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We analytically describe the noise properties of a heralded electron source made from a standard electron gun, a weak photonic coupler, a single photon counter, and an electron energy filter. We describe the sub-Poissonian statistics of the source, the engineering requirements for efficient heralding, and several potential applications. We use simple models of electron beam processes to demonstrate advantages which are situational, but potentially significant in electron lithography and scanning electron microscopy.

Two studies of electrons generated from laser-triggered emitters have found highly predictable electron–electron energy correlations. These studies, at vastly different energy scales, may lead to heralded electron sources, enabling quantum free-electron optics and low-noise, low-damage electron beam lithography and microscopy.

In this work, we report the use of commercial Gallium Nitride (GaN) power electronics to precisely switch complex distributed loads, such as electron lenses and deflectors, without impedance matching. Depending on the chosen GaN field effect transistor (GaNFET) and driver, these GaN pulsers are capable of generating pulses ranging from 100 - 650 V and 5 - 60 A in 0.25 - 8 ns using simple designs with easy control, few-nanosecond propagation delays, and MHz repetition rates. We experimentally demonstrate a simple 250 ps, 100 V pulser measured by a directly coupled 2 GHz oscilloscope. By introducing resistive dampening, we can eliminate ringing to allow for precise 100 V transitions that complete a -10 V to -90 V transition in 1.5 ns, limited primarily by the inductance of the oscilloscope measurement path. The performance of the pulser attached to various load structures is simulated, demonstrating the possibility of even faster switching of internal fields in these loads. These circuits also have 0.25 cm\\(\\mathrm{^2}\\) active regions and <1 W power dissipation, enabling their integration into a wide variety of environments and apparatus. The proximity of the GaNFETs to the load due to this integration minimizes parasitic quantities that slow switching as well as remove the need to match from 50 \\({\\Omega}\\) lines by allowing for a lumped element approximation small loads. We expect these GaN pulsers to have broad application in fields such as optics, nuclear sciences, charged particle optics, and atomic physics that require nanosecond, high-voltage transitions.

This work demonstrates electron energy loss spectroscopy of 2D materials in a 1-30 keV electron microscope, observing 100-times stronger electron-matter coupling relative to 125 keV microscopes. We observe that the universal curve relating beam energy to scattering holds for the transition from bulk graphite to graphene, albeit with a scale factor. We calculate that optimal coupling for most 2D materials and optical nanostructures falls in this range, concluding that spectroscopy of such systems will greatly benefit from use of this previously unexplored energy regime.

We analytically describe the noise properties of a heralded electron source made from a standard electron gun, a weak photonic coupler, a single photon counter, and an electron energy filter. We argue the traditional heralding figure of merit, the Klyshko efficiency, is an insufficient statistic for characterizing performance in dose-control and dose-limited applications. Instead, we describe the sub-Poissonian statistics of the source using the fractional reduction in variance and the fractional increase in Fisher Information. Using these figures of merit, we discuss the engineering requirements for efficient heralding and evaluate potential applications using simple models of electron lithography, bright-field scanning transmission electron microscopy (BFSTEM), and scanning electron microscopy (SEM). We find that the advantage in each of these applications is situational, but potentially significant: dynamic control of the trade-off between write speed and shot noise in electron lithography; an order of magnitude dose reduction in BFSTEM for thin samples (e.g. 2D materials); and a doubling of dose efficiency for wall-steepness estimation in SEM.