A quantum logic gate for free electrons

TL;DR

This paper demonstrates a quantum logic gate for free electrons using vortex electron states in a transmission electron microscope, enabling quantum information processing with electron beams.

Contribution

It introduces a method to implement quantum logic gates for free electrons using optical elements in TEMs, a novel approach in electron quantum computing.

Findings

Successfully designed a TEM-based quantum gate for electron qubits

Numerical and experimental validation of the gate's operation

Potential for scalable quantum information processing in electron microscopes

Abstract

The topological charge $m$ of vortex electrons spans an infinite-dimensional Hilbert space. Selecting a two-dimensional subspace spanned by $m=\pm 1$, a beam electron in a transmission electron microscope (TEM) can be considered as a quantum bit (qubit) freely propagating in the column. A combination of electron optical quadrupole lenses can serve as a universal device to manipulate such qubits at the experimenter's discretion. We set up a TEM probe forming lens system as a quantum gate and demonstrate its action numerically and experimentally. High-end TEMs with aberration correctors are a promising platform for such experiments, opening the way to study quantum logic gates in the electron microscope.