Classification of SL_2 deformed Floquet conformal field theories

摘要

Classification of the nonequilibrium quantum many-body dynamics is a challenging problem in condensed matter physics and statistical mechanics. In this work, we study the basic question that whether a (1 + 1) dimensional conformal field theory (CFT) is stable or not under a periodic driving with N noncommuting Hamiltonians. Previous works showed that a Floquet (or periodically driven) CFT driven by certain SL_2 deformed Hamiltonians exhibit both nonheating (stable) and heating (unstable) phases. In this work, we show that the phase diagram depends on the types of driving Hamiltonians. In general, the heating phase is generic, but the nonheating phase may be absent in the phase diagram. For the existence of the nonheating phases, we give sufficient and necessary conditions for N = 2 and sufficient conditions for N ＞ 2. These conditions are composed of N layers of data, with each layer determined by the types of driving Hamiltonians. Our results also apply to the single quantum quench problem with N = 1.