Breaking the Temperature Barrier: How Quantum Ground State Acoustics Could Revolutionize Quantum Physics
Researchers have made a breakthrough in cooling sound waves in optical fibers, bringing them closer to the quantum ground state and bridging classical and quantum mechanics.
Breakthrough in Cooling Sound Waves in Optical Fibers
Researchers from the Stiller Research Group have achieved a significant breakthrough in cooling sound waves in an optical fiber, bringing them close to the quantum ground state. By using laser cooling and stimulated Brillouin scattering, they were able to reduce thermal noise and potentially bridge classical and quantum mechanics.
In their study published in Physical Review Letters, the researchers lowered the temperature of a sound wave in an optical fiber by 219 K using laser cooling. This is ten times further than what had previously been reported. Ultimately, they were able to reduce the initial phonon number by 75% at a temperature of 74 K.
The drastic reduction in temperature was made possible by the use of laser light. Through the nonlinear optical effect of stimulated Brillouin scattering, the laser light effectively cooled the acoustic vibrations, creating an environment with less thermal noise.
Advantages of Glass Fibers and Implications for Quantum Communications
Glass fibers have several advantages, including their strong interaction with light and sound over long distances. In this experiment, the researchers used a 50 cm long optical fiber, in which a sound wave extending over the full length of the core was cooled to extremely low temperatures.
This achievement opens up possibilities for broadband applications in quantum technology. Dr. Birgit Stiller, the head of the quantum optoacoustics group, highlights the exciting potential for manipulating long acoustic phonons and reaching the quantum ground state in waveguides.
The ability to cool sound waves in waveguide systems allows for deeper insights into the fundamental nature of matter. It also has implications for high-speed communication systems and future quantum technologies.
Quantum Mechanics Perspective on Sound and Phonons
From a quantum mechanics perspective, sound can be described as a particle called a phonon. The phonon represents the smallest amount of energy in an acoustic wave at a specific frequency. By minimizing the number of phonons, researchers can observe and study the quantum behavior of sound.
Reaching the quantum ground state, where the number of phonons approaches zero, allows for the measurement of quantum effects. This breakthrough in cooling sound waves brings researchers closer to understanding the fundamental nature of matter and paves the way for new experiments.
The use of waveguide systems, such as optical fibers, provides a continuous propagation of acoustic waves with a broad bandwidth. This makes them promising for applications in high-speed communication systems and other quantum technologies.
