Illuminating Molecular Symmetries with Bicircular High-Order-Harmonic Generation

TL;DR

This paper develops a comprehensive theory for bicircular high-order-harmonic generation in molecules with N-fold rotational symmetry, enabling direct identification of molecular symmetries from harmonic spectra.

Contribution

It introduces a rotating frame approach to predict harmonic spectra for arbitrary frequency ratios, revealing universal symmetry fingerprints in ultrafast molecular responses.

Findings

Molecular symmetries produce characteristic harmonic signatures

The theory applies to arbitrary frequency ratios in bicircular fields

Symmetry fingerprints are universally observable in ultrafast responses

Abstract

We present a complete theory of bicircular high-order-harmonic emission from N-fold rotationally symmetric molecules. Using a rotating frame of reference we predict the complete structure of the high-order-harmonic spectra for arbitrary driving frequency ratios and show how molecular symmetries can be directly identified from the harmonic signal. Our findings reveal that a characteristic fingerprint of rotational molecular symmetries can be universally observed in the ultrafast response of molecules to strong bicircular fields.