We are pleased to announce that the Best Poster Awards, sponsored by Entropy (ISSN: 1099-4300) for the 14th Italian Quantum Information Science Conference (IQIS 2022), were granted to Veronica Panizza (University of Trento) and Giovanni Di Fresco (University of Palermo). Congratulations!

The winning posters are as follows:

“Entanglement Witnessing for Lattice Gauge Theories”
by Veronica Panizza
Abstract: LGTs are at the core of fundamental physics and, recently, substantial theoretical and experimental efforts have gone into simulating LGTs using quantum technologies. In the quantum realm, entanglement plays a crucial role and its detection can be efficiently performed using entanglement witnesses. Yet, entanglement witnessing in LGTs is extremely challenging due to the gauge constraints, that severely limit the operators that can be employed to detect quantum correlations. In this work, we develop the theoretical framework of entanglement witnessing in lattice gauge theories and, by way of illustration, consider bipartite entanglement witnesses in a U(1) LGT (with and without fermionic matter). Our framework, which avoids the costly measurements required, e.g., by full-tomography, opens the way to future theoretical and experimental studies of entanglement in an important class of many-body models.

“Criticality and Compatibility in Multi-Parameter Quantum Metrology”
by Giovanni Di Fresco
Abstract: Many-body systems near a quantum phase transition (QPT) exhibit several properties which makes them appealing for metrological purposes. Indeed, it is now well established that the divergences of the quantum Fisher information (QFI) observed near a QPT can be used to increase the precision in the estimation of a parameter. Meanwhile, when it comes to the simultaneous estimation of multiple parameters, the benefits of criticality are much harder to analyze due to possible incompatibilities arising from the Heisenberg uncertainty. This involves the use of quite convoluted quantities, as the Holevo-Cramer-Rao bound, which are generally difficult to evaluate. Here we study the quantumness (R), a scalar index, which provides an asymptotic bound on the compatibility of a metrological scheme. The advantage of this approach is that R can be easily evaluated once the QFI and the mean Uhmlann curvature are known. Moreover, a scaling analysis of R reveals that many-body criticalities generally improve the compatibility in a multi-parameter framework. We also evaluate R in different representative systems, such as Ising chain and XY chain, in which we find this positive criticality effects.