Bulletin of the American Physical Society
Mid-Atlantic Section 2022 Meeting
Volume 67, Number 20
Friday–Sunday, December 2–4, 2022; University Park, PA, Pennsylvania State University
Session B03: Quantum Materials |
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Chair: Ish Gupta, Pennsylvania State University Room: Pennsylvania State University Thomas 118 |
Friday, December 2, 2022 5:00PM - 5:35PM |
B03.00001: Quantum emitters in two-dimensional materials Invited Speaker: Chitraleema Chakraborty Quantum emitters in solids are promising building blocks for quantum information processing, quantum communications, and quantum sensing. Atomically thin materials that host quantum emitters, when compared to three-dimensional materials, have the advantage of reduced total internal reflection and easy coupling with interconnects. In this talk, I will share the story of the discovery and control of quantum emitters in two-dimensional materials in tunable van der Waals heterostructure. Further, I will also discuss the possibility of ab-initio prediction, deterministic generation, and integration with photonic devices, which offers a compelling solution to scalable solid-state quantum photonics. Our work opens the frontier of quantum optics in two-dimensional materials with the potential to revolutionize solid-state quantum devices. |
Friday, December 2, 2022 5:35PM - 5:47PM |
B03.00002: Dynamic mass generation on two-dimensional correlated quantum hyperbolic lattices Noble Gluscevich, Bitan Roy Free electrons hopping on hyperbolic lattices, constructed by periodically tilling regular p-gon with q nearest-neighbor sites on a curved space of negative curvature can harbor a variety of emergent band structures. In particular, for even p, they can be grouped into three broad categories: (a) hyperbolic Fermi liquids, (b) hyperbolic Dirac liquids and (c) hyperbolic flat bands, respectively accommodating constant, vanishing and divergent density of states near the half-filling. Irrespective of these microscopic details, from numerical self-consistent Hartree-Fock analyses we show that the nearest-neighbor (V_1) and on-site (U) Coulomb repulsions respectively gives rise to charge-density-wave and antiferromagnet orders featuring staggered pattern of average electronic density and magnetization in all these systems. Both quantum orders open a mass gap near the charge neutrality point. While these orderings take place for infinitesimal strength of Coulomb interactions in hyperbolic Fermi liquid and flat bands, on hyperbolic Dirac materials such orderings take place beyond critical couplings via a quantum phase transition. We also present the scaling behavior of such mass gaps with interaction strengths, as well as showcase their spatial variations. |
Friday, December 2, 2022 5:47PM - 5:59PM |
B03.00003: Dynamic metal at the grain boundary of Floquet topological insulators Daniel J Salib Driven quantum materials often feature emergent topology solely arising from the time periodic drive, otherwise absent in static crystals, among which the dynamic bulk-boundary correspondence encoded by nondissipative gapless modes residing near the Floquet zone center and/or boundaries are the most prominent ones. Here we show that such dynamic topological crystal can harbor topologically robust gapless matallic state along the grain boundary in its interior when the Floquet-Bloch band inversion occurs at a finite momentum (Kinv), such that the Burgers vector (b) of the constituting array of dislocations satisfies Kinv ⋅ b=π (modulo 2π). Such in-gap topological bulk metal, which can appear at the center and/or edge of the underlying periodic Floquet Brillouin zone, results from the hybridization among the localized modes bound to the core of individual dislocation. We exemplify these general outcomes by considering a paradigmatic representative of time-reversal symmetry breaking two-dimensional insulating system. Possible experimental setup underpinning such emergent driven topological metallic states in real materials are also discussed. |
Friday, December 2, 2022 5:59PM - 6:11PM |
B03.00004: Electric Field Tunable Band Gap in Commensurate Twisted Bilayer Graphene Spenser Talkington, Eugene J Mele Bernal bilayer graphene exhibits a band gap that is tunable through the infrared with an electric field. We show that sublattice odd commensurate twisted bilayer graphene (C-TBG) exhibits a band gap that is tunable through the terahertz with an electric field. We show that from the perspective of terahertz optics the sublattice odd and even forms of C-TBG are "inflated" versions of Bernal and AA stacked bilayer graphene respectively with energy scales reduced by a factor of 110 for the 21.79 degree commensurate unit cell. This lower energy scale is accompanied by a correspondingly smaller gate voltage, which means that the strong-field regime is more easily accessible than in the Bernal case. Finally, we show that the interlayer coherence energy is a directly accessible experimental quantity through the position of a logarithmic divergence in the optical conductivity. |
Friday, December 2, 2022 6:11PM - 6:23PM |
B03.00005: Z2 nontrivial Moiré minibands and interaction-driven Quantum anomalous Hall insulators in Topological Insulator based Moiré Heterostructures Kai-Jie Yang, Chaoxing Liu, Peizhe Tang, Andrei B Bernevig, Zhen Bi, Zian Xu, Yanjie Feng, Frank Schindler, Yuanfeng Xu We studied the electronic band structure and its topological property of a topological insulator thin film under a Moir'e superlattice potential. The $mathbb Z_2$ non-trivial isolated mini-bands can generally appear for the low-energy Moir'e mini-band spectrum in the phase diagram when the Moir'e potential form a hexagonal lattice with six-fold rotation symmetry. The conduction (valence) mini-bands can be topologically non-trivial when the hexagonal lattice has two minima (maxima). For the nontrivial conduction mini-band case, we find both the two isolated lowest Kramers' pairs of conduction mini-bands have nontrivial $mathbb Z_2$ invariant when there is inversion, while only the isolated lowest Kramers' pair of mini-bands is topologically non-trivial when the inversion symmetry is broken. The Coulomb interaction can potentially drive the lowest conduction Kramers' mini-bands into the quantum anomalous Hall state at half-filling, which is further stablized in the inversion asymmetric case. We propose the atomic Sb layer on top of Sb$_2$Te$_3$ films to realize our model via the first principles calculations. |
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