SAMOP 2023 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 43: QI Poster II (joint session QI/Q)
Q 43.15: Poster
Wednesday, March 8, 2023, 16:30–19:00, Empore Lichthof
Optimizing for an arbitrary Schrödinger cat state — •Matthias G. Krauss1, Anja Metelmann2, Daniel M. Reich1, and Christiane P. Koch1 — 1Freie Universität, Berlin, Germany — 2Karlsruhe Institute of Technology, Karlsruhe, Germany
Schrödinger cat states are non-classical superposition states that are useful in quantum information science, for example for computing or sensing. Optimal control theory provides a set of powerful tools for preparing such superposition states, for example in experiments with superconducting qubits [Ofek, et al. Nature 536, 2016]. We present a set of cat state functionals which provide more freedom to the optimization algorithms, compared to state-to-state functionals. By using Krotov’s method [Reich et al. J. Chem. Phys. 136, 2012], we demonstrate their application by optimizing the dynamics of a Kerr-nonlinear system with two-photon driving and analyze the robustness of the cat state preparation under single and two-photon decay. In addition, we explore the generation of cat states in higher order Kerr systems. Furthermore, we show the versatility of the framework by applying it to a Jaynes-Cummings model and optimize towards arbitrary entangled cat states. We identify the strategy of the obtained control fields and determine the quantum speed limit as a function of the cat state’s excitation. Finally, we extend the investigation to open quantum systems to analyze the benefit of reoptimization together with the changes in the control strategy induced by decay.