Recipe for preparing a molecular ensemble with macroscopic threefold symmetry

We propose how to prepare a molecular ensemble with macroscopic threefold symmetry. By utilizing the special laser electric field trajectory with threefold symmetry, which can be formed by superposing a counterrotating circularly polarized fundamental pulse and its second harmonic pulse, sample molecules with threefold symmetry such as BX3 (X = F, Cl, Br, I) can be aligned with their three arms along (or in between) the laser electric fields with threefold symmetry depending on the sign of the hyperpolarizability of the sample molecule. We show that this method is feasible with practical experimental conditions as for the rotational temperature of the sample molecules and the intensities of the two wavelengths. This method will open up physics of symmetry concerning a molecular ensemble with macroscopic threefold symmetry.