Simple innovation is expected to open up new avenues for quantum science.
If we can exploit it, quantum technology promises amazing new possibilities. But first, scientists need to convince quantum systems to remain in a state of infatuation for longer than a few millionths of a second.
A group of scientists now University of ChicagoPritzker School of Molecular Engineering has published the discovery of a simple modification that allows quantum systems to stay on – or “coherent” – 10,000 times longer than before. Although the scientists tested their technique on a specific type of quantum system called a solid-state qubit, they claim that it is applicable to a wide variety of other quantum systems and therefore could revolutionize quantum communication, computation and perception.
Research published August 13, 2020, at Science.
Study lead author David Awschalom, Liew Family Professor of Molecular Engineering, senior scientist at Argonne National Laboratory and director of the Chicago Quantum Exchange, said: “Breakthrough This discovery lays the foundation for exciting new research directions in quantum science. “The wide applicability of this discovery, coupled with its remarkably simple implementation, allows this close association to affect many aspects of quantum engineering. It allows for new research opportunities that were previously thought to be impractical. “
At the atomic level, the world operates according to the rules of quantum mechanics – very different from what we see around in everyday life. These various rules can translate into technologies like virtually uncontrollable networks or extremely powerful computers; The US Department of Energy announced blueprints for the future quantum Internet during an event at UChi Chicago on July 23. But the fundamental technical challenges remain: Needed quantum states an extremely quiet and stable space to operate, as they are easily disturbed by background noise. vibrations, changes in temperature or stray electromagnetic fields.
So scientists try to find ways to keep the system coherent for as long as possible. A common approach is to isolate the system from noisy surroundings, but this can be difficult to use and complicated. Another technique involves making all materials as pure as possible, which can be expensive. Scientists at UChi Chicago have a different solution.
“With this approach, we don’t try to eliminate the noise in the surroundings; instead, we “fool” the system into thinking it was making no noise, “said postdoctoral researcher Kevin Miao, the first author of the paper.
In parallel with the conventional electromagnetic pulses used to control quantum systems, the team applied a continuous alternating magnetic field. By precisely adjusting this field, scientists can rapidly spin the electron spins and allow the system to “tune” the rest of the noise.
Miao explained: “To understand this principle, it’s like sitting on a Ferris wheel with people screaming around you. “When the car is still, you can hear them perfectly, but if you are spinning fast, the noise will turn into the background.”
This small change allows the system to remain coherent up to 22 milliseconds, four orders of magnitude higher than without modification – and much longer than any previously reported electron spin system. . (For comparison, a blink of an eye takes about 350 milliseconds.) The system is capable of modulating almost completely to certain types of temperature fluctuations, physical vibrations, and electromagnetic interference, all of which destroy quantum coherence.
This simple fix could open up discoveries in almost every field of quantum technology, scientists say.
“This approach creates a path to scalability,” Awschalom said. “It will make it practical to store quantum information in electron spin. Extended storage times will allow for more complex operations in quantum computers and allow quantum information to travel from spin-based devices to travel longer distances in the network. “
“With this approach, we don’t try to eliminate the noise in the surroundings; instead, we “fool” the system into thinking it is making no noise. “- Kevin Miao, postdoctoral researcher
Although their tests were performed in a solid-state quantum system using silicon carbide, the scientists believe the technique will have similar effects in other types of quantum systems, for example. such as superconducting quantum bits and molecular quantum systems. This level of flexibility is unusual for such a technical breakthrough.
“There are a lot of candidates for quantum technology that have been put aside because they cannot maintain quantum coherence for a long time,” said Miao. “Those things can be reassessed now that we have this way to massively improve interoperability.
“The best part is it’s incredibly easy to do,” he added. “The science behind it is very complicated, but the logistics of adding an alternating magnetic field is very simple.”
Other UChi Chicago scientists participating in the study were graduate student Joseph Blanton, postdoctoral researcher Chris Anderson, graduate students Alexandre Bourassa and Alex Crook, and scientist Argonne Gary Wolfowicz. Hiroshi Abe and Takeshi Ohshima together with the National Institute of Quantum and Radioactive Science and Technology are also co-authors. The team used the resources at the Pritzker Nano Fabrication Facility. The team is working with the Polsky Center for Entrepreneurship and Innovation to commercialize this discovery.
See: “Universal coherent protection in solid state qubits” by Kevin C. Miao, Joseph P. Blanton, Christopher P. Anderson, Alexandre Bourassa, Alexander L. Crook, Gary Wolfowicz, Hiroshi Abe, Takeshi Ohshima and David D. Awschalom, August 13, 2020, Science.
DOI: 10.1126 / science.abc5186
Expense: DARPA, Air Force Scientific Research Office, Naval Research Office, National Science Foundation, Japan Science Promotion Association.