Controlling Floquet states on ultrashort time scales

Lucchini, Matteo; Medeghini, Fabio; Wu, Yingxuan; Vismarra, Federico; Borrego-Varillas, Rocío; Crego, Aurora; Frassetto, Fabio; Poletto, Luca; Sato, Shunsuke A.; Hübener, Hannes; Giovannini, Umberto De; Rubio, Ángel; Nisoli, M.

doi:10.1038/s41467-022-34973-4

Cited by 10 publications

(8 citation statements)

References 38 publications

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“…Calculations of V int m (z eh ) is more demanding. We first expand Vint given by equation (8) in Taylor series…”

Section: Electron-hole Floquet States In Hk Framementioning

confidence: 99%

“…Special attention is particularly paid to the off-resonant regime when absorption of energy from highfrequency laser beam is largely diminished on a short subpicosecond time scale [6], even though, the optical field can modify the dynamics of the system at the microscopic level to a large extent. These are the premises of emergent Floquet engineering which enables for reversible and nondestructive manipulations of properties of quantum matter [5,[7][8][9][10] with many prominent applications to date. For example, an irradiation of many-body system with optical field may break the time-translation symmetry cast by periodic stimulus and form * Author to whom any correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

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Excitonic Floquet states in quantum wire

Chwiej,

Dziembaj

2023

J. Phys.: Condens. Matter

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Floquet engineering is a rapidly growing branch in condensed matter physics which allows to change the properties of nanomaterials like energy structure, conductivity, magnetization, topology, etc. on demand utilizing the electric and magnetic components of THz light ﬁeld coupling with charge and spin of electrons and holes. Here we use the Floquet theory to study the dynamical eﬀects of laser light coupling to an electron-hole pair conﬁned in a quantum wire. Due to much stronger conﬁnement of particles in transverse direction than in longitudinal one, excitonic states becomes signiﬁcantly susceptible to electric ﬁeld oscillating along the wire, the energies of the bound states grow while their probabilities of radiative recombination are gradually decreased for increasing light ﬁeld intensities in moderate regime (I < 105 W/cm2). This eﬀect can be further enhanced by combining both, the oscillating in time and static electric ﬁelds applied along the wire. Then, some pairs of energy levels may mutually mix and undergo fast symmetry transformations as function of oscillating ﬁeld intensity, hence creating narrow (∼ few meV) avoided crossings accompanied with large changes in recombination probability, their positions in energy spectra can be precisely manipulated by tuning the strength of static electric ﬁeld. Described mechanism of changing the bright states into the dark ones is made with the help of laser ﬁeld so it could be advantageous to use this property to build the fast (∼ THz) optical bright-dark state switcher for an exciton in the most populated ground state.most populated ground state.

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“…Calculations of V int m (z eh ) is more demanding. We first expand Vint given by equation (8) in Taylor series…”

Section: Electron-hole Floquet States In Hk Framementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Excitonic Floquet states in quantum wire

Chwiej,

Dziembaj

2023

J. Phys.: Condens. Matter

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“…This technique was successfully used to observe Floquet-Bloch bands and sidebands [2,38], Floquetrelated gap opening and band hybridization [39], charge dynamics in topological surface states and their coupling to the continuum [40][41][42], photoionization time delays [43][44][45], and more [46]. Very recently, it was also employed for uncovering the coherent build-up and subsequent dephasing of the Floquet phase itself with sub-laser-cycle resolution [47,48]. However, no work to date has analyzed the energy and momentum resolved sub-laser-cycle motion of charges between the Floquet-Bloch states in ARPES.…”

Section: Introductionmentioning

confidence: 99%

Tracking electron motion within and outside of Floquet bands from attosecond pulse trains in time-resolved ARPES

Neufeld,

Hübener,

Giovannini

et al. 2024

J. Phys.: Condens. Matter

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Floquet engineering has recently emerged as a technique for controlling material properties with light. Floquet phases can be probed with time- and angle-resolved photoelectron spectroscopy (Tr-ARPES), providing direct access to the laser-dressed electronic bands. Applications of Tr-ARPES to date focused on observing the Floquet-Bloch bands themselves, and their build-up and dephasing on sub-laser-cycle timescales. However, momentum and energy resolved sub-laser-cycle dynamics between Floquet bands have not been analyzed. Given that Floquet theory strictly applies in time-periodic conditions, the notion of resolving sub-laser-cycle dynamics between Floquet states seems contradictory – it requires probe pulse durations below a laser cycle that inherently cannot discern the time-periodic nature of the light-matter system. Here we propose to employ attosecond pulse train probes with the same temporal periodicity as the Floquet-dressing pump pulse, allowing both attosecond sub-laser-cycle resolution and a proper projection of Tr-ARPES spectra on the Floquet-Bloch bands. We formulate and employ this approach in ab-initio calculations in light-driven graphene. Our calculations predict significant sub-laser-cycle dynamics occurring within the Floquet phase with the majority of electrons moving within and in-between Floquet bands, and a small portion residing and moving outside of them in what we denote as ‘non-Floquet’ bands. We establish that non-Floquet bands arise from the pump laser envelope that induces non-adiabatic electronic excitations during the pulse turn-on and turn-off. By performing calculations in systems with poly-chromatic pumps we also show that Floquet states are not formed on a sub-laser-cycle level. This work indicates that the Floquet-Bloch states are generally not a complete basis set for sub-laser-cycle dynamics in steady-state phases of matter.

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“…Starting from an approach similar to that reported in Ref. [33], in this work we will interpret a RABBITT trace in terms of interference of Floquet ladder states [34,35] and develop an analytical form that can be used to extract time-delay information from all the interference paths, including those avoided in a standard RABBITT regime. We will show that while ionization paths involving more than one IR photon become relevant already at relatively low IR intensities, their effect can be accounted for.…”

Section: Introductionmentioning

confidence: 99%

Floquet interpretation of attosecond RABBITT traces

Lucchini

2023

Phys. Rev. A

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Originally proposed for the temporal characterization of train of attosecond pulses, the reconstruction of attosecond beating by interference of two-photon transitions (RABBITT), has become a wide-spread, powerful technique, capable to capture ultrafast electron dynamics through an interferometric approach. Starting from the well-known strong-field approximation (SFA) description of a two-color photoelectron spectrum, here we develop a model that interprets a RABBITT trace as the interference of different Floquet ladder states generated in the continuum by a femtosecond infrared (IR) pulse after ionization by the attosecond radiation. In turn, this allowed us to develop an analytical model capable of predicting the amplitude and phase of the oscillating sidebands and mainbands while including the effect of non-standard interference paths and, in first approximation, of the finite IR pulse envelope. Our results thus suggest a way to extend the RABBITT model to higher intensities and beating frequencies, and disentangle different oscillating signals in a congested photoelectron spectrogram as the one associated with molecular targets.

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Controlling Floquet states on ultrashort time scales

Cited by 10 publications

References 38 publications

Excitonic Floquet states in quantum wire

Excitonic Floquet states in quantum wire

Tracking electron motion within and outside of Floquet bands from attosecond pulse trains in time-resolved ARPES

Floquet interpretation of attosecond RABBITT traces

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