  Achieving low-error, exchange-interaction operations in quantum dots for
quantum computing imposes simultaneous requirements on the exchange energy's
dependence on applied voltages. A double quantum dot (DQD) qubit, approximated
with a quadratic potential, is solved using a full configuration interaction
method. This method is more accurate than Heitler-London and Hund-Mulliken
approaches and captures new and significant qualitative behavior. We show that
multiple regimes can be found in which the exchange energy's dependence on the
bias voltage between the dots is compatible with current quantum error
correction codes and state-of-the-art electronics. Identifying such regimes may
prove valuable for the construction and operation of quantum gates that are
robust to charge fluctuations, particularly in the case of dynamically
corrected gates.
