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Qubits With Staying Power

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The researchers' device is a ladder-like structure etched into diamond.

The researchers' device is a ladder-like structure etched into diamond. The gaps between the ladder's "rungs" act like a mirror, temporarily trapping light particles emitted at the ladder's center.

Credit: MIT News

Massachusetts Institute of Technology (MIT) and Brookhaven National Laboratory researchers say they have developed a new technique that extends the superposition time of a promising type of qubit a hundredfold. The researchers say their breakthrough could enable the indefinite extension of quantum-secured communication links, a commercial application of quantum information technology that currently has a range of less than 100 miles, and eventually practical quantum computers.

The new qubit design employs nitrogen atoms embedded in synthetic diamond. The researchers found that when nitrogen atoms happen to be situated next to gaps in the diamond's crystal lattice, they produce "nitrogen vacancies," which enable researchers to optically control the magnetic spin of individual electrons and atomic nuclei.

"Amongst all the crystals, diamond is a particularly good host for capturing an atom, because it turns out that the nuclei of diamond are mostly free of magnetic dipoles, which can cause noise on the electron spin," says MIT professor Dirk Englund.

The new device consists of a ladder-like diamond structure with a nitrogen vacancy at its center, which is suspended horizontally above a silicon substrate.

"The higher collection efficiency will lead to both faster generation and faster verification of entanglement, so it is analogous to being able to increase the clock rate of a computing device," says University of Cambridge researcher Mete Atature.

From MIT News
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