Machine Learning Engineer

About Sesame

Sesame believes in a future where computers are lifelike - with the ability to see, hear, and collaborate with us in ways that feel natural and human. With this vision, we're designing a new kind of computer, focused on making voice companions part of our daily lives. Our team brings together founders from Oculus and Ubiquity6, alongside proven leaders from Meta, Google, and Apple, with deep expertise spanning hardware and software. Join us in shaping a future where computers truly come alive.

About The Role

We are seeking a Machine Learning Engineer specializing in post-training optimization to refine and enhance large language models (LLMs) and AI companions. This role focuses on alignment tuning, preference optimization, reinforcement learning (RLHF), and continual learning to create AI systems that are more conversational, emotionally aware, and adaptive to user interactions. You will work on making AI more intelligent, personalized, and capable of remembering and reasoning over long-term interactions, ensuring alignment with human values and real-world applications.

Responsibilities:

• Implement fine-tuning strategies such as alignment tuning, preference modeling, and reinforcement learning to enhance AI fluency, coherence, and alignment with user preferences.
• Improve AI’s ability to engage in empathetic, context-aware conversations, remember interactions, and dynamically personalize responses.
• Develop methods for LLM-based agents to reason, plan, and take actions, making interactions more natural and goal-driven.
• Track model drift, bias emergence, and performance degradation, ensuring real-world robustness through continual adaptation.
• Design feedback loops and adaptive learning strategies that allow models to refine their behavior based on implicit and explicit user feedback.
• Optimize LLMs on domain-specific datasets, enhancing contextual understanding and reducing hallucinations.
• Work with AI researchers, engineers, and product teams to bring cutting-edge post-training techniques into production.
• Develop scalable methodologies for AI evaluation, integrating human feedback and real-world testing to ensure continuous improvement.
  
  

Required Qualifications:

• Strong expertise in machine learning, reinforcement learning (RLHF, PPO, etc.), and deep learning techniques.
• Proficiency in Python, PyTorch, TensorFlow, and modern ML frameworks.
• Experience with LLM fine-tuning, preference learning, and alignment techniques.
• Deep understanding of natural language processing (NLP), conversational AI, and agentic AI systems.
• Ability to analyze and mitigate biases, ethical concerns, and safety risks in AI systems.
• Experience with deploying models in cloud environments (AWS, Azure, GCP) and optimizing ML pipelines for scalability.
• Strong communication skills, with the ability to work across research, engineering, and product teams.
  
  

Benefits:

• 401k matching
• 100% employer-paid health, vision, and dental benefits
• Unlimited PTO and sick time
• Flexible spending account matching (medical FSA)
  
  

Sesame is committed to a workplace where everyone feels valued, respected, and empowered. We welcome all qualified applicants, embracing diversity in race, gender, identity, orientation, ability, and more. We provide reasonable accommodations for applicants with disabilities—contact [email protected] for assistance.

Compensation Range: $190K - $320K