Personal details
Publications in international refereed journals
Multiple Bifurcations in atom optics
W. K. Hensinger, B. Upcroft, G.J. Milburn,
N.R. Heckenberg and H. Rubinsztein-Dunlop,
Physical Review A Vol.64, 063408, 2001
Abstract:
We report the observation of multiple
bifurcations in a non-linear Hamiltonian system: laser cooled atoms in a
standing wave with single frequency intensity modulation. We provide clear
evidence of the occurrence of bifurcations by analyzing the atomic
momentum distributions.
Dynamical tunneling of ultra-cold atoms
W. K. Hensinger, H. Häffner, A. Browaeys,
N.R. Heckenberg, K. Helmerson, C. McKenzie, G. J. Milburn, W. D. Phillips, S. L.
Rolston, H. Rubinsztein-Dunlop, and B. Upcroft
Nature Vol. 412, 5 July, 52-55, 2001
Abstract:
The divergence of quantum and classical
descriptions of particle motion is clearly apparent in quantum tunneling between
two regions of classically stable motion. An archetype of such non-classical
motion is tunneling through an energy barrier. In the 1980s, a new process,
‘dynamical’ tunneling, was predicted, involving no potential energy
barrier; however, a constant of the motion (other than energy) still forbids
classically the quantum-allowed motion. This process should occur, for example,
in periodically driven, nonlinear Hamiltonian systems with with one degree of
freedom. Such system may be chaotic, consisting of regions in phase space of
stable, regular motion embedded in a sea of chaos. Previous studies predicted
dynamical tunneling between these stable regions. Here we observe dynamical
tunneling of ultra-cold atoms from a Bose-Einstein condensate in an
amplitude-modulated optical standing wave. Atoms coherently tunnel back and
forth between their initial state of oscillatory motion (corresponding to an
island of regular motion) and the state oscillating 180° out of phase with the
initial state.
Experimental study of the quantum driven pendulum and its classical analogue in
atom optics
W.K. Hensinger, A.G. Truscott, B. Upcroft,
M. Hug, H.M. Wiseman, N.R. Heckenberg, H. Rubinsztein-Dunlop
Physical Review A Vol. 64, 033407, 2001
Abstract:
We present experimental results for the dynamics
of cold atoms in a far detuned amplitude modulated optical standing wave. Phase
space resonances constitute distinct peaks in the atomic momentum distribution
containing up to 65 % of all atoms resulting from a mixed quantum chaotic phase
space. We characterize the atomic behavior in classical and quantum regimes and
present the applicable quantum and classical theory, which we have developed and
refined. We show experimental proof that the size and the position of the
resonances in phase space can be controlled by varying several parameters such
as the modulation frequency, the scaled well depth, the modulation amplitude and
the scaled Planck's constant of the system. We have found a surprising stability
against amplitude noise. We present methods to accurately control the velocity
of an ensemble of atoms using these phase space resonances which could be used
for efficient phase space state preparation.
Atoms in an amplitude modulated standing wave - dynamics and pathways to quantum
chaos
W.K. Hensinger, A.G. Truscott, B. Upcroft,
N.R. Heckenberg and H. Rubinsztein-Dunlop
Journal of Optics B: Quantum and
Semiclassical optics, Vol. 2(5): 659-667, 2000
Abstract:
Cold rubidium atoms are subjected to an
amplitude modulated far detuned standing wave of light to form a quantum driven
pendulum. Here we discuss the dynamics of these atoms. Phase space resonances
and chaotic transients of the system exhibit dynamics which can be useful in
many atom optics applications as they can be utilized as means for phase space
state preparation. We explain the occurence of distinct peaks in the atomic
momentum distribution, analyze them in detail and give evidence for the
importance of the system for quantum chaos and decoherence studies.
Coherent atomic beam splitter using transients of a chaotic system
A.G. Truscott, M.E.J. Friese, W.K.
Hensinger, H.M. Wiseman, H. Rubinsztein-Dunlop and N.R. Heckenberg
Physical Review Letters, Vol. 84(18):
4023-4026, 2000
Abstract:
A coherent atomic beam splitter can be
realised using the transient dynamics of a chaotic system. We have
experimentally observed such an effect using ultra-cold rubidium atoms. Our
experimental results are in good agreement with numerical simulations of the
Schrodinger equation for the system.
Variations of
relative line intensity in saturation spectroscopy due to low magnetic fields
W.K. Hensinger, A.G. Truscott, H.
Rubinsztein-Dunlop and N.R. Heckenberg
Optical and Quantum Electronics, Vol.
31(5/7): 391-403, 1999
Abstract:
We have observed dramatic line intensity
variations in the saturation spectrum of Rb85 and Rb87 due to magnetic fields of
magnitude on the order of 100 nT. These variations are detected by rotation of
the plane of polarisation of the pump beam and probe beam relative to the
magnetic field axis. A modified rate equation model is proposed which accounts
for all experimentally observed features. Our results may explain some
discrepancies between theory and experiment observed by other authors.
Furthermore, our study should lead to a better understanding of the processes
involved in saturation spectroscopy.
Popular Science articles about my research
Nature, News and Views, 5th of July, 2001
Nature, Physics Portal, Research Highlights, 5th of July, 2001
Science, ScienceNow 6th of July, 2001
University of Queensland News, 3rd of August, 2001
IOP
PhysicsWeb, 5th of July, 2001
Other publications
Coherent
dynamical tunneling and quantum chaos with Bose-Einstein condensates
W. K.
Hensinger
Invited article for the Australia & New Zealand Physicist, January/February 2002
Experimental tests of quantum nonlinear dynamics in atom optics
W. K. Hensinger
PhD thesis, The Univeristy of Queensland 2002
Cold atoms in an amplitude modulated optical lattice – dynamical
tunneling
W. K. Hensinger, H.
Häffner, A. Browaeys, N. R. Heckenberg, K. Helmerson, C. McKenzie, G. J.
Milburn, W. D. Phillips, S. L. Rolston, H. Rubinsztein-Dunlop, and B. Upcroft
Laser Spectroscopy, Proceedings of the 15th International conference on Laser
Spectroscopy in Snowbird, Utah, USA, June 10-15, 2001
Pathways to increase problem solving skills, motivation and depth of knowledge
in a first year physics course,
W. K. Hensinger, proceedings of the
Effective teaching and learning at university conference in Brisbane, Australia,
2000,
accessible at http://www.tedi.uq.edu.au/conferences/teach_conference00/papers/hensinger.html
Book review on "Basic Vacuum
Technology" by Chambers, Fitch and Halliday
W. Hensinger,
in LABNEWS December 1998/ January 1999
Introducing a more successful first
year physics curriculum to increase problem solving skills, motivation and depth
of knowledge
W.K. Hensinger,
Report for the award of the Graduate
Certificate of Education (Tertiary Education), The Universty of Queensland 1999
Studies on the atomic alignment in
saturation spectroscopy of rubidium
W.K. Hensinger,
MSc thesis, The University of Queensland
1998
Academic awards
2002 Recipient of the 2002 Optical Society of America / International Society for Optical Engineering joint student prize presented at the ACOLS 2001 conference in Brisbane, Australia
2001 Invited speaker at the 15th International Conference on Laser Spectroscopy 2001 in Snowbird, Utah, USA
2001 Recipient of the 2001 Postgraduate Student prize of the Australian Optical Society.
2000 Recipient of a Graduate School Research Travel Award from the Graduate School at the University of Queensland in 2000 to conduct experiments at the National Institute of Standards in Gaithersburg, USA.
1999 Commendation as "Most effective Teacher" for the first year physics course PH144 at the University of Queensland in 1999 by the Dean of the Faculty Engineering, Physical Sciences and Architecture
1999 Honorary mention of my poster at the Twelfth Conference of the Australian Optical Society (AOS'99) held at 6-9 July 1999 in Sydney, Australia
1999 Award of a staff development scholarship and a departmental scholarship to undertake a Graduate Certificate in Education (Tertiary Education) course.
1999 Award of a departmental top-up scholarship starting January 1999
1998 Prize for the best poster at the Australasian Conference on Optics, Lasers and Spectroscopy held at 14-17 December 1998 in Christchurch, New Zealand.
1998 Award of an OPRS and UQPRS scholarship for international students to undertake PhD studies at the University of Queensland covering living expenses, travel expenses and tuition fees.
1997 Award of an additional scholarship of the Friedrich-Ebert-Stiftung to undertake MSc. studies at the University of Queensland covering all living expenses, tuition fees and travelling expenses
1996 Appointment as Fellow of the Friedrich-Ebert-Stiftung accompanied by a scholarship covering all living expenses, travelling expenses for pre-doctoral studies and the possibility to participate at seminars and conferences of the Friedrich Ebert-Stiftung for highly gifted and qualified students.
1990 Award of a Youth for Understanding Scholarship.
updated by Winfried Hensinger in October 2001