21 research outputs found
Bose-Einstein condensate in gases of rare atomic species
We report on the successful extension of production of Bose-Einstein
Condensate (BEC) to rare species. Despite its low natural abundance of 0.13%,
Yb is directly evaporatively cooled down to BEC. Our successful
demonstration encourages attempts to obtain quantum gases of radioactive atoms,
which extends the possibility of quantum many-body physics and precision
measurement. Moreover, a stable binary mixture of Yb BEC and Yb
BEC is successfully formed.Comment: 5 pages, 3 figures. Accepted for Phys. Rev.
Coherent driving and freezing of bosonic matter wave in an optical Lieb lattice
While kinetic energy of a massive particle generally has quadratic dependence
on its momentum, a flat, dispersionless energy band is realized in crystals
with specific lattice structures. Such macroscopic degeneracy causes the
emergence of localized eigenstates and has been a key concept in the context of
itinerant ferromagnetism. Here we report the realization of a "Lieb lattice"
configuration with an optical lattice, which has a flat energy band as the
first excited state. Our optical lattice potential possesses various degrees of
freedom about its manipulation, which enables coherent transfer of a
Bose-Einstein condensate into the flat band. In addition to measuring lifetime
of the flat band population for different tight-binding parameters, we
investigate the inter-sublattice dynamics of the system by projecting the
sublattice population onto the band population. This measurement clearly shows
the formation of the localized state with the specific sublattice decoupled in
the flat band, and even detects the presence of flat-band breaking
perturbations, resulting in the delocalization. Our results will open up the
possibilities of exploring physics of flat band with a highly controllable
quantum system.Comment: 13 pages, 9 figures. v2: Title changed, 1 reference correcte
Realization of SU(2)*SU(6) Fermi System
We report the realization of a novel degenerate Fermi mixture with an
SU(2)*SU(6) symmetry in a cold atomic gas. We successfully cool the mixture of
the two fermionic isotopes of ytterbium 171Yb with the nuclear spin I=1/2 and
173Yb with I=5/2 below the Fermi temperature T_ F as 0.46T_F for 171Yb and
0.54T_F for 173Yb. The same scattering lengths for different spin components
make this mixture featured with the novel SU(2)*SU(6) symmetry. The nuclear
spin components are separately imaged by exploiting an optical Stern-Gerlach
effect. In addition, the mixture is loaded into a 3D optical lattice to
implement the SU(2)*SU(6) Hubbard model. This mixture will open the door to the
study of novel quantum phases such as a spinor Bardeen-Cooper-Schrieffer-like
fermionic superfluid.Comment: 4 pages, 5 figures V2: revised reference
Interaction and filling induced quantum phases of dual Mott insulators of bosons and fermions
Many-body effects are at the very heart of diverse phenomena found in
condensed-matter physics. One striking example is the Mott insulator phase
where conductivity is suppressed as a result of a strong repulsive interaction.
Advances in cold atom physics have led to the realization of the Mott
insulating phases of atoms in an optical lattice, mimicking the corresponding
condensed matter systems. Here, we explore an exotic strongly-correlated system
of Interacting Dual Mott Insulators of bosons and fermions. We reveal that an
inter-species interaction between bosons and fermions drastically modifies each
Mott insulator, causing effects that include melting, generation of composite
particles, an anti-correlated phase, and complete phase-separation. Comparisons
between the experimental results and numerical simulations indicate intrinsic
adiabatic heating and cooling for the attractively and repulsively interacting
dual Mott Insulators, respectively