Phonons extend qubit coherence time threefold in diamond-based system
Researchers at Harvard demonstrated that continuously applying microscopic mechanical vibrations, or phonons, to a diamond-based qubit extended its coherence time by about three times. This approach could protect quantum information and potentially enable compact sound-based quantum networks on chips. The findings were published in Nature Physics.
The phononic cavity is central to this work, trapping mechanical vibrations so they interact more strongly with the electron spin inside the silicon-vacancy qubit. Because phonons have much shorter wavelengths than light at equivalent frequencies, components built around them can be considerably smaller, enabling denser chip-scale integration.
The team's "all-mechanical" approach replaces conventional microwave decoupling pulses with a continuous phonon driving field, transforming the qubit into a "dressed" state. This matters because standard microwave protection methods perform poorly inside phononic cavities, previously forcing researchers to choose between strong phonon coupling or long coherence times.
This advance could accelerate development of compact quantum networks built directly on microchips, potentially benefiting industries reliant on secure communications and complex simulation. Hybrid quantum systems combining multiple qubit types may also become more practical. However, the threefold coherence improvement, while meaningful, remains far from what error-corrected quantum computers require, so widespread commercial impact is likely years away.