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Realization of the Hofstadter Hamiltonian with ultracold atoms in optical lattices.
It is shown that for two atomic spin states with opposite magnetic moments, the experimental implementation of an optical lattice that allows for the generation of large homogeneous and tunable artificial magnetic fields with ultracold atoms naturally realizes the time-reversal-symmetric Hamiltonian underlying the quantum spin Hall effect.
Direct measurement of the Zak phase in topological Bloch bands
Geometric phases that characterize the topological properties of Bloch bands play a fundamental role in the band theory of solids. Here we report on the measurement of the geometric phase acquired by
Measuring the Chern number of Hofstadter bands with ultracold bosonic atoms
Chern numbers characterize the quantum Hall effect conductance—non-zero values are associated with topological phases. Previously only spotted in electronic systems, they have now been measured in
Observation of chiral currents with ultracold atoms in bosonic ladders
Laser-assisted tunnelling allows quantum gases in optical lattices to be exposed to tunable artificial magnetic fields. Using such fields to confine a bosonic gas to an array of one-dimensional
Experimental realization of strong effective magnetic fields in an optical lattice.
The ground state of this system is studied and it is observed that the frustration induced by the magnetic field can lead to a degenerate ground state for noninteracting particles.
Transmission of near-resonant light through a dense slab of cold atoms
The optical properties of randomly positioned, resonant scatterers is a fundamentally difficult problem to address across a wide range of densities and geometries. We investigate it experimentally
A Thouless quantum pump with ultracold bosonic atoms in an optical superlattice
Thouless introduced the idea of a topological charge pump: the quantized motion of charge due to the slow cyclic variation of a periodic potential. This topologically protected transport has now been
Single-electron pulses for ultrafast diffraction
The generation and application of single-electron pulses for the generation and use of photoelectric emission from metal surfaces with tunable ultraviolet pulses in the femtosecond regime, and the bandwidth, efficiency, coherence, and electron pulse duration are investigated in dependence on excitation wavelength, intensity, and laser bandwidth.
Periodically driven quantum matter: The case of resonant modulations
Quantum systems can show qualitatively new forms of behavior when they are driven by fast time-periodic modulations. In the limit of large driving frequency, the long-time dynamics of such systems