Low-noise conditional operation of singlet-triplet coupled quantum dot qubits

摘要

We theoretically study the influence of charge noise on a controlled phasegate, implemented using two proximal double quantum dots coupledelectrostatically. Using the configuration interaction method, we present afull description of the conditional control scheme and quantitatively calculatethe gate error arising from charge fluctuations. Our key finding is that theexistence of noise-immune sweet spots depends on not only the energy detuningbut also the device geometry. The conditions for sweet spots with minimalcharge noise are predicted analytically and verified numerically. Going beyondthe simple sweet-spot concept we demonstrate the existence of other optimalsituations for fast and low-noise singlet-triplet two-qubit gates.