New 
Principal Applied Scientist
 Microsoft | |
 United States, Washington, Redmond | |
 Oct 17, 2025 | |
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OverviewTheMSAI Search Relevance teamis at the forefront of delivering world-class search quality across Microsoft's ecosystem. We are the driving force behind the relevance of results inCopilot Search experiencesand serve as the coreretrieval layer in the RAG architecturepoweringBizchat. Our impact also extends to maintaining high search quality across traditional endpoints likeOutlook,Teams, andSharePoint Search. Our team thrives at the intersection of innovation and applied machine learning.We are looking for a Principal Applied Scientist to help us deliver breakthrough applied machine learning and information retrieval solutions at enterprise scale. This role is a unique opportunity to apply state-of-the-art techniques-including dense retrieval, hybrid search, multilingual large language models (LLMs), RAG (Retrieval-Augmented Generation), and transformer-based re-ranking models and agentic search-to solve complex challenges in Copilot-driven enterprise search.As a Principal Applied Scientist, you'll be responsible for delivering mission-critical innovations that directly improve Copilot experiences such as:Agentic Search in modern orchestrator architecturesAdapting advanced vector search algorithms (e.g., FAISS, ANN, ScaNN) for enterprise-scale semantic retrievalImproving classic and neural keyword search quality through deep language understandingDesigning and training relevance models, including LLM fine-tuning and learning-to-rank (LTR) approachesBuilding robust evaluation pipelines using offline metrics and online A/B experimentationDriving cross-org collaboration with platform partners, other applied science teams, and product teams across time zonesThis role requires a mix of technical depth, strategic execution, and people management to shape the next generation of AI-powered search experiences.Microsoft's mission is to empower every person and every organization on the planet to achieve more. As employees we come together with a growth mindset, innovate to empower others, and collaborate to realize our shared goals. Each day we build on our values of respect, integrity, and accountability to create a culture of inclusion where everyone can thrive at work and beyond.
ResponsibilitiesDrive end-to-end applied science projects: From ideation and design to implementation, experimentation, and shipping, you will lead high-impact projects that directly improve Copilot Chat, Copilot Search, and BizChat experiences. This includes identifying search and relevance gaps, formulating innovative hypotheses, and delivering scalable solutions.Inspire help to grow a high-performing applied science team: mentor, and empower a team of applied scientists-owning their technical direction, project execution, and career development. You will guide day-to-day work, ensure scientific and engineering rigor, and be accountable for the team's output and impact.Innovate with scientific rigor: Invent and apply cutting-edge techniques in machine learning, natural language processing, and information retrieval to address real-world challenges at enterprise scale. You will design novel approaches for improving retrieval, ranking, query understanding, and semantic search in Copilot systems.Document, share, and amplify learnings: Promote a culture of transparency and innovation by capturing experimental results, documenting methodology, and publishing internal learnings. You'll drive knowledge sharing that enables broader impact across the organization.Translate business goals into scientific strategy: Partner closely with product and business stakeholders to align team efforts with high-priority objectives. You will translate ambiguous product requirements into clear, data-driven, and technically feasible directions.Collaborate across organizations and time zones: Work cross-functionally with platform engineering teams, peer science orgs, and product managers to ensure alignment, resolve dependencies, and unblock progress. You'll be a key bridge between applied science innovation and product delivery.Embody our Culture and Values | |