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Q: Fachverband Quantenoptik und Photonik

Q 11: Quantum Information (Concepts and Methods) I

Q 11.4: Vortrag

Montag, 11. März 2019, 14:45–15:00, S HS 001 Chemie

Detecting Coherence via Spectrum Estimation — •Xiao-Dong Yu and Otfried Gühne — University of Siegen, 57068 Siegen, Germany

Quantum coherence is a fundamental feature of quantum mechanics, describing the capability of a quantum state to exhibit quantum interference phenomena. Consequently, it is an essential ingredient in quantum information processing, and plays a central role in emergent fields, such as quantum metrology and quantum thermodynamics.

In recent years, the quantification of coherence has attracted a lot of interest, but the lack of efficient methods to measure the coherence in experiments limits the applications. In this work, we address this problem by introducing an experiment-friendly method for coherence and spectrum estimation. This method is based on the theory of majorization and can not only be used to prove the presence of coherence, but also result in a rather precise lower bound of the amount of coherence. As an illustration, we show how to characterize the freezing phenomenon of coherence with only two local measurements for any N-qubit quantum systems.

As the majorization theory is also widely-used in physics, statistics, and economics, our approach may also have many other applications. As examples, we show that our method can be used for the characterization of distillability and entanglement transformations.