# Attosecond Electron Pulse Trains and Quantum State Reconstruction in Ultrafast Transmission Electron Microscopy

## TL;DR

This paper presents a novel method for preparing, controlling, and characterizing free-electron quantum states using optical fields, enabling attosecond pulse trains and quantum state tomography for ultrafast electron microscopy.

## Contribution

It introduces a new framework for electron quantum state manipulation and a quantum state tomography technique called SQUIRRELS, advancing ultrafast electron microscopy capabilities.

## Key findings

- Demonstrated attosecond electron pulse trains in microscopy.
- Developed SQUIRRELS for reconstructing electron density matrices.
- Showed potential for nanoscale electron-matter entanglement studies.

## Abstract

We introduce a framework for the preparation, coherent manipulation and characterization of free-electron quantum states, experimentally demonstrating attosecond pulse trains for electron microscopy. Specifically, we employ phase-locked single-color and two-color optical fields to coherently control the electron wave function along the beam direction. We establish a new variant of quantum state tomography - "SQUIRRELS" - to reconstruct the density matrices of free-electron ensembles and their attosecond temporal structure. The ability to tailor and quantitatively map electron quantum states will promote the nanoscale study of electron-matter entanglement and the development of new forms of ultrafast electron microscopy and spectroscopy down to the attosecond regime.

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Source: https://tomesphere.com/paper/1706.03680