One of the hardest problems in quantum computing is keeping a qubit coherent long enough to perform useful operations. Environmental noise, magnetic fluctuations, temperature changes, stray electric fields, constantly pushes qubits toward decoherence. The standard approach is to use pulse sequences that cancel out low-frequency noise, but these sequences are often incompatible with the hardware used to couple qubits together.
A team led by Eliza Cornell, Benjamin Pingault, and Marko Lončar at Harvard University has demonstrated a solution that takes the opposite approach: instead of fighting the environment, embrace a mechanical one.
Published in Nature Physics, the work uses a single silicon-vacancy (SiV) center in diamond, a type of spin qubit, and subjects it to mechanical strain that creates “dressed” quantum states that are inherently insensitive to low-frequency noise. The result is all-mechanical coherence protection, combined with ultrafast control at a Rabi frequency of 800 MHz.
Why phonons
Most quantum network architectures use photons to carry quantum information between stationary qubits. Photons are fast and travel well, but they have limitations: they require large device footprints, introduce crosstalk, and are difficult to confine at the chip scale.
Phonons, quantized mechanical vibrations, offer an alternative. They have smaller device footprints, reduced crosstalk, long cavity lifetimes at low temperatures, and natural coupling to both solid-state spins and electromagnetic waves. A phononic quantum network would store and process information in stationary spin qubits and use phonons to carry information between them on the same chip.
The problem has been that coupling a spin to a resonant phononic cavity and simultaneously using dynamical decoupling pulse sequences to suppress noise have been technically incompatible, until now.
All-mechanical protection
The team’s central innovation is to perform all quantum operations, optical initialization, gate operations, and readout, in a dressed basis created by mechanical strain applied to the SiV center. The strain generates dressed states that are naturally protected from low-frequency environmental noise, without requiring additional pulse sequences.
This mechanical dressing is fully compatible with the phononic cavity that will eventually be needed to couple distant qubits. The phonon that protects the qubit and the phonon that links it to another qubit are the same physical mechanism.
The Rabi frequency of 800 MHz is unusually fast for a spin qubit, enabling quantum gates on sub-nanosecond timescales. This is critical for quantum error correction, where gate speed relative to decoherence time determines whether error correction is feasible.
Implications for quantum networks
The result establishes the basic building block for a phononic quantum network. The next step is to demonstrate two-qubit gates mediated by phonons between separate SiV centers on the same chip, a milestone that would open the door to on-chip quantum processors built around mechanical vibrations rather than electromagnetic fields.
The work was supported by the National Science Foundation, the Air Force Office of Scientific Research, the Packard Foundation, and Amazon Web Services, among others. Device fabrication was performed at the Center for Nanoscale Systems at Harvard.
Limitations and caveats
The demonstration was performed at cryogenic temperatures (dilution refrigerator range), which is standard for solid-state spin qubits but limits practical deployment. The mechanical dressing technique adds complexity to the device fabrication, requiring precise strain engineering in diamond. The current results show single-qubit control; entangling operations between two mechanically dressed spins have not yet been demonstrated.
Source
1. Cornell, E., Xu, Z., Wang, Z., Warner, H. K., Mann, E., Haas, M., Maity, S., Joe, G., Jiang, L., Rabl, P., Pingault, B., & Lončar, M. (2026). All-mechanical coherence protection and fast control of a spin qubit. Nature Physics. https://doi.org/10.1038/s41567-026-03369-2