SiC can boast some of the quantum merits of diamond

Researchers at the University of Science and Technology in Hefei and Wuhan University in China have demonstrated SiC can boast some of the quantum merits of diamond (nitrogen-vacancy (NV) centers) with the additional advantage of optical control at the wavelengths used by the telecommunications industry.

The photon-spin interactions for NV centers in diamond need light at visible wavelengths although telecommunications wavelengths are much longer. And this technology need diamonds too.

It turns out there are types of defects in SiC that might also be useful for quantum technologies. SiC is widely used in power electronics, so commercially viable avenues for producing SiC devices already exist. Over the past 10 years, vacancies and divacancies (where one or a pair of atoms in the lattice are absent) in SiC began to attract interest when researchers learned that they could also control their spin states with light at room temperature with long coherence times. The observation of NV centers in SiC really piqued interest, as these were optically active at the wavelengths used by the telecommunications industry as opposed to the shorter visible wavelengths needed to control the spin states of vacancies and divacancies in SiC.

Simply blasting a sample with nitrogen atoms can create NV centers in SiC, as the impact causes nitrogen atoms to take the place of host atoms and elbow a neighboring atom out the way at the same time.

When a quantum system with two available states is illuminated by light at the frequency exactly equating to the energy difference between the states, the system will flip between states at a characteristic frequency. By measuring these “Rabi oscillations,” the researchers could confirm that they had coherent control over their system, and that this lasts with a coherence time (T2) of 17.2 μs.

The observed coherence times are still shorter than those for NV centers in diamond where a T2 of milliseconds has been observed. However, it does compete with the coherence times observed for divacancies in SiC, with the additional advantage of operating at telecommunication wavelengths. In addition, the researchers already have in mind strategies that could increase the decoherence time further, including lower nitrogen concentration and the dynamic decoupling technology.

The work poses a “coherent” argument for further investigations of NV centers in SiC for quantum computing. (Phys.org)

The study has been published in Physical Review Letters.

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