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Emmi Ruokokoski took part in the study where the first experimental observations of a monopole in a synthetic magnetic field were made (insert a link to a previous article). As a result of this discovery, it is believed that it is possible to find monopoles, or magnets with only one magnetic pole, from a real magnetic field. The work conducted in the research group is a central part of Ruokokoski's new thesis.

When carrying out the experiments, a monopole was discovered in cold atomic gas­, also called a gaseous condensate, which behaves completely differently from the gases we encounter in our everyday life. Close to the absolute zero temperature, the behaviour of the gas is governed by quantum mechanics.

Ruokokoski participated in the research by numerically solving the gas dynamics using parameters received from an experimental group at Amherst College in the United States. The research group created and detected topological point-like defects that are equivalent to Dirac's monopole and to 't Hooft–Polyakov monopole.

– Certain topological textures are not easily transformed into textures with a different topology. For this reason, topological textures are often long-lived. For example a sphere and a torus (a doughnut) have a different topology. A sphere can not be made into a doughnut by simply stretching, it has to be pierced. Piercing or stitching is laborious, and that is why a sphere remains a sphere and a doughnut will not close its hole by itself, explains Ruokokoski.

Topological textures are present in many different systems, from cold superfluids to sun plasma. In addition, some unified theories predict that topological defects such as magnetic monopoles were born in the early universe.

Gaseous condensates can be modelled starting from the first principles, and they can be accurately controlled with external magnetic fields and commercial lasers. Furthermore, the development of a gas cloud can be documented with lasers – in some cases resulting even in video image.

– Condensates have multiple uses! Ruokokoski describes them as a certain kind of miniature laboratories, where vastly different natural phenomena can be studied.

The work has not been easy, and the results have required collective efforts from the research group.

– The fact that things do not always go the way one expects makes research interesting. That is when one can find something completely new, or at the very least learn something new, contemplates Ruokokoski.

There is still a long way to travel before finding a magnetic monopole particle. This discovery shows that the quantum-mechanical monopole defect can exist in nature, and therefore consolidates the belief in the existence of a magnetic monopole.

Ruokokoski has worked with this topic for already four years, and her time working in the School of Science is nearing completion. The future brings new work challenges in the shape of cancer treatment planning.

Defense of dissertation:

Emmi Ruokokoski will defend the dissertation Mon 29 June 2015 at 12 noon in Aalto University, School of Science, lecture hall D, Otakaari 1, Espoo.

Opponent Professor Hendricus Stoof, Utrecht University, Netherlands

Custos Academician Risto Nieminen, Aalto University School of Science, Department of Applied Physics

Electronic dissertation https://aaltodoc.aalto.fi/handle/123456789/16541

School of Science electronic dissertations: