Scientists Harness a Single Phonon to Control Quantum Spin for the First Time

For the first time, researchers have shown that a single quantum of sound—called a phonon—can interact with a single atomic spin. The breakthrough came from a team at Harvard, where scientists used a tiny diamond chip to observe this effect. Their work opens new possibilities for quantum technologies and precision sensing. The experiment relied on a diamond chip measuring just 5 mm by 5 mm. Inside it, a nanometer-scale mechanical resonator vibrated alongside a single atomic defect, known as a color-center spin qubit. These defects acted as quantum memory, storing information in their spin states.

A key challenge in quantum research has been achieving strong interactions between spins and phonons. Here, the mechanical resonator made this possible. Even a single phonon was enough to change the quantum state of the atomic spin, proving that sound vibrations could control quantum information.

Graham Joe, the study’s lead author and a former Harvard graduate student, highlighted the significance of the result. The spin qubit acted as an extremely sensitive probe, detecting tiny changes in its mechanical surroundings. This sensitivity could lead to better ways of sensing the environment around a single atom.

The experiment also showed that mechanical vibrations can last for long periods while taking up very little space. This makes phonons promising as carriers of quantum information, potentially linking different quantum systems in future devices. The findings demonstrate new tools for precision sensing and the development of quantum acoustic devices. By connecting spins and phonons, the research moves closer to practical applications in quantum computing and environmental detection. The team’s approach could also help integrate separate quantum systems into a single, functional network.