Laser pulse driven control of charge and spin order in the two-dimensional Kondo lattice

Proposed Rabi-Kondo Correlated State in a Laser-Driven Semiconductor Quantum Dot

Spin exchange between a single-electron charged quantum dot and itinerant electrons leads to an emergence of Kondo correlations. When the quantum dot is driven resonantly by weak laser light, the resulting emission spectrum allows for a direct probe of these correlations. In the opposite limit of vanishing exchange interaction and strong laser drive, the quantum dot exhibits coherent oscillations between the single-spin and optically excited states. Here, we show that the interplay between strong exchange and non-perturbative laser coupling leads to the formation of a new nonequilibrium quantu…

Photoinduced $η$ pairing in the Kondo lattice model

The previous theoretical study has shown that pulse irradiation to the Mott insulating state in the Hubbard model can induce the enhancement of superconducting correlation due to the generation of $η$ pairs. Here, we show that the same mechanism can be applied to the Kondo lattice model, an effective model for heavy electron systems, by demonstrating that the pulse irradiation indeed enhances the $η$-pairing correlation. As in the case of the Hubbard model, the non-linear optical process is essential to increase the number of photoinduced $η$ pairs and thus the enhancement of the superconducti…

Chern Kondo Insulator in an Optical Lattice

We propose to realize and observe Chern Kondo insulators in an optical superlattice with laser-assisted $s$ and $p$ orbital hybridization and synthetic gauge field, which can be engineered based on the recent cold atom experiments. Considering a double-well square optical lattice, the localized $s$ orbitals are decoupled from itinerant $p$ bands and are driven into a Mott insulator due to strong Hubbard interaction. Raman laser beams are then applied to induce tunnelings between $s$ and $p$ orbitals, and generate a staggered flux simultaneously. Due to the strong Hubbard interaction of $s$ orb…

Kondo hybridization and quantum criticality in $β$-YbAlB$_4$ by laser-ARPES

We report an angle-resolved photoemission (ARPES) study of $β$-YbAlB$_4$, which is known to harbor unconventional quantum criticality (QC) without any tuning. We directly observe a quasiparticle peak (QP), emerging from hybridization, characterized by a binding energy and an onset of coherence both at about 4 meV. This value conforms with a previously observed reduced Kondo scale at about 40 K. Consistency with an earlier study of carriers in $β$-YbAlB$_4$ via the Hall effect strongly suggests that this QP is responsible for the QC in $β$-YbAlB$_4$. A comparison with the sister polymorph $α$-Y…

Conversion of charge input into Kondo response

We show how the charge input signal applied to the gate electrode in double quantum dot may be converted to a pulse in the Kondo cotunneling current as a spin response of a nano-device in a strong Coulomb blockade regime. The stochastic component of the input signal comes as the infrared cutoff of Kondo transmission.

太赫兹辐射驱动的重费米子系统中的近藤相干与超辐射的对比

Kondo coherence versus superradiance in THz radiation-driven heavy-fermion systems

本研究以典型重费米子化合物CeCu_5.9Au_0.1为对象，通过探究太赫兹脉冲延迟响应对电场强度的依赖关系，证实其源于近藤相干而非超辐射，证明凝聚态相干性在该体系中占主导。

Transport measurement of the orbital Kondo effect with ultracold atoms

The Kondo effect in condensed-matter systems manifests itself most sharply in their transport measurements. Here we propose an analogous transport signature of the orbital Kondo effect realized with ultracold atoms. Our system consists of imbalanced Fermi seas of two components of fermions and an impurity atom of different species which is confined by an isotropic potential. We first apply a π/2 pulse to transform two components of fermions into two superposition states. Their interactions with the impurity atom then cause a "transport" of fermions from majority to minority superposition state…

Kondo effect in Complex Quantum Dots in the presence of an oscillating and fluctuating gate signal

We show how the charge input signal applied to the gate electrode in a double and triple quantum dot may be converted to a pulse in the Kondo cotunneling current being a spin response of a nano-device under a strong Coulomb blockade. The stochastic component of the input signal results in the infrared cutoff of Kondo transmission. The stochastization of the orbital component of the Kondo effect in triple quantum dots results in a noise-induced SU(4) - SU(2) quantum transition.

Controlling ultracold atoms in multi-band optical lattices for simulation of Kondo physics

We show that ultracold atoms can be controlled in multi-band optical lattices through spatially periodic Raman pulses for investigation of a class of strongly correlated physics related to the Kondo problem. The underlying dynamics of this system is described by a spin-dependent fermionic or bosonic Kondo-Hubbard lattice model even if we have only spin-independent atomic collision interaction. We solve the bosonic Kondo-Hubbard lattice model through a mean-field approximation, and the result shows a clear phase transition from the ferromagnetic superfluid to the Kondo-signet insulator at the i…

Effect of transport current on suppression of superconductivity with ultrashort laser pulse

We study the suppression of superconductivity with ultrashort laser pulse in the presence of transport current. The theoretical model is based on the BCS relations for the superconducting state coupled with kinetic equations for nonequilibrium Bogoliubov quasiparticles and phonons. The results of numerical simulation for picosecond and femtosecond laser pulses of optical and infrared ranges are given. We discuss the effects of main problem parameters, including the current density.

Towards A Possible Charge-Kondo effect in Optical Lattices

The Kondo effect underpins a large body of recent developments in the physics of $d$- and $f$-band compounds. Although its {\it charge} analog is a rarity in solids, the recent observations of the charge Kondo effect and the consequent rise in superconducting T$_c$ encourage a search for other accessible systems. Motivated by the possibility of wilfully tuning the {\it sign} of the inter-electronic interaction in optical lattices, we study conditions for the elusive {\it charge Kondo liquid} (CKL) state to manifest. We propose that a combination of Feshbach resonances and sequentially controll…