  Chirality is a pervasive form of symmetry that is intimately connected to the
physical properties of solids, as well as the chemical and biological activity
of molecular systems. However, its control with light is challenging, because
inducing chirality in a non-chiral material requires that all mirrors and all
roto-inversions be simultaneously broken. Electromagnetic fields exert only
oscillatory forces that vanish on average, mostly leading to entropy increase
that does not break symmetries, per se. Here, we show that chirality of either
handedness can be generated in the non-chiral piezoelectric material BPO$_4$,
in which two compensated sub-structures of opposite handedness coexist within
the same unit cell. By resonantly driving either one of two orthogonal, doubly
degenerate vibrational modes at Terahertz frequency, we rectify the lattice
distortion and exert a displacive force onto the crystal. The staggered
chirality is in this way uncompensated in either direction, inducing chiral
structure with either handedness. The rotary power of the photo-induced phases
is comparable to the static value of prototypical chiral alpha-quartz, limited
by the strength of the pump laser pulse.
