The urgent demand for sustainable energy storage devices necessitates the development of novel conceptual and technological paradigms that extend beyond the constraints imposed by classical thermodynamic limits. in order to present the material innovations required to enable viable room-temperature quantum technologies, this Review outlines the potential of dinuclear Cu(II) complexes as promising model platforms for the development of room-temperature quantum batteries. We address how the quantum properties of these dinuclear materials can be harnessed to store and extract energy, and how they can be handled and engineered by the management of the intra-molecular magnetic coupling and external thermodynamic conditions. Through macroscopic magnetometric mappings, we present how the maximum extractable work (ergotropy) can be directly quantified without invasive quantum tomography. Furthermore, we review the operational simulation of these materials using quantum computing approaches using the variational quantum thermalizer (VQT) algorithm on noisy intermediate-scale quantum (NISQ) devices. Finally, we provide an outlook on future research directions, highlighting the critical material engineering and quantum error mitigation strategies required to transition these coordination compounds from theoretical models to functional macroscopic solid-state quantum energy storage devices at room temperature.
We theoretically investigate the transport properties of a topological insulator (TI) connected to two-dimensional altermagnetic (AM) leads in the absence of an external magnetic field. Exploiting the intrinsic time-reversal symmetry breaking of altermagnets, we report the emergence of a field-free transverse differential conductivity in the resulting AM-TI-AM heterostructure. Our analysis reveals that this transverse response is highly sensitive to the orientation of the Néel vector: a finite transverse conductivity manifests when the Néel vector possesses an out-of-plane component, whereas it strictly vanishes for in-plane orientations (θ= π/2) under symmetric chemical potentials (μ_t = μ_b) due to the restoration of symmetry between the k_y and -k_y momentum channels. Conversely, when asymmetric chemical potentials are applied (μ_t ≠ μ_b), this symmetry is broken, yielding a finite transverse response even for an in-plane Néel vector. Furthermore, we demonstrate that while the longitudinal differential conductivity exhibits Fabry-Pérot-type oscillations as a function of the TI's chemical potential, the transverse conductivity displays a distinct antisymmetric dependence. Notably, the oscillatory behavior of the longitudinal conductivity persists even at finite temperatures. Spatially, the transverse current contribution decays exponentially with position inside the TI region. We also find that both the longitudinal and transverse differential conductivity exhibit periodic oscillations with the junction parameter χ_t=χ_b. These findings provide a fundamental understanding of field-free transverse responses in spin-momentum locked boundary states, highlighting the potential of AM-TI heterojunctions for next-generation spintronic applications.
Collective spin systems in solid-state materials are promising platforms for quantum-enhanced sensing. In systems such as nitrogen-vacancy centers in diamond, donor spins in silicon, and magnetic materials, interactions among many spins can generate collective quantum correlations that improve measurement precision beyond the standard quantum limit. This tutorial develops an intuitive, materials-oriented framework for understanding these effects through nonlinear collective-spin dynamics. We show how nonlinear interactions reshape collective spin states in phase space, redistribute quantum fluctuations, and generate metrologically useful states such as spin-squeezed and entangled states. We then connect these ideal collective dynamics to microscopic interactions and realistic solid-state systems, discussing how interaction strength, disorder, decoherence, and experimental control affect sensing performance. Different platforms and experiments are compared to highlight key material properties, advantages, and limitations. The tutorial focuses on a materials-oriented understanding of nonlinear collective-spin sensing, rather than a comprehensive comparison of experimental platforms or a practical guide to sensing experiments.
Tin telluride (SnTe) is a topological crystalline insulator: a variant of the well-known topological insulator class where the topological protection arises from crystal symmetries. The topological surface states (TSSs) have been experimentally observed in angle-resolved photoemission spectroscopy and scanning tunneling microscopy measurements. Conclusive detection in electronic transport measurements remains a challenge, not in small part because of the high intrinsic bulk conductivity. This review summarizes recent progress in understanding the TCI phase in SnTe and related ternary compounds through a wide variety of electronic transport experiments, with magnetotransport as the workhorse. For example, using the Hall, weak antilocalization and Shubnikov–de Haas effects, system properties like carrier density, phase coherence, and the Fermi surface can be studied. However, disentangling contributions to the electronic transport originating from the bulk and the surface proves to be an omnipresent obstacle. Developments in transport experiments rely strongly on advances made in material engineering. Therefore, we put a spotlight on novel and improved synthesis methods, new nanostructuring approaches like selective-area growth, ultrathin films, and doping. Additionally, the interplay between the TSSs and magnetism, superconductivity and crystal perturbations can all result in nonlinear or emergent quantum phenomena or (higher-order) topological phase transitions. Especially the interplay between topology and (induced) superconductivity is of interest for anticipated applications in topological quantum computing, and is therefore a driving force behind the research on this material system. We have chosen to highlight experiments that pave the way for the exploration of these more exotic quantum states and applications, in addition to an overview and assessment of the seminal works on the material system. Together, these findings illuminate the challenges and opportunities in surface state transport in SnTe-based topological materials.
Photocatalytic materials form an important class of quantum materials in which the electronic structure governs charge-carrier behaviour and reaction pathways through quantum-mechanical processes. To accelerate the discovery of superior photocatalytic quantum materials, we present a quantum-enhanced machine learning framework that integrates many-body electronic-structure descriptors with ensemble machine-learning algorithms. The framework explicitly incorporates quantum coherence lengths, electron–phonon coupling strengths, exciton binding energies, and spin–orbit coupling parameters obtained from density functional theory (DFT) and many-body perturbation theory GW approximation and the Bethe–Salpeter equation (GW-BSE) calculations. The database is based on a screened library of 8642 photocatalytic materials that have been experimentally characterised in H $ _2$ evolution reactions and contains 152 descriptors relating to electronic correlations, quantum confinement effects, and spin-dependent properties. Five-fold cross-validation yields $R^2 = 0.82$ and MAE $ = 0.28$ log units, $n$ 18% relative improvement in prediction accuracy ( $R^2$ : 0.82 vs 0.69) over a baseline model using only classical descriptors ( $R^2 = 0.69$ , MAE $ = 0.38$ log units). High-throughput screening of 45 000 hypothetical compositions yielded 214 candidate quantum materials; DFT and GW-BSE validation on representative subset of 23 of these candidates showed 72% agreement within quantum uncertainty bounds. quantum coherence shows a statistically significant association with photocatalytic charge separation, with optimal coherence lengths of 15–35 nm being strongly correlated with increased hydrogen-evolution production. Our findings indicate that many-body interactions, including exciton dissociation dynamics and quantum tunnelling contributions to interfacial charge transfer, are predictive of photocatalytic activity in emerging quantum materials.
