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“Large atoms” allow quantum processing and communication in one



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MIT researchers have introduced a quantum computing architecture that can perform low-error quantum computing while quickly sharing quantum information between processors. The work represents a key step towards a complete quantum computing platform.

Prior to this discovery, small quantum processors successfully performed tasks exponentially faster than conventional computers. However, it was difficult to control quantum information between remote parts of the processor. In conventional computers, cable connections are used to route information back and forth through the processor during computation. In a quantum computer, however, the information itself is quantum mechanical and fragile, which requires fundamentally new strategies for the simultaneous processing and communication of quantum information on a chip.

“One of the major challenges in quantum computer scaling is to enable quantum bits to interact when not placed together,”

; said William Oliver, associate professor of electrical engineering and computer science, associate director at MIT Lincoln Laboratory, and associate director of the Electronics Research Laboratory. “For example, the qubits of the nearest neighbors can easily interact, but how can I make ‘quantum connections’ that connect qubits to distant places?”

The answer is to go beyond conventional light substance interactions.

While natural atoms are small and point-like in the wavelength of light they interact with, in a newspaper published in a magazine natureScientists show that this may not be the case for superconducting “artificial atoms.” Instead, they constructed “huge atoms” from superconducting quantum bits or qubits connected in a tunable configuration to a microwave transmission line or waveguide.

This allows scientists to adjust the strength of wave-waveguide interactions so that brittle horseshoes can be protected from decoding or any natural decay that would otherwise be accelerated by the waveguide while performing high fidelity operations. After performing these calculations, the bond strength of the waveguide waves is readjusted, and the curves are able to release quantum data into the waveguide in the form of photons or light particles.

“Connecting a quatt to a waveguide is usually bad enough for qubit operations because it can significantly shorten its lifespan,” said Bharath Kannan, a colleague at MIT and the first author of the article. “However, a waveguide is needed to release and route quantum information throughout the processor. We have shown that it is possible to maintain the coherence of the area, even if it is strongly connected to the waveguide. Then we have the ability to determine when we want to release the information stored in the quit. We have shown how huge atoms can be used to turn the waveguide interaction on and off. ‘ “

Scientists claim that the system implemented by scientists represents a new regime of light substance interactions. Unlike models that consider atoms to be point objects smaller than the wavelength of the light they interact with, superconducting qubits or artificial atoms are essentially large electrical circuits. When connected to a waveguide, they form a structure as large as the wavelength of the microwave light with which they interact.

The huge atom transmits its information as microwave photons at multiple locations along the waveguide, so the photons interact with each other. This process can be tuned to complete the destructive interference, which means that the information in the quit is protected. In addition, even though no photons are actually released from the huge atom, several waves along the waveguide are still able to interact with each other and perform operations. All the time, the qubits remain firmly connected to the waveguide, but due to this type of quantum interference, they can remain intact and be protected from decoding, while one- and two-flower operations are performed with high fidelity.

“We use quantum interference effects, which allow huge atoms, to prevent qubits from sending their quantum information into the waveguide until we need it,” says Oliver.

“This allows us to experimentally test a new mode of physics that is difficult to access with natural atoms,” says Kannan. “The effects of a huge atom are extremely clear and easy to observe and understand.”

The work seems to have great potential for further research, adds Kannan.

“I think one of the surprises is actually the relative ease with which superconducting qubits are able to enter this vast atomic regime,” he says. “The tricks we used are relatively simple, and as such we can imagine how to use them for other applications without a lot of additional overhead.”

The coherence time of the qubits incorporated into the giant atoms, i.e. the time remaining in the quantum state, was approximately 30 microseconds, almost the same for non-waveguide-bound qubits ranging from 10 to 100 microseconds. scientists.

In addition, the research demonstrates two-bit twisted operations with 94 percent fidelity. This represents the first time scientists have cited two-bit fidelity for oscillations that have been strongly associated with a waveguide, because the fidelity of such operations using conventional small atoms is often low in such an architecture. Kannan says that with greater calibration, operational tuning procedures, and optimized hardware design, fidelity can be further improved.


The fields of Rydberg strontium atoms are promising for use in quantum computers


More information:
Waveguide quantum electrodynamics with superconducting artificial giant atoms, nature (2020). DOI: 10,1038 / s41586-020-2529-9, www.nature.com/articles/s41586-020-2529-9

Provides a technology institute in Massachusetts



Citations: “Large Atoms” Enable Quantum Processing and Communication in One (2020, July 29) Obtained on July 29, 2020 from https://phys.org/news/2020-07-giant-atoms-enable-quantum.html

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