The visualization of the magnetic responses of a two-dimensional (2D) superconducting material on the nanoscale is a powerful approach to unravel the underlying supercurrent behavior and to investigate critical phenomena in reduced dimensions. In this study, scanning quantum microscopy is utilized to explore the local magnetic response of the 2D superconductor 2H-NbSe2. Our technique enables both static and dynamic sensing of superconducting vortices with high sensitivity and a spatial resolution down to 30 nm, unveiling unexpected phenomena linked to the intrinsic 2D nature of the superconductor, which are challenging to detect with more conventional local probes. Vortices do not arrange in a hexagonal lattice, but form a distorted vortex glass with expanding vortex size. A vortex can exhibit strong local dynamics due to thermal excitation. As the critical temperature is approached, a clear melting of the vortex glass is identified, leading to distinct configurations under different cooling conditions. Vortex fluctuations can also be probed through spin Hahn-echo measurements, which reveal the spin decoherence even well below the critical temperature -- and, intriguingly, enhanced decoherence at lower temperatures. Spatiotemporal microscopy of the magnetic dynamics associated with vortex excitations and fluctuations provides direct evidence of 2D superconducting phenomena at the nanoscale.

Информационно-аналитический ресурс о событиях в мире: текущие новости, еженедельные обзоры, обсуждения.

Boston MA (SPX) May 06, 2025 - MIT physicists have captured the first images of individual atoms freely interacting in space. The pictures reveal correlations among the free-range particles that until now were predicted but nev

The braiding of Majorana zero modes (MZMs) forms the fundamental building block for topological quantum computation. Braiding protocols which involve the physical exchange of MZMs are typically envisioned on a network of topological superconducting wires. An essential component of these protocols is the transport of MZMs, which can be performed by using electric gates to locally tune sections ("piano keys") of the wire between topologically trivial and non-trivial phases. In this work, we numerically simulate this piano key transport on a superconducting wire which contains either disorder (uncorrelated and correlated) or noise. We focus on the impact of these additional effects on the diabatic error, which describes unwanted transitions between the ground state and excited states. For disorder, we show that the behavior of the average diabatic error is predominantly controlled by the statistics of the minimum bulk energy gap. When the disorder is spatially correlated, we demonstrate that this leads to an increase in the diabatic error due to a further suppression of the minimum bulk energy gap and highlight the scaling of this suppression with the piano key size. For noise, we illustrate that the diabatic error is significantly enhanced due to optical transitions which depend on the minimum bulk energy gap as well as the frequency modes present in the noise. The results presented here serve to further characterize the diabatic error in disordered and noisy settings, which are important considerations in practical implementations of physical braiding schemes.

Scientific Data - SuperBand: an Electronic-band and Fermi surface structure database of superconductors

Imagine a world in which free-floating electric vehicles charge wirelessly as they glide down highways, laptops are hundreds of times more powerful, and clean energy flows in limitless supply.

Transition-metal dichalcogenides (TMDs) offer an extremely rich material platform in the exploration of unconventional superconductivity. The unconventional aspects include exotic coupling mechanisms such as the Ising pairing, a complex interplay with other electronic orders such as charge-density waves (CDWs), symmetry-breaking and topological effects, and non-trivial gap structures such as multi-gap and possible nodal phases. Among TMDs, titanium diselenide (1$T$-TiSe$_2$) is one of the most studied and debated cases. Hints to an anomalous structure of its superconducting order parameter have emerged over the years, possibly linked to its spatial texturing in real and reciprocal space due to the presence of a 2$\times$2$\times$2 CDW phase, or to a pressure-driven multi-band Fermi surface. However, a direct evidence for a non-trivial structure of the superconducting gap in this material is still lacking. In this work, we bring the first evidence for a two-gap structure in the recently-discovered H-intercalated TiSe$_2$ superconductor (with T$_c \simeq 3.6$ K) by an extensive experimental study that combines magnetotransport measurements, point-contact spectroscopy and scanning tunnel spectroscopy. We show that the temperature dependence of the upper critical field (for $\vec B \parallel c$) as well as the shape of the point-contact and tunneling spectra strongly suggest the existence of two distinct superconducting gaps, and can indeed all be fitted in a self-consistent way with the same gap amplitudes $Δ_1 = 0.26 \pm 0.12$ meV and $Δ_2 =0.62 \pm 0.18$ meV.

El rápido desarrollo que está experimentando la computación cuántica está desmontando poco a poco las opiniones que ponen en duda el potencial de esta...

Researchers at QuTech in Delft merge superconductors and quantum dots to study Majorana bound states for stable quantum computation, showcasing key properties in a chain of three coupled quantum dots.

Researchers at QuTech in Delft have combined superconductors and quantum dots to observe and manipulate so-called Majorana bound states, which have properties that could enable stable quantum computation. By building a chain of three coupled quantum dots in a two-dimensional electron gas, they were able to demonstrate properties of Majoranas that are essential for the study of Majorana-based quantum bits.

Yellowstone's Potential Role in Global Solutions Revealed in New Study

Using a state-of-the-art numerical scheme, we show that the Higgs mode under excitation exhibits chirped oscillations and exponential decay when fluctuations are included. This is in stark contrast to conventional BCS collisionless dynamics which predict power-law decay and the absence of chirping. The chirped amplitude mode enables us to determine the local modification of the effective potential even when the system is in a long-lived prethermal state. We then show that this chirped amplitude mode is an experimentally observable quantity since the photoinduced (super)current in pump-probe experiments serves as an efficient proxy for the order parameter dynamics, including the chirped dynamics. Our result is based on the attractive Hubbard model using dynamical mean-field theory within the symmetry-broken state after a excitation across the superconducting gap. Since the collective response involves long timescales, we extend the hierarchical low-rank compression method for nonequilibrium Green's functions to symmetry-broken states and show that it serves as an efficient representation despite long-lived memory kernels.