Optimal control of the operating point of a single electron DQD coupled to a superconducting resonator*

The single electron double quantum dot with micromagnets as described in [1] is a highly versatile architecture. Direct electrical control of gate voltages allows control of the resonant frequency of such a qubit, as well as of its magnetic dipole, through hybridization of the charge and spin degrees of freedom via a small transverse magnetic field gradient. Such a system presents three distinct operating points (OPs) of interest:

-One strongly localized OP with dominant spinlike characteristics, which is well-protected from its environment;
-A strongly delocalized OP with strong chargelike characteristics, at resonance with a superconducting resonator, for long-distance interactions;
-A second delocalized OP off-resonance with the resonator, allowing for fast electrical control of the qubit state.

In this work, we use the GRAPE algorithm to quickly and reliably change the OP of such a qubit by dynamically changing its orbital energy and degree of hybridization, showing high fidelity even in the presence of decoherence.

[1] Benito, M. and Mi, X. and Taylor, J. M. and Petta, J. R. and Burkard, G. Phys. Rev. B 96, 235434 (2017)