This, coupled with Brauenstein's result (see 1999 above), called the validity of NMR quantum computation into question.[15] Emanuel Knill, Raymond Laflamme, and Gerard Milburn show that optical quantum computing is possible with single photon sources, linear optical elements, and single photon detectors, launching the field of linear optical quantum computing. Robert Raussendorf and Hans J. Briegel propose measurement-based quantum computation.[16] 2002 The Quantum Information Science and Technology Roadmapping Project, involving some of the main participants in the field, laid out the Quantum computation roadmap. The Institute for Quantum Computing established at the University of Waterloo in Waterloo, Ontario by Mike Lazaridis, Raymond Laflamme and Michele Mosca.[17] 2003 Todd D. Pittman and collaborators at Johns Hopkins University, Applied Physics Laboratory and independently Jeremy L. O'Brien and collaborators at the University of Queensland, demonstrate quantum controlled-not gates using only linear optical elements.[18][19] DARPA Quantum Network becomes fully operational on October 23, 2003.