Microscopic evolution of doped Mott insulators from polaronic metal to Fermi liquid

Koepsell, Joannis; Bourgund, Dominik; Sompet, Pimonpan; Hirthe, Sarah; Bohrdt, Annabelle; Wang, Yao; Grusdt, Fabian; Demler, Eugene; Salomon, Guillaume; Groß, Christian; Bloch, Immanuel

doi:10.1126/science.abe7165

Cited by 76 publications

(33 citation statements)

References 61 publications

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“…Close to half-filling, these fluctuations appear as virtual doublon-hole pairs that can still be observed experimentally, for example in density snapshots obtained by quantum gas microscopy [27,28]. The presence of virtual doublons and holes may obfuscate the density distribution of the system especially at low doping, such as in studies of single holes injected in a Mott insulator [14,16,29] and studies of spin-charge as well as charge-charge correlations at finite doping [10]. In such cases it can therefore be desirable to eliminate virtual density excitations by studying the simpler the t − J − 3s model.…”

Section: Introductionmentioning

confidence: 97%

“…However, if experimental measurements are performed in the original basis, the measured state could lie outside the low-energy sector due to quantum fluctuations (virtual excitations). Quantum simulation experiments are now exploring new regimes and access novel observables, such as spin-charge correlations [9,10], with increasing accuracy. Details of the measurement procedure are therefore becoming more and more important.…”

Section: Introductionmentioning

confidence: 99%

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Schrieffer-Wolff Transformations for Experiments: Dynamically Suppressing Virtual Doublon-Hole Excitations in a Fermi-Hubbard Simulator

Kale,

Huhn,

et al. 2022

Preprint

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In strongly interacting systems with a separation of energy scales, low-energy effective Hamiltonians help provide insights into the relevant physics at low temperatures. The emergent interactions in the effective model are mediated by virtual excitations of high-energy states: For example, virtual doublon-hole excitations in the Fermi-Hubbard model mediate antiferromagnetic spin-exchange interactions in the derived effective model, known as the t − J − 3s model. Formally this procedure is described by performing a unitary Schrieffer-Wolff basis transformation. In the context of quantum simulation, it can be advantageous to consider the effective model to interpret experimental results. However, virtual excitations such as doublon-hole pairs can obfuscate the measurement of physical observables. Here we show that quantum simulators allow one to access the effective model even more directly by performing measurements in a rotated basis. We propose a protocol to perform a Schrieffer-Wolff transformation on Fermi-Hubbard low-energy eigenstates (or thermal states) to dynamically prepare approximate t − J − 3s model states using fermionic atoms in an optical lattice. Our protocol involves performing a linear ramp of the optical lattice depth, which is slow enough to eliminate the virtual doublon-hole fluctuations but fast enough to freeze out the dynamics in the effective model. We perform a numerical study using exact diagonalization and find an optimal ramp speed for which the state after the lattice ramp has maximal overlap with the t − J − 3s model state. We compare our numerics to experimental data from our Lithium-6 fermionic quantum gas microscope and show a proof-of-principle demonstration of this protocol. More generally, this protocol can be beneficial to studies of effective models by enabling the suppression of virtual excitations in a wide range of quantum simulation experiments.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Schrieffer-Wolff Transformations for Experiments: Dynamically Suppressing Virtual Doublon-Hole Excitations in a Fermi-Hubbard Simulator

Kale,

Huhn,

et al. 2022

Preprint

Self Cite

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“…While ground-state and finite-temperature properties of various QIMs are well-understood, thanks to the multitude of powerful methods including NRG [4,6], densitymatrix renormalization group (DMRG) [7,8], exact diagonalization [9][10][11], continuous-time Monte Carlo methods [12] and, in some cases exact solutions [13][14][15], recently the focus shifted to non-equilibrium properties and real-time dynamics of QIMs [16][17][18][19][20][21][22][23][24][25], thanks to new experimental capabilities [26][27][28][29][30][31][32][33][34][35][36][37]. One typical experimental setup of interest in mesoscopic systems and ultracold atomic gases is that of a quantum quench, where the Hamiltonian of the system is changed suddenly (e.g., reservoirs are connected to the impurity).…”

Section: Introductionmentioning

confidence: 99%

Non-equilibrium quantum impurity problems via matrix-product states in the temporal domain

Thoenniss¹,

Lerose²,

Abanin³

2022

Preprint

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Describing a quantum impurity coupled to one or more non-interacting fermionic reservoirs is a paradigmatic problem in quantum many-body physics. While historically the focus has been on the equilibrium properties of the impurity-reservoir system, recent experiments with mesoscopic and cold-atomic systems enabled studies of highly non-equilibrium impurity models, which require novel theoretical techniques. We propose an approach to analyze impurity dynamics based on the matrix-product state (MPS) representation of the Feynman-Vernon influence functional (IF). The efficiency of such a MPS representation rests on the moderate value of the temporal entanglement (TE) entropy of the IF, viewed as a fictitious "wave function" in the time domain. We obtain explicit expressions of this wave function for a family of one-dimensional reservoirs, and analyze the scaling of TE with the evolution time for different reservoir's initial states. While for initial states with shortrange correlations we find temporal area-law scaling, Fermi-sea-type initial states yield logarithmic scaling with time, closely related to the real-space entanglement scaling in critical 1d systems. Furthermore, we describe an efficient algorithm for converting the explicit form of the reservoirs' IF to MPS form. Once the IF is encoded by a MPS, arbitrary temporal correlation functions of the interacting impurity can be efficiently computed, irrespective of its internal structure. The approach introduced here can be applied to a number of experimental setups, including highly non-equilibrium transport via quantum dots and real-time formation of impurity-reservoir correlations.

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“…For instance, quantum-gas microscopes for ultracold atoms in optical lattices offer single-atom, single-site, and spin-state resolution [7][8][9][10][11]. They enable measurements of non-local observables, which are inaccessible in different physical platforms [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Snapshot based characterization of particle currents and the Hall response in synthetic flux lattices

Buser,

Schollwöck,

Grusdt

2021

Preprint

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Microscopic evolution of doped Mott insulators from polaronic metal to Fermi liquid

Cited by 76 publications

References 61 publications

Schrieffer-Wolff Transformations for Experiments: Dynamically Suppressing Virtual Doublon-Hole Excitations in a Fermi-Hubbard Simulator

Schrieffer-Wolff Transformations for Experiments: Dynamically Suppressing Virtual Doublon-Hole Excitations in a Fermi-Hubbard Simulator

Non-equilibrium quantum impurity problems via matrix-product states in the temporal domain

Snapshot based characterization of particle currents and the Hall response in synthetic flux lattices

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