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Center for Nonlinear Studies |
Quantum mechanics is an inherently linear theory. However, collective effects in many body quantum systems can give rise to effectively nonlinear dynamics. In this talk, we discuss whether and to what extent such nonlinear effects can be exploited to enhance the rate of quantum evolution. To this end, we compute a suitable version of the quantum speed limit for numerical and analytical examples. We find that the quantum speed limit grows with the strength of the nonlinearity, yet it does not trivially scale with the “degree” of nonlinearity. This is then further elaborated on in the context of quantum thermometry. In particular, we show that quantum thermometers that are described by nonlinear Schrödinger equations allow for a significantly enhanced precision, that means larger quantum Fisher information. We conclude the discussion by introducing a generalized Landau-Zener model, in which nonlinear dynamics can be leveraged to suppress excitations and coherences of the corresponding linear scenario. As a final result, we show that the nonlinear term in the evolution equation acts like an effective shortcut to adiabaticity for the linear Landau-Zener problem.
Bio:
Sebastian Deffner is a theoretical physicist and a professor in the Department of Physics at the University of Maryland, Baltimore County (UMBC). He is known for his contributions to the development of quantum thermodynamics with focus on the thermodynamics of quantum information, quantum speed limit for open systems, quantum control and shortcuts to adiabaticity. Before he joined UMBC, he was a Director’s Funded Postdoctoral Fellow at T4.
Host: Akram Touil (T-4)