# Quantum Atom Optics

The new interdisciplinary field of quantum-atom optics (QAO) has formed at the intersection of atomic, molecular and optical physics, condensed matter physics, and computational physics. The field is driven by an unprecedented level of experimental control of degenerate Bose and Fermi systems that have a well-defined theoretical basis in quantum many-body theory. This leads to tests of theory that were previously unavailable, and thus the development of fundamental knowledge.

In the theory core of the ARC Centre of Excellence for Quantum-Atom Optics (ACQAO) we pursue cutting-edge developments in quantum many-body physics that lead to our growing understanding of QAO systems. We approach these systems from a microscopic perspective, focusing on how to generate, manipulate and measure many-body correlations.

#### Our motivating scientific questions are:

- How are the many-body states of QAO systems best characterised, and

how is the formation of these states to be understood as a non-equilibrium,

dynamical process? - What kinds of entanglement and many-body correlations can be generated

in QAO systems, and in what ways can they be efficiently detected? - How do QAO systems test fundamental predictions of quantum mechanics

and many-body theory? - What new theoretical and computational methods must be developed to

provide quantitative answers to these questions?

We provide ideas, simulations and advanced quantitative models for leading experimental groups in Australia and worldwide. As an outcome of ACQAO experimental and theoretical work, we expect practical tools that utilize many-body quantum behaviour of QAO systems, e.g. continuously pumped atom laser, sources of entangled atoms, and matter-wave interferometers for precision measurements.

#### Our research program is structured around five themes:

1) Atom lasers and formation of quantum degenerate gases

2) Coherent manipulations of matter waves

3) Quantum statistics and pairing correlations in ultracold Bose and Fermi systems

4) Macroscopic correlations, entanglement and fundamental tests5) Computational physics and theoretical methods for Bose and Fermi systems

## Recent project reports

**2010**

- Exact Quantum Dynamics of Fermionic systems

M. Ögren, K. V. Kheruntsyan, and J. F. Corney - Atom Interferometry below the standard quantum limit

S. A. Haine - Interferometry and EPR Entanglement in a BEC

M. D. Reid, Q. -Y. He1, B. Opanchuk, S. Hoffmann, A. Sidorov, P. D. Drummond, C. Gross, and M. Oberthalers - Relative number squeezing in condensate collisions

V. Krachmalnicoff, J.-C. Jaskula, M. Bonneau, G. B. Partridge, D. Boiron, A. Aspect, C. I. Westbrook, P. Deuar, P. Zin, M. Trippenbach, and K. V. Kheruntsyan

- Superfluidity in dilute gas Bose-Einstein condensates

C. Feng, T. M. Wright, T. Simula, A. S. Bradley, B. P. Anderson, and M. J. Davis - C-field simulations of thermal Bose-Einstein condensates

G. M. Lee, T. M. Wright, S. A. Haine, M. C. Garrett, C. J. Foster, A. S. Bradley, N. P. Proukakis, and M. J. Davis - Formation of topological defects in Bose-condensed gases

J. Sabbatini, G. M. Lee, M. C. Garrett, S. A. Haine, A. S. Bradley, B. P. Anderson, W. H. Zurek, and M. J. Davis - BEC superpositions in twin wells

T. J. Haigh, A. J. Ferris, and M. K. Olsen - Measurement of density fluctuations as a new probe of the physics of quasi-1D Bose gases

J. Armijo, T. Jacqmin, K. V. Kheruntsyan, and I. Bouchoule - Momentum distribution of a weakly interacting quasi-1D Bose gas

P. B. Blakie, M. J. Davis, A. van Amerongen, N. J. van Druten, and K. V. Kheruntsyan - Quadripartite CV entanglement and cluster states

S. L. W. Midgley, M. K. Olsen, A. S. Bradley, and O. Pfister

**2009**

- Exact Quantum Dynamics of Fermionic systems

M. Ögren, K. V. Kheruntsyan and J. F. Corney - Superfluidity in dilute gas Bose-Einstein condensates

A. G. Sykes, C. Feng, D. C. Roberts, A. S. Bradley, B. P. Anderson, and M. J. Davis. - Formation of topological defects in Bose-condensed gases

J. Sabbatini, G. M. Lee, S. A. Haine, A. S. Bradley, B. P. Anderson, and M. J. Davis - Spontaneous Four-Wave Mixing of de Broglie Waves: Beyond Optics

V. Krachmalnicoff1, J.-C. Jaskula, M. Bonneau, G. B. Partridge, D. Boiron, C. I. Westbrook, P. Deuar, P. Zi ´n, M. Trippenbach, and K. V. Kheruntsyan - Quantum dynamics and entanglement in Bose-Einstein condensates

M. K. Olsen, A. J. Ferris, C. M. Caves, S. W¨uster, B. J. Da¸browska-W¨uster, and M. J. Davis - Nonlinear dynamics of Bose-Einstein condensates

S. A. Haine, C. J. Foster, E. D. van Ooijen, N. R. Heckenberg, H. Rubinsztein-Dunlop, P. van der Straaten, and M. J. Davis - Extending the realms of numerical stochastic integration

M. K. Olsen - Non-local spatial pair correlations in a 1D Bose gas

P. Deuar1, A. G. Sykes, D. M. Gangardt, M. J. Davis - Quantum-atom optics with molecular dissociation

M. Ögren1, C. M. Savage, S. Midgley, M. J. Davis, M. K. Olsen, and K. V. Kheruntsyan - C-field simulations of thermal Bose-Einstein condensates

G. M. Lee, S. A. Haine, M. C. Garrett, C. J. Foster, A. S. Bradley, R. N. Bisset, P. B. Blakie, C. Ticknor, T. Simula, and M. J. Davis