arXiv subjects

Rami Mrad

Publications and source records attributed to Rami Mrad.

3 recordsLinked to original sources

arXiv2026

Quantum-Nondemolition Probing of Multiphoton Transitions between Dressed States in a Strongly Driven Jaynes--Cummings System

The response of the Jaynes--Cummings (JC) model to strong driving has been examined previously, but the origin of intriguing features near emitter--cavity resonance remains poorly understood because of the large background in conventional transmission spectroscopy. Here we introduce a spectroscopic approach for circuit quantum electrodynamics that combines strong cavity driving with quantum-nondemolition qubit readout. Separating the drive and readout substantially enhances the measurement sensitivity as compared with conventional cavity-transmission spectroscopy. With this technique, we identify the near-resonant features as multiphoton transitions between emitter--photon dressed states of the same parity, and resolve transitions between dressed states of opposite parity. Away from resonance, we also observe selective enhancement and suppression of multiphoton transitions, together with transitions involving the second excited state of the anharmonic qubit. Our approach opens a route to resolving the rich transition structure of the JC ladder and probing strongly driven light--matter interactions.

quant-ph↗

arXiv2024

Discovery of 2D Materials via Symmetry-Constrained Diffusion Model

Generative model for 2D materials has shown significant promise in accelerating the material discovery process. The stability and performance of these materials are strongly influenced by their underlying symmetry. However, existing generative models for 2D materials often neglect symmetry constraints, which limits both the diversity and quality of the generated structures. Here, we introduce a symmetry-constrained diffusion model (SCDM) that integrates space group symmetry into the generative process. By incorporating Wyckoff positions, the model ensures adherence to symmetry principles, leading to the generation of 2,000 candidate structures. DFT calculations were conducted to evaluate the convex hull energies of these structures after structural relaxation. From the generated samples, 843 materials that met the energy stability criteria (Ehull < 0.6 eV/atom) were identified. Among these, six candidates were selected for further stability analysis, including phonon band structure evaluations and electronic properties investigations, all of which exhibited phonon spectrum stability. To benchmark the performance of SCDM, a symmetry-unconstrained diffusion model was also evaluated via crystal structure prediction model. The results highlight that incorporating symmetry constraints enhances the effectiveness of generated 2D materials, making a contribution to the discovery of 2D materials through generative modeling.

cond-mat.mtrl-sci↗

arXiv2024

Generative Design of Crystal Structures by Point Cloud Representations and Diffusion Model

Efficiently generating energetically stable crystal structures has long been a challenge in material design, primarily due to the immense arrangement of atoms in a crystal lattice. To facilitate the discovery of stable material, we present a framework for the generation of synthesizable materials, leveraging a point cloud representation to encode intricate structural information. At the heart of this framework lies the introduction of a diffusion model as its foundational pillar. To gauge the efficacy of our approach, we employ it to reconstruct input structures from our training datasets, rigorously validating its high reconstruction performance. Furthermore, we demonstrate the profound potential of Point Cloud-Based Crystal Diffusion (PCCD) by generating entirely new materials, emphasizing their synthesizability. Our research stands as a noteworthy contribution to the advancement of materials design and synthesis through the cutting-edge avenue of generative design instead of the conventional substitution or experience-based discovery.

cs.AI↗