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Quantum sensors based on solid-state defects, in particular nitrogen-vacancy (NV) centers in diamond, enable precise measurement of magnetic fields, temperature, rotation, and electric fields. Cavity quantum electrodynamic (cQED) readout, in which an NV ensemble is hybridized with a microwave mode, can overcome limitations in optical spin detection and has resulted in leading magnetic sensitivities at the pT-level. This approach, however, remains far from the intrinsic spin-projection noise limit due to thermal Johnson-Nyquist noise and spin saturation effects. Here we tackle these challenges by combining recently demonstrated spin refrigeration techniques with comprehensive nonlinear modeling of the cQED sensor operation. We demonstrate that the optically-polarized NV ensemble simultaneously provides magnetic sensitivity and acts as a heat sink for the deleterious thermal microwave noise background, even when actively probed by a microwave field. Optimizing the NV-cQED system, we demonstrate a broadband sensitivity of 576 ± 6 fT/ around 15 kHz in ambient conditions. We then discuss the implications of this approach for the design of future magnetometers, including near-projection-limited devices approaching 3 fT/ sensitivity enabled by spin refrigeration.
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http://dx.doi.org/10.1038/s41467-024-54333-8 | DOI Listing |
ACS Omega
September 2025
Laboratório de Modelagem Molecular Aplicada e Simulação (LaMMAS), Universidade Estadual de Goiás, Anápolis, GO 75001-970, Brazil.
In this work, we report a theoretical investigation of the third-order nonlinear optical properties of the metronidazolium-picrate salt. The effects of the crystal environment are accounted for by the Iterative Charge Embedding approach, and the electronic calculations are carried out at the DFT (CAM-B3LYP/6-311++G-(d,p)) level. Furthermore, we use the results to parametrize a cavity Quantum Electrodynamics model for a quantum memory based on the Off-Resonant Cascaded Absorption protocol.
View Article and Find Full Text PDFNanoscale Horiz
September 2025
Theoretical Chemical Physics Group, Research Institute for Materials Science and Engineering, University of Mons, 20 Place du Parc, Mons B-7000, Belgium.
Two-photon spontaneous emission (TPSE) is a second-order quantum process with promising applications in quantum optics that remains largely unexplored in molecular systems, which are usually very inefficient emitters. In this work, we model the first molecular two-photon emitters and establish the design rules, highlighting their differences from those governing two-photon absorbers. Using both time-dependent density functional theory and Pariser-Parr-Pople calculations, we calculate TPSE in three π-conjugated molecules and identify a dominant pathway.
View Article and Find Full Text PDFJ Am Chem Soc
September 2025
State Key Laboratory of Advanced Materials for Intelligent Sensing and Key Laboratory of Organic Integrated Circuits, Ministry of Education & Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Institute of Molecular Plus, Department of Chemistry, Tianjin University, Tianjin 300072, China.
Incorporating boron atoms into organic macrocycles imparts unique chemical, electronic, and optical properties. The concept of making use of dative boron-nitrogen (B ← N) bonds for the construction of macrocycles has been proposed, but very few examples have been prepared with functional structures, much less pillar-like and other prismatic macrocycles, and their various functionalities have not been fully exploited. Here, we introduce a "functional molecular wall" synthetic protocol based on the self-assembly characteristics of B ← N dative bonds to construct highly symmetrical macrocycles, forming a quasi-pentagonal-shaped macrocycle (named [5]pyBN-) with a pillar-like structure.
View Article and Find Full Text PDFLight Sci Appl
September 2025
State Key Lab for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China.
The fiber-based saturable absorber (SA) that enables mode-locking within a ring cavity serves as the core component of the ultrafast all-fiber lasers. However, the integration of SAs onto fibers with high compactness suffers from imbalanced saturable absorption properties and unstable mode-locking performance. Here, we present a robust mode-locking SA by integrating a nanocavity composed of a two-dimensional graphene heterostructure on the fiber end facet.
View Article and Find Full Text PDFSci Adv
September 2025
School of Physical and Chemical Sciences, University of Canterbury, Christchurch 8140, New Zealand.
High-precision, Sagnac interferometry has long been proposed as a route to test fundamental questions in physics such as the magnitude of relativistic precessions (e.g., the Lense-Thirring effect).
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