Mitigating noise for singlet-only always-on gapless exchange (SAGE) qubits: Single-qubit gates

Singlet-only always-on gapless exchange (SAGE) spin qubits encode a single qubit in the spins of four electrons. In contrast to conventional exchange-only qubits, which suffer from infidelities due to magnetic field gradients from local nuclear environments and variations in the g-factor, SAGE qubits are energetically protected from local fluctuations in magnetic field. Consequently, the dominant source of noise is fluctuations in the electric field which, in gate-defined semiconducting quantum dots, is well-described by 1/f noise. In this talk, using a Hubbard model to define the underlying electronic structure of the effective spin model, we study the effect of this noise on single-qubit gate fidelity. Moreover, we construct a dynamical decoupling sequence that can effectively eliminate charge noise which, consequently, can increase qubit lifetime and single-gate fidelities.