10 research outputs found
Information transfer by quantum matterwave modulation
Classical communication schemes that exploit wave modulation are the basis of
the information era. The transfer of information based on the quantum
properties of photons revolutionized these modern communication techniques.
Here we demonstrate that also matterwaves can be applied for information
transfer and that their quantum nature provides a high level of security. Our
technique allows transmitting a message by a non-trivial modulation of an
electron matterwave in a biprism interferometer. The data is encoded by a Wien
filter introducing a longitudinal shift between separated matterwave packets.
The transmission receiver is a delay line detector performing a dynamic
contrast analysis of the fringe pattern. Our method relies on the Aharonov-Bohm
effect and has no light optical analog since it does not shift the phase of the
electron interference. A passive eavesdropping attack will cause decoherence
and terminating the data transfer. This is demonstrated by introducing a
semiconducting surface that disturbs the quantum state by Coulomb interaction
and reduces the contrast. We also present a key distribution protocol based on
the quantum nature of the matterwaves that can reveal active eavesdropping
Near-monochromatic tuneable cryogenic niobium electron field emitter
Creating, manipulating, and detecting coherent electrons is at the heart of
future quantum microscopy and spectroscopy technologies. Leveraging and
specifically altering the quantum features of an electron beam source at low
temperatures can enhance its emission properties. Here, we describe electron
field emission from a monocrystalline, superconducting niobium nanotip at a
temperature of 5.9 K. The emitted electron energy spectrum reveals an
ultra-narrow distribution down to 16 meV due to tunable resonant tunneling
field emission via localized band states at a nano-protrusion's apex and a
cut-off at the sharp low-temperature Fermi-edge. This is an order of magnitude
lower than for conventional field emission electron sources. The self-focusing
geometry of the tip leads to emission in an angle of 3.7 deg, a reduced
brightness of 3.8 x 10exp8 A/(m2 sr V), and a stability of hours at 4.1 nA beam
current and 69 meV energy width. This source will decrease the impact of lens
aberration and enable new modes in low-energy electron microscopy, electron
energy loss spectroscopy, and high-resolution vibrational spectroscopy.Comment: to be published in Phys. Rev. Lett. (2022
Data transmission by quantum matter wave modulation
Classical communication schemes exploiting wave modulation are the basis of our information era. Quantum information techniques with photons enable future secure data transfer in the dawn of decoding quantum computers. Here we demonstrate that also matter waves can be applied for secure data transfer. Our technique allows the transmission of a message by a quantum modulation of coherent electrons in a biprism interferometer. The data is encoded in the superposition state by a Wien filter introducing a longitudinal shift between separated matter wave packets. The transmission receiver is a delay line detector performing a dynamic contrast analysis of the fringe pattern. Our method relies on the Aharonov-Bohm effect but does not shift the phase. It is demonstrated that an eavesdropping attack will terminate the data transfer by disturbing the quantum state and introducing decoherence. Furthermore, we discuss the security limitations of the scheme due to the multi-particle aspect and propose the implementation of a key distribution protocol that can prevent active eavesdropping
Quantum decoherence by Coulomb interaction
The performance of modern quantum devices in communication, metrology or
microscopy relies on the quantum-classical interaction which is generally
described by the theory of decoherence. Despite the high relevance for long
coherence times in quantum electronics, decoherence mechanisms mediated by the
Coulomb force are not well understood yet and several competing theoretical
models exist. Here, we present an experimental study of the Coulomb-induced
decoherence of free electrons in a superposition state in a biprism electron
interferometer close to a semiconducting and metallic surface. The decoherence
was determined through a contrast loss at different beam path separations,
surface distances and conductibilities. To clarify the current literature
discussion, four theoretical models were compared to our data. We could rule
out three of them and got good agreement with a theory based on macroscopic
quantum electrodynamics. The results will enable the determination and
minimization of specific decoherence channels in the design of novel quantum
instruments.Comment: 6 pages article plus 2 pages supplemental materia
2020 GenZ Story Express Projects: George Reinitz
2020 GenZ Story Express Projects: George Reinitz: Due to Covid-19 safety concerns, this year’s workshop was held on Zoom. Final projects are typically displayed at the Project Nuremberg Lawyers Luncheon at Temple Beth El in Boca Raton and at Lynn’s annual Celebration of the Arts. Since those events were cancelled, this iBook was created as a tribute to the Holocaust survivor.https://spiral.lynn.edu/genz-workshop/1000/thumbnail.jp