Plasmonically engineered nitrogen-vacancy spin readout.

Ultra-precise readout of single nitrogen-vacancy (NV) spins holds promise for major advancements in quantum sensing, computing, and communication technologies. Here we present a rigorous open quantum theory capable of simultaneously capturing the optical, vibronic, and spin interactions of the negatively charged NV center, both in the presence and absence of plasmonic interaction. Our theory is verified against existing experiments in the literature.

Classification of mandibular molar furcation involvement in periapical radiographs by deep learning.

Purpose: The purpose of this study was to classify mandibular molar furcation involvement (FI) in periapical radiographs using a deep learning algorithm.

Materials And Methods: Full mouth series taken at East Carolina University School of Dental Medicine from 2011-2023 were screened. Diagnostic-quality mandibular premolar and molar periapical radiographs with healthy or FI mandibular molars were included.

The battle of the sexes in humans is highly polygenic.

Sex-differential selection (SDS), which occurs when the fitness effects of alleles differ between males and females, can have profound impacts on the maintenance of genetic variation, disease risk, and other key aspects of natural populations. Because the sexes mix their autosomal genomes each generation, quantifying SDS is not possible using conventional population genetic approaches. Here, we introduce a method that exploits subtle sex differences in haplotype frequencies resulting from SDS acting in the current generation.

Magnetic fields reveal signatures of triplet-pair multi-exciton photoluminescence in singlet fission.

The photophysical processes of singlet fission and triplet fusion have numerous emerging applications. They involve the separation of a photo-generated singlet exciton into two dark triplet excitons and the fusion of two dark triplet excitons into an emissive singlet exciton, respectively. The role of the excimer state and the nature of the triplet-pair state in these processes have been a matter of contention.

A framework for multiexcitonic logic.

Exciton science sits at the intersection of chemical, optical and spin-based implementations of information processing, but using excitons to conduct logical operations remains relatively unexplored. Excitons encoding information could be read optically (photoexcitation-photoemission) or electrically (charge recombination-separation), travel through materials via exciton energy transfer, and interact with one another in stimuli-responsive molecular excitonic devices. Excitonic logic offers the potential to mediate electrical, optical and chemical information.

Magnetic Field Effects in Triplet-Triplet Annihilation Upconversion: Revisiting Atkins and Evans' Theory.

In their seminal description of magnetic field effects on chemiluminescent fluid solutions, Atkins and Evans considered the spin-dependent interactions between two triplets, incorporating the effects of the diffusion of the molecules in the liquid phase. Their results, crucial for the advancement of photochemical upconversion, have received renewed attention due to the increasing interest in triplet-triplet annihilation for photovoltaic and optoelectronic applications. Here we revisit their approach, using a modern formulation of open quantum system dynamics and extend their results.

Tuning the Photoluminescence Anisotropy of Semiconductor Nanocrystals.

Semiconductor nanocrystals are promising optoelectronic materials. Understanding their anisotropic photoluminescence is fundamental for developing quantum-dot-based devices such as light-emitting diodes, solar cells, and polarized single-photon sources. In this study, we experimentally and theoretically investigate the photoluminescence anisotropy of CdSe semiconductor nanocrystals with various shapes, including plates, rods, and spheres, with either wurtzite or zincblende structures.

Amplification is the primary mode of gene-by-sex interaction in complex human traits.

Sex differences in complex traits are suspected to be in part due to widespread gene-by-sex interactions (GxSex), but empirical evidence has been elusive. Here, we infer the mixture of ways in which polygenic effects on physiological traits covary between males and females. We find that GxSex is pervasive but acts primarily through systematic sex differences in the magnitude of many genetic effects ("amplification") rather than in the identity of causal variants.

Power Dependence of the Magnetic Field Effect on Triplet Fusion: A Quantitative Model.

Two strategies for improving solar energy efficiencies, triplet fusion and singlet fission, rely on the details of triplet-triplet interactions. In triplet fusion, there are several steps, each of which is a possible loss mechanism. In solution, the parameters describing triplet fusion collisions are difficult to inspect.

Top-down patterning of topological surface and edge states using a focused ion beam.

The conducting boundary states of topological insulators appear at an interface where the characteristic invariant ℤ switches from 1 to 0. These states offer prospects for quantum electronics; however, a method is needed to spatially-control ℤ to pattern conducting channels. It is shown that modifying SbTe single-crystal surfaces with an ion beam switches the topological insulator into an amorphous state exhibiting negligible bulk and surface conductivity.

Photochemical Upconversion in Solution: The Role of Oxygen and Magnetic Field Response.

Upconversion processes effectively convert two or more low energy photons into one higher energy photon, and they have diverse prospective applications in photovoltaics and biomedicine. We focus on two specific mechanisms for photochemical upconversion in solution: triplet-triplet annihilation (TTA) and singlet oxygen mediated energy transfer (SOMET). TTA is spin-selective, whereas SOMET is not, so the interplay between these two upconversion mechanisms can be examined via their different magnetic field responses.

Silicon-Aluminum Phase-Transformation-Induced Superconducting Rings.

The development of devices that exhibit both superconducting and semiconducting properties is an important endeavor for emerging quantum technologies. We investigate superconducting nanowires fabricated on a silicon-on-insulator (SOI) platform. Aluminum from deposited contact electrodes is found to interdiffuse with Si along the entire length of the nanowire, over micrometer length scales and at temperatures well below the Al-Si eutectic.

Interactions between Fermi polarons in monolayer WS.

Interactions between quasiparticles are of fundamental importance and ultimately determine the macroscopic properties of quantum matter. A famous example is the phenomenon of superconductivity, which arises from attractive electron-electron interactions that are mediated by phonons or even other more exotic fluctuations in the material. Here we introduce mobile exciton impurities into a two-dimensional electron gas and investigate the interactions between the resulting Fermi polaron quasiparticles.

Influence of Device Geometry and Imperfections on the Interpretation of Transverse Magnetic Focusing Experiments.

Spatially separating electrons of different spins and efficiently generating spin currents are crucial steps towards building practical spintronics devices. Transverse magnetic focusing is a potential technique to accomplish both those tasks. In a material where there is significant Rashba spin-orbit interaction, electrons of different spins will traverse different paths in the presence of an external magnetic field.

Stability of superconducting resonators: Motional narrowing and the role of Landau-Zener driving of two-level defects.

Frequency instability of superconducting resonators and qubits leads to dephasing and time-varying energy loss and hinders quantum processor tune-up. Its main source is dielectric noise originating in surface oxides. Thorough noise studies are needed to develop a comprehensive understanding and mitigation strategy of these fluctuations.

Neuron-Inspired Steiner Tree Networks for 3D Low-Density Metastructures.

Three-dimensional (3D) micro-and nanostructures have played an important role in topological photonics, microfluidics, acoustic, and mechanical engineering. Incorporating biomimetic geometries into the design of metastructures has created low-density metamaterials with extraordinary physical and photonic properties. However, the use of surface-based biomimetic geometries restricts the freedom to tune the relative density, mechanical strength, and topological phase.

Selection and isolation define a heterogeneous divergence landscape between hybridizing Heliconius butterflies.

Hybridizing species provide a powerful system to identify the processes that shape genomic variation and maintain species boundaries. However, complex histories of isolation, gene flow, and selection often generate heterogeneous genomic landscapes of divergence that complicate reconstruction of the speciation history. Here, we explore patterns of divergence to reconstruct recent speciation in the erato clade of Heliconius butterflies.

Two-dimensional spectroscopy beyond the perturbative limit: The influence of finite pulses and detection modes.

Ultra-fast and multi-dimensional spectroscopy gives a powerful looking glass into the dynamics of molecular systems. In particular, two-dimensional electronic spectroscopy (2DES) provides a probe of coherence and the flow of energy within quantum systems, which is not possible with more conventional techniques. While heterodyne-detected (HD) 2DES is increasingly common, more recently fluorescence-detected (FD) 2DES offers new opportunities, including single-molecule experiments.

Eliminating Quantum Phase Slips in Superconducting Nanowires.

In systems with reduced dimensions, quantum fluctuations have a strong influence on the electronic conduction, even at very low temperatures. In superconductors, this is especially interesting, since the coherent state of the superconducting electrons strongly interacts with these fluctuations and therefore is a sensitive tool to study them. In this paper, we report on comprehensive measurements of superconducting nanowires in the quantum phase slip regime.

Bilirubin analogues as model compounds for exciton coupling.

A series of phycobilin analogues have been investigated in terms of coupled excitonic systems. These compounds consist of a monomer, a tetrapyrrole structurally similar to bilirubin (bR), and two conjugated bR analogues. Spectroscopic and computational methods have been used to investigate the degree of interchromophore coupling.

Towards understanding two-level-systems in amorphous solids: insights from quantum circuits.

Amorphous solids show surprisingly universal behaviour at low temperatures. The prevailing wisdom is that this can be explained by the existence of two-state defects within the material. The so-called standard tunneling model has become the established framework to explain these results, yet it still leaves the central question essentially unanswered-what are these two-level defects (TLS)? This question has recently taken on a new urgency with the rise of superconducting circuits in quantum computing, circuit quantum electrodynamics, magnetometry, electrometry and metrology.

Passive On-Chip Superconducting Circulator Using a Ring of Tunnel Junctions.

We present the design of a passive, on-chip microwave circulator based on a ring of superconducting tunnel junctions. We investigate two distinct physical realizations, based on Josephson junctions (JJs) or quantum phase slip elements (QPS), with microwave ports coupled either capacitively (JJ) or inductively (QPS) to the ring structure. A constant bias applied to the center of the ring provides an effective symmetry breaking field, and no microwave or rf bias is required.