The room temperature nitrogen-vacancy measurement setup.
NV center measurement results. (a) The result of scanning the sample. (b) The ESR result of the NV center. A(B) denotes the PL counts measured when the MW is on(off) The measured data is fitted using the Voight profile. The position of the dip is 2.8716 Β± 0.0002 GHz. The uncertainties of the measured data are in the order of 10β3 . Red (blue) dots are the data measured by us (TA).
The photo of lens AFM.
The schematic of a noise floor measurement using a current amplifier. π π, π π , and π π‘ are resistances of a feedback, sample, and terminator and πΆπ is an input capacitance, respectively.
The measured root mean square (RMS) voltage versus gain for all combinations of resistors and the BNC cables. Dashed lines are the theoretically calculated noise amplitude. Since the thermal noise is dominant for the 100 kΞ© case, the noise values are indistinguishable between different BNC cables that the theoretical value is drawn only once. Left: unfiltered raw data. Right: 60 Hz notch filtered applied to the left data and the inset represents the frequency response of the applied filter.
Lecturer: Dohun Kim
Contributions: All students worked equally on all experiments. Special thanks to Jinsoo Kim and Shinyoung Hwang who initially set up the room temperature NV center setup.
Senior Physics Laboratory Spring Semester 2024
Electron spin resonance of nitrogen-vacancy centers in room temperature
From the room temperature optics setup, we measured electron spin resonance (ESR) of nitrogen-vacancy (NV) centers in diamonds, which is a good platform for quantum sensing and computing. We successfully measured the photoluminescence dip at 2.8716 GHz, matching the theoretical zero-field splitting of the NV center's ground state. Aligning the complex optics setups and control via LabView was the challenging part of this experiment. From this experiment, I learned the energy structures of the NV center and its control technique.
Atomic Force Microscopy
Gained foundational knowledge of atomic force microscopy (AFM) and hands-on experience with Lens AFM by imaging a variety of samples.
Low-noise measurement
In this project, I conducted low-noise measurements using custom-built current amplifiers to analyze the noise characteristics of basic circuit components, such as resistors and BNC cables. By evaluating thermal and capacitive noise, the results were consistent with noise floor estimations, though saturation effects were observed at higher gains. Throughout this project, I learned understanding the noise source and its amplitude is crucial as how the amplifier is connected to matter in case amplifiers are used many times.