Nanoscale quantum light sources are essential building blocks for integrated quantum photonic systems. Here, we report a wavelength-scale entangled-photon source based on van der Waals-engineered NbOBr2 and benchmark its performance for telecom-wavelength quantum light generation. By exploiting the material's second-order nonlinearity, we generate quantum-correlated photon pairs via spontaneous parametric down-conversion. We then use a 90° twisted stacking to induce quantum interference in photon-pair generation, yielding polarization-entangled photons. This approach enables tunability of the quantum optical state via control of the excitation laser polarization. We experimentally obtain entanglement fidelities exceeding 95% for Bell states, along with a high coincidence-to-accidental ratio of ∼335 and a brightness approximately 1 order of magnitude higher than recently reported telecom sources based on transition metal dichalcogenide two-dimensional materials. These results establish twisted van der Waals engineering as a powerful platform for highly tunable, high-brightness quantum light sources at telecom wavelengths.
Nidhin Prasannan, K. Mourzidis, V. Jindal et al.· Nano letters (Print)· 0 citations
Control of upper limb force is crucial for motor skill acquisition. Rodent models have been instrumental in elucidating the behavioral and neural mechanisms underlying skilled movements. Integrating these models with advanced neuroimaging approaches, such as awake functional magnetic resonance imaging (fMRI) in behaving mice, enables whole-brain mapping of motor activity. However, experimental paradigms supporting awake fMRI during upper limb motor behavior in mice remain limited. Here, we developed an MRI-compatible head–fixation system that enables male and female mice to perform a unilateral forepaw force control task for water reward during ultrahigh-field (11.1 T) fMRI. Mice successfully acquired the task, as evidenced by increased rewarded presses, convergence of force output toward the rewarded threshold, and reduced force variability. Significant activation clusters related to forepaw force were identified across multiple cortical regions, including the primary and secondary motor cortex, anterior cingulate cortex, and primary somatosensory cortex. Activation extended to subcortical structures, including the cerebellum, striatum, hypothalamus, and thalamus (ventrolateral and ventroposterior nuclei). Analysis of limb kinematics from synchronized video recordings revealed strong spatial correspondence between forepaw-related and force-dependent activation maps. Region-of-interest analyses further identified engagement of medullary structures, specifically the lateral rostral medulla and caudal medulla (CauM), in forepaw force control. Notably, the cerebellum and CauM exhibited later peak responses relative to cortical regions. Together, these results establish a robust framework for awake fMRI during forelimb motor tasks and provide a comprehensive map of cortical, subcortical, and brainstem circuits underlying forelimb force control in mice.
V. Jindal, Jason Veizaj, Zoë Schuler et al.· eNeuro· 0 citations
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