We formulate and prove a general weak limit theorem for quantum random walks in one and more dimensions. With X(n) denoting position at time n, we show that X(n)/n converges weakly as n--> infinity to a certain distribution which is absolutely continuous and of bounded support. The proof is rigorous and makes use of Fourier transform methods. This approach simplifies and extends certain preceding derivations valid in one dimension that make use of combinatorial and path integral methods.
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http://dx.doi.org/10.1103/PhysRevE.69.026119 | DOI Listing |
Phys Rev Lett
December 2024
National University of Singapore, Department of Physics, Singapore 117551.
We uncover emergent universality arising in the equilibration dynamics of multimode continuous-variable systems. Specifically, we study the ensemble of pure states supported on a small subsystem of a few modes, generated by Gaussian measurements on the remaining modes of a globally pure bosonic Gaussian state. We find that beginning from highly entangled, complex global states, such as random Gaussian states and product squeezed states coupled via a deep array of linear optical elements, the induced ensemble attains a universal form, independent of the choice of measurement basis: it is composed of unsqueezed coherent states whose displacements are distributed normally and isotropically, with variance depending on only the particle-number density of the system.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Universidade Federal de Pernambuco, Departamento de Física, Centro de Ciências Exatas e da Natureza, Recife, Pernambuco 50670-901 Brazil.
We introduce and explore the notion of texture of an arbitrary quantum state, in a selected basis. In the first part of this Letter we develop a resource theory and show that state texture is adequately described by an easily computable monotone, which is also directly measurable. It is shown that textures are useful in the characterization of unknown quantum gates in universal circuit layers.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Tel Aviv University, School of Physics and Astronomy, Tel Aviv 6997801, Israel.
Measurement-based quantum computation (MBQC) is a universal platform to realize unitary gates, only using measurements that act on a preprepared entangled resource state. By deforming the measurement bases, as well as the geometry of the resource state, we show that MBQC circuits always transmit and act on the input state but generally realize nonunitary logical gates. In contrast to the stabilizer formalism that is often used for unitary gates, we find that ZX-calculus is an ideal computation method for these nonunitary gates.
View Article and Find Full Text PDFACS Nano
January 2025
Creative Research Initiative Center for Nanospace-confined Chemical Reactions (NCCR), Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea.
Unlike homogeneous metal complexes, achieving absolute control over reaction selectivity in heterogeneous catalysts remains a formidable challenge due to the unguided molecular adsorption/desorption on metal-surface sites. Conventional organic surface modifiers or ligands and rigid inorganic and metal-organic porous shells are not fully effective. Here, we introduce the concept of "ligand-porous shell cooperativity" to desirably reaction selectivity in heterogeneous catalysis.
View Article and Find Full Text PDFThe study investigates the effectiveness of immersive virtual reality (VR) as a nonpharmaceutical approach to manage postoperative pain in patients following thoracoscopic surgery. In this single-center, triple-arm pilot randomized controlled trial (RCT), 61 postsurgical patients with a postoperative pain numerical rating scale (NRS) score ≥4 after receiving standard analgesia were included and assigned to either a quantum clinics-VR (QTC-VR) group, a Placebo-VR group, or a control group. The QTC-VR group engaged in a daily 10-minute interactive pain relief 3D-VR program, while the Placebo-VR group watched a daily 10-minute relaxation-based 2D film through VR headsets for three days following surgery.
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