Lead AI/ML Engineer ( NLP, Transformers, Vector Databases, and RAG),

Optum India; Hyderabad; On-site; INR 3,500,000 - 7,000,000; Full time

Job summary

Optum India seeks a Lead AI/ML Engineer focused on NLP, Transformers, vector databases, embeddings, retrieval, and RAG. You will drive end-to-end LLM training, knowledge-graph grounding, and semantic search initiatives across production systems.

Ideal candidates have 11–15+ years in Data Science/Applied AI with strong Python, PyTorch, and SQL skills, and hands-on experience with FAISS/Weaviate/Milvus. Leadership and collaboration across teams are essential.

Qualifications

• Master's degree in Computer Science, ML, AI or related field.
• 11–15+ years of Data Science and AI/ML experience with production systems.

Responsibilities

• Lead end-to-end training and fine-tuning of LLMs (open- and closed-source).
• Architect GraphRAG pipelines with knowledge graphs for grounding.
• Design and optimize semantic and dense vector embeddings for retrieval.
• Develop semantic retrieval systems with advanced segmentation and indexing.

Skills

NLP

Transformers

Vector databases

Embeddings

RAG

Python

SQL

PyTorch

Semantic search

LLM training

Fine-tuning

Education

Master's degree

Tools

FAISS

Weaviate

Milvus

Job description

The Lead AI/ML Engineer is a primary driver in the design and development of state-of-the-art Artificial Intelligence solutions with a strong focus on Natural Language Processing (NLP), Transformer-based architectures, Vector Database technologies, and Retrieval-Augmented Generation (RAG). The Lead AI/ML Engineer works closely with senior data scientists, machine learning engineers, software engineers, and subject matter experts on current company technologies and forward-looking projects. They drive research, innovation, and solution implementation in the creation of next-generation AI systems.

Key Responsibilities

• Lead end-to-end training and fine-tuning of Large Language Models (LLMs), including both open-source (e.g., Qwen, LLaMA, Mistral) and closed-source (e.g., OpenAI, Gemini, Anthropic) ecosystems.
• Deep knowledge and extensive experience with Machine/Deep Learning frameworks including transformer architectures, state space models, large language models, and agentic approaches.
• Architect and implement GraphRAG pipelines, including knowledge graph representation and retrieval for enhanced contextual grounding.
• Design, train, and optimize semantic and dense vector embeddings for document understanding, search, and retrieval.
• Develop semantic retrieval systems with advanced document segmentation and indexing strategies.
• Knowledge of algorithms and techniques within a computational domain with emphasis on text processing.

This keeps the JD exactly as is while making it immediately obvious that the role's primary focus is NLP, Transformers, Vector Databases, Embeddings, Retrieval, and RAG.

Preferred Qualifications

• Master's degree in Computer Science, Machine Learning, Artificial Intelligence, or a related field.
• 11-15+ years of experience in Data Science, Applied AI/ML, and Statistical Modeling, with a strong track record of developing, deploying, and scaling production-grade AI solutions.

Deep expertise in:

• Natural Language Processing (NLP)
• Fundamental Machine Learning
• State Space-Based Architectures
• Strong Python programming, SQL, database querying, data preparation, and analysis skills
• Exploratory Data Analysis (EDA)
• Experience with PyTorch
• LLM training and fine-tuning (e.g., GPT, LLaMA, Mistral, Qwen)
• Semantic Search and Vector Databases (e.g., FAISS, Weaviate, Milvus)
• Model Fusion and Ensemble Techniques (Stacking, Boosting, Gating)
• Optimization Algorithms (Bayesian, Particle Swarm, Genetic Algorithms)
• Reinforcement Learning (e.g., RLHF, PPO, DPO, GRPO), Supervised Fine-Tuning (SFT), LoRA, QLoRA, Axolotl

Key focus areas:

NLP, Transformer-Based Architectures, Vector Database Technologies, Semantic Search, Embedding Models, and Retrieval-Augmented Generation (RAG).