We demonstrate a general method of engineering the joint quantum state of photon pairs produced in spontaneous parametric down-conversion. The method makes use of a superlattice structure of nonlinear and linear materials, in conjunction with a broadband pump, to manipulate the group delays of the signal and idler photons relative to the pump pulse, and realizes photon pairs described by a joint spectral amplitude with arbitrary degree of entanglement. This method of group-delay engineering has the potential of synthesizing a broad range of states including factorizable states crucial for quantum networking and states optimized for Hong-Ou-Mandel interferometry. Experimental results for the latter case are presented, illustrating the principles of this approach.
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http://dx.doi.org/10.1103/PhysRevLett.97.223602 | DOI Listing |
Phys Rev Lett
December 2024
CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, 230026, China.
Photonic simulators are increasingly used to study physical systems for their affluent manipulable degrees of freedom. The advent of photonic chips offers a promising path towards compact and configurable simulators. Thin-film lithium niobate chips are particularly well suited for this purpose due to the high electro-optic coefficient, which allows for the creation of lattices in the frequency domain.
View Article and Find Full Text PDFPsychol Rep
December 2024
Department of Psychology, University of Cambridge, Cambridge, UK.
Historically, debates over relationships between spoken lexical form and meaning have been dominated by views of arbitrariness. However more recent research revealed a different perspective, in which non-arbitrary mappings play an important role in the makeup of a lexicon. It is now clear that phoneme-sound symbolism - along with other types of form-to-meaning mappings - contributes to non-arbitrariness (iconicity) of spoken words, which is present in many forms and degrees in different languages.
View Article and Find Full Text PDFMol Phylogenet Evol
December 2024
Instituto Patagónico para el Estudio de los Ecosistemas Continentales, Consejo Nacional de Investigaciones Científicas y Técnicas (IPEEC-CONICET), Boulevard Almirante Brown 2915, U9120ACD, Puerto Madryn, Chubut, Argentina.
Disputes over species descriptions, stemming from conceptual disparities and arbitrary species boundaries, are among the primary challenges of modern taxonomy. In this study, we introduce a straightforward workflow, grounded in evolutionary theory, designed to tackle these challenges. We exemplified this approach using Patagonian lizards from the Diplolaemus clade.
View Article and Find Full Text PDFSci Robot
December 2024
Department of Physics, University of Konstanz, Universitaetsstrasse 10, Konstanz, 78464, Germany.
Swarm robots offer fascinating opportunities to perform complex tasks beyond the capabilities of individual machines. Just as a swarm of ants collectively moves large objects, similar functions can emerge within a group of robots through individual strategies based on local sensing. However, realizing collective functions with individually controlled microrobots is particularly challenging because of their micrometer size, large number of degrees of freedom, strong thermal noise relative to the propulsion speed, and complex physical coupling between neighboring microrobots.
View Article and Find Full Text PDFPhys Rev E
November 2024
Physics Institute, Federal University of Rio Grande do Sul, 91501-970 Porto Alegre, Brazil.
We derive exact equations for the spectral density of sparse networks with an arbitrary distribution of the number of single edges and triangles per node. These equations enable a systematic investigation of the effects of clustering on the spectral properties of the network adjacency matrix. In the case of heterogeneous networks, we demonstrate that the spectral density becomes more symmetric as the fluctuations in the triangle-degree sequence increase.
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