Global Alliance in Management Education

About: Global Alliance in Management Education is a based out in . It is known for research contribution in the topics: Magnetic field & Skyrmion. The organization has 577 authors who have published 2057 publications receiving 72848 citations. The organization is also known as: CEMS & The Global Alliance in Management Education.

Secure quantum remote state preparation of squeezed microwave states

Abstract: Quantum communication protocols based on nonclassical correlations can be more efficient than known classical methods and offer intrinsic security over direct state transfer. In particular, remote state preparation aims at the creation of a desired and known quantum state at a remote location using classical communication and quantum entanglement. We present an experimental realization of deterministic continuous-variable remote state preparation in the microwave regime over a distance of 35 cm. By employing propagating two-mode squeezed microwave states and feedforward, we achieve the remote preparation of squeezed states with up to 1.6 dB of squeezing below the vacuum level. Finally, security of remote state preparation is investigated by using the concept of the one-time pad and measuring the von Neumann entropies. We find nearly identical values for the entropy of the remotely prepared state and the respective conditional entropy given the classically communicated information and, thus, demonstrate close-to-perfect security. Continuous-variable remote state preparation in the microwave domain would allow to leverage the superconducting technology for quantum networks applications. Here, the authors show how to deterministically prepare squeezed Gaussian states across 35 cm using previously shared entanglement.

Excitation band topology and edge matter waves in Bose-Einstein condensates in optical lattices

Abstract: We show that Bose-Einstein condensates in optical lattices with broken time-reversal symmetry can support chiral edge modes originating from nontrivial bulk excitation band topology. To be specific, we analyze a Bose-Hubbard extension of the Haldane model, which can be realized with recently developed techniques of manipulating honeycomb optical lattices. The topological properties of Bloch bands known for the noninteracting case are smoothly carried over to Bogoliubov excitation bands for the interacting case. We show that the parameter ranges that display topological bands enlarge with increasing the Hubbard interaction or the particle density. In the presence of sharp boundaries, chiral edge modes appear in the gap between topological excitation bands. We demonstrate that by coherently transferring a portion of a condensate into an edge mode, a density wave is formed along the edge owing to an interference with the background condensate. This offers a unique method of detecting an edge mode through a macroscopic quantum phenomenon.

Thermalization and Heating Dynamics in Open Generic Many-Body Systems.

Abstract: The last decade has witnessed remarkable progress in our understanding of thermalization in isolated quantum systems. Combining the eigenstate thermalization hypothesis with quantum measurement theory, we extend the framework of quantum thermalization to open many-body systems. A generic many-body system subject to continuous observation is shown to thermalize at a single trajectory level. We show that the nonunitary nature of quantum measurement causes several unique thermalization mechanisms that are unseen in isolated systems. We present numerical evidence for our findings by applying our theory to specific models that can be experimentally realized in atom-cavity systems and with quantum gas microscopy. Our theory provides a general method to determine an effective temperature of quantum many-body systems subject to the Lindblad master equation and thus should be applicable to noisy dynamics or dissipative systems coupled to nonthermal Markovian environments as well as continuously monitored systems. Our work provides yet another insight into why thermodynamics emerges so universally.

Zeno Hall Effect.

Abstract: We show that the quantum Zeno effect gives rise to the Hall effect by tailoring the Hilbert space of a two-dimensional lattice system into a single Bloch band with a nontrivial Berry curvature. Consequently, a wave packet undergoes transverse motion in response to a potential gradient-a phenomenon we call the Zeno Hall effect to highlight its quantum Zeno origin. The Zeno Hall effect leads to retroreflection at the edge of the system due to an interplay between the band flatness and the nontrivial Berry curvature. We propose an experimental implementation of this effect with ultracold atoms in an optical lattice.

Engineering skyrmions and emergent monopoles in topological spin crystals

Abstract: Spin structures with a non-trivial topology can emerge through the complex interplay of underlying magnetic interactions. Representative examples are magnetic skyrmions and hedgehogs observed in various materials. Although the most typical size of a skyrmion is 10–100 nm, there has been remarkable progress in the discovery of ultra-small (<3 nm) skyrmions and hedgehogs in the last few years. The dense topological spin crystals not only hold promise for technological applications but also provide a good arena to explore gigantic responses from emergent electromagnetic fields or Berry curvature. Here, we review design principles as well as electronic functions of versatile topological spin crystals, highlighting the distinct properties between skyrmion- and hedgehog-lattice states. Among them, unconventional outcomes from hedgehog-lattice states, such as their formation mechanisms and transport properties induced by the emergent magnetic monopoles, are discussed. The manipulation of such topological spin crystals, based on the strong couplings between topology and spin-charge-lattice degrees of freedom, may pave the way for electronics emerging in the near future.