Blog Post #3: My Final Weeks at LBNL

With my time at the lab this summer coming to a close, I wanted to quickly reflect on my past few weeks of work here at LBNL. Having the opportunity to perform research here this summer has truly been a blessing and given me an insight into what I may want to pursue in the future. These last few weeks have especially been exciting as many elements of our project have started to come together, such as our new sample holder, microwave antennas, and much more.

As I mentioned in my last blog post, our current narrow band antennas, while able to deliver a strong microwave signal, present a deformity in our data that makes analysis more difficult. To get around this, I have been developing new broadband microwave coil antennas. This has been a challenging yet rewarding process as a multitude of parameters go into affecting the antenna’s performance. Factors such as cable length, separation, and composition as well as the number of coils and how closely they are packed together all affect the performance of the antenna. 

This performance is measured based on two primary factors: reflectivity (the overall ratio of reflected to supplied energy) and resonant frequency (the frequency of lowest reflectance, or the best performance). Our goal is to have the lowest reflectance possible from 2.0 to 4.0 GHz whilst having the antenna’s resonant frequency at approximately 2.87 GHz (for NV- center data collection at zero field). Consistently obtaining these results however presents a multitude of issues. First of all, altering one parameter even slightly can drastically affect the performance of the antenna. It is essential that the same steps for construction are followed during replication. Secondly, any time a parameter is altered, the chance of antenna burnout could become more likely. If burnout does take place, the antenna will need to be recycled and a new design will need to be drafted. Lastly, coil antennas are commonly very fragile. If handled improperly, the antenna could become damaged and no longer perform as desired.

To make this process more straightforward, I set to work on writing a protocol outlining the design and manufacturing of these antennas. Before I could continue with this however, I needed to find an ideal antenna design. After exploring a multitude of cable types, antenna lengths, coil compositions, and even the introduction of liquid electrical insulation, I finally discovered an acceptable design that provided consistent and desirable results. With this protocol now complete, I hope that the future construction of new antennas will be less challenging and more streamlined.

I also mentioned in my last blog post, I was given the opportunity to design a sample holder for our new confocal microscope setup. With the designs complete, I was able to contact our onsite fabrication shop and get to work on obtaining these new pieces for assembly. After a few rounds of revisions and communication with the shop, we were able to get our hands on the necessary pieces to move forward. I will sadly miss the full construction of the new setup as we lacked the necessary screws to fit everything together. Who would know that finding M1.6 non-magnetic screws would be difficult?

In addition to both of these projects, we have continued working on data collection for our Optically Detected Magnetic Resonance (ODMR) with NV- centers. One large setback however has been the lack of an optimal diamond for experimentation, meaning a new one is necessary to move forward. The search for a new diamond has given me the opportunity to tour two laboratories on campus working on similar projects, one with a quantum diamond microscope for magnetic field mapping at micrometer scale, and the other building a microfluidic system for observation of a single live cell with nanodiamonds. Gaining an insight into other applications of our research focus has been incredibly interesting and made me even more excited for the future of these technologies.

I am both excited for the semester but sad that my time at the lab has come to an end for now. With my classes beginning this week, I am already busy with meetings, problem sets, events, and attending courses in-person for the first time in a year and a half. I want to give a big thanks to Cal Energy Corps, this has been a life changing experience and I will be forever grateful for the opportunity. I also want to thank Zhao Hao and Benjamin Gilbert at LBNL for the opportunity to participate in their research. The skills they taught me will be essential for my future career, whether that is in a traditional work environment or further pursuing research.

Thank you so much for taking the time to read my second to last blog post, I look forward to soon giving a full recap of my internship at LBNL!