**Amir Ordacgi Caldeira** (born 1950 in Rio de Janeiro) is a Brazilian physicist. He received his bachelor's degree in 1973 from the Pontifícia Universidade Católica do Rio de Janeiro, his M.Sc. degree in 1976 from the same university, and his Ph.D. in 1980 from University of Sussex. His Ph.D. advisor was the Physics Nobel Prize winner Anthony James Leggett. He joined the faculty at Universidade Estadual de Campinas (UNICAMP) in 1980. In 1984 he did post-doctoral work at the Kavli Institute for Theoretical Physics (KITP) at University of California, Santa Barbara and at the Thomas J. Watson Research Laboratory at IBM. In 1994-1995 he spent a sabbatical at the University of Illinois at Urbana-Champaign. He is currently a Full Professor at Universidade Estadual de Campinas. He was the recipient of the Wataghin Prize, from Universidade Estadual de Campinas, for his contributions to theoretical physics in 1986.

Caldeira's research interests are in theoretical condensed matter physics, in particular quantum dissipation and strongly correlated electron systems. His best known work is on the Caldeira-Leggett model, which is one of the first and most important treatments of decoherence in quantum mechanical systems.

A. O. Caldeira and A. J. Leggett, *"Influence of damping on quantum interference: an exactly soluble model,"* Physical Review A **31**, 1059 (1985).
A. O. Caldeira and A. J. Leggett, *"Quantum tunnelling in a dissipative system",* Annals of Physics **149**, 374 (1983).
A. O. Caldeira and A. J. Leggett, *"Path integral approach to quantum brownian motion",* Physica A **121**, 587 (1983).
A. O. Caldeira and A. J. Leggett, *"Influence of dissipation on quantum tunnelling in macroscopic systems",* Physical Review Letters **46**, 211 (1981).
A. H. Castro Neto and A. O. Caldeira, *"New model for dissipation in quantum mechanics",* Physical Review Letters **67**, 1960 (1991).