What fictional technology lets characters enter shared dreams in Inception?

The fictional technology that lets characters enter shared dreams in Inception is the PASIV device.

PASIV stands for Portable Automated Somnacin Intravenous Device. In the film, it administers the fictional sedative Somnacin and connects multiple people to a shared dream state. The device allows dream architects and participants to experience the same constructed environments.

Inception builds its heist concept around dream layers. A team can enter a dream within a dream, with time passing more slowly at each deeper level. The PASIV device makes those shared experiences possible, but the elaborate rules of the dream world create the film’s main risks, including unstable projections and the danger of remaining trapped.

The word “PASIV” is sometimes mistaken for the name of the drug itself. Somnacin is the fictional chemical, while PASIV is the delivery and connection device. Leonardo DiCaprio stars as the extractor Dom Cobb.