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Scientists have discovered how to make the quantum state last 10,000 times longer



UChi Chicago scientists discovered how to make the quantum state 10,000 times longer

A team of scientists at the University of Chicago’s Pritzker School of Molecular Engineering announced the discovery of a simple modification that allows quantum systems to stay – or “coherent” – 10,000 times longer compared to before. Credit: University of Chicago

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 team of scientists at the University of Chicago’s Pritzker School of Molecular Engineering announced the discovery of a simple modification that allows quantum systems to stay – or “coherent” – 10,000 times longer compared to before. Although the scientists tested their technique on a specific type of quantum system called a solid-state qubit, they suggest it should be applicable to a wide variety of other quantum systems and hence could revolutionize quantum communication, computation and perception.

The study was published August 13 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: “This breakthrough puts the foundation for interesting new research directions in quantum science. “The wide applicability of this discovery, coupled with its remarkably simple implementation, allows this close association to impact many aspects of quantum engineering. It allows for research opportunities. previously thought unrealistic. “

At the atomic level, the world operates according to the laws of quantum mechanics – very different from what we see around in everyday life. These various rules can translate into technologies such as 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 fundamental technical challenges remain: Needed quantum states. an extremely quiet, stable space to operate, as they are easily disturbed by background noise. vibrations, changes in temperature or misplaced electromagnetic fields.

So scientists try to find ways to keep the system coherent for as long as possible. A common approach is to isolate a system from a noisy environment, 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 noise in the surroundings; instead, we” fool “the system into thinking it doesn’t experience noise,” says postdoctoral researcher. Kevin Miao, the first author of the article said.

UChi Chicago scientists discovered how to make the quantum state 10,000 times longer

A team of scientists at the University of Chicago’s Pritzker School of Molecular Engineering announced the discovery of a simple modification that allows quantum systems to stay – or “coherent” – 10,000 times longer compared to before. Credit: University of Chicago

In parallel with the conventional electromagnetic pulses used to control quantum systems, the team applied an additional continuous alternating magnetic field. By precisely tuning this field, scientists can quickly spin the spins of the electron and allow the system to “tune” the rest of the noise.

Miao explained: “To understand the 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 blur into the background.”

This small change allows the system to remain coherent for 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.) This system is able to regulate almost entirely for 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 spins. Long storage times will allow more complex operations in quantum computers and allow quantum information to be transmitted.” from spin-based devices that travel longer distances in the network. “

Although their tests are 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 an engineering breakthrough.

“There are many candidates for quantum technology that have been put aside because they cannot maintain quantum coherence for a long time,” said Miao. “It could be reassessed now that we have this way to massively improve linkability.

“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.”


Scientists developed the first quantum algorithm to characterize noise on large systems


More information:
KC Miao et al., “Universal coherent protection in solid state qubits” Science, August 13, 2020. DOI: 10.1126 / science.abc5186

Provided by University of Chicago



Quote: Scientists discover a way to make quantum states 10,000 times longer (2020, August 13) retrieved August 13, 2020 from https://phys.org/news/ 2020-08-scientists-quantum-states-longer.html

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