Quek Su Ying

@article{ISI:001360396900001,
title = {Nb impurity-bound excitons as quantum emitters in monolayer WS_{2}},
author = {Leyi Loh and Yi Wei Ho and Fengyuan Xuan and Andres Granados del Aguila and Yuan Chen and See Yoong Wong and Jingda Zhang and Zhe Wang and Kenji Watanabe and Takashi Taniguchi and Paul J Pigram and Michel Bosman and Su Ying Quek and Maciej Koperski and Goki Eda},
doi = {10.1038/s41467-024-54360-5},
times_cited = {0},
year = {2024},
date = {2024-11-20},
journal = {NATURE COMMUNICATIONS},
volume = {15},
number = {1},
publisher = {NATURE PORTFOLIO},
address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY},
abstract = {Point defects in crystalline solids behave as optically addressable individual quantum systems when present in sufficiently low concentrations. In two-dimensional (2D) semiconductors, such quantum defects hold potential as versatile single photon sources. Here, we report the synthesis and optical properties of Nb-doped monolayer WS2 in the dilute limit where the average spacing between individual dopants exceeds the optical diffraction limit, allowing the emission spectrum to be studied at the single-dopant level. We show that these individual dopants exhibit common features of quantum emitters, including narrow emission lines (with linewidths <1 meV), strong spatial confinement, and photon antibunching. These emitters consistently occur within a narrow spectral range across multiple samples, distinct from common quantum emitters in van der Waals (vdW) materials that show large ensemble broadening. Analysis of the Zeeman splitting reveals that they can be attributed to bound exciton complexes comprising dark excitons and negatively charged Nb.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:001251520000012,
title = {Exciton-Enhanced Spontaneous Parametric Down-Conversion in Two-Dimensional Crystals},
author = {Fengyuan Xuan and Mingrui Lai and Yaze Wu and Su Ying Quek},
doi = {10.1103/PhysRevLett.132.246902},
times_cited = {7},
issn = {0031-9007},
year = {2024},
date = {2024-06-14},
journal = {PHYSICAL REVIEW LETTERS},
volume = {132},
number = {24},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {We show that excitonic resonances and interexciton transitions can enhance the probability of spontaneous parametric down -conversion, a second -order optical response that generates entangled photon pairs. We benchmark our ab initio many -body calculations using experimental polar plots of second harmonic generation in NbOI 2 , clearly demonstrating the relevance of excitons in the nonlinear response. A strong double-exciton resonance in 2D NbOCl 2 leads to giant enhancement in the second order susceptibility. Our work paves the way for the realization of efficient ultrathin quantum light sources.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:001237790900002,
title = {Evidence for electron-hole crystals in a Mott insulator},
author = {Zhizhan Qiu and Yixuan Han and Keian Noori and Zhaolong Chen and Mikhail Kashchenko and Li Lin and Thomas Olsen and Jing Li and Hanyan Fang and Pin Lyu and Mykola Telychko and Xingyu Gu and Shaffique Adam and Su Ying Quek and Aleksandr Rodin and Castro A H Neto and Kostya S Novoselov and Jiong Lu},
doi = {10.1038/s41563-024-01910-3},
times_cited = {3},
issn = {1476-1122},
year = {2024},
date = {2024-06-03},
journal = {NATURE MATERIALS},
volume = {23},
number = {8},
publisher = {NATURE PORTFOLIO},
address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY},
abstract = {The coexistence of correlated electron and hole crystals enables the realization of quantum excitonic states, capable of hosting counterflow superfluidity and topological orders with long-range quantum entanglement. Here we report evidence for imbalanced electron-hole crystals in a doped Mott insulator, namely, alpha-RuCl3, through gate-tunable non-invasive van der Waals doping from graphene. Real-space imaging via scanning tunnelling microscopy reveals two distinct charge orderings at the lower and upper Hubbard band energies, whose origin is attributed to the correlation-driven honeycomb hole crystal composed of hole-rich Ru sites and rotational-symmetry-breaking paired electron crystal composed of electron-rich Ru-Ru bonds, respectively. Moreover, a gate-induced transition of electron-hole crystals is directly visualized, further corroborating their nature as correlation-driven charge crystals. The realization and atom-resolved visualization of imbalanced electron-hole crystals in a doped Mott insulator opens new doors in the search for correlated bosonic states within strongly correlated materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}