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Quantum spintronics: Single spins in silicon carbide

The Awschalom group published a paper in Nature Materials in 2014 that highlights a new achievement in quantum spintronics: control of a single electron spin in silicon carbide. Previous studies controlling the spin of a single electron have been done in nitrogen vacancy defects in diamond and phosphorous impurity atoms in silicon. While diamond nitrogen vacancy centers can be measured at room temperature, phosphorous donors in silicon require cryogenic temperatures. Silicon, however, is advantageous because it is unparalleled in its current use in nanofabrication and electrical interfacing. Silicon carbide may combine the best properties of both materials by allowing nanofabrication of room temperature quantum computing devices.

The isolation and control of a single electron spin in silicon carbide is the first step toward achieving that goal. In Nature Materials, the Awschalom group demonstrated a single electron spin coherence time of 1.2 ms at cryogenic temperatures. Their study is published alongside another paper by Widmann et al., which reports a spin coherence time of at least 160 μs in the same material at ambient temperature. These long coherence times are attractive for both quantum information processing and nanoscale sensing applications. These papers demonstrate that silicon carbide is a mature enough material to grown with such a low defect concentration that defects can be isolated one at a time. By isotopically purifying surrounding atoms, it may be possible to extend the already remarkably long spin coherence times even further, and by varying the types of vacancies, it seems likely that these materials can be engineered for various applications of quantum spintronics.

This major step forward is paving the way toward the fabrication of optical and electronic devices that can take advantage of quantum spintronics. While there are still many problems to overcome before the successful implementation of these quantum processors, they could eventually operate at room temperature and be integrated with current fabrication techniques using common electronics materials. To read more about the Awschalom group's recent publication, visit the Nature Materials News and Views section.