Quantum papers — 2026-10-19

The Morning Preprint — this day as one edition: the day's papers, the five things worth knowing, and the episodes behind them.

Today we are diving into how subtle structural changes can dramatically alter fundamental physical properties in condensed matter systems. The work that matters most involves understanding how strain can tune superconductivity, as seen in the study on strain-enhanced superconductivity in RuO two thin films.

This research shows that applying compressive strain along the [001] direction pushes certain electronic bands toward the Fermi level and softens specific phonon modes. This action significantly boosts electron-phonon coupling, which in turn increases the critical temperature of superconductivity in RuO two films. The enhancement scales almost linearly with the applied strain.

Another key area is exploring how alloying can simultaneously tune multiple transport characteristics, which is what we see in investigations into Pt-induced semimetallic transport and enhanced thermoelectric response in half-Heusler alloy YNi 0.5Pt 0.5Bi. This work demonstrates that substituting nickel with platinum drives the material toward semimetallic behavior, characterized by hole-dominated conduction and a substantial increase in the room-temperature Seebeck coefficient.

This substitution also reduces thermal conductivity to improve the power factor of the material. We are also looking at how spin-orbit coupling can fundamentally reconstruct pairing channels in correlated systems, as detailed in Pairing-channel reconstruction by Ising spin-orbit coupling in a multiorbital triangular-lattice model.

This study shows that Ising SOC doesn't just protect superconductivity but actively reshapes the low-energy Fermi surfaces and scattering phase space. This reshaping leads to the emergence of both Ising-triplet and topological singlet phases depending on the orbital hybridization.

Furthermore, we are examining how thermal transport can reveal elusive superconducting gaps in heavy-fermion materials, as shown by Band-Resolved Superconducting Gaps via the Thermal Hall Effect in CeRu2. Fixing gap magnitudes using thermal Hall measurements allows researchers to pinpoint which electron sheets carry the larger or smaller pairing gaps based on the sign reversal observed in the thermal Hall conductivity.

Finally, we are touching upon more fundamental aspects of quantum dynamics by studying operator-space entanglement entropy in Random Fermionic Gaussian Dynamics. This work uses a mapping to domain-wall melting problems to derive exact expressions for the time-dependent entanglement entropy in a Brownian SYK two model. This helps connect these complex dynamics to measures of non-gaussianity.

Today's papers

The papers

Important terms

Strain-enhanced superconductivity
This involves applying physical pressure, or strain, to a material like RuO films. This mechanical stress pushes electronic bands closer to the Fermi level and changes vibrations in the crystal lattice, which boosts electron-phonon coupling and raises the superconducting critical temperature.
Semimetallic transport
This describes a material's electrical behavior where it exhibits characteristics between a metal and a semiconductor. In this case, substituting nickel with platinum in YNi0.5Pt0.5Bi changes the conduction to be hole-dominated and significantly increases the room-temperature Seebeck coefficient.
Spin-orbit coupling (SOC) reconstruction
Spin-orbit coupling fundamentally alters how electrons pair up in correlated systems. This effect reshapes the low-energy Fermi surfaces and scattering areas, leading to new superconducting phases like Ising triplets or topological singlets.
Thermal Hall Effect
This measurement technique uses heat flow to probe the elusive superconducting energy gaps in heavy-fermion materials. By analyzing sign reversals in thermal Hall conductivity, researchers can determine which specific electron sheets have larger or smaller pairing gaps.