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Description

Alexa AI is looking for a Principal Applied Scientist to lead the science behind Alexa+, Amazon's LLM-powered conversational assistant. You will own the technical direction for key initiatives spanning large language model fine-tuning, alignment, agentic reasoning, and evaluation — directly shaping the experience for hundreds of millions of customers worldwide.

As a Principal Scientist, you are a hands-on technical leader. You define research directions, design and run rigorous experiments, and ensure that research translates into production systems at scale. You decompose ambiguous, hard problems into clear solutions. Your code, models, and documents are exemplary and frequently referenced across the organization.

You amplify your impact beyond your own work. You lead scientific reviews, scrutinize experimental design and modeling assumptions, and align teams toward coherent strategies. You mentor senior scientists, contribute significantly to hiring, and keep the broader scientific community current on state-of-the-art techniques. You bring business and industry context to technical decisions and can credibly present to executive leadership.

Key job responsibilities
Define and drive the science roadmap for conversational AI capabilities powered by large language models
Design, implement, and evaluate novel approaches to LLM fine-tuning, alignment (RLHF, DPO), and distillation for production deployment
Architect agentic systems — multi-step reasoning, tool use, planning, and orchestration — that work reliably at scale
Develop evaluation frameworks and methodologies that go beyond standard benchmarks to capture real-world conversational quality
Translate research advances into customer-facing products, working closely with engineering, product, and cross-functional science teams
Publish results at top-tier venues and represent Amazon in the broader research community
Mentor scientists at all levels and contribute to organizational planning, hiring, and technical culture

About the team
Alexa AI is building the science and technology behind Alexa+, Amazon's next-generation conversational assistant. Our team works at the intersection of large language models, reinforcement learning from human feedback and verifiable rewards, agentic architectures, and multilingual/multimodal understanding. We operate at massive scale — our models serve customers across dozens of languages and device types. If you want to push the frontier of conversational AI and see your work used by people every day, come join us.