Variable and Orbital-Dependent Spin-Orbit Field Orientations in an InSb Double Quantum Dot Characterized via Dispersive Gate Sensing
L. Han (TU Delft - QuTech Advanced Research Centre, TU Delft - Qubit Research Division, Kavli institute of nanoscience Delft)
M. Chan (Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre, TU Delft - QRD/Wimmer Group)
D. de Jong (TU Delft - BUS/Quantum Delft, TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft)
C.G. Prosko (Kavli institute of nanoscience Delft, TU Delft - QRD/Kouwenhoven Lab, TU Delft - QuTech Advanced Research Centre)
Ghada Badawy (Eindhoven University of Technology)
Sasa Gazibegovic (Eindhoven University of Technology)
Erik P.A.M. Bakkers (Eindhoven University of Technology)
Leo P. Kouwenhoven (TU Delft - QN/Kouwenhoven Lab, Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre)
F.K. Malinowski (TU Delft - BUS/TNO STAFF, TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft)
Wolfgang Pfaff (University of Illinois at Urbana Champaign)
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Abstract
Utilizing dispersive gate sensing (DGS), we investigate the spin-orbit field (BSO) orientation in a many-electron double quantum dot (DQD) defined in an InSb nanowire. While characterizing the interdot tunnel couplings, we find the measured dispersive signal depends on the electron-charge occupancy, as well as on the amplitude and orientation of the external magnetic field. The dispersive signal is mostly insensitive to the external field orientation when a DQD is occupied by a total odd number of electrons. For a DQD occupied by a total even number of electrons, the dispersive signal is reduced when the finite external magnetic field aligns with the effective BSO orientation. This fact enables the identification of BSO orientations for different DQD electron occupancies. The BSO orientation varies drastically between charge transitions, and is generally neither perpendicular to the nanowire nor in the chip plane. Moreover, BSO is similar for pairs of transitions involving the same valence orbital, and varies between such pairs. Our work demonstrates the practicality of DGS in characterizing spin-orbit interactions in quantum dot systems, without requiring any current flow through the device.