Artificial gauge field switching using orbital angular momentum modes in optical waveguides

Abstract

The discovery of artificial gauge fields controlling the dynamics of uncharged particles that otherwise elude the influence of standard electromagnetic fields has revolutionised the field of quantum simulation. Hence, developing new techniques to induce these fields is essential to boost quantum simulation of photonic structures. Here, we experimentally demonstrate the generation of an artificial gauge field in a photonic lattice by modifying the topological charge of a light beam, overcoming the need to modify the geometry along the evolution or impose external fields. In particular, we show that an effective magnetic flux naturally appears when a light beam carrying orbital angular momentum is injected into a waveguide lattice with a diamond chain configuration. To demonstrate the existence of this flux, we measure an effect that derives solely from the presence of a magnetic flux, the Aharonov-Bohm caging effect, which is a localisation phenomenon of wavepackets due to destructive interference. Therefore, we prove the possibility of switching on and off artificial gauge fields just by changing the topological charge of the input state, paving the way to accessing different topological regimes in a single structure, which represents an important step forward for optical quantum simulation.

Tunable zero modes and quantum interferences in flat-band topological insulators

“…The best-known topological ladder model is probably the Creutz ladder [17], a BDI topological insulator that also shows flat bands in a certain regime, where particles experience a self-localization phenomenon termed "Aharonov-Bohm (AB) caging" due to a magnetic flux. This effect has previously been studied in other 1D and 2D lattices, like the rhombus chain [18][19][20][21] and the T 3 and T 4 lattices [22,23], and has been observed experimentally in several setups [24][25][26][27][28][29].…”

“…Our work considers the single-particle case only, and so it is applicable for both bosonic and fermionic particles. As mentioned above, the Creutz ladder has been implemented in a cold atom system using orbitalmomentum coupling [92,93] and can be simulated in a specific regime [27] in a rhombus chain photonic lattice [27][28][29]. Recently, a Creutz ladder plaquette was also implemented in a superconducting system [94].…”

“…By tuning the different parameters in ladder models, several BDI [12][13][14][15], AIII [15][16][17][18][19] and CII [20,21] topological insulators (TIs) have been found. The best-known topological ladder model is probably the Creutz ladder [22], a BDI topological insulator that also shows flat bands in a certain regime, where particles experience a self-localization phenomenon termed "Aharonov-Bohm (AB) caging" due to a magnetic flux, which has been observed experimentally in several setups [23][24][25][26][27][28]. of the discovery of magic-angle twisted bilayer graphene [29].…”

Two-dimensional excitons from twisted light and the fate of the photon's orbital angular momentum

“…In Ref. 35 , it has been shown that artificial flux is generated in a photonic system when OAM light is injected into a waveguide lattice. Excitons in tunable lattices have recently be shown to form strongly correlated many-body phases, such as Mott insulating phases 36 or checkerboard phases 37 .…”

Two-flux tunable Aharonov-Bohm caging in a photonic lattice

“…introducing topological defects in two-dimensonal structures, 10,11 applying time-dependent modulation [12][13][14] , employing synthetic modal dimensions 15 and, very recently, controlling the orbital angular momentum of the input light beam. 16 What underlies most of the observations carried out in the above systems is the first discovered and most basic consequence of the existence of gauge-fields, the Aharonov-Bohm (AB) effect 17 . The paramount importance of this effect ranges from metrological applications to basic physics 18 .…”