Simulating Two-Qubit Gates Under the Influence of Charge Defects in an FD-SOI Device

The exchange interaction has been successfully used to mediate qubit entanglement in various semiconductor quantum devices. Using the finite-element method, we combine a nonlinear Poisson solver with single-and many-body Schrödinger solvers to simulate the exchange interaction between a pair of spin qubits in a fully depleted silicon-on-insulator (FD-SOI) device. We also modify the Poisson solver to account for charge impurities and evaluate the effect of a single impurity on the exchange interaction strength, including its dependence on the impurity's position. The effect of the impurity on the exchange strength is then analyzed to calculate the average two-qubit gate fidelity achievable via the exchange interaction when the system is subject to charge noise arising from a charge randomly tunneling in and out of an interface impurity trap. The presented approach demonstrates the possibility of simulating key quantum-device performance metrics, such as two-qubit gate fidelity, starting only from the device geometry.