title: Prediction and real-time compensation of qubit decoherence via machine learning.
abstract: The wide-ranging adoption of quantum technologies requires practical, high-performance advances in our ability to maintain quantum coherence while facing the challenge of state collapse under measurement. Here we use techniques from control theory and machine learning to predict the future evolution of a qubit's state; we deploy this information to suppress stochastic, semiclassical decoherence, even when access to measurements is limited. First, we implement a time-division multiplexed approach, interleaving measurement periods with periods of unsupervised but stabilised operation during which qubits are available, for example, in quantum information experiments. Second, we employ predictive feedback during sequential but time delayed measurements to reduce the Dick effect as encountered in passive frequency standards. Both experiments demonstrate significant improvements in qubit-phase stability over 'traditional' measurement-based feedback approaches by exploiting time domain correlations in the noise processes. This technique requires no additional hardware and is applicable to all two-level quantum systems where projective measurements are possible.
authors.affiliation: ARC Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia.|National Measurement Institute, West Lindfield, New South Wales 2070, Australia.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Mavadia
authors.affiliation: ARC Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia.|National Measurement Institute, West Lindfield, New South Wales 2070, Australia.
authors.forename: Virginia
authors.initials: V
authors.lastname: Frey
authors.affiliation: ARC Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia.|National Measurement Institute, West Lindfield, New South Wales 2070, Australia.
authors.forename: Jarrah
authors.initials: J
authors.lastname: Sastrawan
authors.affiliation: ARC Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia.|National Measurement Institute, West Lindfield, New South Wales 2070, Australia.
authors.forename: Stephen
authors.initials: S
authors.lastname: Dona
authors.affiliation: ARC Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia.|National Measurement Institute, West Lindfield, New South Wales 2070, Australia.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Biercuk