Dr Howard John Carmichael
MSc, DPhil (Waikato), FRSNZ
Research | Current
Quantum Trajectory Theory
Quantum trajectory theory treats the open systems encountered in quantum optics according to a scattering scenario, in which the inputs are classical fields (external fields) and the outputs are classical stochastic processes that model the scattered fields after detection (after their measurement).
The mapping from inputs to outputs is provided by a quantum stochastic process that is set up to account for a particular measurement strategy (eg., photon counting, homodyne/heterodyne detection, etc). Both the formal theory and its applications are under study. Recent work includes the development of a novel measurement scheme to correlate the quadrature amplitudes of an electromagnetic field, applications of this scheme in cavity quantum electrodynamics, and the modeling of multimode aspects of collective radiative phenomena (super-radiance).
Entanglement and Correlation in Composite Systems
Quantum optics has traditionally concerned itself with uniquely quantum mechanical aspects of optical phenomena (eg. photon anti-bunching and squeezing, violations of Bell inequalities). Attention in recent years has been focused on applications of these quantum features of light to novel schemes for processing information (so-called quantum information science). Entangled states are central to the proposed information processing protocols. Current work is directed towards understanding entangled states, and the contextual correlations they describe, in the broadest sense, ie, we are concerned with the physics of composite quantum systems in general. Specific interests include measures of entanglement for open systems, and schemes for the generation and manipulation of this entanglement. Continous variable entanglement is of particular interest. It has been suggested by others that this form of entanglement can be accounted for within stochastic electrodynamics. The suggestion is being assessed. A quantum trajectory theory of continuous variable teleportation is being developed for comparison with the stochastic electrodynamics proposal.
- The Dan Walls Chair in Theoretical Physics
Areas of expertise
- Theoretical Quantum Optics
- Quantum Theory of Open Systems
- Quantum Stochastic Processes
Selected publications and creative works (Research Outputs)
- Gasparinetti, S., Besse, J.-C., Pechal, M., Buijs, R. D., Eichler, C., Carmichael, H. J., & Wallraff, A. (2019). Two-photon resonance fluorescence of a ladder-type atomic system. PHYSICAL REVIEW A, 100 (3)10.1103/PhysRevA.100.033802
- Minev, Z. K., Mundhada, S. O., Shankar, S., Reinhold, P., Gutiérrez-Jáuregui R, Schoelkopf, R. J., ... Devoret, M. H. (2019). To catch and reverse a quantum jump mid-flight. Nature, 570 (7760), 200-204. 10.1038/s41586-019-1287-z
- Gutierrez-Jauregui, R., & Carmichael, H. J. (2018). Quasienergy collapse in the driven Jaynes-Cummings-Rabi model: correspondence with a charged Dirac particle in an electromagnetic field. PHYSICA SCRIPTA, 93 (10)10.1088/1402-4896/aad6fc
- Gutierrez-Jauregui, R., & Carmichael, H. J. (2018). Dissipative quantum phase transitions of light in a generalized Jaynes-Cummings-Rabi model. PHYSICAL REVIEW A, 98 (2)10.1103/PhysRevA.98.023804
- Gutierrez Jauregui, R. (2018). Dissipative Quantum Phase Transitions of Light: Generalized Jaynes-Cummings-Rabi Model The University of Auckland. ResearchSpace@Auckland.
- Whalen, S. J., Grimsmo, A. L., & Carmichael, H. J. (2017). Open quantum systems with delayed coherent feedback. Quantum Science and Technology, 2 (4)10.1088/2058-9565/aa8331
- Whalen, S. J., & Carmichael, H. J. (2016). Time-local Heisenberg-Langevin equations and the driven qubit. Physical Review A, 93 (6)10.1103/PhysRevA.93.063820
- Carmichael, H. J. (2015). Breakdown of photon blockade: A dissipative quantum phase transition in zero dimensions. Physical Review X, 5 (3)10.1103/PhysRevX.5.031028