1,411 research outputs found
-wave chiral superfluidity from an -wave interacting atomic Fermi gas
Chiral -wave superfluids are fascinating topological quantum states of
matter that have been found in the liquid He-A phase and arguably in the
electronic SrRuO superconductor. They are shown fundamentally related
to the fractional quantum Hall state which supports fractional exotic
excitations. A common understanding is that such states require spin-triplet
pairing of fermions due to -wave interaction. Here we report by controlled
theoretical approximation that a center-of-mass Wannier -wave chiral
superfluid state can arise from spin-singlet pairing for an -wave
interacting atomic Fermi gas in an optical lattice. Despite a conceptually
different origin, it shows topological properties similar to the conventional
chiral -wave state. These include a non-zero Chern number and the appearance
of chiral fermionic zero modes bounded to domain walls. Several signature
quantities are calculated for the cold atom experimental condition.Comment: 16 pages and 7 figures including supplementary material
Effective action approach to the p-band Mott insulator and superfluid transition
Motivated by the recent experiment on p-orbital band bosons in optical
lattices, we study theoretically the quantum phases of Mott insulator and
superfluidity in two-dimensions. The system features a novel superfluid phase
with transversely staggered orbital current at weak interaction, and a Mott
insulator phase with antiferro-orbital order at strong coupling and
commensurate filling. We go beyond mean field theory and derive from a
microscopic model an effective action that is capable of describing both the
p-band Mott insulating and superfluid phases in strong coupling. We further
calculate the excitation spectra near the quantum critical point and find two
gapless modes away from the tip of the Mott lobe but four gapless modes at the
tip. Our effective theory reveals how the phase coherence peak builds up in the
Mott regime when approaching the critical point. We also discuss the finite
temperature phase transition of p-band superfluidity.Comment: 9+epsilon pages, 7 figures, one appendix added, accepted by Phys.
Rev.
Detecting -phase superfluids with -wave symmetry in a quasi-1D optical lattice
We propose an experimental protocol to study -wave superfluidity in a
spin-polarized cold Fermi gas tuned by an -wave Feshbach resonance. A
crucial ingredient is to add a quasi-1D optical lattice and tune the fillings
of two spins to the and band, respectively. The pairing order parameter
is confirmed to inherit -wave symmetry in its center-of-mass motion. We find
that it can further develop into a state of unexpected -phase modulation
in a broad parameter regime. Measurable quantities are calculated, including
time-of-flight distributions, radio-frequency spectra, and in situ
phase-contrast imaging in an external trap. The -phase -wave superfluid
is reminiscent of the -state in superconductor-ferromagnet
heterostructures but differs in symmetry and origin. If observed, it would
represent another example of -wave pairing, first discovered in He-3
liquids.Comment: 5 pages, 5 figure
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