A new physical quantity of electrons—orbital angular momentum—has been generated by Masaya Uchida and Akira Tonomura at the RIKEN Advanced Science Institute in Wako, Japan. The work, published today in the international science journal Nature1, could establish novel fields of research and lead to new electron microscopes.
“The ability of optical waves to spiral about their axis as they propagate, which can be described as corkscrew wavefronts, has already found a wide range of applications” explains Uchida.
A wave can be characterized by the shape of its wavefronts: imaginary surfaces that connect all points where the wave is at the same stage in its oscillatory cycle. In a conventional plane wave, these fronts are a series of flat surfaces oriented perpendicular to the direction of propagation.
Since electron waves act like optical waves, Uchida thought that spiraling electron waves were possible.
The researchers had to resolve a daunting technological challenge to generate the electrons with orbital angular momentum. A corkscrew wavefront is imprinted on an electron plane wave when it passes through a three-dimensional (3D) structure shaped into a single twist of the desired spiral. But since the height of the twist—determined by the wavelength of electron wave—is less than 100 nanometers, creating such a spiraling nanostructure is difficult.
The researchers simplified this problem by approximating the spiraling structure to several linear steps like a spiral ‘staircase’. They crushed the graphite from a pencil into thin films and placed them onto a carbon-coated copper grid. These fragments formed stacked layers resembling a spiral staircase.
To prove that the electrons gained orbital angular momentum as they passed through this simple 3D nanostructure, Uchida and Tonomura mixed the output wave with a second plane wave. They observed the characteristic ‘Y’-shaped defect to the parallel-lines pattern that is expected when two plane waves interfere. Measuring the transfer of momentum from the electrons to matter, however, could be a more direct way of identifying spiraling electron waves in the future, the researchers note.
“The next stage of the research is to produce wavefronts with various structure types,” says Uchida. “Just as there are many types of pasta, so there are many shapes of electron wave.”For more information, please contact:
Further Improvement of Qubit Lifetime for Quantum Computers
09.12.2016 | Forschungszentrum Jülich
Electron highway inside crystal
09.12.2016 | Julius-Maximilians-Universität Würzburg
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine