Superconductivity, superfluidity and quantum geometry in twisted multilayer systems

Nature Reviews Physics, Journal Year: 2022, Volume and Issue: 4(8), P. 528 - 542

Published: June 10, 2022

Language: Английский

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Cavity quantum materials

Applied Physics Reviews, Journal Year: 2022, Volume and Issue: 9(1)

Published: Feb. 25, 2022

The emergent field of cavity quantum materials bridges collective many-body phenomena in solid state platforms with strong light–matter coupling electrodynamics. This brief review provides an overview the art and highlights recent theoretical proposals first experimental demonstrations control materials. encompasses between electrons modes, superconductivity, phononics ferroelectricity, correlated systems a cavity, light–magnon coupling, topology Hall effect, as well super-radiance. An outlook potential future developments is given.

Language: Английский

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Time-resolved ARPES studies of quantum materials

Reviews of Modern Physics, Journal Year: 2024, Volume and Issue: 96(1)

Published: Feb. 27, 2024

Time-resolved angle-resolved photoemission spectroscopy provides access to light-induced changes in the electronic band structure and interactions of solids, out-of-equilibrium electron dynamics. This article reviews history future prospects for development technique, offers an overview recent achievements studying unoccupied light-driven states, photoinduced phase transitions, electron-phonon scattering, dynamics quantum materials, including topological insulators, unconventional superconductors, traditional novel semiconductors, excitonic spin-textured systems.

Language: Английский

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Shift-current response as a probe of quantum geometry and electron-electron interactions in twisted bilayer graphene

Physical Review Research, Journal Year: 2022, Volume and Issue: 4(1)

Published: Feb. 28, 2022

Moir\'e materials, and in particular twisted bilayer graphene (TBG), exhibit a range of fascinating phenomena that emerge from the interplay band topology interactions. We show nonlinear second-order photoresponse is an appealing probe this rich interplay. A dominant part shift current, which determined by geometry electronic wave functions carrier properties thus becomes strongly modified electron-electron analyze its dependence on twist angle doping investigate role In absence interactions, response system dictated two energy scales: (i) mean direct transitions between hole electron flat bands (ii) gap dispersive bands. Including interactions both enhances at noninteracting characteristic frequencies produces new resonances. attribute these changes to filling-dependent renormalization TBG. Our results highlight connection nontrivial geometric TBG optical response, as well demonstrate how probes can access moir\'e materials.

Language: Английский

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Engineering Flat Bands in Twisted-Bilayer Graphene away from the Magic Angle with Chiral Optical Cavities

Physical Review Letters, Journal Year: 2024, Volume and Issue: 132(16)

Published: April 18, 2024

Twisted bilayer graphene (TBG) is a recently discovered two-dimensional superlattice structure which exhibits strongly correlated quantum many-body physics, including strange metallic behavior and unconventional superconductivity. Most of TBG exotic properties are connected to the emergence pair isolated topological flat electronic bands at so-called magic angle, θ≈1.05°, nevertheless very fragile. In this work, we show that, by employing chiral optical cavities, can be stabilized away from angle in an interval approximately 0.8°<θ<1.3°. As highlighted simplified theoretical model, time reversal symmetry breaking (TRSB), induced nature cavity, plays fundamental role flattening gapping out rest spectrum. Additionally, TRSB suppresses Berry curvature induces phase transition, with gap closing Γ point, towards band two Chern number equal 0. The efficiency cavity discussed as function twisting light-matter coupling characteristic frequency. Our results demonstrate possibility engineering using devices, extending onset phases moiré superlattices wider range angle.

Language: Английский

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Relating the topology of Dirac Hamiltonians to quantum geometry: When the quantum metric dictates Chern numbers and winding numbers

SciPost Physics, Journal Year: 2022, Volume and Issue: 12(1)

Published: Jan. 12, 2022

Quantum geometry has emerged as a central and ubiquitous concept in quantum sciences, with direct consequences on metrology many-body physics. In this context, two fundamental geometric quantities are known to play complementary roles:~the Fubini-Study metric, which introduces notion of distance between states defined over parameter space, the Berry curvature associated Berry-phase effects topological band structures. fact, recent studies have revealed relations these important quantities, suggesting that properties can, special cases, be deduced from metric. work, we establish general exact metric invariants generic Dirac Hamiltonians. particular, demonstrate indices (Chern numbers or winding numbers) bounded by volume determined Our theoretical framework, builds Clifford algebra matrices, is applicable insulators semimetals arbitrary spatial dimensions, without chiral symmetry. This work clarifies role matter, unexplored responses metrological applications broad class quantum-engineered systems.

Language: Английский

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Recent developments in fractional Chern insulators

Elsevier eBooks, Journal Year: 2023, Volume and Issue: unknown, P. 515 - 538

Published: Feb. 7, 2023

Language: Английский

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Topological Flat Bands in 2D Breathing‐Kagome Lattice Nb₃TeCl₇

Advanced Materials, Journal Year: 2023, Volume and Issue: 35(41)

Published: July 27, 2023

Flat bands (FBs) can appear in two-dimensional (2D) geometrically frustrated systems caused by quantum destructive interference (QDI). However, the scarcity of pure 2D crystal structures natural materials makes FBs hard to be identified, let alone modulate relating electronic properties. Here, experimental evidence complete QDI induced FB contributed breathing-kagome layers Nb atoms Nb3 TeCl7 (NTC) is reported. An identical chemical state and localization characteristics are experimentally confirmed, based on which NTC demonstrated a superior concrete candidate for tight-binding model. Furthermore, it theoretically establishes tunable roles on-site energy over sites bandwidth, position, topology NTC. This work opens an aveanue manipulate these 4d transition-metal-based materials.

Language: Английский

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Nontrivial quantum geometry of degenerate flat bands

Physical review. B./Physical review. B, Journal Year: 2022, Volume and Issue: 106(16)

Published: Oct. 31, 2022

The importance of the quantum metric in flat-band systems has been noticed recently many contexts such as superfluid stiffness, dc electrical conductivity, and ideal Chern insulators. Both degenerate nondegenerate bands can be naturally described via geometry different Grassmannian manifolds, specific to band degeneracies. Contrary (Abelian) Berry curvature, a resulting from collapse collection is not simply sum individual metrics. We provide physical interpretation this phenomenon terms transition dipole matrix elements between two bands. By considering toy model, we show that gets enhanced, reduced, or remains unaffected depending on which collapse. longitudinal conductivity stiffness are known proportional for systems, makes them suitable candidates observation phenomenon.

Language: Английский

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Effective theory of lattice electrons strongly coupled to quantum electromagnetic fields

Physical review. B./Physical review. B, Journal Year: 2022, Volume and Issue: 105(16)

Published: April 13, 2022

Recent experiments have revealed the tantalizing possibility of fabricating lattice electronic systems strongly coupled to quantum fluctuations electromagnetic fields, e.g., by means geometry confinement from a cavity or artificial gauge fields in simulators. In this work, we develop high-frequency expansion construct effective models for electrons continuum off-resonant photon modes with arbitrary dispersion. The theory is nonperturbative light-matter coupling strength, and therefore particularly suitable ultrastrong regime. Using models, demonstrate how dispersion topology energy bands can be tuned cavity. particular, quasi-one-dimensional physics emerge two-dimensional square due spatially anisotropic band renormalization, topologically nontrivial anomalous Hall state induced honeycomb when setup breaks time-reversal symmetry. We also that photon-mediated interaction induces an unconventional superconducting paired phase distinct pair-density-wave discussed truncated coupling. Finally, study realistic Fabry-P\'{e}rot Our work provides systematic framework explore emergent phenomena strong points out new directions engineering orders topological states solids.

Language: Английский

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