Senior Research Scientist (Must be based in UK)

PolyAI automates customer service through lifelike voice assistants that let customers lead a conversation. Our voice assistants make it possible for businesses to deliver outstanding customer service that rivals their human agents. Our customers, which include the world's leading logos, are expanding how they use our platform, driving automation of critical customer service operations and integrating PolyAI into their daily customer service workflows.

We are looking for a Senior Research Scientist to join our world-class team and lead cutting-edge work on large language model (LLM) post-training. This is not just about applying standard fine-tuning techniques - it's about building the future of dialogue systems with novel approaches to reasoning, reinforcement learning, audio-first LLMs, and more.

As a Senior Research Scientist at PolyAI, you'll lead impactful research projects from ideation through to deployment. You'll be driving innovation in how we train and adapt LLMs for real-world conversations - spanning 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 play a key role in shaping the scientific direction of our research, mentoring junior colleagues, and collaborating 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 an eye for 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 the level of responsibility. This role also 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 we encourage you to 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

TELUS Health EAP 24/7 - offers you and your chosen family confidential, judgment-free support for any work, health, or life challenge

♥ Enhanced parental leave

Bike2Work scheme

Annual learning and development allowance

We're all about making WFH work for you - that's why we offer a one-off WFH allowance when you join. Offering perks like noise-cancelling headphones or a comfortable desk chair to boost your comfort and focus!

Company-funded fertility and family-forming programmes

Menopause care programme with Maven

Private healthcare and dental cover, discounts on gym members and relaxation apps, and access to a range of mental health programs

At PolyAI, we take great pride in our values - they guide everything we do. We believe that a strong culture leads to meaningful work and lasting impact.

Our core values are:

Only the best We expect the best from our people, we hire people that expect the best from themselves, and we nurture this drive for excellence.

Ownership We care deeply about what we do. We take ownership of our initiatives, decisions and outcomes.

Relentlessly improve We demand more from ourselves and are always evolving. Continuous, obsessive improvement is the only way we will transform the world of conversational AI.

Bias for action Our world moves quickly and so do we. We take calculated risks and we deliver impact fast.

Disagree and commit We are all working toward the same goal. If we don't agree with something, we work hard to understand it and when a decision is made, we accept it and give it our all.

Build for people We want the world to enjoy the experiences they have with us. We are building for a future that prefers automation.

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

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