During the last five years, there has been an increasing interest in generating high-frequency —short wavelength— beams with controllable polarization, due to their potential applications to perform ultrafast studies of chiral and/or dichroic systems at the nanometer scales. Rather sophisticated configurations have already demonstrated polarization control at the sub-femtosecond scale through high-order harmonic generation (HHG) in atomic gases [1,2]. In parallel, different works have recently shown the suitability of solid systems to emit highorder harmonics in a non-perturbative regime [3,4]. Among them, gapless graphene is a relevant system due to its unique optical and conductivity properties. Very recently, in opposite to what happens in atomic systems, it has been shown experimentally that high-order harmonics are emitted in graphene when driven by elliptically polarized laser pulses .
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