# Director's Colloquium

## Engineered Quantum Systems

**Gerard Milburn**

**Thursday 12 July 2012 12–1pm**

**Leonard Huxley Theatre**

**Professor Gerard Milburn****University of Queensland**

The last decade has seen a revolution in the variety and size of physical systems which can be subjected to coherent quantum control. Given sufficiently sophisticated fabrication, certain collective degrees of freedom can be engineered so as to enable coherent quantum control. Another important feature of these systems is worth noting: they are often anything but microscopic. The old equivalence of quantum/classical with microscopic/macroscopic begins to look a little dated in the light of recent advances in engineered quantum systems. Of course the old puzzles of quantum theory remain just as evident as ever, but are now seen in the context of a single, rather large, quantum system that can exhibit both classical and quantum degrees of freedom in one and the same device.

Engineered quantum systems are now moving beyond single technology platforms towards hybrid systems. Examples include combining optical and microwave control of electron and nuclear spins in solids such as NV diamond, combining superconducting electronic circuits with trapped ions and molecules and interfacing microwave and optical cavities via nanomechanical and micromechanical quantum resonators. The continued development of this field will require a more systems-level engineering perspective to address such issues as; noise and decoherence in complex, multi-platform systems, quantum and classical control of diverse physical components with diverse timescales, in-line quantum information processing and quantum memories, coexistence of discrete and continuous dynamics etc. In this talk I will give some examples of how these issues arise in the context of particular hybrid quantum systems and give some (admittedly speculative) examples of possible quantum enabled technologies based on hybrid quantum systems.

**Gerard Milburn's** research interests are in the fields of: Quantum Information Theory, Quantum Optics, Quantum Control and Measurement Theory, Quantum Nanomechanical Systems, Theory of Mesoscopic Electronic Systems, Quantum Chaos and Atomic BEC. Gerard Milburn obtained a PhD in theoretical Physics from the University of Waikato in 1982 for work on squeezed states of light and quantum nondemolition measurements. He is currently an Australian Research Council Federation Fellow at the University of Queensland. Gerard Milburn is a Fellow of the Australian Academy of Science and The American Physical Society.

**Refreshments will be available in the RSPE Tearoom from 11:30. ALL WELCOME.**