Meet the physicist trying to cram a billion mass-producible qubits onto a chip the size of a coaster

[Golden Dan]

At SLAC National Accelerator Laboratory, Q-NEXT collaborator Shannon Harvey works on quantum dots, a type of qubit made by confining an electron to a space smaller than its own wavelength, forcing it into a set of discrete, controllable energy states, roughly the quantum equivalent of a single musical chord separating out into pure individual tones

What makes quantum dots distinctive among qubit types is scalability. Unlike some quantum computing approaches that require exotic, hard to manufacture components, quantum dots are tunable like a radio and, crucially, mass producible, meaning millions or even billions of them could in principle be packed onto a chip roughly the size of a drink coaster and used to build a genuinely large scale quantum computer

That scalability is simultaneously the feature and the problem. A chip crowded with that many quantum dots becomes noisy, and noise causes the qubit's energy to fluctuate unpredictably, which destroys the fine control researchers need to actually use it for computation. Harvey's work isn't really about building better individual dots anymore, it's about the surrounding systems engineering, what materials keep the environment quiet, how to connect dots to the rest of the chip without introducing new noise, what temperature the devices should run at, and how to space them to avoid interference

Harvey works inside SLAC's Millikelvin Facility, an open environment without traditional walls between research groups, where she's found unexpected overlap with cosmologists building particle detectors for studying deep space, since both fields ultimately grapple with the same underlying challenge, controlling and reading out extremely faint, easily disturbed signals. The work is funded through the US Department of Energy's Q-NEXT center, one of the national quantum information science research hubs led by Argonne National Laboratory

Tiny Quantum Dots Offer Scalable Solutions for Next Generation Computingwww.azoquantum.com