Overview

PolyAI automates customer service through lifelike voice assistants that enable natural conversations. Our customers, including leading brands, use PolyAI to automate critical customer service operations and integrate our platform into daily workflows.

We are looking for a Senior Research Scientist to join our world-class team and lead cutting-edge work on large language model post-training. This role focuses on building the future of dialogue systems with novel approaches to reasoning, reinforcement learning, audio-first LLMs, and more. As a Senior Research Scientist, you’ll lead research projects from ideation through deployment and drive innovation in training and adapting LLMs for real-world conversations across voice, text, and multimodal contexts.

You’ll work on frontier techniques such as:

• Conversational reinforcement learning
• Streaming and continuous turn-taking
• Audio-native LLMs
• Distillation of reasoning models
• Long-context
• Efficient adaptation

You’ll also shape the scientific direction of our research, mentor junior colleagues, and collaborate cross-functionally to bring research into production.

Responsibilities

• Lead and execute complex research projects with clear business impact.
• Design and implement novel post-training strategies including preference tuning, reward modeling, and synthetic supervision.
• Develop innovative model architectures and training approaches for conversational AI, including speech-aware and multimodal models.
• Conduct empirical studies to assess model performance in live deployments and iterate quickly based on real-world data.
• Generate, collect, and annotate training data — including synthetic and real-world conversational datasets — with attention to quality and bias mitigation.
• Design robust evaluation metrics and benchmarks for LLM-based assistants in customer service domains.
• Work closely with engineering and product teams to integrate research into production environments.
• Collaborate with legal and compliance teams to ensure responsible use of data and models.

Stay current with academic and industry advances in LLMs, ASR, TTS, RLHF, and multimodal learning.

Requirements

• PhD in Machine Learning, Natural Language Processing, Computer Science, or a related field.
• 5+ years of hands-on experience in deep learning.
• Proven track record of research innovation, including published work or deployed systems.
• Strong programming skills in Python and deep learning frameworks like PyTorch.
• Demonstrated expertise in at least one domain area such as reinforcement learning, conversational AI, audio modelling, or LLM alignment.
• Experience leading projects end-to-end, from ideation to deployment.
• Excellent communication skills with the ability to write clear technical documents and explain complex concepts to diverse audiences.
• Comfortable working in ambiguity and driving clarity through experimentation and data.

Preferred Qualifications

• Experience with speech technologies such as ASR and TTS.
• Familiarity with cloud environments (AWS, GCP, Azure).
• Exposure to RLHF, reward modelling, or human preference data collection.
• Prior work on real-time systems, streaming inference, or memory-efficient model deployment.

We offer competitive compensation based on experience, expertise, and level of responsibility. This role includes equity, giving you the opportunity to share in the long-term success of the business.

The listed expectations reflect what we're hiring for, so please review the job description carefully.

Benefits

• Participation in the company’s employee share options plan
• 25 days holiday, plus bank holidays
• Flexible working from home policy
• Work from outside of the UK for up to 6 months each year
• Enhanced parental leave
• Bike2Work scheme
• Annual learning and development allowance
• One-off WFH allowance when you join
• Company-funded fertility and family-forming programmes
• Menopause care programme with Maven
• Private healthcare and dental cover, discounts on gym memberships, and access to mental health programs

At PolyAI, we pride ourselves on our values. Our core values are:

• Only the best — We hire and aim for excellence and nurture this drive.
• Ownership — We take responsibility for initiatives, decisions, and outcomes.
• Relentlessly improve — We strive for continuous, obsessive improvement.
• Bias for action — We move quickly and deliver impact.
• Disagree and commit — We understand differing views and commit to decisions.
• Build for people — We deliver automated experiences that empower users.

PolyAI is proud to be an equal-opportunity employer. We celebrate diversity and are committed to an inclusive environment for all employees. All employment decisions are based on business needs without regard to ethnicity, religion, sexual orientation, gender identity, family or parental status, national origin, neurodiversity status, or disability status.

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