Universal signature of non-quantum systems

Revista, Zen, PHYSICS, 10

The quest for non-Abelian anyons, exotic quasiparticles fundamental to topological quantum computing, remains a forefront challenge in condensed matter physics. This paper explores the universal topological signatures that characterize non-Abelian anyons when hosted within engineered flat band systems. Flat bands, distinguished by their quenched kinetic energy, dramatically enhance interaction effects, providing a unique platform for stabilizing exotic many-body phases and fostering the emergence of non-Abelian statistics. We theoretically investigate how specific lattice geometries and tuning parameters in various engineered platforms, such as Moiré superlattices, photonic crystals, and ultracold atomic gases, can lead to the formation of topological flat bands conducive to non-Abelian anyonic excitations. Our analysis identifies several universal signatures, including robust ground state degeneracy sensitive to system topology, characteristic patterns in topological entanglement entropy, and distinct braiding statistics manifested through non-Abelian holonomies and fractional quantum numbers. These signatures are shown to be robust against local perturbations and largely independent of microscopic details, providing reliable indicators for experimental detection. We discuss the implications for developing fault-tolerant quantum computation and outline potential experimental methodologies for probing these predicted signatures, emphasizing the transformative potential of engineered flat bands in advancing topological quantum science.

Tao Shang, Xiaojie Zhao, Chao Wang +1 more

Sergio Cecotti

Shirley Cheung, C. H. LEE, Yunlei Zhao

Blind signatures play a critical role in digital cash systems. In this paper, we investigate the blind signature functionality in the framework of universally composable (UC) security — the strongest security guarantees up to now for cryptographic protocols over the Internet. We present the universally composable blind signature functionality, [Formula: see text]. Our approach is based on a new UC signature functionality [Formula: see text], which is a modified version of the original signature functionality [Formula: see text] presented by Canetti. We also prove that [Formula: see text] and [Formula: see text] are actually equivalent with respect to non-adaptive adversaries. Our result is of both theoretical and practical consequence to future research studies and practical implementations of digital cash systems with universally composable security.

Chris Fields, James F. Glazebrook

Masayuki Abe, Miyako Ohkubo

This paper studies non-committing type of universally composable (UC) blind signature protocols where an adversary does not necessarily commit to a message when requesting a signature. An ordinary UC blind signature functionality requires users to commit to the message to be blindly signed. It is thereby impossible to realise in the plain model. This paper first shows that even non-committing variants cannot be realised in the plain model. We then characterise UC non-committing blind signatures in the common reference string model by presenting equivalent stand-alone security notions under static corruption. The usefulness of the characterisation is demonstrated by showing that Fischlin’s basic stand-alone blind signature scheme can be transformed into a UC non-committing blind signature protocol without using extra cryptographic components. We extend the results to the adaptive corruption model and present analogous notions, theorems, and constructions both in the erasure model and the non-erasure model.