Sub-Cycle Strong-Field Interferometry

TL;DR

This paper proposes a nonlinear interferometry method using strong laser fields to resolve electron wave-function beating on sub-cycle time scales, enabling detailed spectral analysis of quantum systems beyond single-photon techniques.

Contribution

It introduces a theoretical scheme for strong-field interferometry that can access a wide range of electronic states, including non-dipole levels, with high temporal and spectral resolution.

Findings

Reveals electron wave-function beating on sub-cycle timescales.

Enables retrieval of broad-band spectral information.

Accesses both dipole- and non-dipole-accessible electronic levels.

Abstract

A nonlinear interferometry scheme is described theoretically to induce and resolve electron wave- function beating on time scales shorter than the optical cycle of the time-delayed pump and probe pulses. By employing two moderately intense few-cycle laser fields with a stable carrier-envelope phase, a large range of the entire electronic level structure of a quantum system can be retrieved. In contrast to single-photon excitation schemes, the retrieved electronic states include levels that are both dipole- and non-dipole-accessible from the ground electronic state. The results show that strong-field interferometry can reveal both high-resolution and broad-band spectral information at the same time with important consequences for quantum-beat spectroscopy on attosecond or even shorter time scales.