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Non-perturbative formulation for zero mode of Bose-Einstein condensate

Yusuke Nakamura, Junichi Takahashi, Y. Yamanaka

Nov 21, 20130 citations

FINITE TEMPERATURE FIELD THEORY OF BOSE-EINSTEIN CONDENSATES

David A. W. Hutchinson

Recent Progress in Many-Body TheoriesSep 1, 20001 citation

Beyond Gibbs' method in statistical physics: theorem on non-polynomial averages and non-perturbation in fluctuations theory of Bose–Einstein condensation

Vl. V. Kocharovsky, Vl. V. Kocharovsky

General theorem on non-polynomial averages in statistical physics, including anomalous averages, is found. It generalizes a well-known Wick's theorem and, in particular, yields a fully quantum kinetic theory of Bose–Einstein condensation. A non-perturbation-in-fluctuations BEC rate is presented.

Journal of Modern OpticsNov 10, 20079 citations

Ultra-Dilute Gas of Polarons in a Bose–Einstein Condensate

Luis A. Peña Ardila

We investigate the properties of a dilute gas of impurities embedded in an ultracold gas of bosons that forms a Bose–Einstein condensate (BEC). This work focuses mainly on the equation of state (EoS) of the impurity gas at zero temperature and the induced interaction between impurities mediated by the host bath. We use perturbative field-theory approaches, such as Hugenholtz–Pines formalism, in the weakly interacting regime. In turn, for strong interactions, we aim at non-perturbative techniques such as quantum–Monte Carlo (QMC) methods. Our findings agree with experimental observations for an ultra dilute gas of impurities, modeled in the framework of the single impurity problem; however, as the density of impurities increases, systematic deviations are displayed with respect to the one-body Bose polaron problem.We investigate the properties of a dilute gas of impurities embedded in an ultracold gas of bosons that forms a Bose–Einstein condensate (BEC). This work focuses mainly on the equation of state (EoS) of the impurity gas at zero temperature and the induced interaction between impurities mediated by the host bath. We use perturbative field-theory approaches, such as Hugenholtz–Pines formalism, in the weakly interacting regime. In turn, for strong interactions, we aim at non-perturbative techniques such as quantum–Monte Carlo (QMC) methods. Our findings agree with experimental observations for an ultra dilute gas of impurities, modeled in the framework of the single impurity problem; however, as the density of impurities increases, systematic deviations are displayed with respect to the one-body Bose polaron problem.

AtomsMar 2, 20229 citations

Nonperturbative Renormalization Group and Bose-Einstein Condensation

Jean-Paul Blaizot

arXiv:0801.0009Lecture notes in physicsJan 1, 20129 citations

The weakly interacting Bose gas at the critical temperature

Jean Zinn‐Justin

Abstract Chapter 20 examines effects of weak repulsive interactions in a Bose–Einstein condensate and the transition from Bose–Einstein condensate to superfluid phase transition. Renormalization group methods are used and a universal amplitude is calculated by non–perturbative methods. After the discovery of the predicted Bose–Einstein condensation, which is a property of free bosons, an interesting issue was the effects of weak repulsive interactions. In this chapter, it is shown that, near the transition temperature, the initial non–relativistic field theory can be replaced by a relativistic effective Euclidean field theory known to describe a superfluid phase transition (a dimensional reduction). These theoretical considerations are illustrated by an evaluation of the universal variation of the transition temperature at weak coupling. For this purpose, the O(2) symmetry of the model is generalized to O(N) symmetry, and large N techniques are used.Abstract Chapter 20 examines effects of weak repulsive interactions in a Bose–Einstein condensate and the transition from Bose–Einstein condensate to superfluid phase transition. Renormalization group methods are used and a universal amplitude is calculated by non–perturbative methods. After the discovery of the predicted Bose–Einstein condensation, which is a property of free bosons, an interesting issue was the effects of weak repulsive interactions. In this chapter, it is shown that, near the transition temperature, the initial non–relativistic field theory can be replaced by a relativistic effective Euclidean field theory known to describe a superfluid phase transition (a dimensional reduction). These theoretical considerations are illustrated by an evaluation of the universal variation of the transition temperature at weak coupling. For this purpose, the O(2) symmetry of the model is generalized to O(N) symmetry, and large N techniques are used.

Jun 19, 20190 citations

Non perturbative Quantum Field Methods in Bose Einstein Condensates

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