Harvard team strengthens the link between diamond qubits and vibrating beams

[KurtAngle]

Researchers at Harvard are working on better ways to connect defect qubits in diamond to mechanical motion. Quantum Zeitgeist reports on a preprint from Marko Lončar's group showing that a technique used to make mechanical resonators ring for longer can also strengthen their coupling to silicon vacancy centres

Silicon vacancy centres are defects in diamond that can act as qubits and interact with light. The team embedded them in tensioned diamond nanobeams, tiny strips of diamond that vibrate, and measured how the defects responded to both static and dynamic strain

Dissipation dilution is a method that extends how long a mechanical resonator keeps vibrating, but there was concern it might weaken the coupling to the defects. The researchers found it does the opposite, strengthening the coupling by concentrating strain near where the beam is clamped

The article reports about a threefold improvement in strain sensitivity, alongside longer mechanical coherence. The longer term goal is spin and mechanical coherence lasting seconds, which would help build hybrid quantum systems that convert information between qubits, vibrations and light

This is a preprint, and the article summarising it is a little muddled about who did the work, so the original paper is the place to check details. Coherence lasting seconds is still a goal rather than a result. Even so, hybrid systems linking different kinds of quantum objects are likely to matter for future quantum networks

Could mechanical resonators become useful quantum memories? And is diamond still the best material for defect qubits?

Harvard University Enhances Defect-Diamond Link For Long Coherencequantumzeitgeist.com