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Student Colloquium - Lærke Lyhne Nielsen: Quantum phase transitions: Why do they matter?

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Monday 23 April 2018,  at 14:15 - 15:00

Supervisor: Thomas Pohl

When you cool a system down to very low temperatures you can reach an energy scale where the macroscopic behaviour of your system becomes quantum mechanical. Non-the less, the equations describing the dynamics in these regimes are ultimately classical. In fact, any phase transition at finite temperature can be described by a classical theory.

By definition, quantum phase transitions occur at zero temperature. The motivation for this talk is to find out how does the behaviour at T=0 influence the finite temperature regions realizable in experiments? I will introduce the most important concepts from the classical theory of phase transitions. Then I will discuss quantum phase transitions through the example of the transverse field ising model and finally present the results from an experimental study of the finite temperature behaviour near a quantum critical point.