Estimating entanglement monotones in spin systems using symmetries

Abstract:One way to characterize complex many-body systems is to investigate their entanglement structure. Given an arbitrary state of N spin-½ particles, we ask: is this state entangled? If yes, can we quantify how much entanglement it contains? To answer these questions, we make use of the concepts of entanglement witnesses and entanglement monotones. We present general methods to find both lower and upper bounds to these monotones and elaborate on how symmetries can help us to significantly simplify these methods. As a case-study of interest, we consider thermal states of fully connected spin models that can be described in terms of the first and second moments of collective spin observables. Notably, the states arising from such models are permutationally invariant and entanglement can be witnessed using the set of optimal spin-squeezing inequalities. Of particular interest is to find out whether this set also provides an optimal lower bound to entanglement monotones for spin-squeezed states?

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Time: Dec 11, 2024 02:30 PM WarsawZoom link: https://us05web.zoom.us/j/83922907300?pwd=S2Y2RiCKa7sD55bf3Rp2i6aamQuSkN.1‍

Meeting ID: 839 2290 7300‍

Passcode: 41FiTq