Caltech’s revolutionary new nanophotonic chip ‘squeezes out’ more light

Computers and electronic communications have come a long way since the days of radiotelegraphy and vacuum tubes. In fact, consumer devices now pack levels of processing power and memory that would have been unimaginable just a few decades ago.

But as microcomputing and information-processing devices become ever smaller and more powerful, they come up against some fundamental limitations imposed by the laws of quantum physics. For this reason, the future of the field may lie in photonics – the light-based parallel to electronics. Photonics is theoretically similar to electronics but substitutes photons for electrons. They have a huge potential advantage in that photonic devices may be able to process data much faster than their electronic counterparts, including for quantum computers.

Alireza Marandi. 1 credit

Currently, the field is still very active in basic research and lacks crucial devices needed to become practical. However, a new photonic chip developed at Caltech could represent a critical breakthrough for the field, particularly for enabling photonic quantum information processors. It can generate and measure quantum states of light in a way that was previously only possible with large and expensive lab equipment.

Lithium niobite, a salt whose crystals have many applications in optics, serves as the basis for the chip. One side of the chip generates so-called compressed light states and they are measured on the other side. A compressed state of light is, to put it very simply, light when it has been made less “noisy” at the quantum level. Compressed states of light have recently been used to increase the sensitivity of LIGO, the observatory that uses laser beams to detect gravitational waves. If you plan to process data with light-based quantum devices, that same quieter state of light is important.

“The quality of the quantum states we have obtained exceeds the demands of quantum information processing, which was once the territory of large experimental setups,” says Alireza Marandi. He is an assistant professor of electrical engineering and applied physics at Caltech. “Our work marks a milestone in the generation and measurement of quantum states of light in an integrated photonic circuit.”

According to Marandi, this technology shows a path towards the eventual development of quantum optical processors operating at terahertz clock frequencies. For comparison, that’s thousands of times faster than the microelectronic processor in a MacBook Pro.

This technology may find practical applications in communications, sensing and

” data-gt-translate-attributes=”[{” attribute=””>quantum computing in the next five years, says Marandi.

“Optics has been among the promising routes for realization of quantum computers because of several inherent advantages in scalability and ultrafast logical operations at room temperature,” says Rajveer Nehra, a postdoctoral scholar and one of the lead authors of the paper. “However, one of the main challenges for scalability has been generating and measuring quantum states with sufficient qualities in nanophotonics. Our work addresses that challenge.”

Reference: “Few-cycle vacuum squeezing in nanophotonics” by Rajveer Nehra, Ryoto Sekine, Luis Ledezma, Qiushi Guo, Robert M. Gray, Arkadev Roy and Alireza Marandi, 15 September 2022, Science.
DOI: 10.1126/science.abo6213

The paper describing the research appears in the September 15 issue of the journal Science. Co-authors include Nehra and Qiushi Guo, both postdoctoral scholar research associates in electrical engineering; and electrical engineering graduate students Ryoto Sekine (MS ’22), Luis Ledezma, Robert M. Gray, and Arkadev Roy.

Funding for the research was provided by NTT Research, the Army Research Office, the National Science Foundation, the Air Force Office of Scientific Research, and
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