The study, published in the journal Quantum Information Processing by M. Y. Abd-Rabbou and colleagues at institutions including the University of Chinese Academy of Sciences, Al-Azhar University, Prince Sattam bin Abdulaziz University and Imam Mohammad Ibn Saud Islamic University, tackles a problem that is easy to state but hard to solve. Bidirectional quantum teleportation allows two parties to exchange quantum states simultaneously, a capability that would be enormously valuable in distributed quantum networks. But the physical channels that carry the entanglement between the parties are never perfect. They are built from real spins embedded in real environments, and those environments conspire to degrade the very correlations the protocol depends on.

At the heart of the new work is a specific choice of channel: an open Heisenberg XYZ spin system. The Heisenberg model describes interacting quantum spins whose exchange couplings can differ along the x, y and z axes — hence the three letters. Such systems are natural candidates for solid-state quantum communication because entanglement can be generated and distributed directly through the intrinsic spin-spin interactions of the material. Yet the authors go beyond the standard model by adding a term known as the Dzyaloshinskii–Moriya interaction, an antisymmetric spin-orbit coupling that arises in certain magnetic materials when inversion symmetry is broken.

That antisymmetric term turns out to be far more than a small correction. Because it breaks the exchange symmetry between the two communicating parties, it induces a fundamental directional asymmetry in the information transfer. In plain terms, teleporting a state from Alice to Bob through the channel does not behave in the same way as teleporting a state from Bob back to Alice. The fidelity of the reconstructed state — a measure of how closely the output matches the intended input — becomes direction-dependent. For engineers designing a future quantum network, this asymmetry is a crucial practical consideration: the same physical link may perform differently depending on which way the information is being sent.

To quantify how well the protocol survives in an imperfect world, the researchers subjected the channel to two of the most common and damaging forms of environmental noise: Markovian amplitude damping and pure dephasing. Amplitude damping models the loss of energy from the system to its surroundings — the quantum analogue of a qubit slowly relaxing to its ground state — while pure dephasing scrambles the relative phases between quantum states without exchanging energy. Both processes erode entanglement, and both are unavoidable features of real devices. The team evaluated the performance of the bidirectional teleportation protocol using directional state fidelities, tracking separately how well each direction of communication fares as the noise acts on the shared channel.

But fidelity alone does not tell the whole story. The authors also turned to quantum Fisher information, a cornerstone of quantum metrology that measures how much information a quantum state can carry about an unknown parameter. In this context, the quantum Fisher information serves as a sensitive probe of how much useful quantum information survives the teleportation process in each direction. By computing it under the same noisy conditions, the researchers gained a second, independent window onto the degradation of the channel — one that connects the teleportation protocol to the broader framework of quantum estimation and precision measurement.

The most forward-looking element of the study, however, is its use of active control to fight back against decoherence. The team applied DRAG pulses — Derivative Removal by Adiabatic Gate pulses — a technique first developed by Motzoi, Gambetta, Rebentrost and Wilhelm in 2009 to eliminate leakage in weakly nonlinear qubits. In superconducting and other weakly anharmonic systems, driving a qubit too hard can accidentally populate states outside the computational two-level subspace, corrupting the operation. DRAG pulses counteract this by adding a carefully calibrated quadrature component to the control signal, which suppresses the unwanted transitions before they accumulate.

In the context of the teleportation channel, the DRAG scheme serves a different but equally vital purpose: actively protecting the distributed entanglement that both directions of the protocol rely upon. The authors show that the optimized quadrature correction suppresses computational leakage and elevates the performance bounds across all of the evaluated metrics — the directional fidelities and the quantum Fisher information alike. In other words, precise pulse engineering does not merely prevent errors in individual gates; it raises the ceiling on how well the entire two-way teleportation process can perform in the presence of both intrinsic channel asymmetry and environmental noise. The numerical results establish the operational limits of asymmetric quantum communication channels and demonstrate, in the authors’ words, the necessity of precise pulse calibration for maintaining a quantum advantage.

The work sits within a rapidly growing literature on bidirectional teleportation. Since Kiktenko, Popov and Fedorov showed in 2016 that even a single imperfect Bell state can support two-way transfer, proposals have proliferated: schemes using 2n Bell states for arbitrary numbers of qubits, asymmetric protocols teleporting different numbers of qubits in each direction, controlled versions mediated by multi-qubit cluster states, and extensions to continuous variables and high-dimensional systems. Recent studies have also probed how correlated noise, memory effects, amplitude damping and dephasing degrade bidirectional protocols. What distinguishes the new contribution is its combination of a physically grounded, asymmetric spin channel — complete with the Dzyaloshinskii–Moriya interaction — with a modern pulse-control strategy, treating the channel and its control as a single integrated problem rather than two separate ones.

The implications reach beyond teleportation itself. Spin chains with Dzyaloshinskii–Moriya interactions are relevant to spintronics, quantum optics and the design of entanglement-distribution hardware, and DRAG-style pulse shaping is already a workhorse of superconducting-qubit and Rydberg-atom experiments. By mapping out exactly how directional asymmetry and decoherence constrain performance — and by showing how calibrated pulses push those constraints back — the study offers a practical recipe for anyone building quantum links where information must flow both ways. As quantum networks edge closer to reality, the lesson is clear: the quality of a quantum channel is not fixed by its material alone, but by how cleverly we drive it. The full article is available in Quantum Information Processing, volume 25, article 341.

Subject of Research: Bidirectional quantum teleportation through a noisy Heisenberg XYZ spin channel with Dzyaloshinskii–Moriya interaction and DRAG pulse control

Article Title: Bidirectional quantum teleportation through an open Heisenberg XYZ with Dzyaloshinskii–Moriya interaction channel driven by DRAG pulses

Article References: Abd-Rabbou, M. Y., Aljuaydi, F., Jaradat, E. K., & Alghwali, A. S. A. (2026). Bidirectional quantum teleportation through an open Heisenberg XYZ with Dzyaloshinskii–Moriya interaction channel driven by DRAG pulses. Quantum Information Processing, 25(10), Article 341. https://doi.org/10.1007/s11128-026-05348-1

Image Credits: AI Generated

DOI: 10.1007/s11128-026-05348-1

Keywords: quantum teleportation, bidirectional teleportation, Heisenberg XYZ model, Dzyaloshinskii–Moriya interaction, DRAG pulses, decoherence, quantum Fisher information, entanglement, amplitude damping, dephasing, quantum networks, spintronics

The method, called beam-shift-based four-dimensional electron magnetic circular dichroism, builds on a phenomenon first demonstrated in a transmission electron microscope in 2006. When electrons pass through a magnetic material, the energy-loss spectra of the transmitted beam differ subtly depending on the relative orientation of the electron beam and the local magnetization, an effect known as electron magnetic circular dichroism, or EMCD. The dichroic signal is sensitive to the spin and orbital magnetic moments of the atoms in the beam path. Earlier work by Jan Rusz and collaborators showed theoretically and experimentally that EMCD could, in favorable geometries, deliver magnetic information at atomic-plane resolution, but extracting a full three-dimensional vector from such data remained a formidable challenge.

The innovation of the new study lies in how the electron probe is manipulated. By deliberately shifting the incident beam within the convergent beam geometry of a three-beam diffraction condition, the researchers gain access to different Cartesian components of the magnetization vector. In a three-beam condition, a systematic row of diffraction spots is strongly excited, and the dynamical diffraction of the electrons through the crystal makes the EMCD signal selectively sensitive to particular magnetization components. Shifting the beam and analyzing the resulting four-dimensional data set, which records a full energy-loss spectrum at every probe position, allows the team to separate the out-of-plane component along the beam direction from the two in-plane components. Simulations of the relative dynamical diffraction coefficients guided the choice of detector integration windows, and the team demonstrated that in each optimized configuration the target magnetic component dominates the extracted signal, keeping crosstalk between components under control.

To validate the approach, the researchers turned to yttrium orthoferrite, YFeO3, a canted antiferromagnet that has fascinated physicists since the 1960s. In an ideal antiferromagnet, neighboring spins point in exactly opposite directions and cancel out. In YFeO3, the Dzyaloshinskii–Moriya interaction tilts, or cants, the two antiferromagnetically coupled spin sublattices slightly toward each other, producing a weak net magnetization. The material also undergoes a field-induced spin reorientation transition, in which an external magnetic field forces the spins to swing toward the field direction. Because several competing interactions of comparable strength are at play, YFeO3 is an ideal test bed for a technique that claims to read out the energetics of the spin Hamiltonian directly.

The crystals used in the study were grown at the Shanghai Institute of Ceramics by Anhua Wu, Wenhao Di and Liangbi Su. At the TRACE electron microscopy centre at City University of Hong Kong, Qi Wang and Miao Zhang, the two co-first authors, recorded atomic-resolution imaging and compositional maps of the YFeO3 structure along multiple zone axes, confirming the positions of the yttrium, iron and oxygen atoms. They then acquired four-dimensional EMCD data sets in two distinct three-beam conditions, one exciting the (022) systematic reflections and the other the (202) reflections. In each condition, raw positive and negative electron energy-loss spectra were extracted from individual, consecutively numbered iron atomic planes, and their difference yielded the EMCD signal plane by plane.

The results were striking. The EMCD signals from the odd-numbered and even-numbered iron planes were almost exactly reversed, confirming the antiferromagnetic coupling between adjacent planes along both in-plane directions. More importantly, when the researchers converted the relative EMCD strengths into quantitative magnetization directions, they found that the two spin sublattices were not canted symmetrically. The moments on the odd-numbered planes were tilted by 11.6 degrees from the [100] direction, while those on the even-numbered planes were tilted by 19.5 degrees from the opposite direction. This asymmetry in the spin reorientation angles had been inferred indirectly in earlier bulk studies using Mössbauer spectroscopy and nuclear magnetic resonance, but it had never been seen directly at the level of individual atomic planes.

Why should the two sublattices respond differently to the same external field? The answer, according to the team’s analysis, lies in the interplay of the spin Hamiltonian terms on adjacent, antiferromagnetically coupled atomic planes. Because the two sublattices carry nearly opposite moments, the Zeeman energy of an applied field acts with opposite sign on the two sets of planes, while the single-ion anisotropy, which pins each moment to the crystal lattice, contributes differently depending on the local orientation. The researchers inferred the superexchange coupling, Dzyaloshinskii–Moriya interaction, single-ion anisotropy and Zeeman energy contributions from their measured spin configurations and found that the observed asymmetry arises primarily from the single-ion anisotropy and the opposite Zeeman energies of the adjacent planes. The net effect is that both magnetic moments end up nearly aligned with the external magnetic field, exactly as expected for the field-induced spin reorientation transition, but through a pathway that is visibly asymmetric at the atomic scale.

The quantitative work was supported by an extensive simulation effort. Miao Zhang performed the dynamical diffraction calculations that connect the measured dichroic signals to intrinsic magnetization components, solving a system of linear equations in which a matrix of simulation coefficients relates the experimental spectra of each sublattice to the underlying out-of-plane and in-plane magnetization. Gustav Bihlmayer of Forschungszentrum Jülich carried out density functional theory calculations of the electronic and magnetic structure of YFeO3, providing independent theoretical grounding for the inferred energy terms. Statistical analysis across five odd-numbered and five even-numbered planes, with error bars representing the standard error of the mean, gave the quantitative claims a firm footing. The team also extracted the orbital-to-spin magnetic moment ratio of the iron atoms, finding a value of 0.046, which confirms that the orbital moment in YFeO3 is almost completely quenched, as expected for iron oxide systems with strong crystal-field effects.

The significance of the technique extends well beyond one material. Three-dimensional nanomagnetism has become one of the liveliest frontiers in condensed matter physics, driven by applications in antiferromagnetic spintronics, skyrmionics and topological spin textures such as hopfions. Existing three-dimensional imaging methods, including X-ray vector nanotomography, electron holographic vector field tomography and Lorentz ptychography, can map magnetic textures with impressive fidelity, but none of them simultaneously resolve the magnetization vector in three dimensions and the atomic positions that host it. By bridging that resolution gap, the beam-shift-based 4D EMCD method allows experimentalists to correlate specific atomic configurations with specific energy contributions, which is precisely the correlation needed to test and refine spin Hamiltonian models rather than simply fitting them to bulk measurements.

There are practical implications as well. Canted antiferromagnets such as YFeO3 are candidates for ultrafast, low-dissipation spintronic devices because their antiferromagnetic resonance frequencies are high and their net stray fields are small, and recent work has demonstrated anisotropic long-range spin transport in this very material. Engineering such devices requires knowing exactly how anisotropy, exchange and Dzyaloshinskii–Moriya terms compete at the atomic scale, particularly at defects, interfaces and domain walls. A method that can now watch spins rotate plane by plane under an applied field, and assign the energetic cost of each rotation to its microscopic origin, turns the spin Hamiltonian from a fitting device into something closer to a measurable map. The raw experimental data have been released on Zenodo, and the authors suggest that the approach opens an avenue for the atomic-scale characterization and engineering of the energetics described by the spin Hamiltonian, a capability that magnetic materials researchers have sought since the Hamiltonian itself was first written down.

Subject of Research: Atomic-scale 3D vector magnetometry of competing spin Hamiltonian interactions in canted antiferromagnets

Article Title: Atomic-scale visualization of three-dimensional magnetization vectors with competing spin Hamiltonian interactions

Article References: Wang, Q., Zhang, M., Bihlmayer, G., Li, J., Wu, A., Di, W., Su, L., Song, Y., Hung, S.-W., Rusz, J., Dunin-Borkowski, R. E., & Zhong, X. (2026). Atomic-scale visualization of three-dimensional magnetization vectors with competing spin Hamiltonian interactions. Nature Nanotechnology, 21(10), 1390-1397. https://doi.org/10.1038/s41565-026-02270-6

Image Credits: AI Generated

DOI: 10.1038/s41565-026-02270-6

Keywords: electron magnetic circular dichroism, 4D EMCD, spin Hamiltonian, antiferromagnetism, YFeO3, Dzyaloshinskii–Moriya interaction, single-ion anisotropy, superexchange, Zeeman energy, spin reorientation, atomic-resolution microscopy, 3D magnetization

The physical stage for the study is deceptively simple: two interacting spin-1/2 particles, the quantum mechanical equivalent of two tiny bar magnets coupled to each other. The researchers model their interaction using the isotropic XXX Heisenberg model, one of the canonical frameworks of condensed matter and quantum information theory. To make the description more realistic, they include two additional ingredients that matter enormously in real magnetic materials. The first is the antisymmetric Dzyaloshinskii-Moriya interaction, or DM interaction, an exotic coupling that arises when the symmetry between spins is broken and which is known to shape magnetic textures in materials ranging from thin films to topological magnets. The second is an external magnetic field applied along the z-axis, which tilts the energy landscape and drives the spin pair through its evolution.

What distinguishes the new work is its geometric perspective. Instead of describing quantum evolution purely through equations of motion, the authors work within the Fubini-Study formalism, a mathematical framework that treats the set of all quantum states as a curved space equipped with a natural notion of distance. Within this space, they derive the quantum metric tensor, an object that tells you how quickly two neighboring quantum states become distinguishable as the system evolves. This metric is far more than a bookkeeping device: it encodes the statistical distinguishability of states and connects directly to concepts such as the quantum speed limit, the fundamental bound on how fast a quantum system can change, and to metrological precision in sensing applications.

One of the most striking findings concerns the shape of the space in which the two-spin system lives. The researchers show that the quantum evolution unfolds on a compact three-dimensional torus, a donut-shaped manifold whose nontrivial topology provides a natural arena for describing the system’s evolution. Yet, remarkably, despite this toroidal topology, the associated quantum state manifold remains intrinsically flat. This subtle combination, a topologically interesting setting with vanishing intrinsic curvature, has direct consequences for how geometric phases accumulate. The geometric phase, a cousin of Berry’s phase discovered in the 1980s, captures the global properties of the trajectory traced by a quantum state through state space. Unlike the ordinary dynamical phase, which depends on the energy and duration of the evolution, the geometric phase records only the shape of the path, and it therefore carries information that no local measurement of energy can provide.

The study then turns to entanglement, the quintessentially quantum phenomenon in which two particles share correlations that no classical system can reproduce. Using Wootters concurrence, the standard measure of entanglement for two-qubit systems, the team established a direct quantitative bridge between entanglement and geometry. By rewriting the geometric phase, the Fubini-Study distance, and the evolution speed of the system entirely in terms of concurrence, they demonstrated that these seemingly independent quantities all arise from the same underlying quantum evolution. The implications are concrete: as entanglement between the two spins increases, the states traversed by the system become more distinguishable from one another, and the quantum evolution proceeds faster. Entanglement, in other words, is not merely a resource for communication protocols but a driver of the very geometry and tempo of quantum motion.

The Dzyaloshinskii-Moriya interaction enters this picture as a genuine control knob. Because the DM coupling modifies the quantum coherences of the spin pair, it reshapes the entanglement landscape and thereby adjusts the geometric and dynamical properties that depend on it. By tuning the strength of the DM interaction or the external magnetic field, one can in principle sculpt how quickly the system evolves, how distinguishable successive states become, and how much geometric phase accumulates over a cycle. This positions the two-spin Heisenberg system not just as a theoretical curiosity but as a candidate platform for geometric quantum control schemes, in which gate operations are engineered through the topology and curvature of state-space trajectories rather than through finely timed pulses alone.

The most practically resonant part of the analysis concerns quantum teleportation, the protocol by which an unknown quantum state is transferred between distant locations using shared entanglement and classical communication. Teleportation is judged by its fidelity, a number expressing how faithfully the state arrives at its destination compared with the best any classical strategy could achieve. The researchers examined teleportation through its relationship to the geometric phase, the evolution speed, and the Fubini-Study distance, and uncovered a clean correlation: high teleportation fidelities are associated with larger geometric phases, greater distinguishability between the quantum states involved, and higher evolution speeds. This means that the very geometric features that make a quantum evolution interesting from a foundational standpoint also signal when a pair of spins will perform well as a teleportation channel.

The broader significance of this unification lies in economy of description. Quantum state geometry has recently attracted intense attention across quantum materials, where geometric tensors govern superfluid weights, orbital magnetic susceptibility and topological responses. Meanwhile, information geometry has found roles in quantum circuit analysis, phase transitions and precision measurement. What the Moroccan team’s work adds is an explicit demonstration, in a fully solvable interacting spin model, that the geometric quantities appearing in these disparate contexts are not parallel descriptions but literally the same objects, expressed through concurrence, and that they conspire to determine the performance of quantum information tasks such as teleportation. A single measurement of a system’s geometric properties could, in principle, forecast its usefulness as an entanglement resource.

The work arrives at a moment when experimental platforms, from superconducting circuits to trapped ions and spin chains, are increasingly capable of measuring geometric phases, state distinguishability and entanglement dynamics with high precision. The authors note that their research received no specific external funding and used no experimental datasets, marking it as a purely theoretical contribution, but one with a clear experimental fingerprint. As quantum technologies push toward devices in which teleportation channels and geometric gates must be characterized and certified, frameworks that tie these capabilities to observable geometric quantities could become standard diagnostic tools. For now, the study stands as an elegant reminder that in quantum mechanics, even the shape of the space of possibilities is physically consequential, dictating how fast states evolve, how strongly they entangle, and how reliably quantum information can traverse the universe.

Subject of Research: Geometric and dynamical properties of a two-spin XXX Heisenberg system and their interplay with entanglement and quantum teleportation

Article Title: Quantum geometry and dynamics of two interacting spins: interplay with entanglement and quantum teleportation

Article References: Boukacem, C., Yachi, M., Latifi, O., Amghar, B., Nebdi, H., & Slaoui, A. (2026). Quantum geometry and dynamics of two interacting spins: interplay with entanglement and quantum teleportation. Quantum Information Processing, 25(10), Article 313. https://doi.org/10.1007/s11128-026-05315-w

Image Credits: AI Generated

DOI: 10.1007/s11128-026-05315-w

Keywords: quantum geometry, Fubini-Study metric, entanglement, Wootters concurrence, geometric phase, Heisenberg model, Dzyaloshinskii-Moriya interaction, quantum teleportation, evolution speed, quantum state manifold, topology, quantum information