Sammy Umezawa

Sammy, please tell us a bit about yourself. 

In June 2023, I completed my Bachelors in Computer Engineering at the University of California,  Santa Barbara. I had prior research experience at the Quantum Photonics Lab in the UCSB Electrical  and Computer Engineering department from June 2021 until graduation. I was originally on-track for a  software engineering career, but I pivoted to applied physics after becoming enthralled by quantum  electronics research during my time at QPL. I am currently applying to various graduate programmes to pursue that field. 

Thanks. can you tell us a bit about your IRTE research experience? 

I worked on the precharacterisation of Si/SiGe spin qubit shuttling devices. 

The group I worked for, the Quantum Technology Group at RWTH Aachen, includes a team of  researchers dedicated to accomplishing the coherent (i.e. no data loss) transfer of electron spin qubits  across long distances on a semiconductor chip. These devices, called shuttling devices, are comprised  of a silicon and silicon-germanium alloy semiconductors with many metal gates on top. The gates  apply voltage signals to facilitate the formation and controlled movement of electrons.  Precharacterisation is a sequence of tests at 4 Kelvin to measure the robustness of those metal gates  before queuing those devices for further experiments. I also wrote a plotter in Python to help make  statistical inferences about the Si/SiGe heterostructure designs based on precharacterisation data. 

What did your research project entail? 

The goal of my project was to aid the team in identifying the best devices based on the 4K  precharacterisation parameters. A secondary goal was to make a workflow in the lab that gathers data  from each measured device and plot histograms or scatter plots to visualize the performance of the  devices and associate it to the heterostructure design.  

The notion of different designs comes from the fact that the research team is still optimizing the design of the heterostructure yielding the best quantum dot formation and control for the long-term goal of  making spin states hop from one quantum dot to the next, i.e. shuttling. The team partners with various  vendors to fabricate distinct heterostructures, while metal gates are fabricated in-house. 

I contributed both raw data and methods to interpret the data. I am proud in particular for having helped the group find three ‘hero’ devices with optimal performance for shuttling experiments. 

You lived in Aachen for 12 weeks. Can you tell us about the laboratory and your experience living in Aachen. 

The Quantum Technology Group at RWTH Aachen pursues bold quantum research endeavors that  entail very rewarding scientific experiences. It is arguably the best German semiconductor spin qubit  group and one of the best in Europe. The laboratory is also in an extensive partnership with a nearby  national laboratory (Forschungszentrum Jülich) as well as many other partnerships that gives further  momentum to the group’s quantum electronics projects. Last but not least, the group benefits from a  very refreshing workplace environment. I am very grateful for receiving a wholehearted welcome  during my time there. 

The city of Aachen is strikingly convenient: in the weekdays there are extensive bus services to just 

about anywhere within Aachen for any errand. Even without the bus, the lab, the city and school  registration services, groceries, department stores, ATMs, and the gym are all walking distance. The  fact that Aachen’s supermarkets and various food stands and restaurants are all walking distance grants  a very underrated freedom and spontaneity to one’s culinary choices in day to day life there. 

In the weekends there are various parks and landmarks to visit in the tri-border area surrounding  Aachen, or train rides to major North-Rhine Westphalia cities like Cologne or Düsseldorf or even to  major cities in the Netherlands and Belgium. Whatever your choice may be, Aachen is great for  spontaneous one-day trips, and quite convenient for longer ones. The transportation system is quite  reliable, perhaps the sole exception being the trains within Germany (Belgian and Dutch trains are very punctual).  

Please tell us about your weekend travel experiences. 

I was blessed with many opportunities to travel during my internship. 

I had three separate excursions to major North-Rhine Westphalian cities Düsseldorf and Bonn. My  highlights include going on a trip with fellow interns to a manor on a hill called Schloss Drachenburg,  visiting restaurants and bars with friends in Bonn and Düsseldorf, the Japanese street in Düsseldorf,  and spending several hours inside a train or replacement busses on the way back home. The last one  may seem tiring or boring at first, and perhaps frustrating for the locals, but they were fun adventures  of their own! My favourite experience was the ML4Q retreat in a small countryside town called Eitorf  for MS, PhD, and postdoctoral researchers from participating quantum research groups around North Rhine Westphalia. There was not only networking and interesting scientific colloquiums, but also  various group activities to spend more time with and befriend researchers based in Europe.  

I also took a five day vacation towards the end of my internship. The first day I spent in towns nearby  Aachen called Monschau and Stolberg, both of which boasts serene scenery and remarkably fresh air.  Along with an exploration of the Aachen district in North-Rhine Westphalia, I was able to visit the  Belgian cities Bruges, Antwerp, and Brussels and the Dutch cities Utrecht and Amsterdam over the  next four days.  

Because this was my first ever trip in Europe and my first trip in roughly six years, I absorbed as much  as I could of the people, the culture, and the moments there. I made many good friends that I hope to  correspond with for many years to come. 

Can you share any overall impressions of your experience? 

I had no idea what Germany or Western Europe was like, let alone the academic world of that region  prior to this experience. In the 12 weeks I had a small taste, albeit a very exquisite and impressive one.  A major impression I had is that the people there, both within RWTH Aachen and outside may seem  difficult to talk to at first, but are not only actually very friendly but also very rewarding to listen to.  Although it is hard to articulate succinctly, there is an undeniable satisfaction being able to interact with people from different worlds. It was very hard to say goodbye to the friends I made there. 

I had incredible support both hands-on and theoretical, which allowed me to learn an incredible amount of experiment electronics and semiconductor spin qubits, both of which I would make great use of in  the future. I am very open to another research experience (perhaps a PhD) in Europe and I certainly  hope to start doing my own experiments in quantum electronics. This trip not only opened up new 

research opportunities, but also new perspectives both as a scholar and as a person, for which I will be  forever grateful.