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Q: Fachverband Quantenoptik und Photonik

Q 22: Posters: Quantum Optics and Photonics II

Q 22.37: Poster

Dienstag, 10. März 2020, 16:30–18:30, Empore Lichthof

Fundamental Bounds for Qubit Reset — Daniel Basilewitsch¹, •Jonas Fischer^{1, 2, 3}, Daniel M. Reich^{1, 3}, Dominique Sugny², and Christiane P. Koch^{1, 3} — ¹Theo. Physik, Universität Kassel, D-34132 Kassel, Germany — ²Lab. ICB, Université de Bourgogne-Franche Comté, F-21078 Dijon Cedex, France — ³Freie Universität Berlin, Theo. Physik, Arnimallee 14, 14195 Berlin, Germany

One of the most fundamental tasks in the field of quantum technology is the purification or reset of a qubit. This process is interesting from a theoretical point of view because it raises the question of how fast entropy can be exported from a system, as well as for applications like quantum computing or quantum cryptography.

We consider a controllable qubit in contact with an environment. The environment can be mapped onto a representative pseudo-mode, decaying into a weakly coupled heat bath [D. Basilewitsch et al, New J. Phys. 19, 113042 (2017)], which does not play a role for the speed limit and can be neglected. Because qubit and ancilla can be flexibly engineered, we investigate which sort of coupling and control is optimal for the reset task and search for a global speed limit.

Using the Cartan decomposition we can deduce necessary conditions for the interaction and control. We give the optimal choice for the control field depending on the coupling and also determine the overall speed limit.