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
Quantum gas turns supersolid
23.04.2019 | Universität Innsbruck
Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun
18.04.2019 | University of Warwick
Researchers led by Francesca Ferlaino from the University of Innsbruck and the Austrian Academy of Sciences report in Physical Review X on the observation of supersolid behavior in dipolar quantum gases of erbium and dysprosium. In the dysprosium gas these properties are unprecedentedly long-lived. This sets the stage for future investigations into the nature of this exotic phase of matter.
Supersolidity is a paradoxical state where the matter is both crystallized and superfluid. Predicted 50 years ago, such a counter-intuitive phase, featuring...
A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter
A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.
Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...
The technology could revolutionize how information travels through data centers and artificial intelligence networks
Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers...
Physicists observe how electron-hole pairs drift apart at ultrafast speed, but still remain strongly bound.
Modern electronics relies on ultrafast charge motion on ever shorter length scales. Physicists from Regensburg and Gothenburg have now succeeded in resolving a...
17.04.2019 | Event News
15.04.2019 | Event News
09.04.2019 | Event News
23.04.2019 | Information Technology
23.04.2019 | Earth Sciences
23.04.2019 | Life Sciences