3 research outputs found
Coherent multi-flavour spin dynamics in a fermionic quantum gas
Microscopic spin interaction processes are fundamental for global static and
dynamical magnetic properties of many-body systems. Quantum gases as pure and
well isolated systems offer intriguing possibilities to study basic magnetic
processes including non-equilibrium dynamics. Here, we report on the
realization of a well-controlled fermionic spinor gas in an optical lattice
with tunable effective spin ranging from 1/2 to 9/2. We observe long-lived
intrinsic spin oscillations and investigate the transition from two-body to
many-body dynamics. The latter results in a spin-interaction driven melting of
a band insulator. Via an external magnetic field we control the system's
dimensionality and tune the spin oscillations in and out of resonance. Our
results open new routes to study quantum magnetism of fermionic particles
beyond conventional spin 1/2 systems.Comment: 9 pages, 5 figure
Momentum-Resolved Bragg Spectroscopy in Optical Lattices
Strongly correlated many-body systems show various exciting phenomena in
condensed matter physics such as high-temperature superconductivity and
colossal magnetoresistance. Recently, strongly correlated phases could also be
studied in ultracold quantum gases possessing analogies to solid-state physics,
but moreover exhibiting new systems such as Fermi-Bose mixtures and magnetic
quantum phases with high spin values. Particularly interesting systems here are
quantum gases in optical lattices with fully tunable lattice and atomic
interaction parameters. While in this context several concepts and ideas have
already been studied theoretically and experimentally, there is still great
demand for new detection techniques to explore these complex phases in detail.
Here we report on measurements of a fully momentum-resolved excitation
spectrum of a quantum gas in an optical lattice by means of Bragg spectroscopy.
The bandstructure is measured with high resolution at several lattice depths.
Interaction effects are identified and systematically studied varying density
and excitation fraction.Comment: 13 pages, 5 figure