Proximity-induced superconductivity in a 2D Kondo lattice of an f-electron-based surface alloy

Realizing hybrids of low-dimensional Kondo lattices and superconducting substrates leads to fascinating platforms for studying the exciting physics of strongly correlated electron systems with induced superconducting pairing. Here, we report a scanning tunneling microscopy and spectroscopy study of a new type of two-dimensional (2D) La-Ce alloy grown epitaxially on a superconducting Re(0001) substrate. We observe the characteristic spectroscopic signature of a hybridization gap evidencing the coherent spin screening in the 2D Kondo lattice realized by the ultrathin La-Ce alloy film on normal conducting Re(0001). Upon lowering the temperature below the critical temperature of rhenium, a superconducting gap is induced with an in-gap Shiba band arising from the interaction of residual unscreened magnetic moments with the superconducting substrate. A positive correlation between the Kondo hybridization gap and the binding energy of the subgap Shiba band maximum is found. Our results open up a promising route toward the design of artificial superconducting Kondo and heavy fermion systems.Comment: 18 pages, 4 figures, supplemental material

Atomic-Scale Interface Engineering of Majorana Edge Modes in a 2D Magnet-Superconductor Hybrid System

Topological superconductors are predicted to harbor exotic boundary states - Majorana zero-energy modes - whose non-Abelian braiding statistics present a new paradigm for the realization of topological quantum computing. Using low-temperature scanning tunneling spectroscopy (STS), we here report on the direct real-space visualization of chiral Majorana edge states in a monolayer topological superconductor, a prototypical magnet-superconductor hybrid system comprised of nano-scale Fe islands of monoatomic height on a Re(0001)-O(2$\times$1) surface. In particular, we demonstrate that interface engineering by an atomically thin oxide layer is crucial for driving the hybrid system into a topologically non-trivial state as confirmed by theoretical calculations of the topological invariant, the Chern number.Comment: 26 pages, 9 figure

FiFo: Fishbone Forwarding in Massive IoT Networks

Massive Internet of Things (IoT) networks have a wide range of applications, including but not limited to the rapid delivery of emergency and disaster messages. Although various benchmark algorithms have been developed to date for message delivery in such applications, they pose several practical challenges such as insufficient network coverage and/or highly redundant transmissions to expand the coverage area, resulting in considerable energy consumption for each IoT device. To overcome this problem, we first characterize a new performance metric, forwarding efficiency, which is defined as the ratio of the coverage probability to the average number of transmissions per device, to evaluate the data dissemination performance more appropriately. Then, we propose a novel and effective forwarding method, fishbone forwarding (FiFo), which aims to improve the forwarding efficiency with acceptable computational complexity. Our FiFo method completes two tasks: 1) it clusters devices based on the unweighted pair group method with the arithmetic average; and 2) it creates the main axis and sub axes of each cluster using both the expectation-maximization algorithm for the Gaussian mixture model and principal component analysis. We demonstrate the superiority of FiFo by using a real-world dataset. Through intensive and comprehensive simulations, we show that the proposed FiFo method outperforms benchmark algorithms in terms of the forwarding efficiency.Comment: 13 pages, 16 figures, 5 tables; to appear in the IEEE Internet of Things Journal (Please cite our journal version that will appear in an upcoming issue.

Quantum Circuit Designs of Point Doubling Operation for Binary Elliptic Curves

In the past years, research on Shor’s algorithm for solving elliptic curves for discrete logarithm problems (Shor’s ECDLP), the basis for cracking elliptic curve-based cryptosystems (ECC), has started to garner more significant interest. To achieve this, most works focus on quantum point addition subroutines to realize the double scalar multiplication circuit, an essential part of Shor’s ECDLP, whereas the point doubling subroutines are often overlooked. In this paper, we investigate the quantum point doubling circuit for the stricter assumption of Shor’s algorithm when doubling a point should also be taken into consideration. In particular, we analyze the challenges on implementing the circuit and provide the solution. Subsequently, we design and optimize the corresponding quantum circuit, and analyze the high-level quantum resource cost of the circuit. Additionally, we discuss the implications of our findings, including the concerns for its integration with point addition for a complete double scalar multiplication circuit and the potential opportunities resulting from its implementation. Our work lays the foundation for further evaluation of Shor’s ECDLP