arXiv subjects

André Koch Liston

Publications and source records attributed to André Koch Liston.

3 recordsLinked to original sources

arXiv2026

Molecular spin qubits in a van der Waals bottle

Advancing quantum information technologies requires qubits whose coherence can be precisely engineered. Among the qubit platforms in development, molecular spin qubits (MSQs) stand out for their atomic scale tunability and chemical specificity, making them powerful candidates for sensing, simulation, and information processing. However, integrating MSQs into solid-state architectures without degrading their coherence remains a central challenge. Here, we introduce van der Waals (vdW) confinement within two-dimensional materials as a strategy for stabilizing quantum states in MSQs by engineering their local electronic, vibrational, and symmetry environments. Using cobaltocene as a model system, we show that confinement within vdW SnS2 and CdPS3 single crystals reorganizes the single-ion energy landscape and slows spin-lattice relaxation by over two orders of magnitude relative to unconfined cobaltocene. The confined MSQs adopt deterministic orientations and self-assemble into ordered, atomically precise superlattices, establishing vdW confinement as a pathway for integrating MSQs into functional quantum devices.

cond-mat.mtrl-sci↗

arXiv2026

Observation of Coherent Ferron Emission and Propagation

Excitation of ordered quantum phases gives rise to collective modes and quasiparticles, as exemplified by spin waves and magnons emerging from magnetic order. Extending this paradigm to ferroelectric materials suggests the existence of polarization waves and their fundamental quanta, ferrons. Here, we report the generation and transport of polarization waves, i.e., coherent ferrons, in the van der Waals ferroelectric material NbOI2. Upon excitation by a short laser pulse, the polarization wave emits intense and narrow-band terahertz (THz) radiation at the ferroelectric transverse optical phonon frequency, modulates the ferroelectric order parameter, and propagates uniaxially along the polar axis at hypersonic velocities of ~105 m/s. These long-lived, uniaxial, and dipole-carrying polarization waves may find applications in narrow-band THz emission, ferronic information processing, and coherent electric control.

cond-mat.mtrl-sci↗

arXiv2026

Giant optical spin-orbit interactions in ferroelectric van der Waals waveguides

Optical spin-orbit interactions (SOI) link photonic spin to momentum, offering a route toward on-chip polarization control and beam steering. Nevertheless, achieving sufficient optical SOI and nonlinearities on sub-micrometer scales - a prerequisite for dense photonic integration - remains an outstanding challenge. Here, we show that highly birefringent van der Waals (vdW) waveguides provide an ideal, chip-compatible platform to address this limitation. We focus on the ferroelectric semiconductor NbOI2, which exhibits record optical nonlinearities and dielectric anisotropy. Using femtosecond optical microscopy, we image light propagation and harmonic conversion beyond the total internal reflection barrier over tens of micrometers in NbOI2 slab waveguides. We report giant optical spin-splitting through the optical spin Hall effect, which facilitates spatial separation of optical spin currents on sub-micrometer scales, in quantitative agreement with a microscopic light-matter interaction model. We further leverage optical spin-momentum locking to realize polarization-controlled waveguide steering. We generalize these observations across various vdW waveguides and empirically confirm a scaling law linking dielectric anisotropy to geometric spin-splitting. Our results establish highly anisotropic vdW waveguides as an ideal platform for densely integrated opto-spintronic technologies.

cond-mat.mtrl-sci↗