Beijing Institute of Quantum Information: Using fiber-integrated frequency conversion to achieve quantum entanglement distribution over 100 kilometers
In the 1960s, the advent of laser opened a new era of science and application. From supermarket code scanning to myopia surgery, traditional laser photon manipulation technology has long been integrated into daily life. In the past two decades, scientists have successfully developed new lasers that can control "phonons" (quantized energy units of mechanical vibrations). Precise control of phonons is expected to bring more possibilities to laser technology, such as taking advantage of unique quantum properties such as entangled states.
A research team from the University of Rochester and the Rochester Institute of Technology in the United States has recently developed a dual-mode compressed phonon laser that can achieve high-precision control of phonons at the nanometer scale.
The research team published a related paper in the journal Nature Communications, detailing how to enable nanoscale mechanical vibration quanta (phonons) to maintain laser-like coherent output while achieving thermal noise compression through dual-mode coupling and nonlinear cooling, thereby significantly reducing the fluctuations of phonon lasers.
Professor Nick Vamivakas, one of the corresponding authors of the paper, and his collaborators demonstrated the phonon laser for the first time in 2019. They used optical tweezers to capture and suspend nanoparticles in a vacuum, and achieved coherent oscillation of phonons through their mechanical oscillations.
However, to make this technology usable for high-precision measurements, they had to overcome a key challenge-noise, the interference that interferes with accurate readings of signals. This problem exists in both photon and phonon lasers.
"Laser appears to the naked eye as a stable beam of light, but in fact there are a large number of fluctuations, which can introduce noise into the measurement process." Nick Vamivakas explained, "We achieved effective suppression of phonon laser fluctuations by applying parametric coupling modulation to the two oscillation modes in the optical tweezers suspension system, combined with nonlinear parameter cooling."
This figure shows the core device and principle of the experiment. (a) illustrates the optical tweezers suspension system and how to achieve two-mode coupling through modulation; (b) explains the generation of asymmetric potential wells and the rotational coupling mechanism; () visually presents the phonon down-conversion process with the sum of two frequencies as the driving frequency through the energy level diagram, which is the physical basis for achieving dual-mode compression.
The core breakthrough of the research team is the realization of dual-mode thermomechanical compression: on the two orthogonal vibration modes of x and y of suspended silica nanoparticles (diameter 100nm) in optical tweezers, the sum of the two mode frequencies is used as the driving frequency for coupling modulation. At the same time, combined with nonlinear parameter cooling, the system is stabilized, directly compressing and reducing the inherent thermal noise of the phonon laser.
Nick Vamivakas said that this noise suppression capability allows the system's acceleration measurement accuracy to surpass traditional photon laser and radio frequency wave measurement technologies.
