Electron-Enabled Nanoparticle Diffraction

TL;DR

This paper introduces a novel electron diffraction method to generate and observe large quantum superpositions of levitated nanoparticles, enabling faster experiments and improved coherence for macroscopic quantum tests.

Contribution

It presents a scheme for creating high-mass quantum superpositions of nanoparticles via electron diffraction, achieving larger momentum splits and shorter interference times than traditional methods.

Findings

Achieves momentum splitting ~1000 times greater than two-photon recoil methods.

Allows observation of nanoparticle self-interference within shorter free-fall times.

Facilitates nanoparticle reuse in rapid experimental cycles.

Abstract

We propose a scheme for generating high-mass quantum superposition states of an optically pre-cooled, levitated nanoparticle through electron diffraction at its sub-nanometer crystal lattice. When a single electron undergoes Bragg diffraction at a free-falling nanoparticle, momentum conservation implies that the superposition of Bragg momenta is imprinted onto the relative coordinate between electron and nanoparticle, which entangles their wavefunctions. By imaging the electron interferogram, one maps the nanoparticle state onto a superposition of Bragg momenta, as if it was diffracted by its own lattice. This results in a coherent momentum splitting approximately 1000 times greater than what is achievable with two-photon recoils in conventional standing-wave gratings. Self-interference of the nanoparticle can thus be observed within drastically shorter free-fall times in a time-domain Talbot interferometer configuration, significantly relaxing source requirements and alleviating decoherence from environmental factors such as residual gas and thermal radiation. Shorter interference times also allow for a recapture of the nanoparticle within its initial trapping volume, facilitating its reuse in many rapid experimental duty cycles. This opens new possibilities for experimental tests of macroscopic quantum effects within a transmission electron microscope.