Centre for Atom Optics and Ultrafast Spectroscopy Swinburne University of Technology 2012, Volume 7, Number 1

Location
Swinburne University of Technology
Hawthorn Campus
Melbourne, Australia
Further Information: www.swinburne.edu.au/caous

Overview
Established in 1999, the Centre for Atom Optics and Ultrafast Spectroscopy (CAOUS) is a leading centre of excellence in atom optics, ultracold Fermi gases, ultrafast laser science, applied optics and theoretical physics. CAOUS is in the Faculty of Engineering and Industrial Sciences of the Swinburne University of Technology, and is located at the university’s Hawthorn campus in the inner suburbs of Melbourne. The Centre also administers part of the Australian Research Council (ARC) Centre of Excellence for Coherent X-Ray Science (CXS).

Key Contact
Professor Russell McLean
Acting Director, Centre for Atom Optics and Ultrafast Spectroscopy
Telephone: +61 3 9214 8555
E-mail: rmclean@swin.edu.au

Research Foci

• Atom Optics: developing and utilizing microfabricated atom chips for trapping and manipulating ultracold atoms and Bose-Einstein condensates (BECs) of rubidium-87. These have applications for miniaturization and integration of atom optical elements and atom interferometers, quantum sensor development and quantum information processing. The group also uses light induced atomic coherence to control optical properties of atomic media, providing a convenient platform for proof-of-principle experiments in quantum telecommunication.

• Ultracold Fermi Gases: studying fermionic (half-integral spin) lithium-6 gases in an optical trap and cooled down to within one hundred billionths of a degree of absolute zero. The ability to control the inter-particle interactions through the use of a magnetically tunable Feshbach resonance allows the group to prepare a BEC of bosonic (integral spin) lithium-6 dimer molecules or a degenerate Fermi gas of lithium-6 atoms and to have access to different types of superfluid which span from a BEC of bound molecules to a BCS (Bardeen–Cooper–Schrieffer) superfluid of correlated Cooper pairs.

• Strongly Correlated Fermion Theory: motivated by the rapid experimental developments in degenerate Fermi gases, theories are being developed to describe these systems. They are controlled at an unprecedented level and are well described by quantum many-body models. The program involves themes designed to develop fundamental knowledge of the underlying physics, and to provide theoretical guidance to experiments at Swinburne University of Technology.

• Foundations of Quantum Mechanics: The well-known 1935 paper of Einstein et al. (EPR) led to the famous Bell theorem, which has been called “the most profound discovery of Science”. The Schr?dinger cat paradox raises an even more important issue – how to reconcile quantum realities with classical realities at the macroscopic level. Quantum information is the study of how to apply quantum mechanics in the development of new technologies, such as quantum memories, which can store a quantum state indefinitely.

• Computational and Phase-space Theory: developing new computational algorithms for simulating quantum and classical many-body systems, including BEC and ultracold fermion systems, with access to modern GPU-enabled supercomputers on the Swinburne University of Technology campus. As a cross-disciplinary application, we solve sophisticated models in bioinformatics, to understand and analyze genetic drift and genetic correlations.

• Ultrafast Science: utilizes two ultrafast laser systems. The first consists of two independently tunable sources of femtosecond laser pulses, which are used to study optical properties and dynamic processes in systems of interest in physics, chemistry, and biology, including semiconductor quantum dots and quantum wells, light-harvesting protein complexes and carotenoid molecules. The second system produces intense femtosecond laser pulses, which are used to generate pulses of coherent soft X-ray radiation, with the long term goal of generating coherent X-rays in the “water window”, for imaging biologically important molecules.

• Applied Optics: developing optical fibre sensors based on Surface-Enhanced Raman Scattering (SERS) and fibre Bragg gratings. Evanescent field interactions are investigated for distributed chemical sensing. Another major thrust involves the development of optical methods for nerve stimulation.

Recent Projects

• Atom Optics: On-chip Ramsey interferometry has been used to monitor the phase evolution of a two-component BEC, in two ground hyperfine states, and a long coherence time of 2.5s has been observed. Trapping and cooling of rubidium-87 atoms has been successfully realized in multiple sites of a 10 micron-period magnetic lattice on an atom chip at temperatures down to 1–2 microKelvin.
Frequency up-conversion of low power laser light has been realized via phase-matched four-wave mixing in hot rubidium vapor. This technique allows the generation of coherent radiation in the UV and mid-IR spectral ranges.

• Ultracold Fermi Gases: Universal behavior has been demonstrated for superfluid pairing in the BEC to BCS (Bose–Einstein condensation to Bardeen–Cooper–Schrieffer) crossover using Bragg spectroscopy of an ultracold gas of fermionic lithium-6 atoms, including an extensive study of the universal contact parameter.
Researchers in this group have prepared the world’s first isolated 2D Fermi gas.

• Strongly Correlated Fermion Theory: A high-temperature expansion has been developed to study the thermodynamics and dynamics of strongly correlated Fermi gases near the BEC–BCS crossover region, and new exact universal relations have been derived for describing the asymptotically large momentum and frequency behavior.

• Foundations of Quantum Mechanics: A new type of quantum squeezing – planar spin squeezing – has been identified and shown to provide a novel route to quantum enhanced interferometry and measurement.

• Computational and Phase-space Methods: Numerical algorithms useful for tracking the number of mutations in genetically diverse viral species have been developed, and applied to models of RNA virus infection.

• Ultrafast Science: A new technique has been developed for generating high fluxes of highly coherent soft X-rays using high harmonic generation of femtosecond laser pulses. This source has recently been used to implement new imaging techniques such as coherent diffractive imaging and the study atomic and molecular structures.
A technique has been developed for retrieving the phase information from intensity measurements, which has been used to reveal coherent coupling in biomolecules and coupled semiconductor quantum wells.

• Applied Optics: A touch sensor has been developed for use in cochlear implants. Ongoing research into optical fibre chemical sensors is currently directed towards integrating spectroscopic sensing techniques with microfluidic systems. This has potential applications in blood glucose monitoring in diabetics, water purity monitoring, metabolyte monitoring and bacteria detection.