Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled to its motion, i.e. its orbit within the chip. This spin-orbit coupling allows targeted manipulation of the electron spin by an external electric field, but it also causes the spin’s orientation to decay, which leads to a loss of information.
In an international collaboration with colleagues from the US and Brazil, scientists from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute, headed by Professor Dominik Zumbühl, have developed a new method that allows for targeted spin manipulation without the accompanying decay.
Controlling spins over long distances
The scientists have developed a chip on which an electron rotates uniformly in its orbit through the material without decay of the spin. The spin’s orientation follows a spiral pattern similar to a helix. If the voltages applied by two gate electrodes change, it affects the wavelength of the helix; the orientation of the spin can thus be influenced by a voltage change.
The Rashba and Dresselhaus fields predominantly determine the helical movement of the spin. In the experiment described above, the Dresselhaus and Rashba fields can be kept at the same level, while the overall strength of the two fields can simultaneously be controlled: in this way, the spin’s decay can be suppressed.
This allows the researchers to use voltages to adjust the spin’s orientation over distances greater than 20 micrometers, which is a particularly large distance on a chip and corresponds to many spin rotations. Spin information can thus be transmitted e.g. between different quantum bits.
Adjusting the fields with electrical voltages
This method is only possible because, as this work showed experimentally for the first time, both the Rashba field and the Dresselhaus field can be adjusted with electrical voltages. Although this was predicted more than 20 years ago in a theoretical study, it has only now been possible to demonstrate it thanks to a newly-developed measurement method based on quantum interference effects at low temperatures near absolute zero. It is expected, however, that the helix will also be able to be controlled with voltages at higher temperatures and even at room temperature.
Basis for further developments
“With this method, we can not only influence the spin orientation in situ but also control the transfer of electron spins over longer distances without losses,” says Zumbühl. The outstanding collaboration with colleagues from the University of São Paulo, the University of California and the University of Chicago provides the basis for a whole new generation of devices that build on spin-based electronics and create prospects for further experimental work.
Florian Dettwiler, Jiyong Fu, Shawn Mack, Pirmin J. Weigele, J. Carlos Egues, David D. Awschalom, and Dominik M. Zumbühl
Stretchable Persistent Spin Helices in GaAs Quantum Wells
Physical Review X (2017), doi: 10.1103/PhysRevX.7.031010
Professor Dominik Zumbühl, University of Basel, Department of Physics, tel.: +41 61 207 36 93, email: email@example.com
Olivia Poisson | Universität Basel
Researchers demonstrate three-dimensional quantum hall effect for the first time
19.08.2019 | Singapore University of Technology and Design
A laser for penetrating waves
19.08.2019 | Helmholtz-Zentrum Dresden-Rossendorf
Soft robots have a distinct advantage over their rigid forebears: they can adapt to complex environments, handle fragile objects and interact safely with humans. Made from silicone, rubber or other stretchable polymers, they are ideal for use in rehabilitation exoskeletons and robotic clothing. Soft bio-inspired robots could one day be deployed to explore remote or dangerous environments.
Most soft robots are actuated by rigid, noisy pumps that push fluids into the machines' moving parts. Because they are connected to these bulky pumps by tubes,...
Researchers at TU Graz are working together with European partners on new possibilities of measuring vehicle emissions.
Today, air pollution is one of the biggest challenges facing European cities. As part of the Horizon 2020 research project CARES (City Air Remote Emission...
Over the next three years, researchers from the Vrije Universiteit Brussel, University of Cambridge, École Supérieure de Physique et de Chimie Industrielles de la ville de Paris (ESPCI-Paris) and Empa will be working together with the Dutch Polymer manufacturer SupraPolix on the next generation of robots: (soft) robots that ‘feel pain’ and heal themselves. The partners can count on 3 million Euro in support from the European Commission.
Soon robots will not only be found in factories and laboratories, but will be assisting us in our immediate environment. They will help us in the household, to...
Scientists at the University of Leeds have created a new form of gold which is just two atoms thick - the thinnest unsupported gold ever created.
The researchers measured the thickness of the gold to be 0.47 nanometres - that is one million times thinner than a human finger nail. The material is regarded...
An international team of scientists involving the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg has unraveled the light-induced electron-localization dynamics in transition metals at the attosecond timescale. The team investigated for the first time the many-body electron dynamics in transition metals before thermalization sets in. Their work has now appeared in Nature Physics.
The researchers from ETH Zurich (Switzerland), the MPSD (Germany), the Center for Computational Sciences of University of Tsukuba (Japan) and the Center for...
16.08.2019 | Event News
14.08.2019 | Event News
12.08.2019 | Event News
19.08.2019 | Information Technology
19.08.2019 | Physics and Astronomy
19.08.2019 | Life Sciences