Research Engineer, Applied Research

Job summary

Responsibilities

We're working to bring the transformative power of AI to every organization in the world. To do so, it is important to us that the diversity of our employees represents the diversity of our customers.

• Tackle unsolved applied AI and ML problems. Pushing the boundaries of post-training, voice AI, and long-horizon task execution, building agents that can reason, adapt, and…
• Determine when to build specialized models and when to use externally provided frontier intelligence, balancing quality, speed, and cost to deliver customer value.
• Turn ambiguous product and customer problems into well-framed machine learning problems.
• Develop, fine-tune, evaluate, and deploy models that improve Sierra’s customer-facing AI agents.
• Advance our post-training work, from supervised fine-tuning toward reinforcement learning and long-horizon optimization.

What they're looking for

• Strong experience building and deploying production machine learning and AI systems. We welcome backgrounds across applied ML, including search, ranking, recommendations…
• Excellent judgment in framing product problems as ML tasks and selecting the simplest & most effective approach.
• Experience working deeply with data, experimentation, evaluation, and model iteration.
• A practical, evidence-driven approach to ML, with strong judgement around when a problem calls for modeling and when a simpler solution will deliver the best outcome.
• The ability to operate with high agency and work across the stack when needed to deliver an outcome.