[3] Kachru is best known for his extensive research on flux compactifications (including work with Steve Giddings and Joseph Polchinski), which can stabilize the extra dimensions of string theory.
In collaboration with Renata Kallosh, Andrei Linde, and Sandip Trivedi, he found the first models of accelerated expansion of the universe in low energy supersymmetric string compactifications (see KKLT mechanism).
[4] He made notable contributions to string theory duality (with Cumrun Vafa), the AdS/CFT correspondence (with Eva Silverstein), and to the construction of models of cosmic inflation.
He has also done significant work on the holographic description of finite density quantum matter, the theory of non-Fermi liquids, and the understanding of moonshine and its connections to physics and geometry.
As of September 2023, Kachru is working with PDT Partners, and according to his website his "current scientific research is focused on understanding dynamics of various liquid global financial markets".