Nonlinear doublon production in a Mott insulator: Landau-Dykhne method applied to an integrable model

Oka, Takashi

doi:10.1103/physrevb.86.075148

Cited by 104 publications

(149 citation statements)

References 51 publications

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“…Tunnelling dominates for γ < 1, while multiphoton absorption dominates for γ > 1. For sufficiently high fields (1-10 MV cm -1 ) at THz and mid-infrared frequencies, the tunnelling regime (γ < 1) is operative, resulting in novel phenomena and unexpected effects such as massive population transfer between bands far in excess of the photon energy (that is, E g >> ħω) 44,48,49 . An exciting research direction that will remain outside of the scope of this Review is the electrical and optical control of magnetism 50,51 .…”

Section: Nature Materials Doi: 101038/nmat5017mentioning

confidence: 99%

Towards properties on demand in quantum materials

2017

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Q uantum materials are on the ascent. This term embodies a vast portfolio of compounds and phenomena where ramifications of quantum mechanics are demonstrably real. Quantum materials are in the vanguard of contemporary physics in part because these systems afford an exceptional venue to uncover the many roles of symmetry, topology, dimensionality and strong correlations in macroscopic observables. Here we set out to explore the ways and means of creating new states of matter in quantum materials and manipulating their phases via external stimuli. Practical control of these properties is a precondition for exploiting quantum advantages in new photonic, electronic and energy technologies, a task of significant societal impact 1 . We will primarily focus on the following classes of quantum materials: transition metal oxides, Fe-and Cu-based high-T c superconductors, van der Waals semiconductors, topological insulators and Weyl semimetals, and, finally, graphene.The properties of quantum materials are anomalously sensitive to external stimuli. In these systems, interactions associated with spin, charge, lattice and orbital degrees of freedom are commonly on par with the electronic kinetic energy. A rather fragile balance between coexisting and competing ground states can be readily shifted via external stimuli, leading to a raft of quantum phases and transitions between them 2,3 . Furthermore, certain classes of driven quantum states (Fig. 1a and Box 1) are explicit products of coherent interaction between light and matter 4-6 . Alternatively, the properties of quantum materials can be pre-programmed by directly manipulating the electronic wavefunction and the attendant Berry phase that give rise to the anomalous velocity of electrons in a solid [7][8][9] . These complementary avenues of controls mean that investigations no longer need to be reduced to merely observing (in contrast, for example, to astrophysics). Instead, it is now feasible to attain, in a predictable fashion, 'properties on demand' by steering a quantum material towards a desirable ground, metastable or transient state. The past decade has witnessed an explosion in the field of quantum materials, headlined by the predictions and discoveries of novel Landau-symmetry-broken phases in correlated electron systems, topological phases in systems with strong spin-orbit coupling, and ultra-manipulable materials platforms based on two-dimensional van der Waals crystals. Discovering pathways to experimentally realize quantum phases of matter and exert control over their properties is a central goal of modern condensed-matter physics, which holds promise for a new generation of electronic/photonic devices with currently inaccessible and likely unimaginable functionalities. In this Review, we describe emerging strategies for selectively perturbing microscopic interaction parameters, which can be used to transform materials into a desired quantum state. Particular emphasis will be placed on recent successes to tailor electronic interaction parameters through th...

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Section: Nature Materials Doi: 101038/nmat5017mentioning

confidence: 99%

Towards properties on demand in quantum materials

2017

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“…In solids, the quantum mechanical wavefunctions of electrons form the band structure separated by the energy gaps, and the tunneling can occur between these bands when an electric field is applied. This is called Zener tunneling through the energy gap and has been actively studied [1][2][3][4][5][6][7][8][9][10]. A concise formula, i.e., Landau-Zener formula [1,2], has been obtained for a model Hamiltonian describing the two-band system as…”

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confidence: 99%

Nonreciprocal Landau–Zener tunneling

2020

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We theoretically study Landau-Zener tunneling in noncentrosymmetric systems, i.e., the crystals without spatial inversion symmetry. A generalized Landau-Zener formula has been derived taking into account the geometric nature of the wavefunctions. The obtained formula shows that nonreciprocal tunneling probability originates from the difference in the Berry connections of the Bloch wavefunctions across the band gap, i.e., shift vector. We also discuss application of our formula to tunneling in a one-dimensional model of a ferroelectrics.Introduction. -Tunneling phenomenon is one of the most remarkable and unique consequences of the wave nature of particles in quantum mechanics, where a particle can penetrate through classically forbidden regions. In solids, the quantum mechanical wavefunctions of electrons form the band structure separated by the energy gaps, and the tunneling can occur between these bands when an electric field is applied. This is called Zener tunneling through the energy gap and has been actively studied [1][2][3][4][5][6][7][8][9][10]. A concise formula, i.e., Landau-Zener formula [1,2], has been obtained for a model Hamiltonian describing the two-band system as

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“…For A 0 =0.3, the weight in the lower Hubbard band −3.5ω1.5 is depleted, and the shape of the spectral distribution in the upper Hubbard band does not change much. This resembles the quantum tunneling regime [81], while the precise connection is…”

Section: Appendix a Transient Behavior Of Single-particle Spectral Fmentioning

confidence: 93%

Time-dependent spectral properties of a photoexcited one-dimensional ionic Hubbard model: an exact diagonalization study

Okamoto

2019

New J. Phys.

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Motivated by the recent progress in time-resolved nonequilibrium spectroscopy in condensed matter, we study an optically excited one-dimensional ionic Hubbard model by exact diagonalization. The model is relevant to organic crystals, transition metal oxides, or ultracold atoms in optical lattices. We implement numerical pump-probe measurements to calculate time-dependent conductivity and single-particle spectral functions. In general, short optical excitation induces a metallic behavior imprinted as a Drude peak in conductivity or an in-gap density of states. In a Mott insulator, we find that the induced Drude peak oscillates at the pump frequency and its second harmonic. The former comes from the oscillation of currents, and the latter from the interference of single-and three-photon excited states. In a band insulator, the Drude peak oscillates only at the pump frequency, and quantities such as the double occupancy do not oscillate. The absence of the second harmonic oscillation is due to the degeneracy of multi-photon excited states. The in-gap density of states in both insulators correlates with the Drude weight and the energy absorption for weak pumping. Strong pumping leads to saturation of the in-gap density of states and to suppression of the Drude weight in the Mott regime. We have also checked that the above features are robust for insulators in the intermediate parameter range. Our study demonstrates the distinct natures of the multi-photon excited states in two different insulators.Alternatively, we can regard it as a variant of the Falicov-Kimball model [41] where f-electrons are chargeordered and frozen. Here we ignore the dynamics of the underlying objects that give the staggered modulation. This means that our results are relevant to experimental data for a short period of time before the ionic motion sets in; the model serves as a starting point for further investigation with dynamical phonons. There is also an experimental realization of the model in ultracold atoms [42].We employ an exact diagonalization method to solve the time-dependent Schrödinger equation, and implement numerical pump-probe measurements to obtain time-dependent conductivity [43-45] and singleparticle spectral functions [46,47]. Short optical pulses applied to a Mott insulator (MI) or a band insulator (BI) make the system metallic, which is indicated by a nonzero Drude peak in conductivity. We find that the Drude peak oscillates at the pump frequency in both cases, while also at the second harmonic in the MI. The second harmonic oscillation in the Mott regime is explained by a constructive interference of single-and three-photon excited states. We have confirmed that the distinct dynamic behaviors still appear for intermediate cases unless the energy gap becomes too small. The relation between the in-gap density of states and the Drude weight is also discussed.The paper is organized as follows. In section 2, an ionic Hubbard model is introduced. Section 3 is devoted to the details of the exact diagonalization method and pump...

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Nonlinear doublon production in a Mott insulator: Landau-Dykhne method applied to an integrable model

Cited by 104 publications

References 51 publications

Towards properties on demand in quantum materials

Towards properties on demand in quantum materials

Nonreciprocal Landau–Zener tunneling

Time-dependent spectral properties of a photoexcited one-dimensional ionic Hubbard model: an exact diagonalization study

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