Abstract
External driving is emerging as a promising tool for exploring new phases in quantum systems. The intrinsically non-equilibrium states that result, however, are challenging to describe and control. We study the steady states of a periodically driven one-dimensional electronic system, including the effects of radiative recombination, electron-phonon interactions, and the coupling to an external fermionic reservoir. Using a kinetic equation for the populations of the Floquet eigenstates, we show that the steady-state distribution can be controlled using the momentum and energy relaxation pathways provided by the coupling to phonon and Fermi reservoirs. In order to utilize the latter, we propose to couple the system and reservoir via an energy filter which suppresses photon-assisted tunneling. Importantly, coupling to these reservoirs yields a steady state resembling a band insulator in the Floquet basis. The system exhibits incompressible behavior, while hosting a small density of excitations. We discuss transport signatures, and describe the regimes where insulating behavior is obtained. Our results give promise for realizing Floquet topological insulators.
Highlights
The availability of coherent driving fields such as lasers opens many exciting possibilities for controlling quantum systems
One of the most outstanding questions in the field is to identify which types of systems, baths, and system-bath couplings can lead to nonequilibrium steady states enabling Floquet topological insulators to exhibit behaviors similar to those of their equilibrium counterparts [32,33]
We considered the open-system dynamics of a resonantly driven electronic system coupled to acoustic phonons and the electromagnetic environment, as well as to an external fermionic reservoir
Summary
The availability of coherent driving fields such as lasers opens many exciting possibilities for controlling quantum systems. One of the most outstanding questions in the field is to identify which types of systems, baths, and system-bath couplings can lead to nonequilibrium steady states enabling Floquet topological insulators to exhibit behaviors similar to those of their equilibrium counterparts [32,33]. Our main message is that the driven electronic system can approach the Floquet-insulator steady state when appropriately coupled to phonon and Fermi reservoirs In order for this to work, the coupling to the fermionic reservoir must be “engineered” to avoid the deleterious effects of photon-assisted tunneling. This can be accomplished by connecting the system to the reservoir via a narrow-band energy filter (see Fig. 2 and Sec. IV C). This implies that a steady-state Floquet topological insulator phase may be within reach
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