A quantum light squeezer to reduce quantum noise

“Light squeezer” reduces quantum noise in lasers, could enhance quantum computing and gravitational-wave detection.


MIT Physicists have designed first of its kind of quantum “light squeezer” that operates at room temperature to reduce quantum noise in an incoming laser beam by 15 percent.

This new quantum light squeezer contains a marble-sized optical cavity, fixed in a vacuum chamber. It has two mirrors- one of which is smaller than the diameter of a human hair. The giant mirror stands stationary while the other is movable, suspended by a spring-like cantilever.

The system can operate at room temperature because of the shape and structure of the second mirror. When a laser beam enters the cavity, it bounces between the two mirrors. The force emitted by the light makes the second nanomechanical mirror swing back and forth in a way. This enabled scientists to engineer the light exiting the cavity to have unique quantum properties.

The resultant squeezed exiting light can later be used to make more precise measurements, for instance, in quantum computation and cryptology, and the detection of gravitational waves.

Scientists installed the system in a laser experiment built at Louisiana State University, where the scientists made the measurements. With the new squeezer, the scientists were able to characterize the quantum fluctuations in the number of photons versus their timing, as the laser bounced and reflected off both mirrors. This characterization allowed the team to identify and thereby reduce the quantum noise from the laser by 15 percent, producing a more precise “squeezed” light.

Nergis Mavalvala, the Marble Professor and associate head of physics at MIT, said, “As optomechanical squeezers become more practical, this is the work that started it. It shows that we know how to make these room temperature, wavelength-agnostic squeezers. As we improve the experiment and materials, we’ll make better squeezers.”

The paper’s lead author is Nancy Aggarwal, a former physics graduate student in the MIT LIGO Laboratory, now a postdoc at Northwestern University. Other co-authors on the paper along with Mavalvala are Robert Lanza and Adam Libson at MIT; Torrey Cullen, Jonathan Cripe, and Thomas Corbitt of Louisiana State University; and Garrett Cole, David Follman, and Paula Heu of Crystalline Mirror Solutions in Santa Barbara, California.

Journal Reference:
  1. Aggarwal, N., Cullen, T.J., Cripe, J. et al. Room-temperature optomechanical squeezing. Nat. Phys. 16, 784–788 (2020). DOI: 10.1038/s41567-020-0877-x
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