Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effect of phase string on single-hole dynamics in the two-leg Hubbard
  ladder   Optical measurements in doped Mott insulators have discovered the emergence
of spectral weights at mid-infrared (MIR) upon chemical doping and photodoping.
MIR weights may have a relation to string-type excitation of spins, which is
induced by a doped hole generating misarranged spins with respect to their
sublattice. There are two types of string effects: one is an $S^z$ string that
is repairable by quantum spin flips and the other is a phase string irreparable
by the spin flips. We investigate the effect of $S^{z}$ and phase strings on
MIR weights. Calculating the optical conductivity of the single-hole Hubbard
model in the strong-coupling regime and the $t$-$J$ model on two-leg ladders by
using time-dependent Lanczos and density-matrix renormalization group, we find
that phase strings make a crucial effect on the emergence of MIR weights as
compared with $S^{z}$ strings. Our findings indicate that a mutual Chern-Simons
gauge field acting between spin and charge degrees of freedom, which is the
origin of phase strings, is significant for obtaining MIR weights. Conversely,
if we remove this gauge field, no phase is picked up by a doped hole. As a
result, a spin-polaron accompanied by a local spin distortion emerges and a
quasiparticle with a cosine-like energy dispersion is formed in single-particle
spectral function. Furthermore, we suggest a Floquet engineering to examine the
phase-string effect in cold atoms.

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The categories of this paper are: acc-phys
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The categories of this paper are: math
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The categories of this paper are: eess
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The categories of this paper are: q-fin
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The categories of this paper are: adap-org
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The categories of this paper are: q-bio
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The categories of this paper are: funct-an
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The categories of this paper are: physics
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The categories of this paper are: patt-sol
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ph
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The categories of this paper are: q-alg
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The categories of this paper are: ao-sci
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The categories of this paper are: gr-qc