Nuclear-spin swap extends room-temperature entanglement lifetime up to 240-fold

Researchers in China have extended the lifetime of entanglement in a room-temperature, solid-state system by up to a factor of 240. Editors have highlighted the following attributes while ensuring the content's credibility: Add as preferred source Exchanging entanglement from an electron to a silicon-29 nucleus within a silicon carbide color center.

Credit: Jin-Shi Xu Researchers in China have extended the lifetime of entanglement in a room-temperature, solid-state system by up to a factor of 240. Led by Shuo Ren and Rui-Jian Liang at the University of Science and Technology of China in Hefei, the team transferred entangled states from the electron spins of solid-state defects to the spins of surrounding atomic nuclei, which are far more resilient to noise.

Most silicon nuclei have no spin, but around 5% are the isotope silicon-29, whose nuclear spin couples to the electron through the hyperfine interaction, allowing the two to become entangled. Once an entangled state had been prepared between a color center's electron and a nearby nucleus, the protocol transferred the entanglement to two silicon-29 nuclei, where it was stored before being mapped back to the electron for readout.

The team prepared an entangled quantum state with a fidelity of 94%, a measure of how closely the state matches the ideal target. After the transfer into the nuclear spins, the fidelity remained at 92.5%, showing that almost no quantum information was lost.

In addition, entanglement lasted for more than 240 microseconds in the nuclear-spin memory, compared with just over 1 microsecond in the electron alone. Altogether, the team surveyed 200 single color centers in silicon carbide with naturally occurring isotope abundances.

We found that more than 10% host two or more strongly coupled nuclear spins suitable for forming quantum registers," Xu says.

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