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Abstract: We address the experimentally relevant problem of robust mitigation ofdephasing noise acting on a qubit. We first present an extension of a methodfor representing $1-\omega^{\alpha}$ noise developed by Kuopanportti et al. tothe efficient representation of arbitrary Markovian noise. We then add qubitcontrol pulses to enable the design of numerically optimized, two-dimensionalcontrol functions with bounded amplitude, that are capable of decoupling thequbit from the dephasing effects of a broad variety of Markovian noise spectraldensities during arbitrary one qubit quantum operations. We illustrate themethod with development of numerically optimized control pulse sequences thatminimize decoherence due to a combination of $1-\omega$ and constant offsetnoise sources. Comparison with the performance of standard dynamical decouplingprotocols shows that the numerically optimized pulse sequences are considerablymore robust with respect to the noise offset, rendering them attractive forapplication to situations where homogeneous dephasing noise sources areaccompanied by some extent of heterogeneous dephasing. Application to themitigation of dephasing noise on spin qubits in silicon indicates that highfidelity single qubit gates are possible with current pulse generationtechnology.

Author: Kevin C. Young, Dylan J Gorman, K. Birgitta Whaley



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