The state of an electron-spin qubit depends primarily on the spin of the electron it houses. For some materials, the state may also depend on the electron’s “valley degree of freedom,” which relates to the local extremes of a material’s electronic band structure. But obtaining this spin and valley-degree-of-freedom information is difficult. Now, using a system made of coupled graphene quantum dots, Chuyao Tong, of the Swiss Federal Institute of Technology (ETH) in Zurich, and her colleagues demonstrate how to extract an electron’s spin and valley information from how easily that electron passes through the device [1]. Their approach underlines the potential for gaining control of the state of coupled graphene quantum dots, which would make them more useful for quantum technology applications.
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