The Silicon carbide microrings developed by the Vukovi Lab can be seen through a scanning electron microscope. Credit: the lab
The light that surrounds us in daily life is a mix of frequencies, but the light in the "soliton" source is a single pulse of light.
The system used to measure all manner of phenomena and characteristics is based on the color of light that is spread over the comb. Miniature versions of these combs are currently in development and have the potential to enhance many technologies.
The lab of an electrical engineer at the university joined the community recently. The team has demonstrated on-chip frequency combs in a variety of materials. The Jensen Huang Professor of Global Leadership in the School of Engineering and professor of electrical engineering at the University of California, Santa Barbara, said that the quantum optical properties of frequencies have been elusive. The soliton microcomb has a lot of quantum properties and we wanted to study them.
While other labs have made soliton microcombs, the researchers at the University of California, Berkeley, are the first to investigate the system's quantum optical properties using a process that they outline in a paper published in December. The basis of all proposed quantum technologies is based on the idea that microcomb solitons exhibit a relationship between particles that allows them to influence each other even at incredible distances. Most of the light we see on a daily basis does not exhibit any form of entanglement.
"This is one of the first demonstrations that this small frequency comb can generate interesting quantum light on a chip," said Kiyoul Yang, a research scientist in the lab and co-author of the paper. "That can open a new path to explore quantum light using the frequencies comb and integrated circuits for large-scale experiments."
Demonstrating the utility of their tool, the researchers also provided convincing evidence of quantum entanglement within the soliton microcomb, which has yet to be proven by any existing studies.
"I would like to see solitons become useful for quantum computing because it's a highly studied system," said a graduate student who co-authored the paper. We have a lot of technology for generating solitons on chips at low power, so it would be exciting to be able to take that and show that you have entanglement.
A diagram of the comb and microring. The diagram shows the light teeth and the light between them. Credit: the lab
Between the teeth.
Theodor W. Hnsch won the 2005 Nobel Prize for his work on the first Frequency comb. To create what Hnsch studied requires a lot of equipment. The newer version of the system is called the "micro" version, and it is designed to fit on a chip. This design saves money.
The researchers used the resources of the Stanford Nanofabrication Facilities to create a ring of Silicon Carbide that was used to create their comb. If all goes well, the laser builds up intensity and a soliton is born.
"It's fascinating that, instead of having a complicated machine, you can just take a laser pump and a really tiny circle and produce the same sort of specialized light," said a graduate student in the lab. He said generating the microcomb on a chip enabled a wide spacing between the teeth, which was a step towards being able to look at the comb's details.
The next steps involved packing the micro-ring with solitons and detecting single particles of the light. "With the soliton crystal, you can see that there are smaller light waves in between the teeth, which is what we measure to infer the structure," said Guidry. "If you park your detectors there, you can get a good look at the interesting quantum behavior without being drowned out by the coherent light that makes up the teeth."
The researchers decided to try to confirm a theoretical model, called the linearized model, because they were performing some of the first experimental studies of the quantum aspects of this system. They were astonished to find that the experiment matched the theory very well. They have shown that the performance of the microcomb matches a theory that implies entanglement.
The take- home message is that theorists will be able to do more theory because of this system.
Experiments using quantum entanglement.
In data centers, microcombs could boost the speed of data transfer, while in satellites, they could provide more preciseGPS or analyze the chemical composition of far-away objects. The potential for solitons in certain types of quantum computing is something the team is interested in.
The ability to study it from a quantum perspective, as well as the platform, has given the researchers an open mind about what they could do next. The possibility of performing a measurement on their system that proves quantum entanglement is near the top of their list.
Nature Photonics has more information about Jelena Vukovi. www.nature.com/articles/s41566-021-00901-z
Nature Photonics is a journal.
A quantum view of light was retrieved fromphys.org on December 16, 2021.
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