Search

In superconducting circuits, the nonlinearity of Josephson junctions mediates photon interactions, but they are typically dominated by two-photon processes. Here the authors observe multi-photon interactions in a superconducting circuit with Cooper-pair pairing, revealing a new regime of microwave quantum optics.

By coupling two quantum dots via a superconductor-semiconductor hybrid region in a 2D electron gas, the authors achieve efficient splitting of Cooper pairs. Further, by applying a magnetic field perpendicular to the spin-orbit field, they can induce and measure large triplet correlations in the Cooper pair splitting process.

Spin-entangled electron pairs are one possible resource for future solid-state quantum information processing systems. Here, the authors directly prove spin entanglement between two electrons that had previously been a Cooper pair in a superconducting lead but were split using two quantum dots.

Disorder leads to localization of electrons at low temperatures, changing metals to insulators. In a superconductor the electrons are paired up, and scanning tunnelling microscopy shows that the pairs localize together rather than breaking up and forming localized single electrons in the insulating state.

Controllable detection of singlet and triplet Cooper pair splitting via crossed Andreev reflection is demonstrated in spin-polarized quantum dots on a superconducting nanowire platform with strong spin–orbit coupling.

Whether and how the Dirac electrons can be driven into superconducting state remains unclear. Here, Duet al. present systematic study to demonstrate the Dirac electrons condensing into Cooper pairs on the surface of a possible topological superconductor Sr_xBi₂Se₃.

Vertebra lengths differ from the neck to the tail tip and differ between species, evidenced by extreme differences in mouse and jerboa tails. Here, Weber and colleagues identify cellular mechanisms and candidate genes that shape vertebral proportion.

This Review highlights chip-scale superconducting coherent photon source technologies and their rich potential as an important integrated quantum hardware to advance quantum information processing and communication networks.

The authors study a disordered β-Ta film, finding that quasiparticle recombination is governed by the phonon scattering time, which is faster than conventional recombination in ordered superconductors. The authors interpret the results in terms of quasiparticle localization, which helps to understand the quasiparticle relaxation in disordered superconducting circuits.

One of the most counterintuitive fundamental properties of quantum mechanics is non-locality, which manifests itself as correlations between spatially separated parts of a quantum system. Although experimental tests of non-locality (Bell inequalities) have been successfully conducted with pairwise entangled photons, similar demonstrations using electrons have so far not been possible. The realization of a Y-shaped tunable Cooper pair splitter, to split entangled electrons on demand, brings this one step closer.

One minute parity lifetimes are reported in a superconducting transistor made of niobium titanite nitride coupled to aluminium contacts even in the presence of small magnetic fields, enabling the braiding of Majorana bound states.

Owing to electron localization, two-dimensional materials are not expected to be metallic at low temperatures, but a field-induced quantum metal phase emerges in NbSe₂, whose behaviour is consistent with the Bose-metal model.

By pushing scanning tunnelling spectroscopy down to millikelvin temperatures, it is now possible to image a heavy fermion superconductor and measure the superconducting gap symmetry, with gap nodes in unexpected momentum-space locations.

Although quantum phase transitions are attracting increasing attention as the conceptual link between conventional and exotic states of quantum matter—having been implicated, for example, in the properties of high-temperature superconductors—there are few model systems in which they can be studied and understood. Now it is revealed that placing simple elemental chromium under pressure suppresses its normal magnetic state and gives direct experimental access to the underlying quantum phase transition responsible for these changes.

Scanned Josephson tunnelling microscopy is used to image Cooper pair tunnelling from a superconducting microscope tip to the quantum condensate of Bi₂Sr₂CaCu₂O_8+x, thus revealing the spatially modulated density of Cooper pairs predicted from several theories of the cuprate pseudogap phase.

The authors present experimental evidence of three-dimensional superinsulation in a nanopatterned slab of NbTiN. In the electric Meissner state, they find polar nematic order arising from ferroelectric alignment of short electric strings excited by external electromagnetic fields.

UTe₂ is a proposed intrinsic topological superconductor, but its quasiparticle surface band has not yet been visualized. Now this is achieved using quasiparticle interference imaging, revealing the symmetry of the superconducting order parameter.

In high-temperature superconductors, a very low density of states, the pseudogap, exists even above the critical temperature. Here, the authors show that this is also the case for a conventional superconductor, titanium nitride thin films, and that this pseudogap is induced by superconducting fluctuations.

Superconducting spintronics has the potential to enhance device functionality by realising spin polarised supercurrents with greater coherence and reduced dissipation. Here, using ferromagnetic resonance, the authors investigate the temperature dependence of the Gilbert damping for the Fe layer of Nb/Fe/Nb and Nb/Cr/Fe/Cr/Nb stacks and the impact superconducting spin triplets have on the spin pumping behaviour.

The authors reveal an inherent trade-off between logarithmic average phonon frequency and the electron-phonon coupling constant in conventional BCS superconductors. The analysis suggests that achieving room-temperature conventional superconductivity at ambient pressure is extremely unlikely.

The standard model describes many aspects of particle physics but mechanisms such as the binding of quarks into hadrons, still remain a mystery. The authors theoretically outline an analogy with the Cooper pairs of a superinsulator to demonstrate that the mechanisms behind the infinite resistance of a superinsulator are analogous to that which confine quarks into hadrons.

Quarks in the interior of hadrons make up most of ordinary matter, yet their observation is not possible, and their properties can only be probed indirectly. Adopting an analogy between physics of superinsulators and high energy physics, the authors present direct observations of the interior of electric mesons made of Cooper pairs by standard transport measurements.

Finite momentum superconducting pairing refers to a class of unconventional superconducting states where Cooper pairs acquire a non-zero momentum. Here the authors report a new superconducting state in bulk 4Hb-TaS₂, where magnetic fields induce finite momentum pairing via magnetoelectric coupling.

African ancestry is a known risk factor for prostate cancer development, but the genetic determinants of this are incompletely understood. Here, the authors identify 172 potentially pathogenic variants which are enriched in an African population.

The direct contribution of aberrant epithelial cells to lung fibrosis is largely unknown. The authors use murine and human systems to identify how these cells activate fibroblasts, and how reciprocal signals cause them to enter a profibrotic state.

Natural Killer cells are key mediators of anti-tumour immunosurveillance and anti-viral immunity. Here, the authors map regulatory genetic variation in primary Natural Killer cells, providing new insights into their role in human health and disease.

People living in rural areas of the United States have poorer outcomes from acute COVID-19. Here, the authors show that higher mortality rates among rural dwellers persist for up to two years after the initial infection, even after accounting for baseline risk factors.

Chiral superconductors are very rare topological materials. Here, the authors report spontaneous magnetic fields inside the superconducting state and low temperature linear behavior in the superfluid density in LaPt₃P, suggesting a chiral d-wave singlet superconducting state.

A major mystery in cuprate superconductors is how Cooper pairs form and condense. Here, the authors use RIXS and STM techniques to reveal that a charge-ordered insulating phase and enhanced bond-buckling phonons play important roles in this process.

Conventional superconductors were thought to be spin inert, but long-lived, spin-polarized excitations, or quasiparticles, have recently been observed. Here, the authors demonstrate quasiparticle spin resonance in the mesoscopic superconductor aluminium and estimate the spin coherence time.

Pairing interaction appears at room temperature in traditional superconductors with a Cooper instability in the Fermi sea. Here, Maier et al.report that in the pseudogap phase of cuprate, where this instability is absent, superconductivity arises from an increase in the strength of the spin fluctuation pairing interaction as the temperature decreases.

The emergence of a giant phonon anomaly in the pseudogap phase of underdoped cuprate superconductors has been assumed to be a consequence of instability towards a charge density wave state. Here, the authors present a theory suggesting the anomaly arises due to large superconducting fluctuations.

Evidence of quantum phase transitions is normally difficult to be detected. Here, Liu and Wang et al. report divergent critical exponent in ultrathin Pb films with superconducting fluctuations and spin-orbit interaction, indicating an anomalous quantum Griffiths singularity of superconductor-metal transition.

Superconducting circuits are promising for quantum computing, but quasiparticle tunnelling across Josephson junctions introduces qubit decoherence. Ristè et al. convert a transmon qubit into its own real-time quasiparticle tunnelling detector and accurately measure induced decoherence in the millisecond range.

The microscopic pairing mechanism in high-temperature superconductors remains debated. Here, the authors offer a new perspective on this problem by proposing that the strong pairing in Fermi-Hubbard type models relevant to cuprates is driven by a Feshbach resonance, which enhances interactions between doped holes.

Background radiation has been identified as a key factor limiting the coherence times of superconducting circuits. Here, the authors measure the impact of environmental and cosmic radiation on a superconducting resonator with varying degrees of shielding, including an underground facility.