He was appointed to the faculty of the Physics Department of the University of Waikato in 1970, and was awarded a personal chair in physics in 1992, a position held until 1995. When Gardiner arrived, the University of Waikato was only 5 years old, while the School of Science, which covered Physics, Mathematics, Chemistry, Biology and Earth Science, had only commenced teaching at the beginning of 1970, and no research facilities had been established. Dan Walls took up a position at Waikato in 1972, and, working together, he and Gardiner established a major research centre for theoretical quantum optics at Waikato, building active and productive collaborations with groups throughout the world. During this period
He and Peter Drummond developed the positive P-representation
He and Matthew Collett developed the input-output formalism for damped quantum systems, which they used to predict and describe the spectrum of squeezed light.
He wrote the first edition of the book Stochastic Methods , now seen as a standard text in the field of applied stochastic processes.
In 1986 he predicted the inhibition of atomic phase decays for a two-level atom coupled to a squeezed optical reservoir. While challenging to realise in optical systems, the phenomenon was eventually observed in a superconducting qubit system affording sufficient reservoir control.
He wrote the first edition of the book "Quantum Noise", which has become a standard text in the fields of quantum optics and quantum stochastic methods.
In 1993 he developed the theory and application of cascaded quantum systems, in which the optical output of one quantum system becomes the optical input for another quantum system.
In 1995 he left the University of Waikato and for the next nine years worked as an independently funded researcher affiliated to Victoria University of Wellington. This was funded by the New Zealand R&D system, which was willing to fund individuals outside established institutions, and was motivated by the opportunity to leave the increasingly bureaucratic New Zealand University system. During this period his work concentrated on the physics of Ultracold atoms, developing a collaboration with Rob Ballagh of the University of Otago. They produced number of influential scientific publications, mainly concentrating on kinetic processes in Bose–Einstein condensates, funded by successive research contracts with the Marsden Fund and in particular seven papers on quantum kinetic theory . Gardiner characterised this period as "In terms of productivity, it has been the best 10 years research of my life."
In 2005 he was appointed as a Research Professor at the University of Otago. In this period he was active in developing the University of Otago as a major research centre in ultracold atoms, photonics and quantum optics, which was named the Jack Dodd Centre, after former Otago professor Jack Dodd. During this period there was a major reorganisation of government research funding, commencing in 2006, which he and Rob Ballagh strongly criticised, on the grounds that this would exclude university research from any major funding. Ultimately this aspect of the funding reform was not implemented, and in 2007 the Jack Dodd Centre was awarded a $6.4 million research contract by the Foundation for Research, Science and Technology. From that time on, as director of the Jack Dodd Centre, his role developed more into that of a research leader until his retirement in early 2013.
C W Gardiner: A Handbook of Stochastic Methods; Springer, Berlin Heidelberg, 1st ed. 1983; 2nd ed. 1985, 1989, 1998, 2001; 3rd Ed 2004, Russian Edition 1986
Crispin Gardiner: Stochastic Methods; Springer, Berlin Heidelberg, 2009
Quantum Noise
C W Gardiner: Quantum Noise; Springer, Berlin Heidelberg, 1st ed. 1991
C W Gardiner and Peter Zoller: Quantum Noise; Springer, Berlin Heidelberg, 2nd ed. 1999, 3rd ed. 2004
The Quantum World of Ultra-Cold Atoms and Light
Crispin Gardiner and Peter Zoller: The Quantum World of Ultra-Cold Atoms and Light Book I: Foundations of Quantum Optics, Imperial College Press, London and Singapore 2014.
Crispin Gardiner and Peter Zoller: The Quantum World of Ultra-Cold Atoms and Light Book II: Physics of Quantum Optical Devices, Imperial College Press, London and Singapore 2015.
Crispin Gardiner and Peter Zoller: The Quantum World of Ultra-Cold Atoms and Light Book III: Ultra-Cold Atoms, World Scientific, London and Singapore 2014.
2000 Honorary Dr. Rer. Nat. from the University of Innsbruck: In recognition of his outstanding scientific merit in the field of theoretical quantum optics