arXiv subjects

Herman Batelaan

Publications and source records attributed to Herman Batelaan.

At least 19 recordsLinked to original sources

arXiv2024

Unusual crosstalk in coincidence measurement searches for quantum degeneracy

A dip in coincidence peaks for an electron beam is an experimental signature to detect Coulomb repulsion and Pauli pressure. This paper discusses another effect that can produce a similar signature but that does not originate from the properties of the physical system under scrutiny. Instead, the detectors and electronics used to measure those coincidences suffer significantly even from weak crosstalk. A simple model that explains our experimental observations is given. Furthermore we provide an experimental approach to correct for this type of crosstalk.

quant-ph↗

arXiv2024

Topological schemes in spacetime for the electrodynamic Aharonov-Bohm effect

We consider different schemes for the electrodynamic Aharonov-Bohm (AB) effect introduced in Ref. [Phys. Rev. A $\mathbf{108}$, 062218 (2023)], exploring the phenomenon to enhance the understanding of its topological nature in spacetime. In the treated examples, the electric current in a solenoid varies in time, changing its internal magnetic field and producing an external electric field, while a quantum charged particle is in a superposition state inside two Faraday cages in an interferometer. The Faraday cages cancel the electric field at their interiors, such that the particle is always subjected to null electromagnetic fields. We discuss how the AB phase difference depends on the topology of the electric and magnetic fields in spacetime in the different treated situations. In particular, we discuss interesting results when a conducting wire connects the two Faraday cages, with the AB phase depending on the wire position. We also show an amplification of the AB phase when the wire makes several turns around the solenoid, which could enable an experimental verification of the effect.

quant-ph↗

arXiv2024

Laser Pulse Diagnostics of Ultrafast <8 fs Pulses Through Two-Photon Absorption Fluorescence In Liquid Media -- The Role of GVD and Third-Order Dispersion

This study investigates the propagation of an ultrafast laser pulse through a liquid medium. A femtosecond laser oscillator with a pulse duration of less than 8 fs is used. By conducting experiments with coumarin and fluorescein dyes in water, methanol, and chloroform, we analyze two-photon absorption (TPA) fluorescence, a method pioneered by Schr\"oder [Opt. Express 14, 10125 (2006)]. A numerical algorithm we developed to model the fluorescence signal determines the group velocity dispersion (GVD), the third-order dispersion (TOD), and the group delay dispersion (GDD). Autocorrelation measurements combined with a detailed analysis confirm the validity of our method and the accuracy of the retrieved temporal profile of the pulse. This cost-effective approach is robust and useful for laser pulse characterization, outperforming traditional methods in terms of alignment sensitivity. Our method allows us to study the time evolution of the pulses as they propagate through the liquid, determines higher-order phase terms as acquired by the pulse while reflecting off the chirped mirrors and propagating through the liquid, and even works for non-Gaussian spectral intensities of the laser.

physics.optics↗

arXiv2022

Quantified Advantage of Ghost Imaging over Regular Imaging

Ghost imaging is a remarkable technique where light that never interacts with an object is detected with a camera and still the image of the object is recorded. The method relies on the use of correlated light and an additional bucket detector. Ghost imaging has been used in archaeology, bio-medicine, for seeing through turbid media, and promises X-ray imaging improvements, amongst many other applications. However, the advantage of ghost imaging over regular imaging can be difficult to quantify. For classical ghost imaging of a single pixel aperture (the object), we find a closed analytic expression for the signal-to-noise ratio using basic statistics. We find that this signal-to-noise ratio can exceed that of regular imaging with the same exposure of the aperture when the detectors are sufficiently noisy, illustrating a simple and quantifiable advantage. Numerical simulation confirms the theoretical analysis.

physics.optics↗

arXiv2022

Testing Quantum Dissipation Theory with Electron Diffraction

Decoherence can be provided by a dissipative environment as described by the Caldeira-Leggett equation. This equation is foundational to the theory of quantum dissipation. However, no experimental test has been performed that measures for one physical system both the dissipation and the decoherence. Anglin and Zurek predicted that a resistive surface could provide such a dissipative environment for a free electron wave passing close to it. We propose that the electron wave's coherence and energy loss can be measured simultaneously by using Kapitza-Dirac scattering for varying light intensity.

quant-ph↗

arXiv2021

Aloof electron probing of in-plane SPV charge distributions on GaAs surfaces

The motion of free electrons moving parallel and above a semiconductor surface can be influenced by shining laser light onto the surface. Here we report strong deflection of aloof electrons by an undoped GaAs surface illuminated with a 633nm laser. The deflecting electric field from the surface photovoltaic charges extends 100 {\mu}m into the vacuum. As surface photovoltage (SPV) is sensitive to the electronic states of the GaAs surface, the aloof electron beam serves as a probe for SPV charge dynamics at the mesoscopic length scale. The observed in-plane SPV charge distribution persists beyond 1 second after the laser beam is blocked. Our work suggests the possibility of writing designed 2D charge patterns on semiconductor surfaces with a scanning laser beam, providing unusual flexibility for electron beam manipulation.

quant-ph↗

arXiv2021

Simulation of Afshar's Double Slit Experiment

Shahriar S. Afshar claimed that his 2007 modified version of the double-slit experiment violates complementarity [1]. He makes two modifications to the standard double-slit experiment. First, he adds a wire grid that is placed in between the slits and the screen at locations of interference minima. The second modification is to place a converging lens just after the wire grid. The idea is that the wire grid implies the existence of interference minima(wave-like behavior), while the lens can simultaneously obtain which-way information (particle-like behavior). More recently, John G. Cramer [2] argued that the experiment bolstered the Transactional Interpretation of Quantum mechanics (TIQM). His argument scrutinizes Bohr's complementarity in favor of TIQM. We analyze this experiment by simulation using the path integral formulation of quantum mechanics [3] and find that it agrees with the wave particle duality relation given by Englert, Greenberg and Yasin (E-G-Y) [4, 5]. We conclude that the use of Afshar's experiment to provide a testbed for quantum mechanical interpretations is limited.

quant-ph↗

arXiv2021

Comment on Kuwahara et al., Intensity Interference in a Coherent Spin-Polarized Electron Beam, Phys. Rev. Lett. 126, 125501 (2021)

The claim that Kuwahara et al. [1] have reported the observation of a Hanbury Brown-Twiss electron antibunching dip (their Fig. 3) could possibly be explained as an electron source emission rate dependency on the light polarization. Strain on their GaAs/GaAsP sample is uniaxial, and one would expect a linear dichroism in the photoemission possibly as large as 15% [7] - much larger than the 0.1% reported effect. The same concern exist for circular polarized light.

quant-ph↗

arXiv2021

Non-Poissonian ultrashort, nanoscale electron pulses

The statistical character of electron beams used in current technologies, as described by a stream of particles, is random in nature. Using coincidence measurements of femtosecond pulsed electron pairs, we report the observation of sub-Poissonian electron statistics that are non-random due to two-electron Coulomb interactions, and that exhibit an anti-bunching signal of 1 part in 4. This advancement is a fundamental step towards realizing a strongly quantum degenerate electron beam needed for many applications, and in particular electron correlation spectroscopy.

quant-ph↗

arXiv2021

Laser-induced electron emission from Au nanowires: A probe for orthogonal polarizations

Photoelectron field emission, induced by femtosecond laser pulses focused on metallic nanotips, provides spatially coherent and temporally short electron pulses. The properties of the photoelectron yield give insight into both the material properties of the nanostructure and the exciting laser focus. Ultralong nanoribbons, grown as a single crystal attached to a metallic taper, are sources of electron field emission that have not yet been characterized. In this report, photoemission from gold nanoribbon samples is studied and compared to emission from tungsten and gold tips. We observe that the emission from sharp tips generally depends on one transverse component of the exciting laser field, while the emission of a blunted nanoribbon is found to be sensitive to both components. We propose that this property makes photoemission from nanoribbons a candidate for position-sensitive detection of the longitudinal field component in a tightly focused beam.

physics.app-ph↗

arXiv2021

A Low-Power Optical Electron Switch

An electron beam is deflected when it passes over a silicon nitride surface, if the surface is illuminated by a low-power continuous-wave diode laser. A deflection angle of up-to $1.2 \,\textrm{mrad}$ is achieved for an electron beam of $29 \,μ\textrm{rad}$ divergence. A mechanical beam-stop is used to demonstrate that the effect can act as an optical electron switch with a rise and fall time of $6 \,μ\textrm{s}$. Such a switch provides an alternative means to control electron beams, which may be useful in electron lithography and microscopy.

physics.app-ph↗

arXiv2021

Spin-dependent two-color Kapitza-Dirac effects

In this paper we present an analysis of the spin behavior of electrons propagating through a laser field. We present an experimentally realizable scenario in which spin-dependent effects of the interaction between the laser and the electrons are dominant. The laser interaction strength and incident electron velocity are in the nonrelativistic domain. This analysis may thus lead to novel methods of creating and characterizing spin-polarized nonrelativistic femtosecond electron pulses.

quant-ph↗

arXiv2021

Kapitza-Dirac blockade: A universal tool for the deterministic preparation of non-Gaussian oscillator states

Harmonic oscillators count among the most fundamental quantum systems with important applications in molecular physics, nanoparticle trapping, and quantum information processing. Their equidistant energy level spacing is often a desired feature, but at the same time a challenge if the goal is to deterministically populate specific eigenstates. Here, we show how interference in the transition amplitudes in a bichromatic laser field can suppress the sequential climbing of harmonic oscillator states (Kapitza-Dirac blockade) and achieve selective excitation of energy eigenstates, Schrödinger cats and other non-Gaussian states. This technique can transform the harmonic oscillator into a coherent two-level system or be used to build a large-momentum-transfer beam splitter for matter-waves. To illustrate the universality of the concept, we discuss feasible experiments that cover many orders of magnitude in mass, from single electrons over large molecules to dielectric nanoparticles.

quant-ph↗

arXiv2020

Testing Quantum Coherence in Stochastic Electrodynamics with Squeezed Schrödinger Cat States

The interference pattern in electron double-slit diffraction is a hallmark of quantum mechanics. A long standing question for stochastic electrodynamics (SED) is whether or not it is capable of reproducing such effects, as interference is a manifestation of quantum coherence. In this study, we use excited harmonic oscillators to directly test this quantum feature in SED. We use two counter-propagating dichromatic laser pulses to promote a ground-state harmonic oscillator to a squeezed Schrödinger cat state. Upon recombination of the two well-separated wavepackets, an interference pattern emerges in the quantum probability distribution but is absent in the SED probability distribution. We thus give a counterexample that rejects SED as a valid alternative to quantum mechanics.

quant-ph↗

arXiv2020

Photofield electron emission from an optical fiber nanotip

We demonstrate a nanotip electron source based on a graded index multimode silica optical fiber, tapered at one end to a radius of curvature r ~ 50 nm and coated with a thin film of gold. We report observation of laser-induced electron photoemission at tip bias potentials below the onset of dark field emission (FE). Single-photon photofield emission (PFE) is identified as the emission mechanism, which exhibits fast switching times with an upper limit on the order of 1 μs. The explored fiber optic nanotips are flexible back-illuminated emitters, which can be operated in continuous wave (CW) and pulsed modes using lasers with photon energies in the visible range or higher. The mechanical flexibility of the source can facilitate externally controlled positioning. Multiple, individually addressable, nanotips may be assembled into a bundle for applications such as computational electron ghost imaging.

physics.app-ph↗

arXiv2020

Surface plasmon enhanced fast electron emission from metallised fibre optic nanotips

Physical mechanisms of electron emission from fibre optic nanotips, namely, tunnelling, multi-photon, and thermionic emission, either prevent fast switching or require intense laser fields. Time-resolved electron emission from nano-sized sources finds applications ranging from material characterisation to fundamental studies of quantum coherence. We present a nano-sized electron source capable of fast-switching (<1 ns) that can be driven with low-power femtosecond lasers. The physical mechanism that can explain emission at low laser power is surface plasmon enhanced above-threshold photoemission. An electron emission peak is observed and provides support for resonant plasmonic excitation. The electron source is a metal-coated optical fibre tapered into a nano-sized tip. The fibre is flexible and back illuminated facilitating ease of positioning. The source operates with a few nJ per laser pulse, making this a versatile emitter that enables nanometrology, multisource electron-lithography and scanning probe microscopy. Keywords: fibre optic nanotip, surface plasmon resonance, multi-photon emission, above-threshold emission

physics.atom-ph↗

arXiv2019

Asymmetry and non-dispersivity in the Aharonov-Bohm effect

Decades ago, Aharonov and Bohm showed that electrons are affected by electromagnetic potentials in the absence of forces due to fields. Zeilinger's theorem describes this absence of classical force in quantum terms as the "dispersionless" nature of the Aharonov-Bohm effect. Shelankov predicted the presence of a quantum "force" for the same Aharonov-Bohm physical system as elucidated by Berry. Here, we report an experiment designed to test Shelankov's prediction and we provide a theoretical analysis that is intended to elucidate the relation between Shelankov's prediction and Zeilinger's theorem. The experiment consists of the Aharonov--Bohm physical system; free electrons pass a magnetized nanorod and far--field electron diffraction is observed. The diffraction pattern is asymmetric confirming one of Shelankov's predictions and giving indirect experimental evidence for the presence of a quantum "force". Our theoretical analysis shows that Zeilinger's theorem and Shelankov's result are both special cases of one theorem.

quant-ph↗

arXiv2019

Partially coherent quantum degenerate electron matter waves

The use of electron beams is ubiquitous; electron microscopy, scanning tunneling microscopy, electron lithography, and electron diffractometry all use well-collimated and focused beams. On the other hand, quantum degenerate electron beams do currently not exist. The realization of such beams may impact all electron beam technologies and are interesting to pursue. Past attempts to reach degeneracy were hampered by the low degeneracy of continuously emitting electron sources. With the recent advent of ultra-short electron pulses, high degeneracy is expected. Coulomb repulsion and low quantum coherence are hurdles that need to be overcome. A quantum analysis of the electron degeneracy for partially coherent pulsed electron sources is presented. Two-particle coincidence spectra are obtained for source parameters that are currently available. The conclusive demonstration of the fermionic Hanbury-Brown Twiss (HBT) effect for free electrons is shown to be within reach, and our results support the claim that femto-second nanotip electron sources, both polarized and unpolarized, can manifest partial to complete quantum degeneracy with appreciable signal-to-noise-ratios for free electron pulses notwithstanding their small particle numbers.

quant-ph↗