AP 483 & AMO Seminar Series presents "Quantum Electron Microscopy"

Quantum Electron Microscopy
Monday, January 6, 2020 - 4:15pm
Spilker 232
Stewart Koppell (Stanford)
Abstract / Description: 

Of the wide variety of sophisticated techniques employed in optical microscopy, of special interest to physicists are schemes which use quantum correlations to increase sensitivity beyond the classical limit. Such technology would be especially applicable in transmission electron microscopy (TEM) since the image resolution of samples of critical interest (e.g. proteins, polymers, and battery materials) is limited by beam damage. However, in contrast to the fantastic diversity and modularity of light optics, electron optics are significantly constrained. I will describe our project of developing new electron optics to enable dose-efficient TEM. While quantum metrology is generally associated with an entangled probe (which has not yet been demonstrated with freespace electrons), it is also possible to perform quantum-optimal measurements with a single particle using sequential measurements [1]. In fact, it is possible to gain significant information about absorbing samples using only damage-free counterfactual measurements [2]. More typically, TEM samples are phase objects. We have shown that an approach called Multi-Pass TEM (MPTEM) can reduce damage by an order of magnitude for realistic samples [3]. The key new electron optics of the MPTEM are the switchable mirrors, which trap electrons in a cavity where the sample is re-imaged multiple times. We are currently building a 10 keV MPTEM [4] as a proof of concept. [1] Quantum Metrology, Vittorio Giovannetti, Seth Lloyd, and Lorenzo Maccone (2006). [2] Designs for a Quantum Electron Microscope, P. Kruit et al, Ultramicroscopy (2016). [3] Multi-Pass Transmission Electron Microscopy, T. Juffmann et al, Scientific Reports (2017). [4] Design for a 10 keV Multi-Pass Transmission Electron Microscope, S. A. Koppell, Ultramicroscopy (2019).