Coherent single-atom superradiance

Superradiance is a quantum phenomenon emerging in macroscopic systems whereby correlated single atoms cooperatively emit photons. Demonstration of controlled collective atom-field interactions has resulted from the ability to directly imprint correlations with an atomic ensemble. Here we report cavity-mediated coherent single-atom superradiance: Single atoms with predefined correlation traverse a high–quality factor cavity one by one, emitting photons cooperatively with the N atoms that have already gone through the cavity (N represents the number of atoms). Enhanced collective photoemission of N-squared dependence was observed even when the intracavity atom number was less than unity. The correlation among single atoms was achieved by nanometer-precision position control and phase-aligned state manipulation of atoms by using a nanohole-array aperture. Our results demonstrate a platform for phase-controlled atom-field interactions.

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Interfacial-confined coordination to single-atom nanotherapeutics

Nature Communications ◽

10.1038/s41467-021-27640-7 ◽

2022 ◽

Vol 13 (1) ◽

Author(s):

Limei Qin ◽

Jie Gan ◽

Dechao Niu ◽

Yueqiang Cao ◽

Xuezhi Duan ◽

...

Keyword(s):

Therapeutic Strategy ◽

Single Atom ◽

Oxygen Species ◽

High Quality ◽

Efficient Energy ◽

Coordination Strategy ◽

Single Atoms ◽

Highly Active ◽

Narrow Bandgap ◽

Catalytic Sites

AbstractPursuing and developing effective methodologies to construct highly active catalytic sites to maximize the atomic and energy efficiency by material engineering are attractive. Relative to the tremendous researches of carbon-based single atom systems, the construction of bio-applicable single atom materials is still in its infancy. Herein, we propose a facile and general interfacial-confined coordination strategy to construct high-quality single-atom nanotherapeutic agent with Fe single atoms being anchored on defective carbon dots confined in a biocompatible mesoporous silica nanoreactor. Furthermore, the efficient energy conversion capability of silica-based Fe single atoms system has been demonstrated on the basis of the exogenous physical photo irradiation and endogenous biochemical reactive oxygen species stimulus in the confined mesoporous network. More importantly, the highest photothermal conversion efficiency with the mechanism of increased electron density and narrow bandgap of this single atom structure in defective carbon was proposed by the theoretical DFT calculations. The present methodology provides a scientific paradigm to design and develop versatile single atom nanotherapeutics with adjustable metal components and tune the corresponding reactions for safe and efficient tumor therapeutic strategy.

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A Long Bar Type Silicon Resonator with a High Quality Factor

IEEJ Transactions on Sensors and Micromachines ◽

10.1541/ieejsmas.134.26 ◽

2014 ◽

Vol 134 (2) ◽

pp. 26-31 ◽

Cited By ~ 13

Author(s):

Nguyen Van Toan ◽

Masaya Toda ◽

Yusuke Kawai ◽

Takahito Ono

Keyword(s):

Quality Factor ◽

High Quality Factor ◽

High Quality ◽

Type Silicon ◽

Silicon Resonator

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Tunable Carbon Surface from Mono- to Multi-Metallic Single Atoms

10.26434/chemrxiv.12264083 ◽

2020 ◽

Author(s):

Weihong Lai ◽

Heng Wang ◽

Quan jiang ◽

Zichao Yan ◽

Hanwen Liu ◽

...

Keyword(s):

Synergistic Effects ◽

Structural Evolution ◽

Charge Compensation ◽

Catalytic Reactions ◽

Single Atom ◽

Carbon Surface ◽

Hydrogen Electrode ◽

Single Atoms ◽

Mass Activity ◽

Co Doped

Herein, we develop a non-selective charge compensation strategy to prepare multi-single-atom doped carbon (MSAC) in which a sodium p-toluenesulfonate (PTS-Na) doped polypyrrole (S-PPy) polymer is designed to anchor discretionary mixtures of multiple metal cations, including iron (Fe3+), cobalt (Co3+), ruthenium (Ru3+), palladium (Pd2+), indium (In3+), iridium (Ir2+), and platinum (Pt2+) . As illustrated in Figure 1, the carbon surface can be tuned with different level of compositional complexities, including unary Pt1@NC, binary (MSAC-2, (PtFe)1@NC), ternary (MSAC-3, (PtFeIr)1@NC), quaternary (MSAC-4, (PtFeIrRu)1@NC), quinary (MSAC-5, (PtFeIrRuCo)1@NC), senary (MSAC-6, (PtFeIrRuCoPd)1@NC), and septenary (MSAC-7, (PtFeIrRuCoPdIn)1@NC) samples. The structural evolution of carbon surface dictates the activities of both ORR and HER. The senary MSAC-6 achieves the ORR mass activity of 18.1 A·mgmetal-1 at 0.9 V (Vs reversible hydrogen electrode (RHE)) over 30K cycles, which is 164 times higher than that of commercial Pt/C. The quaternary MSAC-4 presented a comparable HER catalytic capability with that of Pt/C. These results indicate that the highly complexed carbon surface can enhance its ability over general electrochemical catalytic reactions. The mechanisms regarding of the ORR and HER activities of the alternated carbon surface are also theoretically and experimentally investigated in this work, showing that the synergistic effects amongst the co-doped atoms can activate or inactivate certain single-atom sites.

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Global optimization of an encapsulated Si/SiO$$_2$$ L3 cavity with a 43 million quality factor

Scientific Reports ◽

10.1038/s41598-021-89410-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

J. P. Vasco ◽

V. Savona

Keyword(s):

Global Optimization ◽

Photonic Crystal ◽

Quality Factor ◽

State Of The Art ◽

Optimization Strategy ◽

High Quality ◽

Optimal Value ◽

Out Of Plane ◽

Fabrication Tolerances ◽

Structural Imperfections

AbstractWe optimize a silica-encapsulated silicon L3 photonic crystal cavity for ultra-high quality factor by means of a global optimization strategy, where the closest holes surrounding the cavity are varied to minimize out-of-plane losses. We find an optimal value of $$Q_c=4.33\times 10^7$$ Q c = 4.33 × 10 7 , which is predicted to be in the 2 million regime in presence of structural imperfections compatible with state-of-the-art silicon fabrication tolerances.

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Coherent suppression of backscattering in optical microresonators

Light Science & Applications ◽

10.1038/s41377-020-00440-2 ◽

2020 ◽

Vol 9 (1) ◽

Author(s):

Andreas Ø. Svela ◽

Jonathan M. Silver ◽

Leonardo Del Bino ◽

Shuangyou Zhang ◽

Michael T. M. Woodley ◽

...

Keyword(s):

Quality Factor ◽

Bulk Material ◽

Near Field ◽

High Quality Factor ◽

Dual Frequency ◽

High Quality ◽

Frequency Combs ◽

Optical Microresonators ◽

Whispering Gallery ◽

The Stability

AbstractAs light propagates along a waveguide, a fraction of the field can be reflected by Rayleigh scatterers. In high-quality-factor whispering-gallery-mode microresonators, this intrinsic backscattering is primarily caused by either surface or bulk material imperfections. For several types of microresonator-based experiments and applications, minimal backscattering in the cavity is of critical importance, and thus, the ability to suppress backscattering is essential. We demonstrate that the introduction of an additional scatterer into the near field of a high-quality-factor microresonator can coherently suppress the amount of backscattering in the microresonator by more than 30 dB. The method relies on controlling the scatterer position such that the intrinsic and scatterer-induced backpropagating fields destructively interfere. This technique is useful in microresonator applications where backscattering is currently limiting the performance of devices, such as ring-laser gyroscopes and dual frequency combs, which both suffer from injection locking. Moreover, these findings are of interest for integrated photonic circuits in which back reflections could negatively impact the stability of laser sources or other components.

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