Senior AI Researcher: LLM post-training for hallucination reduction (f/m/d)

Who we are Aleph Alpha’s mission is to deliver sovereign, human-centric AI to governmental institutions and large enterprises. To that end, we deliver category-defining AI innovation that enables open, accessible, and trustworthy deployment of GenAI in industrial applications. Our organization develops foundational models and next-generation methods that make it easy and affordable for Aleph Alpha’s customers to increase productivity in development, engineering, logistics, and manufacturing processes. About the role We are looking for a (Senior) AI Researcher to join our hallucination reduction capability team to push the boundaries in LLM post-training (SFT and RL). We're one of the few places in Europe training foundation models from scratch. You will be part of a team of (senior) researchers and PhD interns doing cutting-edge research across pre-, mid- and post-training, grounding and specialized models with hundreds of GPUs at our disposal. What will you do • Core Research & Development: Design, execute, and scale post-training methodologies (SFT, RL) specifically aimed at eliminating model hallucinations and making them grounded in evidence. • Uncertainty & Reliability: Research and implement techniques in uncertainty estimation, calibration, self-consistency, and self-correction mechanisms to enable models to identify and signal when they “don't know”. • Post-Training Pipelines: Build and optimize high-throughput, distributed fine-tuning and training pipelines across multi-node GPU clusters. • Evaluation & Benchmarking: Design and implement rigorous evaluation methods to benchmark hallucination rates, truthfulness, and reasoning accuracy. • Technical Ownership: Drive research projects independently from initial hypothesis to scalable production implementation and technical reports. Qualifications • Hands-on experience fine-tuning or post-training LLMs using modern distributed training frameworks. • Track record of research or implementation in at least one of the following domains: • Hallucination mitigation / truthfulness alignment / grounding in RAG • Uncertainty estimation, or out-of-distribution detection • Retrieval-Augmented Generation evaluation / alignment, refusal behavior calibration, or claim verification • Strong programming skills (Python & PyTorch). Compensation and Benefits • Become part of an AI revolution! • 30 days of paid vacation • Access to a variety of fitness & wellness offerings via Wellhub • Mental health support through nilo.health • Substantially subsidized company pension plan for your future security • Subsidized Germany-wide transportation ticket • Budget for additional technical equipment • Flexible working hours for better work-life balance and hybrid working model • JobRad® Bike Lease Find more English Speaking Jobs in Germany on Arbeitnow