Molecular engineers at the University of Chicago have found a way to extend the quantum state of a qubit to 22 milliseconds, representing a huge improvement and a window some say will make quantum computers far more feasible. The secret is an alternating magnetic field, which they say is scientifically “intricate” but easy to apply.
Working with qubits in solid silicon carbide, the scientists extended the time in quantum state of their qubit to 22 milliseconds, which sounds small to our slow human brains, but is almost an eternity for a qubit. In fact, the researchers say it’s 10,000 times longer than the next nearest quantum state finding.
Honestly, it’s almost eternity for your regular computer, too. My not-new MacBook Pro, for example, has a 3.1 GHz processor, meaning it pushes up to 3.1 billion “beats” per second of incremental computer math. In 22 milliseconds, it would crank through 68,200,000 tiny data ticks. Quantum computing doesn’t even operate in the same paradigm, which is part of its appeal—but it’s potentially much faster, almost unfathomably so.
The scientists lengthened the time by using an alternating magnetic field. What does that mean?
Let’s parse some jargon: “We construct a robust qubit embedded in a decoherence-protected subspace, obtained by applying microwave dressing to a clock transition of the ground-state electron spin of a silicon carbide divacancy defect,” the researchers sum up in the paper, published last week in Science.
Basically, they made an interface called a subspace, placed a qubit in it, and then wrapped the entire thing in an atomic-timed beeping protective blanket.
What results is an unprecedentedly long time before the qubit is affected by a phenomenon called decoherence, where it falls out of the critical quantum state. If you think of the qubit as a key item in some epic fantasy movie, the goal is to keep it hidden and sheltered as long as possible before interlopers start to touch it. The more we can shore up everything that keeps it protected, hypothetically, the longer it can continue to operate.
Within quantum systems, observation and disruption in the form of “noise” is a huge part of high decoherence rates. While scientists have concentrated on trying to reduce noise, like dropping qubits into the noise version of a sterile “clean room” for medical research or a Faraday cage, these researchers were inspired by something more like noise-cancelling headphones or “unscented” personal products: they added just enough noise to camouflage the real noise, and tuned it so it doesn’t disrupt the system.
This result is incredibly exciting, but as with any breakthrough, the implications are even more exciting. These researchers studied one solid state qubit setup, but what if the same protective noise field could enable a giant step forward in quantum computing more broadly? What if everything increases 10,000-fold at the same time? The possibilities are almost endless.