A Quantum Field Theory of Superfluids Ⅰ

Eduardo C. Marino

Ville Keränen

Superfluidity is perhaps one of the most remarkable observed macroscopic quantum effect. Superfluidity appears when a macroscopic number of particles occupies a single quantum state. Using modern experimental techniques one dark solitons) and vortices. There is a large literature on theoretical work studying the properties of such solitons using semiclassical methods. This thesis describes an alternative method for the study of superfluid solitons. The method used here is a holographic duality between a class of quantum field theories and gravitational theories. The classical limit of the gravitational system maps into a strong coupling limit of the quantum field theory. We use a holographic model of superfluidity to study solitons in these systems. One particularly appealing feature of this technique is that it allows us to take into account finite temperature effects in a large range of temperatures.

F.W. Cummings, James R. Johnston

Nikolay N. Bogolubov

Jens Cordelair

The intention of this paper is to provide an easy to understand introduction to the peculiarities of entangled systems. A novel description for strong (mass entanglement) and weak (spin-or-bital and thermal entanglement) quantum entangled particles is discussed and applied to the phenomena of superconductivity, superfluidity and ultracold gases. A brief statement about how to represent the physical reality of quantum-entanglement as Quantum-Field-Theory (QFT) is noted.

Maciej T. Jarema, Cameron R. D. Bunney, Vitor S. Barroso +3 more

Abstract Information-theoretic measures, such as entropy and mutual information, provide a comprehensive tool for characterising quantum correlations. They reveal foundational features across quantum many-body systems, quantum field theory (QFT), and even black hole thermodynamics. A striking example is the emergence of area laws , occurring when correlations are constrained to local regions, causing information to scale with boundary area, rather than volume. Whilst area laws have been experimentally observed in discrete quantum systems, they remain under-explored in continuous quantum fields owing to the lack of implementable measurement techniques in these settings. Here, we propose using phononic excitations (third sound) on thin-film superfluid helium as a (2 + 1)-dimensional quantum field simulator. In light of recent advances in high-resolution detection schemes, this platform now offers experimental access to the spatially and temporally resolved effective field. We develop a framework to utilise experimentally accessible observables to reconstruct the covariance matrix and evaluate distributions of mutual information. Our numerical predictions confirm area-law behaviour with characteristic deviations due to effects of confinement. Finally, we outline a clear pathway towards experimental implementation of our proposal considering state-of-the-art imaging and cryogenic technologies.