One of the main challenges in turning quantum technology from potential to reality is getting superfine quantum states to last longer than a few milliseconds – and scientists are simply lifting the bar by a factor of about 10,000.
They did this by tackling what is called decoherence: that is, the disturbance of ambient noise caused by vibrations, fluctuations in temperature, and interference from electromagnetic fields that can break a quantum state very easily,
“With this approach, we are not trying to eliminate noise in the environment,” says quantum engineer Kevin Miao, of the University of Chicago. “Instead, we push the system to think it is not experiencing sound.”
By applying a continuous alternating magnetic field to a kind of quantum system called a qui solid state, in addition to the standard electromagnetic pulses needed to keep such a system under control, the team was able to ‘tune’ unnecessary noise. .
Researchers compare it to sitting on a merry-go-round – the faster you go, the less able you are to hear the sound of your surroundings, because it all becomes one. In this case, spinning electrons are the merry round.
Using the new approach, the solid-state qubit system could remain stable for 22 milliseconds – four orders of magnitude 10,000 times longer than previous efforts, though still less than a tenth of a blink of an eye.
Investigator Kevin Miao. (David Awschalom)
The qubit is the quantum version of a standard computer bit, but instead of just coding 1s and 0s, it can reach a state of superposition that makes it much more powerful.
Decoherence is something of a nemesis for quantum scientists. Other attempts to reduce background noise have led to perfect insulation of quantum systems – which is technically very challenging – or use of the purest possible materials to build them – which can quickly become expensive.
The new approach could offer a more practical solution.
“This breakthrough lays the groundwork for exciting new avenues of research in quantum science,” said physicist David Awschalom, of the U.S. Argonne National Laboratory.
“The broad application of this discovery, coupled with a remarkably simple implementation, allows this robust coherence to influence many aspects of quantum technology. It enables new research possibilities that were previously thought impractical.”
The researchers said it should work in other fields of quantum physics as well, without the need to adapt it too much – superconducting quantum bits and molecular quantum systems, for example, are other systems that could benefit. We’re talking about everything from supercomputers to inaccessible internet.
Our quantum future is still a bit far away, but every scientific step forward brings us a little closer.
“There are a lot of quantum technology candidates who were pushed aside because they could not maintain quantitative coherence for long periods of time,” Miao says. “These could be re-evaluated now that we have this way of massively improving coherence.”
“The best part is, it’s incredibly easy to do. The science behind it is complicated, but the logistics of adding an alternating magnetic field are very simple.”
The study was published in Science.
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