Networking Quantum Computers

Hello! My name is Dominic Siegele, and I will be a junior at Whitman. I am pursuing the 3-2 Engineering through Physics program and minoring in Chinese. This summer, I am interning at the National Institute of Standards and Technology (NIST) in Boulder, Colorado. I learned about this internship through the CCEC, where they brought me in touch with Dr. Tasshi Dennis, who also completed Whitman’s 3-2 Engineering program years ago.

I was particularly interested in this internship because I am working on Networking Quantum Computers. While Dr. Dennis and some of my other coworkers have been working on this project for years, I feel quite fortunate to have played a small part in it. This is not the first time I have been exposed to the quantum world, but it has been the most meaningful experience.

In traditional computer networks, information is transmitted using bits, but quantum computers use qubits, representing positive and negative states and the change in energy between the two states. In an attempt to network these quantum computers, many physics and electrical engineering concepts are being used in this project, including, lasers, optics, circuitry, fabrication, and cryogenics.

The project relies on a device known as a Quantum Transducer, which operates by taking an incoming signal, reflecting it internally multiple times, and then outputting a new signal containing different data for transmission. The primary incoming signal is at 6 GHz, but the information transmitted is on a different frequency that we can control, known as sidebands. To create better sidebands, the Transducer needs to work at temperatures at the MiliKelvin scale. Basically, the lowest temperature environment that we can produce, which is where cryogenics come into play.

During most of the summer, I've been focusing on the microwave aspect of the Transducer. My goal was to create, amplify, and combine signals with other sidebands in order to measure them. This involved understanding circuitry and the devices within the circuit. There was a preexisting circuit in the system that served this purpose, but it was housed in a poorly functional plastic bin. While it did the job, it was in dire need of an upgrade.

To begin with, one of the components in the circuit is Operational Amplifiers and its amplifier circuits. One of three types of amplifiers could potentially be used. The objective was to identify one that would yield the highest gain with the least amount of noise, and this required some testing. After some experimentation, I opted to use the ERA-4+ Op Amp.

After determining which amplifier to use, the next step was to ensure that it had a power source. The main circuit I had to create involved using voltage regulators to maintain a constant voltage, and capacitors to filter out any excess noise. This circuit can be found on the top left side of the box.

I recently finished deciding on the layout of the box. First, I put in each component of the circuit, one by one, to ensure the output was as desired. Finally, we took measurements to confirm that the output met our requirements, and fortunately, it did.

Currently, I'm working on coding one of the devices in the box and a signal generator that provides the input. I expect to work on coding other devices for the last two weeks of my internship at NIST. The work culture there is amazing, with a positive and inclusive atmosphere. I'm excited to apply what I've learned here in both the classroom and beyond!