A group of researchers in the LPA (ENS-PSL/Sorbonne Université) measured spin echoes and Ramsey interferences of electrons embedded in nitrogen-vacancies (NV) centers of a levitating diamond. These measurements showed a large coherence time of the electronic spins as well as a high angular stability of the diamond, a significant steps towards strong coupling between NV spins and rotational modes of the diamonds.
If diamonds are well known as very rare gems, this past decade physicists found another reason to be enthusiastic about these carbon structures : empty crystallographic sites can be filled by other atoms than Carbon, in a controlled way. When inserted Nitrogen atoms couple themselves with a neighbor vacancy, it creates an isolated two-level system that can be studied to test quantum mechanics on a variety of aspects.
A group of researchers in the Laboratoire Pierre Aigrain trapped a micro diamond with such NV centers inside a Paul trap, both under atmospheric conditions and under vacuum. Using spin-echoes sequences, they showed that the lifetime of the excited state (also called T1) is as long as a few milliseconds. Similarly, the coherence time (called T2*) measured thanks to Ramsey interferometry is as long as the T2* of a free diamond. The high electric field of the Paul trap does not modify nor the lifetime or the coherence time of the NV spins.
Coherent manipulations of NV spins inside a magnetic field provide information on the rotational motion of the diamond. Amazingly, the researchers identified a regime where the Paul trap strongly stabilize the rotational motion of the levitating system under atmospheric condition and in vacuum. This setup is a robust platform for precise manipulation of a levitating system.
Published in Physical Review Letters, this demonstration of angular stability opens a path towards strong coupling to the rotational degree of freedom. After technical improvements, it could give some propects in matter wave interferometry or quantum gravity sensing.
Article reference : Physical Review Letters
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