Rostock 2019 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 33: Quantum Information (Quantum Computing) II

Q 33.7: Talk

Wednesday, March 13, 2019, 15:45–16:00, S HS 001 Chemie

Efficient Qubit Initialization using Quantum Optimal Control — •Daniel Basilewitsch¹, Francesco Cosco², Nicola Lo Gullo², Christiane Koch¹, and Sabrina Maniscalco^2,3 — ¹Theoretical Physics, University of Kassel, D-34132 Kassel, Germany — ²QTF Centre of Excellence, Turku Centre for Quantum Physics, Department of Physics and Astronomy, University of Turku, FI-20014 Turun yliopisto, Finland — ³QTF Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland

Qubit reset is a key requirement for any quantum technology as it enables reusable qubits. Since the reset process implies purification of the qubit state, coupling to an environment, which serves as entropy dump, is necessary. As a consequence, the reset duration is primarily determined by the environmental coupling strength, respectively the decay rates induced by it. Here we consider a qubit coupled to an engineered and tunable environment allowing to tune the decay rates over several orders of magnitude. Based on a proposed initialization protocol for this setup [1], we use quantum optimal control theory in order to derive optimized field shapes improving the protocol duration and error. We find that for best reset, coherent and dissipative part of the evolution have to be carefully balanced and we are able to identify the quantum speed limit for the given setup.

[1] J. Tuorila et al., npj Quantum Inf. 3, 27 (2017)