| dc.contributor.advisor | Hell, Stefan Prof. Dr. | |
| dc.contributor.author | Kavatamane Rathnakara, Vinaya Kumar | |
| dc.date.accessioned | 2019-10-22T10:41:23Z | |
| dc.date.available | 2019-10-22T10:41:23Z | |
| dc.date.issued | 2019-10-22 | |
| dc.identifier.uri | http://hdl.handle.net/21.11130/00-1735-0000-0005-1280-5 | |
| dc.identifier.uri | http://dx.doi.org/10.53846/goediss-7691 | |
| dc.language.iso | eng | de |
| dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/4.0/ | |
| dc.subject.ddc | 530 | de |
| dc.title | Quantum Sensing with NV Centers in Diamond | de |
| dc.type | doctoralThesis | de |
| dc.contributor.referee | Hell, Stefan Prof. Dr. | |
| dc.date.examination | 2019-09-27 | |
| dc.subject.gok | Physik (PPN621336750) | de |
| dc.description.abstracteng | This thesis is concerned with studies involving quantum sensing based on Nitrogen-Vacancy
(NV) center in diamond. Essentially, it attempts to address two important problems. First,
enhancing the sensitivity of a single NV center to external static magnetic fields, and
second, probing the phase transitions in a soft condensed matter system using a near
surface NV center. NV center’s sensitivity to time-varying or AC external magnetic fields
is in the range of a few nanotesla and is limited by coherence time of NV. For various applications,
including the bio-magnetic measurements, it is necessary to sense nearly static or DC
fields rather than the AC fields. However, in diamond samples with natural abundance
13C concentration (1.1%), the best reported sensitivity to DC fields is in microtesla range and
is limited by short lived spin dephasing time of NV. In the present work, a novel hybrid
magnetometer consisting of a ferromagnetic material and a single NV center is utilized
to achieve DC field sensitivity down to tens of nanotesla. The ferromagnetic material exhibits
a property known Giant magneto-impedance (GMI) and is sensitive to DC fields under
certain conditions. The achievable sensitivity of GMI sensors is in the range of picotesla. By
positioning a GMI microwire in close vicinity of a NV center, magnetic interaction between
the microwire and NV center can be realized. In the presence of minute changes in the
DC fields in the surroundings, the GMI wire responds and encodes information to the NV
center. By employing a standard magnetometry sequence on NV this information can be
readout. As the sequence relies on long lived NV coherence time, its overall sensitivity
could be enhanced by over two orders of magnitude. Second study deals with detecting the
temperature driven phase transitions in a soft matter system, namely a liquid crystal (LC)
material. The chosen LC material shows distinct ordered phases close to room temperature.
By varying the temperature, transitions from solid-like phases to liquid-like phases in a
thin layer of LC can be induced. The NV sensors located at a few nm depths detect these
transitions in terms of changes in the spin noise signal emanating from nanoscopic volumes
containing LC molecules above the diamond surface. Temperature plays a key role in
determining the soft matter properties. Since NV centers are also known as nanoscale
temperature sensors, it is possible to tune the temperature precisely to the transition points.
This way, NV based method is demonstrated as a dual mode sensing for studying soft
matter systems at nanoscale, with a control over temperature. The work aims at extending
NV centers as novel probes for exploring soft matter systems and address some important
questions in that area. | de |
| dc.contributor.coReferee | Ropers, Claus Prof. Dr. | |
| dc.contributor.thirdReferee | Salditt, Tim Prof. Dr. | |
| dc.contributor.thirdReferee | Balasubramanian, Gopalakrishnan Dr. | |
| dc.contributor.thirdReferee | Bennati, Marina Prof. Dr. | |
| dc.contributor.thirdReferee | Burg, Thomas Dr. | |
| dc.subject.eng | Nitrogen Vacancy (NV) Center in Diamond | de |
| dc.subject.eng | Giant magneto-impedance (GMI) | de |
| dc.subject.eng | Quantum sensing | de |
| dc.subject.eng | Liquid Crystals | de |
| dc.identifier.urn | urn:nbn:de:gbv:7-21.11130/00-1735-0000-0005-1280-5-1 | |
| dc.affiliation.institute | Fakultät für Physik | de |
| dc.identifier.ppn | 1679426761 | |