research we aimed to develop new methodologies in ESR for use in the field of quantum technology, and we focused on three projects. (i) The first project dealt with characterization and spatially selective manipulation of room temperature quantum sensors/memory (nitrogen-vacancy (NV) centers in diamond) with magnetic resonance imaging-based methods. In this work we employed our unique home-made hardware and methods to achieve an unprecedented ESR-imaging resolution: high enough to observe clusters of a few hundreds of NVs in a mesoscopic volume, en-route to distinguishing between single NVs at the nano-scale in a ten-micron-scale volume. Additionally, we used this hardware to demonstrate spatially selective manipulation of electron spins in a small fraction of the full imaged volume. (ii) The second project dealt with characterizing a sample that was identified as a good candidate to be used in high purity quantum state preparation of nuclear spin qubits in a molecular quantum computer, via a method known as heat-bath algorithmic cooling (HBAC). In this work we use ESR and electron-nuclear double resonance (ENDOR) methods to characterize this sample, to examine various properties of the nuclear spins embedded in this molecular quantum computer, and determine that some of its qubits can be utilized for HBAC with electron spins, but some of them do not have the required properties to be useful for this purpose. (iii) The third project dealt with development and characterization of surface micro-resonators, designed to achieve high spin-readout sensitivity. This involved the characterization of a new kind of surface micro-resonators developed recently in our lab, which were fabricated from both a regular electrically-conducting material, and a superconducting material. The regular-conducting resonators of largest dimensions we fabricated ( 50 microns) were found to possess a high enough sensitivity to detect a signal from 6•105 spins per second. The superconducting resonators fabricated were designed to achieve a higher quality-factor, and higher conversion factor; hence providing higher spin-readout sensitivities, and shorter microwave pulse times (i.e. shorter quantum gate operation times). However, in the high-temperature superconducting material used in this work, current vortices formed when the superconductor is placed in strong magnetic fields. These current vortices decrease the resonator’s quality factor, and mainly degrade the ESR signal detected with it. In this work we employ a method to mitigate the formation of these vortices and observe, in real-time, the effect of this correction scheme on the shape of the ESR signal.