Quantum entanglement and quantum correlations are among the most astounding phenomena in physics. In 2022, the Nobel Prize in Physics was awarded for fundamental work in this field. However, making these phenomena technologically usable, for example for data processing, often requires somewhat more complex strategies than those that are currently available. This is precisely what physicist Elizabeth Agudelo is working on at TU Wien's Institute for Atomic and Subatomic Physics. She is investigating different forms of quantum correlations and developing new proposals for their certification. She has now been awarded a prestigious Elise Richter Fellowships from the Austrian Science Fund FWF.

Mysterious quantum entanglement

In our everyday, classical world, every object has a clear, observable state: a car either drives to the left or to the right, a spinning top either rotates clockwise or counterclockwise. In quantum physics, things are different: in a certain sense, a quantum object can assume several states at the same time. An atom can rotate both clockwise and anticlockwise simultaneously; a photon can oscillate both horizontally and vertically. This is referred to as a superposition state. Only when you measure the state do you force the particle to commit to one of the two variants — you cannot say which one it is beforehand. The result is pure chance.

But things get even stranger: it is possible for several quantum particles to share one state. For example, you can create two photons that are both in a superposition state. In that case, despite measurement results being entirely random, these random outcomes can still be correlated. So if you measure one photon, it is fundamentally impossible to predict the outcome, but if the photons are prepared in a certain way, then whatever random outcome will materialise, the partner photon will show the exact same property. In that case, the state of the two photons is called an entangled state.

These unfamiliar correlations between the measurement results of different photons can actually be proven and utilised to build new quantum communication technologies.

Many parties, complicated correlations

These phenomena are well known today, but there is still much more to discover. Elizabeth Agudelo is researching even more complicated forms of quantum correlations: It is possible to find special situations where multiple photons or multiple fields share their quantum properties in subtle ways, you need sophisticated strategies to produce and detect these correlations.

The more control you have over these subtle quantum connections between multiple parties, the more efficiently you can use them technologically — from quantum data transmission to quantum computers. Elizabeth Agudelo is investigating highly complex systems to better integrate the strange world of quanta into our everyday technical lives.

Elizabeth Agudelo

Elizabeth Agudelo comes from Colombia, and she completed her Bachelor's degree in Medellín. She pursued her Master's in Belo Horizonte, Brazil, and completed her PhD in Rostock, Germany. After a short research stay in Colombia, she conducted postdoctoral research in Florence, Italy and joined Prof. Marcus Huber's team in Vienna in 2019.

With her Elise Richter Fellowship, she will now continue her quantum research, having previously been awarded a Marie Skłodowska-Curie Fellowship from the EU, and a FWF Lise Meitner Fellowship.