Erlangen 2022 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 45: Ultracold Atoms and Molecules I (joint session Q/A)
Q 45.7: Talk
Thursday, March 17, 2022, 12:00–12:15, Q-H10
Reservoir-engineered shortcuts to adiabaticity via quantum non-demolition measurements — •Raphael Menu1, Josias Langbehn2, Christiane Koch2, and Giovanna Morigi1 — 1Theoretische Physik, Universität des Saarlandes, D-66123 Saarbrücken, Germany — 2Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
The preparation of a quantum state via a slow tuning of the parameters of the system lies at the heart of the concept of adiabatic quantum computing. Yet, the realization of such types of computation requires a wide time-window over which dissipation effects may occur, ultimately leading to errors. Here, we propose a protocol that achieves fast adiabatic Landau-Zener dynamics by coupling a spin to an external system. The coupling realizes a quantum non-demolition (QND)Hamiltonian, where the external system acts as a meter. When the meter's decay rate is the largest frequency scale of the dynamics, the QND coupling induces an effective dephasing of the spin in the adiabatic basis and the spin dynamics is described by a quantum adiabatic master equation. We show, however, that adiabaticity can be maximized in the non-adiabatic limit when the coupling with the meter tends to suppress diabatic transitions via effective cooling processes. We investigate the protocol efficiency in terms of non-Markovianity measures for the spin-meter dynamics and qualitatively discuss the spectral gap of the incoherent dynamics. We finally show that the protocol is robust against imperfection in the implementation of the QND Hamiltonian.