A laser is composed of an optical resonator and a gain medium. When stimulated emission dominates mirror losses, the emitted light becomes coherent. We propose a new class of coherent light sources based on wavelength sized regular structures of quantum emitters whose eigenmodes form high-Q resonators. Incoherent pumping of few atoms induces light emission with spatial and temporal coherence. We show that an atomic nanoring with a single gain atom at the center behaves like a thresholdless laser, featuring a narrow linewidth. Symmetric subradiant excitations provide optimal operating conditions.
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http://dx.doi.org/10.1103/PhysRevLett.124.253603 | DOI Listing |
Exp Eye Res
January 2025
Department of Ophthalmology, Zhongshan Hospital, Fudan University, Shanghai, China. Electronic address:
The study aimed to compare the effects of different types of excimer laser keratectomy on rabbit corneas and to identify the optimal disease model for corneal ectasia. Additionally, investigating the structural and molecular alterations in the novel disease model helped explore the mechanisms underlying biomechanical cues in corneal ectasia. 2.
View Article and Find Full Text PDFMicromachines (Basel)
December 2024
State Key Laboratory of Intelligent Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
Accurate and efficient measurement of deposited droplets' volume is vital to achieve zero-defect manufacturing in inkjet printed organic light-emitting diode (OLED), but it remains a challenge due to droplets' featurelessness. In our work, coherence scanning interferometry (CSI) is utilized to measure the volume. However, the CSI redundant sampling and image degradation led by the sample's transparency decrease the efficiency and accuracy.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Experimental Physics V, Department of Physics, University of Bayreuth, D-95447 Bayreuth, Germany.
Photosynthetic microbes have evolved and successfully adapted to the ever-changing environmental conditions in complex microhabitats throughout almost all ecosystems on Earth. In the absence of light, they can sustain their biological functionalities through aerobic respiration, and even in anoxic conditions through anaerobic metabolic activity. For a suspension of photosynthetic microbes in an anaerobic environment, individual cellular motility is directly controlled by its photosynthetic activity, i.
View Article and Find Full Text PDFPNAS Nexus
January 2025
The Harrison M. Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1040, USA.
The direct, ultrafast excitation of polar phonons with electromagnetic radiation is a potent strategy for controlling the properties of a wide range of materials, particularly in the context of influencing their magnetic behavior. Here, we show that, contrary to common perception, the origin of phonon-induced magnetic activity does not stem from the Maxwellian fields resulting from the motion of the ions themselves or the effect their motion exerts on the electron subsystem. Through the mechanism of electron-phonon coupling, a coherent state of circularly polarized phonons generates substantial non-Maxwellian fields that disrupt time-reversal symmetry, effectively emulating the behavior of authentic magnetic fields.
View Article and Find Full Text PDFNat Phys
November 2024
Laboratory of Physical Chemistry, ETH Zürich, Zurich, Switzerland.
A dynamical rearrangement in the electronic structure of a molecule can be driven by different phenomena, including nuclear motion, electronic coherence or electron correlation. Recording such electronic dynamics and identifying its fate in an aqueous solution has remained a challenge. Here, we reveal the electronic dynamics induced by electronic relaxation through conical intersections in both isolated and solvated pyrazine molecules using X-ray spectroscopy.
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