Quantum states interrogation using a pre-shaped free electron wavefunction

TL;DR

This paper introduces a novel method for probing quantum two-level systems using pre-shaped free electron wavefunctions, offering atomic-scale resolution and potential applications in material analysis and quantum computing.

Contribution

The paper develops a comprehensive theory for electron-based quantum state interrogation that surpasses laser methods in spatial resolution and control capabilities.

Findings

Enables measurement of full Bloch sphere parameters of TLS

Provides atomic-scale spatial resolution for quantum state interrogation

Facilitates coherent control of qubit states using electron scattering

Abstract

We present a comprehensive theory for interrogation of the quantum state of a two-level system (TLS) based on a free-electron - bound-electron resonant interaction scheme. The scheme is based on free electrons, whose quantum electron wavefunction is pre-shaped or optically modulated by lasers in an electron microscope setup and then inelastically scattered by a quantum TLS target (e.g., atom, quantum dot, crystal defect center, etc.) upon traversing in proximity to the target. Measurement of the post-interaction energy spectrum of the electrons, probes and quantifies the full Bloch sphere parameters of a pre-excited TLS and enables coherent control of the qubit states. The exceptional advantage of this scheme over laser-based ones is the atomic-scale spatial resolution of addressing individual TLS targets. Thus, this scheme opens new horizons for electron microscopy in material interrogation and quantum information technology.