Infrastructure for Control and Readout of a Quantum Bit


Engineering and Applied Sciences


Assistant Professor: Electrical and Systems Engineering

Project Summary

The nitrogen vacancy (NV) center is a defect that can form within a diamond. The electronic spin of this defect can provide the basis states for a quantum bit (qubit) using both microwave and optical frequencies. The goal of this project is to reduce the power required to control this qubit in our experimental setup. I am working at this goal on three levels of complexity. The first area worked on was the FPGA logic board. Another circuit board was designed to mount to it which allows for better access and readout of information. The second area worked on is the microwave board itself. The goal is to use dynamic matching to lower the reflection of the board to below negative ten decibels. For this an LC matching circuit was designed in order to target specific frequencies. However, the current circuit does allow for our desired passband of about one hundred megahertz and we will work on improvements in the future. The difficulties with this board may be due to its length compared to the wavelength of the board as they are quite similar. This must be investigated further. The last area I worked on was the NV device. A small loop antenna is placed around the defect to supply magnetic power to it. I tested the effects of horizontal displacement, vertical displacement, and the outer radius of the loop. This allows for more optimal placement of the antenna when creating a chip with a new NV center. I plan to make further improvements in all three of these areas of our setup as I continue this project.

From this project I better learned the pace in which research takes place. It can often be slow then suddenly speed up. It also taught me much more about advanced electronics than I had previously known. I learned about designing circuits to be un at high frequency and how dynamic matching can greatly affect them. This project helped me learn much more in the field I am studying than would normally be possible this summer. I was able to meet and talk wth experienced students and professors.