Interference in Floquet-Volkov transitions

Park, Sang Tae

doi:10.1103/physreva.90.013420

Cited by 18 publications

(20 citation statements)

References 20 publications

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“…The Dirac bands that form at the surface of this material have here been shown to develop hybridization gaps under irradiation with light, shown in figure 3(a). The opening of hybridization gaps is the most widely predicted feature of Floquet topological phases, however, as pointed out in [28,72] in an photo-emission experiment, the external pump laser can also dress electronic states outside the material. Such a dressing, known as the light-assisted photo-emission effect, also results in a series of satellite bands, but does not reflect a dressing of the electronic structure of the material.…”

Section: Experimental Observation Of Floquet Topological Phasesmentioning

confidence: 99%

Floquet analysis of excitations in materials

Giovannini

Hübener

2019

J. Phys. Mater.

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Controlled excitation of materials can transiently induce changed or novel properties with many fundamental and technological implications. Especially, the concept of Floquet engineering and the manipulation of the electronic structure via dressing with external lasers have attracted some recent interest. Here we review the progress made in defining Floquet material properties and give a special focus on their signatures in experimental observables as well as considering recent experiments realizing Floquet phases in solid state materials. We discuss how a wide range of experiments with non-equilibrium electronic structure can be viewed by employing Floquet theory as an analysis tool providing a different view of excitations in solids.

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Section: Experimental Observation Of Floquet Topological Phasesmentioning

confidence: 99%

Floquet analysis of excitations in materials

Giovannini

Hübener

2019

J. Phys. Mater.

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“…Moreover, owing to the coherent nature of both processes, electrons can scatter directly from Floquet-Bloch states into Volkov states 23 (Fig. 1a).…”

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confidence: 99%

Selective scattering between Floquet–Bloch and Volkov states in a topological insulator

Mahmood¹,

Chan²,

Alpichshev³

et al. 2016

Nature Phys

337

273

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The coherent optical manipulation of solids is emerging as a promising way to engineer novel quantum states of matter 1-5 . The strong time-periodic potential of intense laser light can be used to generate hybrid photon-electron states. Interaction of light with Bloch states leads to Floquet-Bloch states, which are essential in realizing new photo-induced quantum phases [6][7][8] . Similarly, dressing of free-electron states near the surface of a solid generates Volkov states, which are used to study nonlinear optics in atoms and semiconductors 9 . The interaction of these two dynamic states with each other remains an open experimental problem. Here we use time-and angle-resolved photoemission spectroscopy (Tr-ARPES) to selectively study the transition between these two states on the surface of the topological insulator Bi 2 Se 3 . We find that the coupling between the two strongly depends on the electron momentum, providing a route to enhance or inhibit it. Moreover, by controlling the light polarization we can negate Volkov states to generate pure Floquet-Bloch states. This work establishes a systematic path for the coherent manipulation of solids via light-matter interaction.The manipulation of solids using ultrafast optical pulses has opened up a new paradigm in condensed matter physics by allowing the study of emergent physical properties that are otherwise inaccessible in equilibrium 1,2,10 . An important example is provided by the Floquet-Bloch states 11 , which emerge in solids owing to a coherent interaction between Bloch states inside the solid and a periodic driving potential. This is a consequence of the Floquet theorem 12 , which states that a Hamiltonian periodic in time with period T has eigenstates that are evenly spaced by the drive energy (2π/T ). Floquet-Bloch states have generated a lot of interest recently both for realizing exotic states of matter such as a Floquet Chern insulator 7 , as well as understanding non-equilibrium periodic thermodynamics 13,14 . Experimental observation of these states requires the measurement of the transient electronic band structure of a crystal as it is perturbed by light. As has recently been demonstrated 15 in the topological insulator Bi 2 Se 3 , time-and angleresolved photoemission spectroscopy (Tr-ARPES) is a key tool that can achieve this. Characteristic signatures of Floquet-Bloch states in the Tr-ARPES spectra include replicas of the original band structure that are separated by the driving photon energy 15 .In addition to Floquet-Bloch states, light can also generate other coherent phenomena in solids [16][17][18] . In particular, it can dress freeelectron states near the surface of a solid (Fig. 1a), as the surface can provide the momentum conservation necessary for a photon to interact with a free electron. This dressing was first observed in time-resolved photoemission experiments 17 and has subsequently been referred to as laser-assisted photoemission (LAPE). LAPE is typically understood [19][20][21] by invoking the Volkov solution, which is an e...

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“…Even more theoretical works have investigated the FB states. Several of them focus on graphene and the materials based on graphene-in that context the FB states were investigated for carbon nanotubes [6], for graphene in circularly polarized pulses [7], under intense THz pulses in graphene in the Dirac approximation [8] and the transition from the FB states to the Volkov states has also been considered [9].…”

Section: Introductionmentioning

confidence: 99%

Floquet-Bloch shifts in two-band semiconductors interacting with light

2017

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We consider harmonic generation from a semiconductor described in the two-band approximation. In particular, the signatures of the Floquet-Bloch states in the low-order harmonic spectra are studied. We find field-strengthdependent shifts of the position of resonant peaks. The shifts are analogous to the ponderomotive shifts in strong-field physics of atoms and molecules. We illustrate this theory by analyzing low-order harmonics generated from hexagonal boron nitride.

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Interference in Floquet-Volkov transitions

Cited by 18 publications

References 20 publications

Floquet analysis of excitations in materials

Floquet analysis of excitations in materials

Selective scattering between Floquet–Bloch and Volkov states in a topological insulator

Floquet-Bloch shifts in two-band semiconductors interacting with light

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