@misc{10481/70965,
year = {2021},
month = {9},
url = {http://hdl.handle.net/10481/70965},
abstract = {Collective spin operators for symmetric multi-quDit (namely identical D-level
atom) systems generate a U(D) symmetry. We explore generalizations to arbitrary
D of SU(2)-spin coherent states and their adaptation to parity (multi-component
Schrödinger cats), together with multi-mode extensions of NOON states. We write
level, one- and two-quDit reduced density matrices of symmetric N-quDit states,
expressed in the last two cases in terms of collective U(D)-spin operator expectation
values. Then, we evaluate level and particle entanglement for symmetric multi-quDit
states with linear and von Neumann entropies of the corresponding reduced density
matrices. In particular, we analyze the numerical and variational ground state
of Lipkin–Meshkov–Glick models of 3-level identical atoms. We also propose an
extension of the concept of SU(2)-spin squeezing to SU(D) and relate it to pairwise
D-level atom entanglement. Squeezing parameters and entanglement entropies are
good markers that characterize the different quantum phases, and their corresponding
critical points, that take place in these interacting D-level atom models.},
organization = {Spanish Government	PGC2018-097831-B-I00},
organization = {Junta de Andalucia	SOMM17/6105/UGR	
UHU-1262561	
FQM-381},
organization = {Spanish Government
European Commission	FIS2017-84440-C2-2-P},
organization = {Spanish MIU	FPU19/06376},
publisher = {Springer},
keywords = {Quantum phase transitions},
keywords = {Many-body systems},
keywords = {Symmetric quDits},
keywords = {Coherent states},
keywords = {Parity},
keywords = {Pairwise entanglement},
keywords = {Spin squeezing},
title = {Entanglement and U(D)-spin squeezing in symmetric multi-quDit systems and applications to quantum phase transitions in Lipkin–Meshkov–Glick D-level atom models},
doi = {10.1007/s11128-021-03218-6},
author = {Calixto Molina, Manuel and Mayorgas Reyes, Alberto and Guerrero, Julio},
}