Artificial gauge fields in materials and engineered systems

Abstract

Artificial gauge fields are currently realized in a wide range of physical settings. This includes solid-state devices but also engineered systems, such as photonic crystals, ultracold gases and mechanical setups. It is the aim of this review to offer, for the first time, a unified view on these various forms of artificial electromagnetic fields and spinorbit couplings for matter and light. This topical review provides a general introduction to the universal concept of engineered gauge fields, in a form which is accessible to young researchers entering the field. Moreover, this work aims to connect different communities, by revealing explicit links between the diverse forms and realizations of artificial gauge fields.

Floquet analysis of excitations in materials

“…Prominent examples include signatures of light-induced [2] or light-enhanced [3] superconductivity, ultrafast switching of hidden electronic phases [4] and phonon-induced magnetization [5]. In particular, the concept of viewing the non-equilibrium electronic structures as dressed by external fields and thus allowing the control of so-called synthetic gauge fields [6] has attracted much attention because it shows a route towards controlling topological and other properties via a process called Floquet engineering [7]. Based on the theory of differential equations with oscillating coefficients, Floquet phases are thought to occur when a quantum mechanical system is subjected to a periodically oscillating potential, such as a laser.…”

Topological Protection and Control of Quantum Markovianity

“…A synthetic gauge field is applied to the square lattice resonator so as to introduce Peierls phases and a non-vanishing effective magnetic flux ϕ in each plaquette of the array, thus realizing a photonic quantum-Hall topological insulator with chiral edge modes. The artificial gauge field can be accomplished, for instance, by dynamic modulation, using auxiliary cavities, or by other means, as discussed and demonstrated in several recent works [37,[51][52][53][54][55][56][57][58][59][60]. We also mention that different types of reconfigurable two-dimensional photonic lattice configurations, with controllable switching between topologically trivial and non-trivial phases, have been suggested and demonstrated in several other different photonic setups [61][62][63][64][65][66].…”

Quantum decay in a topological continuum

“…Provided that the energies of the discrete levels are entirely embedded in a topological gap of the crystal, decay arises because of the coupling of the discrete levels with the chiral edge states, which thus realize an effective one-dimensional continuum with a dispersion curve as the one shown in Fig.1(d). Chiral edge states emerge in a wide variety of topological quantum and classical systems, such as in quantum Hall systems, in the Haldane model, in Floquet topological insulators and in anomalous Floquet topological insulators to mention a few (see for example [27,28,33] and references therein). Here we discuss multilevel decay in two examples of topological baths, namely in a tight-binding quantum Hall system (the Harper-Hofstadter model), and in anomalous Floquet topological insulators, and compare exact numerical results with the non-Hermitian effective description presented in the previous section.…”

“…A bath showing unidirectional transport can be realized in Floquet topological insulators, where time reversal symmetry is broken by periodic temporal modulation of the underlying Hamiltonian of a crystal [33]. An interesting case is the one of anomalous topological insulators [38], whose topological classification goes beyond that of static systems.…”