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About this paper
Merijn Moody, Zier Mensch, Miranda C. N. Cheng, Peter G. Bolhuis, Max Welling
QMaxCal adds trajectory-level penalties to quantum-control optimization, measuring drift in decoherence channels rather than pulse amplitude or smoothness. Wiener KL penalizes drift from zero, while drift-variance penalizes fluctuations around drift. In simulations, Wiener KL improves four-level transfer under decay, and drift-variance raises six-qubit fidelity from 0.837 to 0.863; results concern diffusive trajectories under Markovian Lindblad noise and depend on noise structure.
Key insights
- Girsanov's theorem provides a differentiable method to calculate the Kullback-Leibler divergence between path measures of Itô diffusion processes, which can be applied to measurement records of open quantum systems.
- The 'drift' component of classical measurement records in continuous monitoring is directly linked to a quantum system's interaction with its decoherence channels, making it an ideal target for regularization.
- Directly penalizing the drift of measurement records allows for steering quantum trajectories to minimize decoherence throughout evolution, offering a qualitatively different and more physically informed strategy than traditional control signal penalties.
Summary by alphaXiv.
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