A lateral gate-controlled double dot structure in Si has been fabricated for studying coupled two qubits. Nonequilibrium single-electron tunneling measurements at 1.4 K show that the second Coulomb peak, associated with a two-electron occupation, splits into two side peaks, and that their separation displays a strong magnetic-field dependence for various interdot coupling constants. Moreover, for some fixed magnetic fields, the separation of the side peaks decays exponentially as a function of the interdot coupling. We attribute this behavior to electron spin exchange and spin swapping between singlet and triplet states in the coupled double dot in the presence of a magnetic field.
Bibliographical noteFunding Information:
The authors acknowledge useful discussions with G. Burkard, D.P. Divincenzo, D. Loss, and R. Nieminen. This work was supported by MOST through the Frontier 21 National Program for Tera-level NanoDevices, the Device Technology for Quantum Information, and CKC Project for Nanoelectronics.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)