Consequences of time-reversal-symmetry breaking in the light-matter interaction: Berry curvature, quantum metric, and diabatic motion

Holder, Tobias; Kaplan, Daniel; Yan, Binghai

doi:10.1103/physrevresearch.2.033100

Cited by 111 publications

(81 citation statements)

References 69 publications

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“…same way v bc denotes the anomalous velocity associated with the Berry curvature, a gr is the anomalous acceleration induced by the metric and b jk the anomalous jerk component. We note that the first two lines conform with known expressions [6,8], whereas the third line is our prediction.…”

Section: Summary Of Resultssupporting

confidence: 84%

“…Two powerful arguments in favor of this proposition will be discussed here: Firstly, there are striking formal similarities between the expressions derived from the gauge theory of deformable bodies [5] and the results obtained from canonical perturbation approaches [6][7][8]. Secondly, we comment on recent progress regarding the second order conductivity, where it is possible to make concrete and experimentally testable predictions based on our proposition.…”

Section: Introductionmentioning

confidence: 72%

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Electrons flow like falling cats: Deformations and emergent gravity in quantum transport

Holder¹

2021

Preprint

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The effective low-energy excitations in a metallic or semimetallic crystalline system (i.e. electronic quasiparticles) always have a finite spatial extent. It is self-evident but virtually unexplored how the associated internal degrees of freedom manifest themselves in the quasiparticle response. Here, we investigate this question by illuminating an intimate connection between the theory of nonlinear response and the equations of motion of classical deformable bodies. This connection establishes that nth-order response in an external perturbation corresponds to nth-order derivatives of the quasiparticle motion, where the resulting motion is anomalous at every order due to the internal degrees of freedom. This new point of view predicts that quasiparticles necessarily move in an emergent curved spacetime, even in a homogeneous and defectless lattice. We underscore these concepts using recent results on the second order electrical conductivity, elucidating the associated anomalous acceleration that the quasiparticle exhibits. Based on our observations, we predict the existence of an infinite series of anomalous components of the quasiparticle motion, and propose a new mapping between response theory in flat space and a gravitational theory for the center-of-mass coordinate.

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Section: Summary Of Resultssupporting

confidence: 84%

Section: Introductionmentioning

confidence: 72%

Electrons flow like falling cats: Deformations and emergent gravity in quantum transport

Holder¹

2021

Preprint

Self Cite

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“…The diagrammatic description of second order optical response has been developed only much later [37,38]. The latter formulation allows to identify the underlying physical processes that create a nonlinear current, and also clarifies the role of finite relaxation rates.…”

mentioning

confidence: 99%

“…The latter formulation allows to identify the underlying physical processes that create a nonlinear current, and also clarifies the role of finite relaxation rates. It turns out that second order optical response is encoded by the (anomalous) acceleration of the quasiparticle while it traverses the lattice [38]. Accelerations (but not velocities) are sensitive to a motion in non-Euclidian space (cf.…”

mentioning

confidence: 99%

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Mixed axial-gravitational anomaly from emergent curved spacetime in nonlinear charge transport

Holder¹,

Kaplan²,

Ilan³

et al. 2021

Preprint

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In 3+1 dimensional spacetime, two vector gauge anomalies are known: The chiral anomaly and the mixed axial-gravitational anomaly. While the former is well documented and tied to the presence of a magnetic field, the latter instead requires a nonzero spacetime curvature, which has made it rather difficult to study. In this work, we show that a quantum anomaly arises in the second-order electrical response for zero magnetic field, which creates a dc-current that can be either longitudinal or transverse to electric field. Consequently, the continuity equation for the chiral current is not conserved at order τ −1 , where τ is the quasiparticle relaxation time. We can identify the anomaly as a mixed axial-gravitational one, and predict a material in which the anomaly-induced current can be isolated in a purely electrical measurement. Our findings indicate that charge transport generically derives from quasiparticle motion in an emergent curved spacetime, with potentially far-reaching consequences for all types of response functions.

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Universal Ensemble‐Embedding Graph Neural Network for Direct Prediction of Optical Spectra from Crystal Structures

Hung,

Okabe,

Chotrattanapituk

et al. 2024

Advanced Materials

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Optical properties in solids, such as refractive index and absorption, hold vast applications ranging from solar panels to sensors, photodetectors, and transparent displays. However, first‐principles computation of optical properties from crystal structures is a complex task due to the high convergence criteria and computational cost. Recent progress in machine learning shows promise in predicting material properties, yet predicting optical properties from crystal structures remains challenging due to the lack of efficient atomic embeddings. Here, Graph Neural Network for Optical spectra prediction (GNNOpt) is introduced, an equivariant graph‐neural‐network architecture featuring universal embedding with automatic optimization. This enables high‐quality optical predictions with a dataset of only 944 materials. GNNOpt predicts all optical properties based on the Kramers‐Krönig relations, including absorption coefficient, complex dielectric function, complex refractive index, and reflectance. The trained model is applied to screen photovoltaic materials based on spectroscopic limited maximum efficiency and search for quantum materials based on quantum weight. First‐principles calculations validate the efficacy of the GNNOpt model, demonstrating excellent agreement in predicting the optical spectra of unseen materials. The discovery of new quantum materials with high predicted quantum weight, such as SiOs, which host exotic quasiparticles with multifold nontrivial topology, demonstrates the potential of GNNOpt in predicting optical properties across a broad range of materials and applications.

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Consequences of time-reversal-symmetry breaking in the light-matter interaction: Berry curvature, quantum metric, and diabatic motion

Cited by 111 publications

References 69 publications

Electrons flow like falling cats: Deformations and emergent gravity in quantum transport

Electrons flow like falling cats: Deformations and emergent gravity in quantum transport

Mixed axial-gravitational anomaly from emergent curved spacetime in nonlinear charge transport

Universal Ensemble‐Embedding Graph Neural Network for Direct Prediction of Optical Spectra from Crystal Structures

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