How a piezoelectric resonator takes over laser tuning for cold atoms
Illustrative image: Unsplash contributor on Pexels
Cooling atoms with a laser requires more than a stable wavelength. The light must also change frequency as the experiment moves from trapping atoms to cooling and measuring them. Equipment that makes those changes can occupy more space and consume more power than the laser control chip itself.
Researchers at the University of Wisconsin-Madison and the University of California, Santa Barbara, have demonstrated an alternative based on a photonic resonator and a piezoelectric actuator. The work, highlighted by Wisconsin’s engineering college, concerns control of a 780nm laser for rubidium experiments. [Source 1]
Moving the reference
The device combines a silicon nitride optical cavity with lead zirconate titanate, or PZT. Applied voltage creates mechanical strain, shifting the cavity’s resonance. A laser locked to that cavity follows the programmed changes in its reference frequency. [Source 2]
This puts frequency control into the resonator rather than an external frequency shifter. The researchers measured tuning of up to 1GHz per volt and an 11MHz small signal modulation bandwidth. Its static electrical consumption, calculated from leakage at an applied 10V, was below 10nW. That figure concerns resonator tuning, not the complete laser and laboratory apparatus. [Source 2]
From tuning to cooling
The team used the device to cool rubidium-87 atoms to 16µK without an external modulator for frequency shifting. That experiment connects the component measurements to an actual cold atom operation, the type needed in compact quantum sensors.
The research was led by Jennifer Choy and Steven Carpenter at Wisconsin, with Daniel Blumenthal and Andrei Isichenko at Santa Barbara. The paper is published in Nature Communications. [Source 1][Source 2]
