Researchers at Stanford University have made a groundbreaking observation by directly witnessing quantum sound jumps in real-time. Their findings have been published in the journal Science.
The team focused on phonons, which are the quantum units of mechanical vibrations. In the classical world, sound diminishes gradually; however, at the quantum level, energy shifts occur in discrete packets.
The scientists successfully captured the moment when a system suddenly transitioned from one energy level to another.
Quantum jumps were first predicted in the early 20th century, with initial observations occurring in trapped ions in 1986 and later in photons in 2007. Previous experiments involving phonons provided indirect evidence, but real-time observation of individual transitions had yet to be achieved.
How the Jump Was Observed
For their experiment, the researchers constructed a microscopic mechanical resonator, akin to a tiny tuning fork. This device was fabricated using techniques typical in chip manufacturing.
A key feature of the resonator was its long decay time of approximately 2 milliseconds. During this interval, the researchers conducted hundreds of measurements to pinpoint the moment when the phonon’s energy shifted from level 1 to level 0.
To facilitate observation, the resonator was coupled with a superconducting qubit, which acted as a sensor, repeatedly checking the system's state without disrupting it during each measurement.
“We observed that vibrating objects can exhibit quantum behavior. This is a necessary condition for many operations in quantum computing and sensing,” stated Amir Safavi-Naeini, the lead researcher.
Importance of Observing Quantum Jumps
One potential application of this research involves error correction in quantum computers. Quantum states are inherently unstable, and transitions between levels can indicate errors in some architectures. To correct these errors, it is essential to identify when they occur.
The researchers believe that the capability to monitor such changes in real-time lays the groundwork for systems based on mechanical resonators. However, they emphasize that this experiment is fundamental research rather than a ready-to-use error correction method.
Another avenue of exploration is the development of highly sensitive sensors. The Stanford team, in collaboration with scientists from the California Institute of Technology, is already investigating the use of the resonator-qubit combination for detecting and identifying proteins within cells.
The authors also suggest possible applications of this technology in electronics. Mechanical vibrations are utilized in smartphones and other devices, and more precise control over these vibrations could lead to the creation of new acoustic components.
In June, Microsoft Quantum and Quantinuum announced a reduction in logical errors in a quantum processor by factors between 11 and 800 compared to comparable physical schemes. At the same time, IBM introduced a system for discovering new error correction codes using AI.