Spin-orbit interaction in InSb double quantum dots characterized using dispersive gate sensing*

We experimentally investigate the consequences of a strong spin orbit interaction in double quantum dot defined in an InSb nanowire. Utilizing dispersive gate sensing, we characterize the tunnel coupling and find the dispersive signal depends on electron charge parity as well as magnitude and direction of the external magnetic field. In particular, we identify the spin-orbit field direction for a number of interdot charge transitions involving different orbitals. We notice that the direction of spin-orbit field is similar for charge transitions corresponding to the same orbitals, but varies randomly between different orbitals, and generally is not perpendicular to the nanowire.