Here are some of the science projects I've worked on…

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Dilution refrigerator system

During my PhD I spent a lot of time working on a system known as a dilution refrigerator. This fridge allowed me to cool superconducting samples to very low temperatures, around 25mK, to explore their properties once they were cold enough to exhibit quantum mechanical properties.

I designed and fabricated custom electronic circuits to allow these cold samples to be measured, including novel filter designs, microwave injection systems, and optically isolated measurement apparatus to probe the quantum world without that pesky classical “noise” getting in. I also occasionally made ice cream with liquid nitrogen.

 

FIB microscope

Before measuring samples in a dilution fridge, one has to first craft them. I used a Focused Ion Beam microscope as part of a series of advanced lithography techniques to pattern materials into circuits.

The ion beam microscope worked by firing a high energy bean of Gallium ions at a surface under high vacuum conditions. The ion beam “etched” away parts of the material, allowing me to create little patterns in the material. The patterns were typically a few micrometers in size. You can even create microscopic 3-dimensional structures using this approach such as bridges and cantilevers.

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Programming quantum computers

I spent several years learning how to program quantum computers. It’s not like normal programming. Instead of defining a program in terms of logic operations, it has to be defined in terms of minimizing an objective (energy) function.

In a quantum computer, each logical bit is called a qubit, and unlike conventional “0 or 1” bits, qubits can be in a mixture of both 0 and 1 during parts of the computation. You can see how that might get confusing pretty quickly.