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First-time geometry of an electron – ScienceDaily

Physicists at the University of Basel can show for the first time what a single electron looks like in an artificial atom. A newly developed method allows them to show the probability of the presence of an electron in a room. This allows for improved control of electron spins, which could serve as the smallest unit of information 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 unit of information (qubit) of a quantum computer. Controlling and switching this spin or pairing with other spins is a challenge that is being addressed by numerous research groups worldwide. The stability of a single spin and the interweaving of different spins depend, among other things, on the geometry of the electrons, which could not be determined experimentally.

Only possible in artificial atoms

Scientists in the teams Under the direction of Professors Dominik Zumbühl and Daniel Loss of the Department of Physics and the Swiss Nanoscience Institute of the University of Basel, a method has now been developed with which they can study the geometry of electrons in Spatially determine quantum dots.

A quantum dot is a potential trap that allows free electrons to be included in an area about 1

000 times larger than a natural atom. Since the trapped electrons behave in a similar way to electrons bound to an atom, quantum dots are also called "artificial atoms."

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

Charge distribution raises light

Scientists use spectroscopic measurements to determine the energy levels in the quantum dot and study the behavior of these levels in magnetic fields of different strength and orientation. Based on their theoretical model, it is possible to determine the probability density and thus the wave function of the electron with an accuracy in the subnanometer range.

"Put 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, working closely with colleagues in Japan, Slovakia, and the United States, thus gain a better understanding of the relationship 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.

"Not only can we map the shape and orientation of the electron, but also the wave function after the controlled configuration of the applied electric fields, which allows us to optimize the 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 rotations. Similar to the binding of two atoms to a molecule, the wave functions of two electrons must lie on one level for successful entanglement.

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

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Materials provided by University of Basel . Note: The content can be edited by style and length.

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