AI Models
UEmbed： Unified Sparse and Dense Multimodal Embeddings
UEmbed：统一稀疏与稠密的多模态嵌入模型
UEmbed: Unified Sparse and Dense Multimodal Embeddings
arXiv.orgSparse retrieval underpins modern search systems, from web search to retrieval-augmented generation. Existing work has introduced Learned Sparse Retrieval (LSR) to push beyond exact lexical matching toward richer semantics. Yet LSR has so far remained tied to encoder-style bidirectional architectures, and its extension to multimodal settings still relies heavily on auxiliary cross-modal modules. To address these limitations, we introduce UEmbed (Unified Embedding), a decoder-only multimodal embedding model that produces both sparse lexical and dense representations in one causal forward pass. UEmbed appends N learnable special tokens to the input and partitions the vocabulary into N disjoint subsets. Each token's causal hidden state predicts sparse weights over its assigned subset, and the N subsets are concatenated into the full sparse vector. Trained on public data, we release UEmbed at 2B, 4B, and 9B scales. UEmbed-9B reaches 71.8 (dense) and 71.0 (sparse) on MMEB-v2, outperforming multimodal embedding models trained on publicly available data (e.g., RzenEmbed). On BEIR, UEmbed also remains competitive with strong dense and sparse baselines. Furthermore, we demonstrate the practical utility of UEmbed across three dimensions: effectiveness, efficiency, and agentic applications. Overall, UEmbed offers a new paradigm: it unifies dense and sparse embeddings in one model, while further extending sparse retrieval to unify text and multimodal inputs.
Open sourceRecommended because
This is worth tracking because it is a concrete model capability signal, not just a passing headline. The source preview points to a change in model capability, availability, benchmark behavior, or developer access. For builders and operators, "UEmbed： Unified Sparse and Dense Multimodal Embeddings" can be used as a checkpoint for model selection, product roadmaps, eval planning, and timing decisions. I keep this thread indexed so future searches around AI model updates, capability shifts, and developer adoption can land on a source-linked page instead of disappearing into a fast-moving feed from arXiv.org.
What to take from this signal
Context
"UEmbed： Unified Sparse and Dense Multimodal Embeddings" is archived here as a source-linked AI signal from arXiv.org. The useful part is the connection between UEmbed, Unified, Sparse, Dense, Multimodal and model selection, product roadmaps, eval planning, and timing decisions, which makes the item more actionable than a normal feed headline. The source context says: Sparse retrieval underpins modern search systems, from web search to retrieval-augmented generation. Existing work has introduced Learned Sparse Retrieval (LSR) to push beyond exact lexical matching toward richer semantics. Yet LSR has so far remained tied to encoder-style bidirectional architectures, and its extension to multimodal settings still relies heavily on auxiliary cross-modal modules. To address these limitations, we introduce UEmbed (Unified Embedding), a decoder-only multimodal embedding model that produces both sparse lexical and dense representations in one causal forward pass. UEmbed appends N learnable special tokens to the input and partitions the vocabulary into N disjoint subsets. Each token's causal hidden state predicts sparse weights over its assigned subset, and the N subsets are concatenated into the full sparse vector. Trained on public data, we release UEmbed at 2B, 4B, and 9B scales. UEmbed-9B reaches 71.8 (dense) and 71.0 (sparse) on MMEB-v2, outperforming multimodal embedding models trained on publicly available data (e.g., RzenEmbed). On BEIR, UEmbed also remains competitive with strong dense and sparse baselines. Furthermore, we demonstrate the practical utility of UEmbed across three dimensions: effectiveness, efficiency, and agentic applications. Overall, UEmbed offers a new paradigm: it unifies dense and sparse embeddings in one model, while further extending sparse retrieval to unify text and multimodal inputs.
Builder takeaway
For an AI builder, the main takeaway is to watch how this signal changes practical decisions around model quality, latency, cost, eval coverage, and release timing. It can inform what to test next, which product surface to compare, and whether the underlying workflow is ready for real users.
Source context
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Search angles
- UEmbed： Unified Sparse and Dense Multimodal Embeddings AI Models context
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- UEmbed, Unified, Sparse, Dense, Multimodal builder takeaway
- AI model updates, capability shifts, and developer adoption
This page keeps a source preview and a stable archive URL for search discovery. The original source remains authoritative.