Reconstructing the quantum critical fan of strongly correlated systems via quantum correlations

Understand

Albeit occurring at zero temperature, quantum critical phenomena are known to have a huge impact on the finite-temperature phase diagram of strongly correlated systems -- an aspect which gives experimental access to their observation.

• In particular the existence of a gapless, zero-temperature quantum critical point is known theoretically to induce the existence of an extended region in parameter space -- the so-called quantum critical fan -- characterized by power-law temperature dependences of all observables, with exponents related to those of the quantum critical point.
• Identifying experimentally the quantum critical fan and its crossovers to the other regions (renormalized classical, quantum disordered) remains nonetheless a big challenge.
• Focusing on paradigmatic models of quantum phase transitions, here we show that quantum correlations - captured by the quantum variance of the order parameter (I.