Quantum quench of Kondo correlations in optical absorption

Latta, Christian; Haupt, Florian; Hanl, Markus; Weichselbaum, Andreas; Claassen, Martin; Wuester, Wolf; Fallahi, P.; Faelt, Stefan; Glazman, L. I.; Delft, Jan von; Türeci, Hakan E.; İmamoğlu, Ataç

doi:10.48550/arxiv.1102.3982

Cited by 7 publications

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“…More recently, there has also been growing interest in inducing such a sudden switch, or quantum quench, by optical excitations of a quantum dot tunnel-coupled to a Fermi sea, in which case the post-quench dynamics leaves fingerprints, characteristic of AO, in the optical absorption or emission line shape. [9][10][11] The intrinsic connection of local quantum quenches to the scaling of the Anderson orthogonality with system size can be intuitively understood as follows. Consider an instantaneous event at the location of the impurity at time t = 0 in a system initially in equilibrium.…”

Section: Introductionmentioning

confidence: 99%

Anderson orthogonality and the numerical renormalization group

2011

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Anderson Orthogonality (AO) refers to the fact that the ground states of two Fermi seas that experience different local scattering potentials, say |GI and |GF , become orthogonal in the thermodynamic limit of large particle number N , in that | GI|GF | ∼ N − 1 2 ∆ 2 AO for N → ∞. We show that the numerical renormalization group offers a simple and precise way to calculate the exponent ∆AO: the overlap, calculated as function of Wilson chain length k, decays exponentially, ∼ e −kα , and ∆AO can be extracted directly from the exponent α. The results for ∆AO so obtained are consistent (with relative errors typically smaller than 1%) with two other related quantities that compare how ground state properties change upon switching from |GI to |GF : the difference in scattering phase shifts at the Fermi energy, and the displaced charge flowing in from infinity. We illustrate this for several nontrivial interacting models, including systems that exhibit population switching.

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Section: Introductionmentioning

confidence: 99%

Anderson orthogonality and the numerical renormalization group

2011

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“…Although the Kondo problem is considered solved, many questions about the original Kondo model actually remain very challenging, such as the the dependence of the Entanglement Entropy (EE) on the size of a spatial sub-system [27][28][29][30], the effect of a quantum quench of the Kondo coupling [31], or how to define and measure ξ K precisely [32]. More generally, a major challenge is to solve the Kondo problem when the LFL is replaced by strongly-interacting degrees of freedom, including in particular, in one spatial dimension, a Luttinger liquid.…”

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Entanglement entropy in a holographic Kondo model

Erdmenger

Flory

Hoyos

et al. 2016

Fortschritte der Physik

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We calculate entanglement and impurity entropies in a recent holographic model of a magnetic impurity interacting with a strongly coupled system. There is an RG flow to an IR fixed point where the impurity is screened, leading to a decrease in impurity degrees of freedom. This information loss corresponds to a volume decrease in our dual gravity model, which consists of a codimension one hypersurface embedded in a BTZ black hole background in three dimensions. There are matter fields defined on this hypersurface which are dual to Kondo field theory operators. In the large N limit, the formation of the Kondo cloud corresponds to the condensation of a scalar field. The entropy is calculated according to the Ryu-Takayanagi prescription. This requires to determine the backreaction of the hypersurface on the BTZ geometry, which is achieved by solving the Israel junction conditions. We find that the larger the scalar condensate gets, the more the volume of constant time slices in the bulk is reduced, shortening the bulk geodesics and reducing the impurity entropy. This provides a new non-trivial example of an RG flow satisfying the g-theorem. Moreover, we find explicit expressions for the impurity entropy which are in agreement with previous field theory results for free electrons. This demonstrates the universality of perturbing about an IR fixed point.Dedicated to the memory of our colleague Peter Breitenlohner

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“…A bias voltage applied between a top semi-transparent Ti/Au Schottky gate and back contacts allows to control the charging state of the QD and the relative alignment of its electronic levels with the Fermi energy of the FR [14]. High-resolution resonance-scattering spectroscopy [15] was performed on a single QD in a fiberbased confocal microscope incorporated in a dilution refrigerator [16]. The electron temperature was varied between 200 mK and 4 K while the applied magnetic field in the Faraday geometry was kept constant at 5 Tesla.…”

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Hyperfine Interaction-Dominated Dynamics of Nuclear Spins in Self-Assembled InGaAs Quantum Dots

2011

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We measure the dynamics of nuclear spins in a self-assembled quantum dot at a magnetic field of 5 Tesla and identify two distinct mechanisms responsible for the decay of the Overhauser field. We attribute a temperature-independent decay which lasts ∼ 100 seconds to intra-dot diffusion induced by hyperfine-mediated indirect nuclear spin interaction. In addition, we observe a gate-voltage and temperature dependent decay stemming from co-tunneling mediated nuclear spin flip processes. By adjusting the gate-voltage and lowering the electron temperature to ∼ 200 milliKelvin, we prolong the corresponding decay time to ∼ 30 hours. Our measurements indicate possibilities for exploring quantum dynamics of the central spin model using a single self-assembled quantum dot.Hyperfine interaction between a single quantum dot (QD) electron and the nuclear spin ensemble defined by the nano-scale confinement provides a realization of the central spin problem [1][2][3][4][5][6]. This model has attracted considerable attention recently since the correlations between the confined electron and the nuclear spin ensemble induced by hyperfine coupling constitute the principal decoherence mechanism for the electron spin [7]. It has been recognized in this context that an enhancement of electron coherence time could be achieved by preparing nuclear spins in eigenstates of the Overhauser (OH) field operator [8,9]: for this approach to be effective, it is essential to understand and characterize the dynamics of prepared (polarized) nuclear spin states.In this Letter, we present measurements of nuclear spin dynamics in a single electron charged self-assembled QD. In contrast to prior work in self-assembled and gateconfined QDs [10-13], we probe nuclear spin dynamics when both the exchange coupling to a Fermionic reservoir (FR) and the dipolar interaction between nuclear spins are vanishingly small. Our observations reveal a spatially limited, temperature-independent, nuclear spin diffusion originating from electron mediated nuclear spin interactions in addition to co-tunneling mediated, temperature dependent, decay of the OH field approaching 10 5 s. Remarkably, the diffusion induced reduction in the OH field taking place on ∼100 s timescale can be strongly suppressed by repeating the preparation cycle consisting of polarization (pump) and free-evolution (wait).The QDs in this sample are separated by a 35 nm GaAs tunnel barrier from a doped n++-GaAs layer. A bias voltage applied between a top semi-transparent Ti/Au Schottky gate and back contacts allows to control the charging state of the QD and the relative alignment of its electronic levels with the Fermi energy of the FR [14]. High-resolution resonance-scattering spectroscopy [15] was performed on a single QD in a fiberbased confocal microscope incorporated in a dilution refrigerator [16]. The electron temperature was varied between 200 mK and 4 K while the applied magnetic field in the Faraday geometry was kept constant at 5 Tesla. We adopted a modulation-free measurement to keep the en...

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Quantum quench of Kondo correlations in optical absorption

Cited by 7 publications

References 0 publications

Anderson orthogonality and the numerical renormalization group

Anderson orthogonality and the numerical renormalization group

Entanglement entropy in a holographic Kondo model

Hyperfine Interaction-Dominated Dynamics of Nuclear Spins in Self-Assembled InGaAs Quantum Dots

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