Google has rolled out a major enhancement to its NotebookLM platform, integrating the newly developed Gemini 3.5 and Antigravity artificial intelligence models. This update substantially increases the workspace’s generative and analytical capabilities, offering deeper document synthesis, improved reasoning, and faster multimodal processing. The release follows a phased deployment strategy, with initial access restricted exclusively to Google AI Ultra subscribers and enterprise accounts. This tiered approach enables Google to stress-test high-compute infrastructure, optimize model latency, and collect structured performance data before broader distribution. The Antigravity architecture specifically enhances computational efficiency, while Gemini 3.5 contributes expanded contextual understanding and advanced automation features for research workflows. Users within the eligible tiers will experience accelerated response times and more accurate information extraction across complex datasets. Google has confirmed that expansion to standard and free-tier users will occur in subsequent update cycles, contingent upon successful scaling and system stabilization. The current restriction reflects an industry-standard validation practice, ensuring that resource-intensive AI integrations maintain reliability before public release. This targeted rollout positions NotebookLM as a competitive professional workspace while allowing Google to incrementally align infrastructure costs with premium revenue streams.