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.

}, isbn = {2047-7538}, doi = {https://doi.org/10.1038/s41377-020-00385-6}, url = {https://www.nature.com/articles/s41377-020-00385-6}, author = {C. J{\"o}rg and G. Queralt{\'o} and M. Kremer and G. Pelegr{\'\i} and J. Schulz and A. Szameit and G. von Freymann and J. Mompart and V. Ahufinger} } @article {280, title = {Atomic-frequency-comb quantum memory via piecewise adiabatic passage}, journal = {Phys. Rev. A}, volume = {98}, year = {2018}, month = {Oct}, pages = {043834}, abstract = {In this paper, we propose a method to create an atomic frequency comb (AFC) in hot atomic vapors using the piecewise adiabatic passage (PAP) technique. Due to the Doppler effect, the trains of pulses used for PAP give rise to a velocity-dependent transfer of the atomic population from the initial state to the target one, thus forming a velocity comb whose periodicity depends not only on the repetition rate of the applied pulses but also on the specific atomic transitions considered. We highlight the advantages of using this transfer technique with respect to standard methods and discuss, in particular, its application to store a single telecom photon in an AFC quantum memory using a high density Ba atomic vapor.

}, doi = {10.1103/PhysRevA.98.043834}, url = {https://link.aps.org/doi/10.1103/PhysRevA.98.043834}, author = {J. L. Rubio and D. Viscor and J. Mompart and V. Ahufinger} } @article {102, title = {Applied Bohmian mechanics}, journal = {European Physical Journal D}, volume = {68}, year = {2014}, month = {10/2014}, pages = {1-42}, type = {Topical Review}, chapter = {286}, abstract = {Bohmian mechanics provides an explanation of quantum phenomena in terms of point-like particles guided by wave functions. This review focuses on the use of nonrelativistic Bohmian mechanics to address practical problems, rather than on its interpretation. Although the Bohmian and standard quantum theories have different formalisms, both give exactly the same predictions for all phenomena. Fifteen years ago, the quantum chemistry community began to study the practical usefulness of Bohmian mechanics. Since then, the scientific community has mainly applied it to study the (unitary) evolution of single-particle wave functions, either by developing efficient quantum trajectory algorithms or by providing a trajectorybased explanation of complicated quantum phenomena. Here we present a large list of examples showing how the Bohmian formalism provides a useful solution in different forefront research fields for this kind of problems (where the Bohmian and the quantum hydrodynamic formalisms coincide). In addition, this work also emphasizes that the Bohmian formalism can be a useful tool in other types of (nonunitary and nonlinear) quantum problems where the influence of the environment or the nonsimulated degrees of freedom are relevant. This review contains also examples on the use of the Bohmian formalism for the many-body problem, decoherence and measurement processes. The ability of the Bohmian formalism to analyze this last type of problems for (open) quantum systems remains mainly unexplored by the scientific community. The authors of this review are convinced that the final status of the Bohmian theory among the scientific community will be greatly influenced by its potential success in those types of problems that present nonunitary and/or nonlinear quantum evolutions. A brief introduction of the Bohmian formalism and some of its extensions are presented in the last part of this review.}, doi = {10.1140/epjd/e2014-50222-4}, url = {http://link.springer.com/article/10.1140\%2Fepjd\%2Fe2014-50222-4}, author = {A. Benseny and G. Albareda and A. S. Sanz and J. Mompart and X. Oriols} } @article {140, title = {Adiabatic Passage of Light in CMOS-Compatible Silicon Oxide Integrated Rib Waveguides}, journal = {IEEE Photonics Technolopgy Letters}, volume = {24}, number = {7}, year = {2012}, month = {04/2012}, pages = {536-538}, chapter = {536}, abstract = {A fully complementary metal-oxide-semiconductor-compatible adiabatic passage of light in the visible range is presented in this letter. We experimentally show that a system of three total internal reflection waveguides, which has been defined by using non-stoichiometric silicon oxide, allows a highly efficient transfer of light between the outermost waveguides by adiabatically following one eigenmode of the system. Furthermore, we demonstrate that such transfer of light is very robust against small variations of the system parameters.}, keywords = {Adiabatic passage of light, integrated optical circuits, silicon technology, total internal reflection (TIR) waveguides}, issn = {1041-1135}, doi = {10.1109/LPT.2011.2180519}, url = {Adiabatic Passage of Light in CMOS-Compatible Silicon Oxide Integrated Rib Waveguides}, author = {R. Menchon-Enrich and A. Llobera and V. J Cadarso and J. Mompart and V. Ahufinger} } @article {PhysRevA.81.043621, title = {Adiabatic splitting, transport, and self-trapping of a Bose-Einstein condensate in a double-well potential}, journal = {Phys. Rev. A}, volume = {81}, year = {2010}, month = {Apr}, pages = {043621}, publisher = {American Physical Society}, abstract = {We show that the adiabatic dynamics of a Bose-Einstein condensate (BEC) in a double-well potential can be described in terms of a dark variable resulting from the combination of the population imbalance and the spatial atomic coherence between the two wells. By means of this dark variable, we extend, to the nonlinear matter-wave case, the recent proposal by Vitanov and Shore [Phys. Rev. A 73, 053402 (2006)] on adiabatic passage techniques to coherently control the population of two internal levels of an atom or molecule. We investigate the conditions to adiabatically split or transport a BEC as well as to prepare an adiabatic self-trapping state by the optimal delayed temporal variation of the tunneling rate via either the energy bias between the two wells or the BEC nonlinearity. The emergence of nonlinear eigenstates and unstable stationary solutions of the system as well as their role in the breaking down of the adiabatic dynamics is investigated in detail.}, doi = {10.1103/PhysRevA.81.043621}, url = {http://link.aps.org/doi/10.1103/PhysRevA.81.043621}, author = {C. Ottaviani and V. Ahufinger and R. Corbal{\'a}n and J. Mompart} } @article {PhysRevA.82.013604, title = {Atomtronics with holes: Coherent transport of an empty site in a triple-well potential}, journal = {Phys. Rev. A}, volume = {82}, year = {2010}, month = {Jul}, pages = {013604}, publisher = {American Physical Society}, abstract = {We investigate arrays of three traps with two fermionic or bosonic atoms. The tunneling interaction between neighboring sites is used to prepare multisite dark states for the empty site (i.e., the hole) which allows for the coherent manipulation of its external degrees of freedom. By means of an ab initio integration of the Schr{\"o}dinger equation, we investigate the adiabatic transport of a hole between the two extreme traps of a triple-well potential. Furthermore, a quantum-trajectory approach based on the de Broglie{\textendash}Bohm formulation of quantum mechanics is used to get physical insight into the transport process. Finally, we discuss the use of the hole for the construction of a coherent single hole diode and a coherent single hole transistor.}, doi = {10.1103/PhysRevA.82.013604}, url = {http://link.aps.org/doi/10.1103/PhysRevA.82.013604}, author = {A. Benseny and S. Fern{\'a}ndez-Vidal and J. Bagud{\`a} and R. Corbal{\'a}n and A. Pic{\'o}n and L. Roso and G. Birkl and J. Mompart} }