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CLIFF: Continual Learning for Incremental Flake Features in 2D Material Identification

Sankalp Pandey, Xuan Bac Nguyen, Nicholas Borys, Hugh Churchill, Khoa Luu

TL;DR

This paper proposes a new Continual-Learning Framework for Flake Layer Classification (CLIFF), the first systematic study of continual learning in the domain of two-dimensional materials, and achieves competitive accuracy with significantly lower forgetting than naive fine-tuning and a prompt-based baseline.

Abstract

Identifying quantum flakes is crucial for scalable quantum hardware; however, automated layer classification from optical microscopy remains challenging due to substantial appearance shifts across different materials. This paper proposes a new Continual-Learning Framework for Flake Layer Classification (CLIFF). To the best of our knowledge, this work represents the first systematic study of continual learning in two-dimensional (2D) materials. The proposed framework enables the model to distinguish materials and their physical and optical properties by freezing the backbone and base head, which are trained on a reference material. For each new material, it learns a material-specific prompt, embedding, and a delta head. A prompt pool and a cosine-similarity gate modulate features and compute material-specific corrections. Additionally, memory replay with knowledge distillation is incorporated. CLIFF achieves competitive accuracy with significantly lower forgetting than naive fine-tuning and a prompt-based baseline.

CLIFF: Continual Learning for Incremental Flake Features in 2D Material Identification

TL;DR

This paper proposes a new Continual-Learning Framework for Flake Layer Classification (CLIFF), the first systematic study of continual learning in the domain of two-dimensional materials, and achieves competitive accuracy with significantly lower forgetting than naive fine-tuning and a prompt-based baseline.

Abstract

Identifying quantum flakes is crucial for scalable quantum hardware; however, automated layer classification from optical microscopy remains challenging due to substantial appearance shifts across different materials. This paper proposes a new Continual-Learning Framework for Flake Layer Classification (CLIFF). To the best of our knowledge, this work represents the first systematic study of continual learning in two-dimensional (2D) materials. The proposed framework enables the model to distinguish materials and their physical and optical properties by freezing the backbone and base head, which are trained on a reference material. For each new material, it learns a material-specific prompt, embedding, and a delta head. A prompt pool and a cosine-similarity gate modulate features and compute material-specific corrections. Additionally, memory replay with knowledge distillation is incorporated. CLIFF achieves competitive accuracy with significantly lower forgetting than naive fine-tuning and a prompt-based baseline.

Paper Structure

This paper contains 26 sections, 8 equations, 4 figures, 4 tables, 1 algorithm.

Figures (4)

  • Figure 1: Comparison of 2D material flake characterization methods. (a) Automated thickness identification using deep learning on optical microscopy images offers a fast, scalable approach capable of processing large numbers of flakes and predicting their layer count. (b) The traditional approach relies on Atomic Force Microscopy (AFM), which is highly accurate but time-consuming and unscalable for high-throughput discovery.
  • Figure 2: The proposed CLIFF approach.
  • Figure 3: Internal architecture of the CLIFF Head. This illustrates the pipeline for new-image features. Replayed features follow the same process to produce student prediction scores.
  • Figure 4: Visual comparison of classification predictions on a Thick_BN flake (Task 1) after training on all four tasks. The bounding box indicates the input crop. CLIFF (Green) correctly predicts the label, whereas Naive Fine-tuning and L2P (Red) fail due to catastrophic forgetting.