Critical Response of a Quantum van der Pol Oscillator.

Classical dynamical systems close to a critical point are known to act as efficient sensors due to a strongly nonlinear response. We explore such systems in the quantum regime by modeling a quantum version of a driven van der Pol oscillator. We find the classical response survives down to one excitation quantum. At very weak drives, genuine quantum features arise, including diverging and negative susceptibilities. Further, the linear response is greatly enhanced by using a strong incoherent pump. These results are largely generic and can be probed in current experimental platforms suited for quantum sensing

Long-Range Coherence and Multiple Steady States in a Lossy Qubit Array.

We show that a simple experimental setting of a locally pumped and lossy array of two-level quantum systems can stabilize states with strong long-range coherence. Indeed, by explicit analytic construction, we show there is an extensive set of steady-state density operators, from minimally to maximally entangled, despite this being an interacting open many-body problem. Such nonequilibrium steady states arise from a hidden symmetry that stabilizes Bell pairs over arbitrarily long distances, with unique experimental signatures. We demonstrate a protocol by which one can selectively prepare these states using dissipation. Our findings are accessible in present-day experiments

Generating symmetry-protected long-range entanglement

Entanglement between spatially distant qubits is perhaps the most counterintuitive and vital resource for distributed quantum computing. However, despite a few special cases, there is no known general procedure to maximally entangle two distant parts of an interacting many-body system. Here we present a symmetry-based approach, whereby one applies several timed pulses to drive a system to a particular symmetry sector with maximal bipartite long-range entanglement. As a concrete example, we demonstrate how a simple sequence of on-site pulses on a qubit array can efficiently produce multiple stable nonlocal Bell pairs, realizable in present-day atomic and photonic experimental platforms. More generally, our approach paves a route for exotic state preparation by harnessing symmetry. For instance, we show how it allows the creation of long-sought-after superconducting η pairs in a repulsive Hubbard model

The Conservation Costs of Game Ranching

The devolution of user rights of wildlife in southern Africa has led to a widespread land-use shift from livestock farming to game ranching. The economic advantages of game ranching over livestock farming are significant, but so too are the risks associated with breeding financially valuable game where free-ranging wildlife pose a credible threat. Here, we assessed whether the conservation potential of game ranching, and a decentralized approach to conservation more generally, may be undermined by an increase in human-wildlife conflict. We demonstrate that game rancher tolerance towards free-ranging wildlife has significantly decreased as the game ranching industry has evolved. Our findings reveal a conflict of interest between wealth and wildlife conservation resulting from local decision-making in the absence of adequate centralized governance and evidence-based best practice. As a fundamental pillar of devolution-based natural resource management, game ranching proves an important mechanism for economic growth, albeit at a significant cost to conservation

Loss of Ezh2 in the medial ganglionic eminence alters interneuron fate, cell morphology and gene expression profiles

IntroductionEnhancer of zeste homolog 2 (Ezh2) is responsible for trimethylation of histone 3 at lysine 27 (H3K27me3), resulting in repression of gene expression. Here, we explore the role of Ezh2 in forebrain GABAergic interneuron development.MethodsWe removed Ezh2 in the MGE by generating Nkx2-1Cre;Ezh2 conditional knockout mice. We then characterized changes in MGE-derived interneuron fate and electrophysiological properties in juvenile mice, as well as alterations in gene expression, chromatin accessibility and histone modifications in the MGE.ResultsLoss of Ezh2 increases somatostatin-expressing (SST+) and decreases parvalbumin-expressing (PV+) interneurons in the forebrain. We observe fewer MGE-derived interneurons in the first postnatal week, indicating reduced interneuron production. Intrinsic electrophysiological properties in SST+ and PV+ interneurons are normal, but PV+ interneurons display increased axonal complexity in Ezh2 mutant mice. Single nuclei multiome analysis revealed differential gene expression patterns in the embryonic MGE that are predictive of these cell fate changes. Lastly, CUT&Tag analysis revealed that some genomic loci are particularly resistant or susceptible to shifts in H3K27me3 levels in the absence of Ezh2, indicating differential selectivity to epigenetic perturbation.DiscussionThus, loss of Ezh2 in the MGE alters interneuron fate, morphology, and gene expression and regulation. These findings have important implications for both normal development and potentially in disease etiologies

Generating Symmetry-Protected Long-Range Entanglement in Many-Body Systems

Entanglement between spatially distant qubits is perhaps the most counterintuitive and vital resource for distributed quantum computing. However, despite a few special cases, there is no known general procedure to maximally entangle two distant parts of an interacting many-body system. Here we present a symmetry-based approach, whereby one applies several timed pulses to drive a system to a particular symmetry sector with maximal bipartite long-range entanglement. As a concrete example, we demonstrate how a simple sequence of on-site pulses on a qubit array can efficiently produce any given number of stable nonlocal Bell pairs, realizable in several present-day atomic and photonic experimental platforms. More generally, our approach paves a route for novel state preparation by harnessing symmetry. For instance, we show how it enables the creation of long-sought-after superconducting $\eta$ pairs in a repulsive Hubbard model

Contrasting magnetic properties of polymorphic TbPt3

In this work, we report the contrasting magnetic behaviour of a bimorphic intermetallic compound TbPt3 that undergoes a structural phase transformation from cubic AuBe5-type structure to the cubic AuCu3-type structure on annealing at high temperature for a very short time. The magnetic ground state configuration of TbPt3 changes from ferromagnetic (FM) in AuBe5-type crystalline phase to antiferromagnetic (AFM) in AuCu3-type phase. However, the AFM ground state of the AuCu3-type compound is unstable, as a moderate magnetic field can induce the FM character through metamagnetic transformation. To understand the said crystallographic as well as magnetic transformations, structural and magnetic ab-initio calculations have been carried out for both phases. From theoretical calculations we have proposed that although the AuBe5-type structure of TbPt3 irreversibly transforms to the AuCu3-type TbPt3 by a very short heat treatment, the application of moderate magnetic field on AuCu3-type structure may result in recovering the magnetic properties of AuBe5-type structure of TbPt3. As the two different polymorphs exist simultaneously at ambient condition, TbPt3 thus provides us a great opportunity to study directly the effect of crystal structure on its physical properties and vice versa.This is a manuscript of an article published as Mondal, Sudipta, Binita Mondal, Shovan Dan, Durga Paudyal, R. Ranganathan, and Chandan Mazumdar. "Contrasting magnetic properties of polymorphic TbPt3." Journal of Alloys and Compounds 920 (2022): 165942. DOI: 10.1016/j.jallcom.2022.165942. Copyright 2022 Elsevier B.V. Posted with permission. DOE Contract Number(s): AC02-07CH11358

Instability and evolution of the magnetic ground state in metallic perovskites GdRh3C1-xBx

We report investigations of the structural, magnetic, electrical transport, and thermal properties of five compositions of the metallic perovskite GdRh3C1−xBx (0.00≤x≤1.00). Our results show that all five compositions undergo magnetic ordering at low temperatures, but the nature of the ordered state is significantly different in the carbon- and the boron-rich compositions, where the former shows signatures of an amplitude-modulated magnetic structure and the latter exhibits evidence of an equal-moment incommensurate antiferromagnetic ordering. We also observe a remarkable field-dependent evolution of conduction carrier polarization in the compositionally disordered compounds. The outcomes indicate that this system is energetically situated in proximity to a magnetic instability where small variations in the control parameter(s), such as the lattice constant and/or electron density, lead to considerably different ground states.</p