Staff Applied AI Researcher (Agentic Search)

You can think of this as Google search, but for AI agents: a system designed for machines, not humans. We are building agentic search, where AI systems actively plan, retrieve, evaluate, and refine information rather than simply returning results. As AI becomes the primary interface to the web, this layer will replace the role of traditional search engines. We are designing these systems to search and reason over web data in real time, under strict latency and reliability constraints. This means solving retrieval, ranking and passage extraction under entirely new access patterns and at significant scale, with systems operating over constantly changing, unstructured data and serving tens of thousands of production workloads 24/7. This role comes with ownership over key parts of our applied AI research direction and system design, with a strong expectation of defining new approaches and shipping measurable impact in production. In the first year, you will own a specific part of the search stack, e.g. ranking or iterative retrieval. What you'll work on: Designing an agent-native search system that handles everything from low-latency single-hop search to complex deep search tasks requiring iterative planning, querying, refinement and reasoning. Training ranking and retrieval models optimized for agent-driven workflows under real world constraints Bringing the latest advances from the research community to our search stack and ship it to production. Your responsibilities: Drive applied research and technical direction across retrieval and ranking systems Design and evolve multi-stage retrieval architectures (query understanding, rewriting, retrieval, reranking and iterative retrieval) Lead experimentation on modern retrieval approaches (embedding research, sparse and hybrid retrieval, reranking, context compression) and bring them into production Develop methods for grounding LLMs in real-time web data at scale, using trust, quality and freshness signals to surface reliable sources Partner with the evaluation team to define new metrics for agentic systems, where correctness is not reducible to clicks Analyze trade-offs across relevance, latency, and cost, and work closely with engineering to deploy systems that operate at web scale Mentor researchers and engineers and help raise the technical bar of the team Must haves: 8+ years of experience in applied AI, ML, or software engineering Proven track record of shipping ML or AI systems to production at scale Deep experience with search, retrieval, ranking or building RAG-based assistants Strong understanding of modern deep learning, especially transformers and embeddings Experience with LLM-integrated or knowledge-intensive systems Experience designing evaluation frameworks and metrics for ML systems Strong programming skills in Python Top-tier publications (ICLR, ICML, NeurIPS, AAAI, EMNLP, ACL) Ability to operate in a fast-moving, product-driven environment with high ownership and autonomy Nice to haves Background in agentic AI systems (agents, tool use, autonomous workflows) Experience with RL post-training of LLMs or VLMs Benefits & Perks: Competitive compensation Career growth and learning opportunities Flexibility and ownership Collaborative and innovative culture Opportunity to work on impactful AI projects International environment and talented teams What's it like to work at Nebius: Fast moving - Bold thinking - Constant growth - Meaningful impact - Trust and real ownership - Opportunity to shape the future of AI Equal Opportunity Statement: