The formation of bars in disk galaxies is a tracer of the dynamical maturity of the population .
Previous studies have found that the incidence of bars in disks decreases from the local Universe to z \sim 1 , and by z > 1 simulations predict that bar features in dynamically mature disks should be extremely rare .
Here we report the discovery of strong barred structures in massive disk galaxies at z \sim 1.5 in deep rest-frame optical images from CANDELS .
From within a sample of 876 disk galaxies identified by visual classification in Galaxy Zoo , we identify 123 barred galaxies .
Selecting a sub-sample within the same region of the evolving galaxy luminosity function ( brighter than L ^ { * } ) , we find that the bar fraction across the redshift range 0.5 \leq z \leq 2 ( f _ { bar } = 10.7 ^ { +6.3 } _ { -3.5 } \% after correcting for incompleteness ) does not significantly evolve .
We discuss the implications of this discovery in the context of existing simulations and our current understanding of the way disk galaxies have evolved over the last 11 billion years .