Search results for "Cold"
showing 10 items of 660 documents
Ultracold atoms in optical lattices
2007
This article focuses on the characteristics and properties ultracold atoms in optical lattices.
Experiments on the dynamics of the Bose–Einstein condensate at finite temperatures
2009
This paper presents the results of our recent experiments on the finite-temperature Bose?Einstein condensate of 87Rb atoms in a magnetic trap, and is devoted to the study of the hydrodynamic properties and dynamics of an ultra-cold atomic gas near the critical temperature. Measurements of the aspect ratio of an expanding atomic cloud allow for verification of the condensate models and study of the interaction between condensed and non-condensed fractions of a finite-temperature sample.
Probing number squeezing of ultracold atoms across the superfluid-Mott insulator transition.
2005
The evolution of on-site number fluctuations of ultracold atoms in optical lattices is experimentally investigated by monitoring the suppression of spin-changing collisions across the superfluid-Mott insulator transition. For low atom numbers, corresponding to an average filling factor close to unity, large on-site number fluctuations are necessary for spin-changing collisions to occur. The continuous suppression of spin-changing collisions is thus a direct evidence for the emergence of number-squeezed states. In the Mott insulator regime, we find that spin-changing collisions are suppressed until a threshold atom number, consistent with the number where a Mott plateau with doubly-occupied …
Exploring quantum matter with ultracold atoms in optical lattices
2005
Seventy years after Einstein's prediction, the seminal achievement of Bose–Einstein condensation in dilute atomic gases in 1995 has provided us with a new form of quantum matter. Such quantum matter can be described as a single giant matter wave. By loading it into an artificial periodic potential formed by laser light—a so-called optical lattice—it has become possible to probe matter far beyond the wave-like description. In a review of a series of experiments with ultracold quantum gases in optical lattices, we show that the granularity of the matter wave field, caused by the discreteness of atoms, gives rise to effects going beyond the simple single matter wave description. Bose–Einstein …
Many-body physics with ultracold gases
2007
This article reviews recent experimental and theoretical progress on many-body phenomena in dilute, ultracold gases. Its focus are effects beyond standard weak-coupling descriptions, like the Mott-Hubbard-transition in optical lattices, strongly interacting gases in one and two dimensions or lowest Landau level physics in quasi two-dimensional gases in fast rotation. Strong correlations in fermionic gases are discussed in optical lattices or near Feshbach resonances in the BCS-BEC crossover.
Quantum coherence and entanglement with ultracold atoms in optical lattices
2008
At nanokelvin temperatures, ultracold quantum gases can be stored in optical lattices, which are arrays of microscopic trapping potentials formed by laser light. Such large arrays of atoms provide opportunities for investigating quantum coherence and generating large-scale entanglement, ultimately leading to quantum information processing in these artificial crystal structures. These arrays can also function as versatile model systems for the study of strongly interacting many-body systems on a lattice.
Trapping of ultracold atoms in a hollow-core photonic crystal fiber
2008
Ultracold sodium atoms have been trapped inside a hollow-core optical fiber. The atoms are transferred from a free space optical dipole trap into a trap formed by a red-detuned gaussian light mode confined to the core of the fiber. We show that at least 5% of the atoms held initially in the free space trap can be loaded into the core of the fiber and retrieved outside.
Exploring Quantum Matter with Ultracold Atoms in Optical Lattices
2005
Publisher Summary This chapter explores quantum matter with ultracold atoms in optical lattices. The chapter focuses on bosonic atoms in optical lattices and on the regime where strong correlations between the atoms become important. In the interaction of atoms with coherent light fields, two fundamental forces arise. The Doppler force is dissipative in nature and can be used to efficiently laser cool a gas of atoms and relies on the radiation pressure together with spontaneous emission. The dipole force creates a purely conservative potential in which the atoms can move. No cooling can be realized with this dipole force, however if the atoms are cold enough initially, they may be trapped i…
Fermionic transport and out-of-equilibrium dynamics in a homogeneous Hubbard model with ultracold atoms
2012
The transport measurements of an interacting fermionic quantum gas in an optical lattice provide a direct experimental realization of the Hubbard model—one of the central models for interacting electrons in solids—and give insights into the transport properties of many-body phases in condensed-matter physics.
Counting atoms using interaction blockade in an optical superlattice.
2008
We report on the observation of an interaction blockade effect for ultracold atoms in optical lattices, analogous to Coulomb blockade observed in mesoscopic solid state systems. When the lattice sites are converted into biased double wells, we detect a discrete set of steps in the well population for increasing bias potentials. These correspond to tunneling resonances where the atom number on each side of the barrier changes one by one. This allows us to count and control the number of atoms within a given well. By evaluating the amplitude of the different plateaus, we can fully determine the number distribution of the atoms in the lattice, which we demonstrate for the case of a superfluid …