Experimental Realization of All-Optical Terahertz Attoclock

TL;DR

This paper demonstrates an all-optical terahertz attoclock that measures ultrafast electron dynamics by detecting emitted THz radiation, providing a contactless and versatile alternative to traditional methods.

Contribution

It introduces a novel THz-based attoclock technique that reconstructs photoionization delays without requiring electron detection, validated by experiments and simulations.

Findings

THz polarization rotation correlates with ionization delay

Intensity-dependent polarization changes observed

Method aligns with conventional attoclock results

Abstract

The attoclock is a powerful tool for probing ultrafast electron dynamics with attosecond precision.Here, we demonstrate an all-optical terahertz (THz) attoclock that reconstructs photoionization dynamics by detecting the THz radiation emitted from Ar atoms ionized by two-color (800 nm/400 nm) laser fields. In this approach, the polarization direction of the emitted THz field reflects the direction of the photoelectron drift velocity and thus serves as a direct observable that encodes the effective ionization delay, analogous to the angular deflection of photoelectrons in conventional attoclocks. By precisely tailoring the relative phase and ellipticity of the driving fields, we observe intensity-dependent rotations of the THz polarization. These rotations, which reveal changes of the effective delay, are consistent with both conventional attoclock measurements and time-dependent Schr\"odinger equation simulations. Our experiment establishes the feasibility of the THz attoclock as a vacuum-free and contactless probe of tunneling dynamics, offering a transformative alternative for investigating condensed-matter systems where photoelectron detection is challenging.