Laying the foundations for quantum mechanical innovations

Her office is located in a corner of Ångström Laboratory’s building 9. It’s light and airy, with large windows facing onto Kronparken. On one wall is a whiteboard covered with formulas and equations, and next to a rectangular desk is a table and chairs.

“This is a great office because there’s plenty of room for visitors. Especially when members of my research group come here and want to discuss various research problems,” says Annica Black-Schaffer.

Her research group currently consists of 12 members: six doctoral students and six postdocs, as well as a few Master’s students. Their research focuses on condensed matter, meaning matter in solid or liquid form, which in turn is determined by the chemical bonds or physical structures they have. The goal of the research is usually to understand various material properties by analysing how the electrons move in the physical structures.

Models start out with pen on paper

The group is especially interested in matter where quantum mechanical effects in a very prominent way determine the properties. To succeed in describing such quantum materials, it’s best to start with models that are as simple as possible, explains Annica Black-Schaffer.

“We often do a combination of analytical and numerical calculations. First with pen and paper, and then we let the computer solve the equations.”

The focus for the research group is on how electrons behave in superconductors. When electrons come into contact with other electrons, interaction occurs. And if the material is cooled down, sometimes close to absolute zero (minus 273 degrees Celsius) this interaction can give result in an electric current flowing entirely without resistance. Transforming the material into a superconductor.

“When electrons interact in this way, they end up in the same quantum state. This is how the material can conduct an electric current entirely without heat losses and thus no energy losses. In the future, this could completely solve the problems involved in electricity transmission. But so far, the technology and the costs of cooling – even if liquid nitrogen sometimes suffices – are just too great,” says Annica Black-Schaffer.

A great many areas of application

To identify materials that can function as superconductors without such extreme cooling would be a dream come true. Researchers have tried to identify such materials, but so far with no success. If researchers can figure out what induces electrons to end up in the same quantum state even at room temperature, superconductors could be exploited much more than they are today, according to Annica Black-Schaffer.

One exciting application is quantum computers, which have enormous computational capacity. Areas of applications include personalised drugs, satellite communications, and data encryption.

“Unfortunately, quantum mechanical phenomena tend to be extremely sensitive to everything – dust, high temperatures, and other disturbances – and that makes today’s quantum computers very sensitive. But there are ideas around of using a special type of superconductor, called a topological superconductor, to produce a more robust quantum computer,” says Annica Black-Schaffer.

Long list of grants and awards

A topological superconductor can have Majorana fermions. These particles behave like half electrons, even though the electron per se is indivisible, explains Annica Black-Schaffer. So, here the electron has the ability to divide itself completely and thus appear to be in two completely different places at the same time. Such quantum mechanical effects give us hope of being able to create a robust quantum computer using a topological superconductor, because it is not sensitive to common disturbances, which are usually local.

But Annica Black-Schaffer’s great interest lies in basic research and not its potential applications. Over the years, she has received a long list of grants and awards. She was particularly grateful for the grant she received in 2010 from the Swedish Research Council to become an assistant professor at Uppsala University.

“The fact that I received my own funding for four years at a university in the same city where I lived was just wonderful. Otherwise, I don’t know what would have happened. So I’m very, very grateful for that grant,” she says.

Administrative responsibilities

Another milestone in her career was her appointment as a Wallenberg Academy Fellow in 2014. Suddenly she had access to more resources and support for her research group and also a mentoring programme, and was also able to prepare an application to the European Research Council (ERC). In 2017, she received an ERC Starting Grant, which was followed in 2022 by an ERC Consolidator Grant. In 2024 she was also named a Wallenberg Scholar.

Although great talent and hard work are clearly behind these successes, she says she has also been very lucky.

“I think you also have to be ready to jump at chances like this when they present themselves. Be well prepared for opportunities when they present themselves.”

Being able to plan is also something that comes in handy in her role as Assistant Head of Department for Research at the Department of Physics and Astronomy. At least half of her working week is devoted to administrative matters and roles on boards and committees. Since she is also married to the Faculty’s Dean of Research David Black-Schaffer, professor of computer systems, work tends to spill over into her free time as well.

“But our research is so different that we almost never talk about it. Although there can be organisational issues such as about supervising doctoral students that we do discuss. In that context, we can gain inspiration from each other,” she says.

New project track in superconductivity

Annica Black-Schaffer met her husband at Stanford University in California, USA, where she went as an exchange student from the Master of Science in Applied Physics and Electrical Engineering programme at Linköping University. Later, she was accepted as a doctoral student in condensed matter physics at Stanford. In 2009, the couple moved to Sweden.

In her current ERC project, she is following an old track that has recently been revived. The project focuses on superconductivity in inhomogeneous systems, where matter has an inherent lack of uniformity. It also relates to the subject area in which she defended her thesis at Stanford – Superconductivity in graphene. But now she is investigating how it can be induced by for example moiré patterns in graphene.

“If you take two layers of pure carbon and twist them at a small angle to each other, they can become superconducting. Now that I’ve started working on graphene again, I’ve more or less come full circle.” At least for now she says, and continues:

“But in the new Wallenberg Scholar project, starting in summer 2025, we will instead be investigating something entirely different. We're going to try to create superconductivity by allowing matter to interact with its surroundings. Generally, such a connection to the environment destroys quantum mechanical effects. But we believe there are opportunities to tailor the connection to create completely new physics. It will be very exciting to see if we can succeed.”

Anneli Björkman