The geometry of an electron determined for the first time

The geometry of an electron determined for the first time
An electron is trapped in a quantum dot, which is formed in a two-dimensional gas in a semiconductor wafer. However, the electron moves within the space and, with different probabilities corresponding to a wave function, remains in certain locations within its confinement (red ellipses). Using the gold gates applied electric fields, the geometry of this wave function can be changed. (Image: University of Basel, Departement of Physics)

Physicists at the University of Basel have shown for the first time how a single electron looks in an artificial atom. A newly developed method enables them to show the probability of an electron being present in a space. This allows improved control of electron spins, which could serve as the smallest information unit in a future quantum computer. The experiments were published in Physical Review Letters and the related theory in Physical Review B.

The spin of an electron is a promising candidate for use as the smallest information unit (qubit) of a computer. Controlling and switching this spin or coupling it with other spins is a challenge on which numerous research groups worldwide are working. The stability of a single spin and the entanglement of various spins depends, among other things, on the geometry of the —which previously had been impossible to determine experimentally.

Only possible in artificial atoms

Scientists in the teams headed by professors Dominik Zumbühl and Daniel Loss from the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have now developed a method by which they can spatially determine the geometry of electrons in quantum dots.

A quantum dot is a potential trap which allows confining in an area which is about 1000 times larger than a natural atom. Because the trapped electrons behave similarly to electrons bound to an atom, are also known as "artificial atoms."

The electron is held in the quantum dot by electric fields. However, it moves within the space and, with different probabilities corresponding to a wave function, remains in specific locations within its confinement.

Charge distribution sheds light

The scientists use spectroscopic measurements to determine the in the quantum dot and study the behavior of these levels in magnetic fields of varying strength and orientation. Based on their theoretical model, it is possible to determine the electron's probability density and thus its wave function with a precision on the sub-nanometer scale.

"To put it simply, we can use this method to show what an electron looks like for the first time," explains Loss.

Better understanding and optimization

The researchers, who work closely with colleagues in Japan, Slovakia and the US, thus gain a better understanding of the correlation between the geometry of electrons and the electron spin, which should be stable for as long as possible and quickly switchable for use as a qubit.

"We are able to not only map the shape and orientation of the electron, but also control the according to the configuration of the applied electric fields. This gives us the opportunity to optimize control of the spins in a very targeted manner," says Zumbühl.

The spatial orientation of the electrons also plays a role in the entanglement of several spins. Similarly to the binding of two to a molecule, the wave functions of two electrons must lie on one plane for successful entanglement.

With the aid of the developed method, numerous earlier studies can be better understood, and the performance of spin qubits can be further optimized in the future.

Explore further

A spin trio for strong coupling

More information: Leon C. Camenzind et al. Spectroscopy of Quantum Dot Orbitals with In-Plane Magnetic Fields, Physical Review Letters (2019). DOI: 10.1103/PhysRevLett.122.207701

Peter Stano et al. Orbital effects of a strong in-plane magnetic field on a gate-defined quantum dot, Physical Review B (2019). DOI: 10.1103/PhysRevB.99.085308

Citation: The geometry of an electron determined for the first time (2019, May 23) retrieved 16 June 2019 from
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

May 23, 2019
The basic premise of oblate/prolate shell propagation is the building block of tetrahedral element stacking. Search YouTube for "The Elements in Six Dimensions"

May 23, 2019
now we can properly model the topology needed for superconductivity

May 23, 2019
its shaped like a torus donut shaped, and the field is not separate from the particle

May 23, 2019
So what is the shape? sphere of diameter xx? I thought electrons were point sources.

Halusis, please state your source of information. Is this the shape of the particle or the electrons position cloud?

May 23, 2019
The article is confusing the shape of the electron likelihood cloud in a bound state with the shape of the particle.

its shaped like a torus donut shaped, and the field is not separate from the particle

? ACME has recently confirmed yo increased precision that the electromagnetic "shape" of an electron is perfectly spherical. Why would anyone expect a particle to have such a complicated geometry as - wrongly, and without references - proposed here?

It is better to say that the particle is not separate from its field, since it is a phenomena (a resonant ripple) of the field [ ].

May 23, 2019
Violation of Uncertainty Principle?

May 23, 2019
The article is badly written and confuses the shape of the wavefunction of an electron with the shape of the electron.

This is actually quite interesting, since the shape of the wavefunction in the absence of a nucleus with its high positive charge is important for predicting how it will act. But the article glosses this over.

May 24, 2019

its shaped like a torus donut shaped, and the field is not separate from the particle

I remember saying to friends after we had watched one the of matrix film's , that reality is a doughnut

May 24, 2019
Dough, the stuff that buys me beer
Ray the guy who sells me beer
Me the guy who drinks the beer
Far, a long way for a beer
So, I think I'll have a beer
La, I'll have another beer
Tea, no thanks I'll have a beer
And that brings us back to


May 24, 2019
Now to figure out how to do the same tests on positrons and see if the results are as expected.

May 26, 2019
The electron is the center of an E field; it is infinite and invisible. When it oscillates, we see it as light, i.e. the field updates. The proton is the same. The centers of each have the same character as the field. The center contains the total value, the summation over each sphere about the center also has the total value. The updates are unidirectional. Therefore, only the center is capable of responding to the field; for it is the motion that seeks to maintain the spheres and the center or at least seek non-existence; which it never reaches, i.e + & - attract, like repel. The Universe! That which allows us and thought! Known since Ancient Egypt as particles! or Magic to Ya'll!

May 28, 2019
but the electrons do have analog spin states, imo

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more