Starts 7 Dec 2017 11:30
Ends 7 Dec 2017 12:30
Central European Time
ICTP
Leonardo Building - Luigi Stasi Seminar Room
The quantum spin-1/2 Ising model exhibits a 2nd-order quantum phase transition (QPT) which is characterised by a set of critical indexes that defines the corresponding universality class. Strictly speaking, 2nd-order QPTs occur only in the thermodynamical limit, nevertheless criticality can be revealed also in finite size systems once the correlation length becomes of the order of the system’s size and finite size scaling behaviour (FSS) is retrieved.
In this talk the question of the robustness of FSS in the Ising model driven out-of-equilibrium by a periodic modulation of the transverse magnetic field across its critical point is addressed [1]. Furthermore, the effects of the Ising QPT on a boundary impurity are investigated, showing that the impurity magnetic observables exhibit FSS with critical exponents belonging to the Ising universality class, although an impurity order parameter arises which differs from the bulk order parameter [2].

[1] S. Lorenzo, J. Marino, F. Plastina, G. M. Palma, and T. J. G. Apollaro, Quantum Critical Scaling under Periodic Driving, Sci. Rep. 7, 5672 (2017).
[2] T. J. G. Apollaro, G. Francica, D. Giuliano, G. Falcone, G. M. Palma, and F. Plastina, Universal scaling for the quantum Ising chain with a classical impurity, Phys. Rev. B 96, 155145 (2017).