# Karol Zyczkowski - "Spin Coherent, Basis Coherent and Anti-coherent states"

## Jagiellonian University, Cracow

Center for Theoretical Physics, Warsaw, Poland

**Organiser:**

Max Planck Institute for the Science of Light

Leuchs Division

**Time and place: **

11 a.m., December 13, 2017, Light Lounge, A.3.500, Staudtstr. 2

**Abstract:**

Among the set of all pure states living in a finite dimensional Hilbert space H_N one distinguishes subsets of states satysfying some natural condition. One basis independent choice, consist in selecting the spin cohrerent states, corresponding to the SU(2) group, or generalized, SU(K) coherent states. Another often studied example is basis dependent, as states coherent with respect to a given basis are distinguished by the fact that the moduli of their off-diagonal elements (called 'coherences') are as large as possible. It is natural to define 'anti-coherent' states, which are maximally distant to the set of coherent states and to quantify the degree of coherence of a given state can by its distance to the set of anticoherent states. For instance, the separable states of a system composed of two subsystems with N levels are coherent with respect to the composite group SU(N)\times SU(N), while in this setup, the anti-coherent states are maximally entangled.