Klemens Hammerer studied physics at the University of Innsbruck. From 2002 to 2006 he was a doctoral researcher in the group of Ignacio Cirac at the Max Planck Institute of Quantum Optics in Garching, and received his PhD from the Technical University of Munich in 2006 with distinction. After working as a university assistant in the group of Peter Zoller in Innsbruck, he moved in 2010 to the Institute for Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences in Innsbruck as a Senior Scientist, and shortly thereafter to Leibniz University Hannover as Professor of Theoretical Physics. Since 2025 he is Professor of Theoretical Quantum Optics at the University of Innsbruck and leads a research group at IQOQI Innsbruck.

His research lies at the interface of quantum optics, quantum information, and precision measurement. It addresses how quantum resources can be utilized in realistic, open systems and how correlated many-body states can be prepared and exploited for metrology, communication, and  
information processing. His work includes theoretical concepts for atomic clocks and quantum sensors with cold atoms and ions, methods for generating spin squeezing and quantum correlations in atomic and solid-state ensembles, studies of quantum optical many-body systems in cavities and waveguides, and the coupling of light to mechanical degrees of freedom in mesoscopic systems. Methodologically, he combines analytical and numerical approaches to the dynamics of open quantum systems, in close connection with experimental platforms.