Mark Megahan
Stretching a diamond is easier than most of us would imagine. Not the kind on an expensive ring, though. What they’re playing with in the lab is a film of it. By stretching them just right, they make new and improved qubits. It’s considered a huge breakthrough for quantum computing.
Stretched diamond qubits
Lab technicians stretched thin films of diamond like some Handiwrap and don’t consider that to be much of a big deal. They’re going apeshape over what they did with it then.
A team of researchers at the Department of Energy’s Argonne National Laboratory, the University of Chicago and Cambridge University, “created quantum bits that can operate with significantly reduced equipment and expense.”
As an extra added bonus they weren’t expecting, “the change also makes the bits easier to control.” The title on their report is a mouthful. “Microwave-Based Quantum Control and Coherence Protection of Tin-Vacancy Spin Qubits in a Strain-Tuned Diamond-Membrane Heterostructure.”
It’s that diamond “membrane” that creates such funky results. By “strain-tuned” they mean like by moving those old TV rabbit ear antennas around.
The technique of stretching thin films of diamond “lets you dramatically raise the operating temperature of these systems, to the point where it’s much less resource-intensive to operate them.”
Alex High, assistant professor with the UChicago Pritzker School of Molecular Engineering explains why that’s so important.
Infrastructure and labor
The quantum qubits are housed in the “nodes” that would relay information along a quantum network. With current state of the art technology, “Most qubits today require a special fridge the size of a room and a team of highly trained people to run it.”
That means “if you’re picturing an industrial quantum network where you’d have to build one every five or 10 kilometers, now you’re talking about quite a bit of infrastructure and labor.” The diamond film solves that problem.
Qubits made from diamonds are the best kind. They can be formed as “Group IV color centers,” known for their ability to maintain quantum entanglement for relatively long periods. Ordinary ones need to be cooled down to almost absolute zero.
By applying a film of diamond to hot glass, since the glass shrinks slower, it forces the film to stretch, just like “pavement expands or contracts as the earth cools or warms beneath it.”
That’s enough to allow qubits to function perfectly at minus 452 degrees Fahrenheit. While still cold, “it can be achieved with less specialized equipment.”
The diamond being stretched also “makes it possible to control the qubits with microwaves. Previous versions had to use light in the optical wavelength to enter information and manipulate the system, which introduced noise and meant the reliability wasn’t perfect. By using the new system and the microwaves, however, the fidelity went up to 99%.“
