Topological strong field physics on sub-laser cycle timescale

Silva, R.E.F.; Jiménez-Galán, Álvaro; Amorim, B.; Smirnova, Olga; Ivanov, Misha

doi:10.1364/cleo_qels.2019.fm4m.5

Cited by 25 publications

(31 citation statements)

References 5 publications

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“…During the last decade, solid-state high-harmonic generation (HHG) has emerged as a novel spectroscopic tool to probe nonperturbative, ultrafast phenomena in a wide range of condensed matter systems . The exciting possibilities include all-optical access to valence charge-density distributions [26], band structure [4,27], transition dipole moments [28], and Berry curvature [29,30], as well as to nonequilibrium laser-driven dynamics [31]. These applications benefit from a detailed understanding of the microscopic mechanisms of HHG, which remains the subject of active experimental and theoretical investigation [32].…”

Section: Introductionmentioning

confidence: 99%

Polarization Flipping of Even-Order Harmonics in Monolayer Transition-Metal Dichalcogenides

et al. 2021

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We present a systematic study of the crystal-orientation dependence of high-harmonic generation in monolayer transition-metal dichalcogenides, WS2 and MoSe2, subjected to intense linearly polarized midinfrared laser fields. The measured spectra consist of both odd- and even-order harmonics, with a high-energy cutoff extending beyond the 15th order for a laser-field strength around ~1 V/nm. In WS2, we find that the polarization direction of the odd-order harmonics smoothly follows that of the laser field irrespective of the crystal orientation, whereas the direction of the even-order harmonics is fixed by the crystal mirror planes. Furthermore, the polarization of the even-order harmonics shows a flip in the course of crystal rotation when the laser field lies between two of the crystal mirror planes. By numerically solving the semiconductor Bloch equations for a gapped-graphene model, we qualitatively reproduce these experimental features and find the polarization flipping to be associated with a significant contribution from interband polarization. In contrast, high-harmonic signals from MoSe2 exhibit deviations from the laser-field following of odd-order harmonics and crystal-mirror-plane following of even-order harmonics. We attribute these differences to the competing roles of the intraband and interband contributions, including the deflection of the electron-hole trajectories by nonparabolic crystal bands.

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Section: Introductionmentioning

confidence: 99%

Polarization Flipping of Even-Order Harmonics in Monolayer Transition-Metal Dichalcogenides

et al. 2021

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“…Examples of ultrafast phenomena include insulator to metal phase transitions, strongly correlated electron dynamics 117 , and topological phase transitions in quantum materials 118 . Theoretical predictions are emerging, which includes calculations on one dimensional model systems focusing on how the trivial to topological phase transition dramatically enhances the efficiency of the HHG process 118 and two-dimensional Haldane model system focusing on how HHG could probe topological invariants 119,120 . This particular aspect, as well as just how phase transitions and correlations manipulate the HHG process at the microscopic level on novel quantum materials, are outstanding questions at this time 121 .…”

Section: Applications Of Attosecond X-ray Sourcesmentioning

confidence: 99%

Attosecond science based on high harmonic generation from gases and solids

Li¹,

Lu²,

Chew³

et al. 2020

Nat Commun

206

126

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Recent progress in high power ultrafast shortwave and mid-wave infrared lasers has enabled gas-phase high harmonic generation (HHG) in the water window and beyond, as well as the demonstration of HHG in condensed matter. In this Perspective, we discuss the recent advancements and future trends in generating and characterizing soft X-ray pulses from gasphase HHG and extreme ultraviolet (XUV) pulses from solid-state HHG. Then, we discuss their current and potential usage in time-resolved study of electron and nuclear dynamics in atomic, molecular and condensed matters. T abletop attosecond light sources in the soft X-ray (SXR) spectral region based on highharmonic generation are highly desirable in chemical and material sciences since they can spectroscopically identify specific elements, as well as the oxidation states, charge states and even the spin states of those elements 1. One of the important spectral regions is the "water window" (282-533 eV), which covers the atomic K-shell excitation of carbon and oxygen. Although high harmonics in the water window were first generated with Ti:Sapphire lasers centered at 800 nm more than 20 years ago 2,3 , the X-ray photon flux was too low for timeresolved applications. The mechanism of HHG in gases can be explained by the semiclassical three-step model 4-6. When driving laser-field strength reaches~10 8 V m −1 , the bound electron in the atomic gas can tunnel through the Coulomb potential barrier and become a free electron. In the oscillating laser field, the free-electron wave packet may return to its parent ion with the right time of birth. At recombination, the interference between the wave packets of the returning and bound electrons produces an oscillating dipole that emits attosecond radiation. Returning electrons with various kinetic energy will recombine at different times giving rise to the chirp in the attosecond radiation 7. This process repeats twice for every optical cycle. The temporal beating of attosecond pulses results in the high-harmonic combs in the spectral domain. Empowered by the advances in driving lasers with center wavelengths around 1.8 μm, soft X-ray high harmonics can be generated with a moderate intensity of 10 14 W cm −2 (see Box 1 for details). Significant progress has recently been made in developing attosecond light within the water window 8. By spectrally broadening pulses from an Optical Parametric Amplifier (OPA) using a gas-filled hollow-core fiber 9 or by broadband phase matching in an Optical Parametric Chirped Pulse Amplifier (OPCPA) 10 , two-cycle, mJ-level pulses centered with 1 kHz repetition

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“…Additionally, attosecond transient absorption experiments for core valence electrons in solids are nowadays in the focus of attention of attosecond condensed matter physics [167,168]. The rapidly emerging field of nonlinear spectroscopy in quantum materials [168][169][170], i.e., topological materials, Weyl semimetals, etc. [161,166,169,170] is attracting the attention of several experimental and theoretical research groups around the world.…”

Section: Toward Nonlinear Ultrafast Spectroscopy Of Quantum Materialsmentioning

confidence: 99%

“…The rapidly emerging field of nonlinear spectroscopy in quantum materials [168][169][170], i.e., topological materials, Weyl semimetals, etc. [161,166,169,170] is attracting the attention of several experimental and theoretical research groups around the world. Those materials are extremely important, since their special features, i.e., topological conducting and isolating bands protected by the fundamental symmetries are robust against energy dissipation and material perturbations [157,158].…”

Section: Toward Nonlinear Ultrafast Spectroscopy Of Quantum Materialsmentioning

confidence: 99%

Quantum interference and imaging using intense laser fields

et al. 2021

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The interference of matter waves is one of the intriguing features of quantum mechanics that has impressed researchers and laymen since it was first suggested almost a century ago. Nowadays, attosecond science tools allow us to utilize it in order to extract valuable information from electron wave packets. Intense laser fields are routinely employed to create electron wave packets and control their motion with attosecond and ångström precision. In this perspective article, which is based on our debate at the Quantum Battles in Attoscience virtual workshop 2020, we discuss some of the peculiarities of intense light-matter interaction. We review some of the most important techniques used in attosecond imaging, namely photoelectron holography and laser-induced electron diffraction. We attempt to ask and answer a few questions that do not get asked very often. For example, if we are interested in position space information, why are measurements carried out in momentum space? How to accurately retrieve photoelectron spectra from the numerical solution of the time-dependent Schrödinger equation? And, what causes the different coherence properties of high-harmonic generation and above-threshold ionization? GraphicAbstract

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Topological strong field physics on sub-laser cycle timescale

Cited by 25 publications

References 5 publications

Polarization Flipping of Even-Order Harmonics in Monolayer Transition-Metal Dichalcogenides

Polarization Flipping of Even-Order Harmonics in Monolayer Transition-Metal Dichalcogenides

Attosecond science based on high harmonic generation from gases and solids

Quantum interference and imaging using intense laser fields

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