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QI: Fachverband Quanteninformation

QI 1: Implementations: Spin Qubits, Atoms, and Photons

QI 1.9: Vortrag

Montag, 5. September 2022, 12:00–12:15, H8

Improving quantum state detection with adaptive sequential observations — Shawn Geller^{1, 2}, Daniel Cole¹, Scott Glancy^{1, 2}, and •Emanuel Knill^{1, 2} — ¹National Institute of Standards and Technology, Boulder, CO, USA — ²University of Colorado at Boulder, Boulder, CO USA

For many quantum systems intended for information processing, one detects the logical state of a qubit by integrating a continuously observed quantity over time. For example, ion and atom qubits are typically measured by driving a cycling transition and counting the number of photons observed from the resulting fluorescence. Instead of recording only the total observed count in a fixed time interval, one can observe the photon arrival times and get a state detection advantage by using the temporal structure in a model such as a Hidden Markov Model. We study what further advantage may be achieved by applying pulses to adaptively transform the state during the observation. We give a three-state example where adaptively chosen transformations yield a clear advantage, and we compare performances on an ion example, where we see improvements in some regimes.