We propose a scheme to realize the frustrated spin-1/2 quantum XX model with
ultracold bosonic atoms in optical lattices. Our approach is based on a square
ladder of magnetic flux close to π with one real and one synthetic spin
dimension. Although this system does not have geometrical frustration, we show
that at low energies it maps into an effective triangular ladder with staggered
fluxes for specific values of the synthetic tunneling. We numerically
investigate its rich phase diagram and show that it contains bond-ordered-wave
and chiral superfluid phases. Our scheme gives access to minimal instances of
frustrated magnets without the need for real geometrical frustration, in a
setup of minimal experimental complexity.Comment: Main text: 5 pages + references, 3 figures; supplemental material: 9
pages, 2 figure