6,568 research outputs found
Tuning a magnetic Feshbach resonance with spatially modulated laser light
We theoretically investigate the control of a magnetic Feshbach resonance
using a bound-to-bound molecular transition driven by spatially modulated laser
light. Due to the spatially periodic coupling between the ground and excited
molecular states, there exists a band structure of bound states, which can
uniquely be characterized by some extra bumps in radio-frequency spectroscopy.
With the increasing of coupling strength, the series of bound states will cross
zero energy and directly result in a number of scattering resonances, whose
position and width can be conveniently tuned by the coupling strength of the
laser light and the applied magnetic field (i.e., the detuning of the ground
molecular state). In the presence of the modulated laser light, universal
two-body bound states near zero-energy threshold still exist. However, compared
with the case without modulation, the regime for such universal states is
usually small. An unified formula which embodies the influence of the modulated
coupling on the resonance width is given. The spatially modulated coupling also
implies a local spatially varying interaction between atoms. Our work proposes
a practical way of optically controlling interatomic interactions with high
spatial resolution and negligible atomic loss.Comment: 9pages, 5figur
Non-Fermi-Liquid/Marginal-Fermi-Liquid Signatures Induced by Van Hove Singularity
We theoretically study the two-dimensional metal that is coupled to critical
magnons and features van Hove singularities on the Fermi surface. When there is
only translationally invariant SYK-liked Yukawa interaction, van Hove points
suppress the contribution from the part of the Fermi surface away from them,
dominating and exhibiting non-Fermi-liquid behavior. When introducing
disordered Yukawa coupling, it leads to a crossover from non-Fermi-liquid to
marginal-Fermi-liquid, and the marginal-Fermi-liquid region exhibits the specific heat and temperature-linear resistivity of strange metal. By
solving the gap equation, we provide the critical temperature for
superconductor induced by van Hove singularities and point out the possible
emergence of pair-density-wave superconductor. Our theory may become a new
mechanism for understanding non-Fermi-liquid or marginal-Fermi-liquid
phenomenons.Comment: 14 pages, 5 figure
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