Senior Applied Scientist

Job ID: 200039824Posted: 2026-07-23Location: United Kingdom, London, LondonEmployment type: Full-TimeWork site: 3 days / week in-officeRole type: Individual ContributorTravel: Less than 25%Profession: Research, Applied, & Data SciencesDiscipline: Applied SciencesCompany: MicrosoftOverviewWe are looking for a Senior Applied Scientist with expertise in modern retrieval technologies to help shape the future of Microsoft 365 Copilot. This role sits within the Copilot and Agents Core (CACore) organization, which powers the intelligence behind Microsoft 365 Copilot by combining advances in generative AI with personalized search, retrieval, ranking and recommendation systems.What You Will DoBuild state-of-the-art retrieval systems that serve millions of enterprise users every day.Research, design and evaluate retrieval and ranking technologies.Improve grounding quality, relevance, personalization and reasoning across Microsoft 365 Copilot experiences.Influence technical strategy and help shape the future retrieval architecture for Copilot.Translate scientific advances into reliable, high-impact product capabilities.Collaboration and ImpactYou will work in an exciting, collaborative environment and partner closely with engineering, product and platform teams. You will also collaborate across Microsoft Research, Azure AI and product groups to deliver AI-powered experiences that help people accomplish more with less effort.Culture and ValuesMicrosoft’s mission is to empower every person and every organization on the planet to achieve more. Employees bring a growth mindset, innovate to empower others and collaborate to realize shared goals. We build on the values of respect, integrity and accountability to create an inclusive culture in which everyone can thriveResponsibilitiesAdvance Retrieval Science Design and run experiments, define offline and online evaluation metrics, and develop scalable retrieval pipelines and models for enterprise-scale search systems. Areas of focus include: Semantic retrieval using late-interaction architectures such as ColBERT Dense retrieval and embedding model fine tuning Modern lexical retrieval approaches such as SPLADE Hybrid retrieval systems combining dense + sparse retrieval Query understanding and representation learning Multi-stage ranking and retrieval optimisation Retrieval-augmented generation (RAG) Personalization and contextual ranking Knowledge retrieval for agentic AI systems Reinforcement learning and reasoning-aware retrieval systems LLM-integrated retrieval architectures You will apply best practices in Responsible AI, Privacy-Preserving ML, and scalability for production-grade enterprise systems. Drive Product Innovation Partner with Engineering, PM and Design to translate product requirements and research advances into scalable and reliable retrieval infrastructure supporting Copilot Search, Chat and Agent experiences. Collaborate Across Microsoft Work closely with Microsoft Research, Azure AI platform teams and product organizations to bring cutting-edge retrieval and ranking advances into large-scale production systems. Champion Customer Impact Deeply understand user retrieval pain points and enterprise grounding challenges, and develop solutions that materially improve relevance, answer quality, freshness and personalization. Lead and Mentor Provide technical leadership and mentorship to scientists and engineers working on retrieval, ranking and recommendation systems. Help establish best practices and contribute to the broader retrieval science strategy across CACore. Define Success Establish and evolve evaluation frameworks and success metrics for retrieval quality, grounding relevance, ranking effectiveness and downstream Copilot quality metrics. Stay Ahead Keep up with the latest advances in retrieval and ranking research, including developments in semantic retrieval, sparse retrieval, RAG systems and LLM-grounded search. Publishing at top-tier venues such as SIGIR, RecSys, WSDM, KDD, ACL and EMNLP is encouraged. QualificationsRequired QualificationsCandidates must meet one of the following requirements:Bachelor's Degree in Statistics, Econometrics, Computer Science, Electrical Engineering, Computer Engineering, or a related field and 4+ years of related experience in statistics, predictive analytics, research, or a related discipline; ORMaster's Degree in Statistics, Econometrics, Computer Science, Electrical Engineering, Computer Engineering, or a related field and 3+ years of related experience in statistics, predictive analytics, research, or a related discipline; ORDoctorate (PhD) in Statistics, Econometrics, Computer Science, Electrical Engineering, Computer Engineering, or a related field and 1+ year of related experience in statistics, predictive analytics, research, or a related discipline; OREquivalent practical experience.Preferred QualificationsThe ideal candidate will have hands-on experience designing, developing, and deploying retrieval and ranking systems at production scale, with demonstrated expertise in one or more of the following areas:Retrieval and Ranking SystemsSemantic retrievalDense retrieval systemsEmbedding model training and fine-tuningSPLADE and sparse retrieval methodologiesHybrid retrieval architecturesSearch and recommendation ranking systemsLarge-scale information retrieval platformsMachine Learning & AIStrong proficiency in Python and modern machine learning frameworks, such as PyTorchExperience developing and deploying machine learning systems in production environmentsExperience building retrieval systems for Retrieval-Augmented Generation (RAG) and agentic AI architecturesExperience integrating retrieval systems with LLM-based productsKnowledge of reinforcement learning and retrieval-aware reasoning systemsEvaluation & ExperimentationExperience evaluating retrieval quality through offline metrics and online experimentationAbility to define and measure ranking effectiveness, relevance, and end-user impactScalability & InfrastructureExperience optimizing retrieval latency, scalability, and serving infrastructureFamiliarity with enterprise search, personalization, and recommendation systemsResearch ExcellenceTrack record of research contributions and publications in top-tier venues, including:SIGIRRecSysKDD with a demonstrated ability to bridge cutting-edge retrieval research with large-scale, production-ready AI systems will be particularly well aligned to the role.Additional RequirementsAbility to meet Microsoft, customer, and/or government security screening requirements.Must successfully pass the Microsoft Cloud Background Check upon hire or transfer and every two years thereafter.Applied Sciences IC4 - The typical base pay range for this role across United Kingdom is 74,700.00 - 122,600.00 per year. Certain roles may be eligible for benefits and other compensation. Find additional benefits and pay information here:This position will be open for a minimum of 5 days, with applications accepted on an ongoing basis until the position is filled.Microsoft is an equal opportunity employer. All qualified applicants will receive consideration for employment without regard to age, ancestry, citizenship, color, family or medical care leave, gender identity or expression, genetic information, immigration status, marital status, medical condition, national origin, physical or mental disability, political affiliation, protected veteran or military status, race, ethnicity, religion, sex (including pregnancy), sexual orientation, or any other characteristic protected by applicable local laws, regulations and ordinances. If you need assistance with religious accommodations and/or a reasonable accommodation due to a disability during the application process, read more about requesting accommodations.