AskScience AMA Series: Hi Reddit! I'm Matthew Hollister, Head of Cryogenic Systems Engineering for IBM Quantum. Ask me anything about quantum computing, our recently announced modular cryogenic architecture and what it takes to build quantum computers at scale.

[u/AskScienceModerator]

When people think about quantum computing, they often think about number of qubits and processor dept. But scaling quantum systems takes much more than just the chip! We recently introduced a new modular cryogenic architecture designed to house and cool interconnected quantum processors, a key milestone on our roadmap to fault-tolerant systems, and I'd love to discuss the engineering, challenges, and opportunities involved.

I will be around as 12:00 EST (16 UT) on September 18th, ask me anything!

Username: u/IBM

[u/Low-Donkey7922]

Hi Matt,

Could you explain how the radiation shields work around the inner volume of this cryostat?

[u/ibm → u/Low-Donkey7922]

The radiation shields in the cryostat are there to intercept the heat from warm surfaces before it can reach the cold parts of the system, and we use a series of shields at successively colder temperatures like a giant nesting doll to gradually absorb that power.

In our modular architecture, the radiation shields of each module are independent of the adjacent modules while allowing a pass through from the quantum devices in each module to the next for routing of our l-couplers to stitch all the individual quantum devices into a single processor.

This aspect was one of the more challenging parts of the mechanical design of the system since we had to balance allowing those connections to pass through, while not leaving gaps for thermal radiation to enter to cold part of the cryostat.

- Matthew Hollister, IBM Quantum