1 research outputs found
Exchange interaction of hole-spin qubits in double quantum dots in highly anisotropic semiconductors
We study the exchange interaction between two hole-spin qubits in a double
quantum dot setup in a silicon nanowire in the presence of magnetic and
electric fields. Based on symmetry arguments we show that there exists an
effective spin that is conserved even in highly anisotropic semiconductors,
provided that the system has a twofold symmetry with respect to the direction
of the applied magnetic field. This finding facilitates the definition of qubit
basis states and simplifies the form of exchange interaction for two-qubit
gates in coupled quantum dots. If the magnetic field is applied along a generic
direction, cubic anisotropy terms act as an effective spin-orbit interaction
introducing novel exchange couplings even for an inversion symmetric setup.
Considering the example of a silicon nanowire double dot, we present the
relative strength of these anisotropic exchange interaction terms and calculate
the fidelity of the gate. Furthermore, we show that the
anisotropy-induced spin-orbit effects can be comparable to that of the direct
Rashba spin-orbit interaction for experimentally feasible electric field
strengths.Comment: 18 pages, 7 figure