All around the world, federal governments are committing huge amounts of money for research and development (R&D) related to quantum projects. Quantum computers, for example, will revolutionize our ability to do calculations beyond what we could ever dream with supercomputers. They’re expected to drive incredible advances in areas such as artificial intelligence. I pursued a science policy article on R&D quantum initiatives for MRS Bulletin. The problem I faced as a writer is how to talk about quantum materials when I have no background in this subject—and, furthermore, when the concept is still elusive even to scientists who are not in this specific field.
A few years ago, when “quantum” was quickly gaining momentum, I took a free online introductory course on quantum mechanics. I particularly learned where semiconducting- and superconducting-based materials play a role in the development of quantum devices and systems. Then last year, I benefited from a Zoom call hosted by the US National Science Foundation (NSF) given for the press to help us understand more about this concept. NSF has a vested interest in helping reporters “get it right.”
While definitely beneficial, neither of these activities helped me as much as interviewing the researchers for the article!
From the online course, I understood that quantum computers are made to correct their own errors, having something to do with coherence.
From the NSF meeting, I learned that money is going into numerous “platforms” of quantum computers because we don’t know, yet, which path will prevail. Because of my familiarity with the race for a vaccine against the COVID-19 virus, I was able to put that comment into context.
However, words like “coherence,” “qubit,” “superconductor,” and “ion-trapped” still floated across my brain like “cookie,” “park,” and “good dog” fall onto the ears of our puppies.
But it was time to interview the researchers. Prior to the zoom calls, I had already looked up their websites and their recently published articles to help me determine who to interview.
The first call was to Anna Grassellino, director of Fermilab’s Superconducting Quantum Materials and Systems Center in Illinois, near Chicago. Their work is specifically on the superconductivity platform for quantum computers, as we can gather from the name of the center. I received an in-depth lesson on the transmon qubit and how long the photon can live inside the cavity before getting absorbed. “We’ll be building a quantum computer using the 3D superconducting architecture,” Dr. Grassellino told me, which is based on their ultrahigh-quality-factor (ultrahigh-q) 3D resonator.
Anna Grassellino, director of Fermilab’s Superconducting Quantum Materials and Systems Center, holding a single-cell superconducting cavity. Credit: Reidar Hahn, Fermilab
The conversation was great because I was able to let her know that I read up on their work, but have no quantum materials background, so she was very generous in showing me a superconducting radio-frequency (SRF) cavity device, explaining how it works. “The key problem that we try to overcome is quantum coherence for the lifetime of the qubit,” Grassellino says. “The lifetime fully depends on how long the photon can live inside of a cavity or the transmon qubit before the quantum state gets destroyed or the photon gets absorbed. That depends on the material we use” (MRS Bulletin, https://doi.org/10.1557/mrs.2020.288).
Next, the UK. Principal investigator David Lucas heads up the UK Quantum Computing & Simulation Hub. He is also a professor at the University of Oxford and I bet he gets good evaluations from his students! While his specialty is on trapped-ion qubits (e.g., a strontium ion-qubit), the Hub pursues the range of platforms. Dr. Lucas tutored me on ion trap and silicon processors, superconductors, diamond nitrogen-vacancy (NV) centers, cold atoms, and photonics. I’ve even saved our recorded interview for future reference, sort of like a personalized text book.
Oxford-built ion trap with a single strontium ion-qubit held at the center. Credit: David Nadlinger, winner of the UK science photo competition 2018.
Dr. Lucas and Dominic O'Brien, the director of the Hub, reinforced the NSF message that the science field does not know, yet, which platform will prevail.
And as we’ve seen with the COVID-19 vaccine, it could be more than one!
-Judy Meiksin
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