2021-08-31

The breakthrough of photonic chip technology has opened the way for realizing quantum computing under real-world conditions

By yqqlm yqqlm

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The number of possible configurations is unlimited, more than the number of atoms in the entire universe To be more, this time you need the help of a quantum computer.

The mainstream use of quantum computing is still decades away, and research teams from universities and private companies around the world are studying different aspects of the technology.

The research team led by Xu Yi, assistant professor of electrical and computer engineering in the School of Engineering and Applied Sciences at the University of Virginia has a place in the physics and applications of photonic devices that detect and shape light for use in communications including And a wide range of uses including calculations. His research group has created a scalable quantum computing platform that drastically reduces the number of devices required to achieve quantum speed on a one-cent-sized photonic chip.

The breakthrough of photonic chip technology has opened the way for realizing quantum computing under real-world conditions

This silicon chip contains three Optical microresonators, they envelop photons and produce a micro comb to effectively convert photons from a single wavelength to multiple wavelengths. Yi’s team verified the generation of 40 quantum modes from a single microresonator, demonstrating that the multiplexing of quantum modes can play a role in an integrated photonic platform.

Olivier Pfister, professor of quantum optics and quantum information at the University of Virginia, and Hansuek Lee, assistant professor at the Korea Advanced Institute of Science and Technology, contributed to this success.

“Nature Communications” recently published the team’s experimental results “squeezed quantum microcomb on a chip”. Two members of the Yi team, Yang Ziqiao, a PhD student in physics, and Mandana Jahanbozorgi, a PhD student in electrical and computer engineering, are the co-first authors of the paper. Funding from the National Science Foundation’s Quantum Communication Engineering Quantum Integration Platform Project supported this research.

The breakthrough of photonic chip technology has opened the way for realizing quantum computing under real-world conditions(1)

Quantum computing is expected to bring a A new way of information processing. Your desktop or laptop computer processes information in a long string of bits. A bit can only hold one of two values: zero or one. Quantum computers process information in parallel, which means they don’t have to wait for a sequence of information to be processed before calculating more information. Their unit of information is called a qubit, which is a mixture that can be one and zero at the same time. A quantum mode, or qumode, spans all variables between 1 and 0-the value to the right of the decimal point.

Researchers are studying different methods to efficiently produce the large number of quantum modes required to achieve quantum speed.

Yi’s photonics-based approach is attractive because a light field is also a full spectrum; every light wave in the spectrum may become a quantum unit. Yi hypothesized that by entangled light fields, light will reach a quantum state.

You may be familiar with optical fibers that transmit information through the Internet. In each fiber, many lasers of different colors are used in parallel. This phenomenon is called multiplexing. Yi brings the concept of multiplexing to the quantum realm.

In 2014, Pfister’s team successfully generated more than 3000 quantum modes in a large-scale optical system. However, using so many quantum modes requires a large footprint to contain the thousands of mirrors, lenses, and other components needed to run algorithms and perform other operations. Xu Yi’s research team created a quantum source in an optical microresonator. This is a ring-shaped, millimeter-sized structure that envelops photons and produces a micro comb. This device can effectively convert photons from a single wavelength to Multiple wavelengths. Light circulates around the ring to build up optical power. Through multiplexing, Yi’s team verified that 40 quantum modes are generated from a single microresonator on a chip, proving that the multiplexing of quantum modes can play a role on an integrated photonic platform. This is just a number they can measure. It is expected that after optimizing the system, thousands of quantum modes can be generated from one device.

Yi’s multiplexing technology has opened up a path for quantum computing under real-world conditions, although errors are inevitable, even in classical computers. But the quantum state is much more fragile than the classical state. The number of qubits required to compensate for errors may exceed one million, and the number of devices will increase accordingly, and multiplexing can reduce the number of devices required by two to three orders of magnitude.

Yi’s photonics-based system provides two additional advantages in the exploration of quantum computing. Quantum computing platforms that use superconducting electronic circuits need to be cooled to a low temperature. Since photons have no mass, quantum computers with integrated photonic chips can run or sleep at room temperature. In addition, Lee uses standard photolithography techniques to fabricate microresonators on silicon chips. This is important because it means that resonators or quantum sources can be mass-produced.

Yi said: “We are proud to promote the frontiers of quantum computing engineering and accelerate the transition from bulk optics to integrated photonics. The research team will continue to explore in the quantum computing platform based on photonics Methods of integrating devices and circuits and optimizing their performance.”