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Salt particles that have dissolved in water never spontaneously come back together in solution to reform solid particles. Moreover, a gas that has expanded in a vacuum remains dispersed and never spontaneously reassembles. The unidirectional nature of these phenomena is the result of a thermodynamic state function called entropy (S). Entropy is the measure of the extent to which the energy is dispersed throughout a system, or in other words, it is proportional to the degree of disorder of a...

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Entropy- and flow-induced superfluid states.

Johan Carlström¹, Egor Babaev²

¹Department of Theoretical Physics, The Royal Institute of Technology, Stockholm SE-10691, Sweden.

Physical Review Letters

|August 16, 2014

Summary

Nontopological phase fluctuations, not just vortices, can create superfluidity. This research explores how energy landscape degeneracies can lead to U(1)-like phases, enabling superfluidity without broken symmetry.

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Area of Science:

Condensed Matter Physics
Quantum Fluids

Background:

Phase fluctuations typically induce transitions to normal states in superfluids and superconductors via vortex proliferation.
Topologically nontrivial fluctuations are conventionally understood as the mechanism driving these transitions.

Purpose of the Study:

To investigate systems where nontopological phase fluctuations can lead to superfluidity.
To redefine superfluidity beyond broken U(1) symmetry, linking it to energy landscape degeneracies.

Main Methods:

Theoretical analysis of systems exhibiting nontopological phase fluctuations.
Examination of energy landscape degeneracies and their relation to U(1)-like phases.

Main Results:

Demonstrated that nontopological phase fluctuations can indeed produce superfluidity.
Identified specific classes of energy landscapes that support U(1)-like phases, enabling superfluidity.

Conclusions:

Superfluidity can arise from nontopological phenomena, challenging conventional understanding.
The concept of superfluidity is broadened to include systems with approximate or exact degeneracies, not solely relying on broken U(1) symmetry.