ﻻ يوجد ملخص باللغة العربية
The recent experimental condensation of ultracold atoms in a triangular optical lattice with negative effective tunneling energies paves the way to study frustrated systems in a controlled environment. Here, we explore the critical behavior of the chiral phase transition in such a frustrated lattice in three dimensions. We represent the low-energy action of the lattice system as a two-component Bose gas corresponding to the two minima of the dispersion. The contact repulsion between the bosons separates into intra- and inter-component interactions, referred to as $V_{0}$ and $V_{12}$, respectively. We first employ a Huang-Yang-Luttinger approximation of the free energy. For $V_{12}/V_{0} = 2$, which corresponds to the bare interaction, this approach suggests a first order phase transition, at which both the U$(1)$ symmetry of condensation and the $mathbb{Z}_2$ symmetry of the emergent chiral order are broken simultaneously. Furthermore, we perform a renormalization group calculation at one-loop order. We demonstrate that the coupling regime $0<V_{12}/V_0leq1$ shares the critical behavior of the Heisenberg fixed point at $V_{12}/V_{0}=1$. For $V_{12}/V_0>1$ we show that $V_{0}$ flows to a negative value, while $V_{12}$ increases and remains positive. This results in a breakdown of the effective quartic field theory due to a cubic anisotropy, and again suggests a discontinuous phase transition.
We experimentally and theoretically study the peak fraction of a Bose-Einstein condensate loaded into a cubic optical lattice as the lattice potential depth and entropy per particle are varied. This system is well-described by the superfluid regime o
Motivated by recent experimental observations (C.V. Parker {it et al.}, Nature Physics, {bf 9}, 769 (2013)), we analyze the stability of a Bose-Einstein condensate (BEC) in a one-dimensional lattice subjected to periodic shaking. In such a system the
We discuss the method for the measurement of the gravity acceleration g by means of Bloch oscillations of an accelerated BEC in an optical lattice. This method has a theoretical critical point due to the fact that the period of the Bloch oscillations
Bose-Einstein condensates (BECs) are macroscopic coherent matter waves that have revolutionized quantum science and atomic physics. They are essential to quantum simulation and sensing, for example underlying atom interferometers in space and ambitio
Interferometric measurements with matter waves are established techniques for sensitive gravimetry, rotation sensing, and measurement of surface interactions, but compact interferometers will require techniques based on trapped geometries. In a step