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The Australian National University

Professor Kenneth Baldwin

BSc, MSc, PhD, FAIP, FOSA, FInstP (UK), FAPS
Deputy Director, Research School of Physics and Engineering; Director, ANU Energy Change Institute
ANU College of Science
T: 02 6125 4702

Areas of expertise

  • Lasers And Quantum Electronics 020502
  • Quantum Optics 020604
  • Atomic And Molecular Physics 020201
  • Optical Physics 0205
  • Nonlinear Optics And Spectroscopy 020503
  • Degenerate Quantum Gases And Atom Optics 020601

Research interests

Professor Baldwin’s research interests lie in developing new laser technologies for precision measurement to test quantum theories of atomic and molecular structure that can be used, for example, to determine how air molecules react to ultraviolet light, thereby enabling better understanding of energy balance and ozone formation in the earth’s atmosphere.  He is also a pioneer in atom optics – a field which uses lasers to create new technologies for atoms which are the analogue of optical elements for light – that can be used e.g. to create nanostructures for better microchips.  Lasers can also be used to cool atoms to the lowest temperatures in the universe, at which point they behave more like waves than particles, enabling them to be used as sensitive detectors e.g. of changes in the earths gravitational field for mineral exploration. 

Professor Baldwin is also the Director of the ANU Energy Change Institute (www.energy.anu.edu.au).  A key to many challenges facing the world today is a world-wide change to carbon-free forms of energy production.  The ECI provides authoritative leadership in Energy Change research through a broad portfolio ranging from future energy technologies, to energy efficiency, regulation, economics, sociology and policy. The ECI comprises more than 200 staff and PhD students and around $100 million in infrastructure and facilities, supported by a major portfolio of external grant funding.

 

Biography

Professor Ken Baldwin is a laser physicist based at the Australian National University, where he is Director of the ANU Energy Change Institute, and Deputy-Director of the Research School of Physics and Engineering. 

Professor Baldwin is a Fellow of the Australian Institute of Physics, The Institue of Physics (UK), the Optical Society of America and the American Physical Society.  He is a past-President of the Australian Optical Society, and is the first Australian to be elected to the Board of Directors of the Optical Society of America.  In 2007, Professor Baldwin was awarded the W.H. Beattie Steel Medal, the highest honour of the Australian Optical Society, and in 2010 he was awarded the Barry Inglis Medal by the National Measurement Institute for excellence in precision measurement.

Professor Baldwin is also a past-President of the Federation of Australian Scientific and Technological Societies (FASTS).  In 2004 he won the Australian Government Eureka Prize for Promoting Understanding of Science, for his role in initiating and championing “Science meets Parliament”.

Researcher's projects

Professor Baldwin's research projects lie in two related fields: the use of laser
techniques (in particular the generation of vacuum ultraviolet – VUV – radiation <200nm) for high resolution spectroscopy of atoms and molecules; and laser cooling to trap and manipulate metastable helium (He*) atoms for atom optics and atomic physics experiments.

Available student projects

In 1935, Einstein, Podolsky and Rosen described a thought experiment commonly referred to as the EPR paradox, the implications of which shook quantum theory to its core. The proposed experiment challenged one of the tenets of quantum mechanics, that is, only after we measure the value of a property for a particle, does that property gain physical reality - before we measure it we must consider it to have many possible values. Einstein's rejection of such a counter-intuitive idea is elucidated in one of his more often quoted sayings: "God does not play dice".

According to Einstein, the solution to such a paradox - under the premises of local realism - was that quantum mechanics offers an incomplete picture of our world and that there exists a set of fixed properties which are hidden from our view (often referred to as local hidden variables). Quantum theory, however, offers a different explanation, stating that the two particles are intrinsically connected (entangled) and that a measurement on one particle instantaneously collapses the wavefunction of both particles causing the second particle's property to have a distinct value. This interpretation has profound implications, since it purports that the two particles are instantaneously connected and implies that quantum mechanics is intrinsically a nonlocal theory.

In 1964, John Bell proposed a method - the Bell theorem - that would test for the existence of "hidden variables", in what has been called "the most profound discovery in science". Bell showed that certain results predicted by quantum mechanics for EPR-entangled particles could not be explained by any theory which preserved the EPR premises of local realism. Bell's inequalities place certain restrictions on statistical outcomes of experiments on correlated particles and define a strict dividing line between local-realistic (hidden-variable) theories and quantum mechanics. Accordingly, violating a Bell inequality shows that quantum mechanics and its nonlocality is a correct and complete theory for understanding the laws of nature and rejects alternative local-realistic theories.

Here at the ANU we are in the process of experimentally testing these fundamental tenets of quantum mechanics with matter waves for the first time. We use an excited state of helium (in a metastable excited state - He*) cooled into a Bose-Einstein condensate (BEC) as our matter wave source to generate entangled matter wave pairs. Single-atom-detection of the atom pairs allows us to formulate Bell inequalities - allowing us to test non-local realism with macroscopic matter waves.

The main outcome of the project will be a new fundamental knowledge of large-scale EPR-entanglement and quantum nonlocality with massive particles. Large-scale entangled states do not appear to have natural manifestations in the world around us, but they can be engineered in laboratory environments. First laboratory demonstrations of EPR-entangled photon states that violated the classical bounds demanded by a Bell inequality have been heralded as among the most important experiments of 20th century quantum physics. Such demonstrations, however, have been so far realised only for massless photons and pairs of massive particles, but never for large ensembles of massive particles. Generation of large-scale entanglement is important for understanding how quantum mechanics works on mesoscopic and macroscopic scales to determine the ultimate size of future quantum devices.

Further Reading

"Characterizing Atom Sources with Quantum Coherence", S.S. Hodgman, R.G. Dall, A.G. Manning, M.T. Johnsson, K.G.H. Baldwin and A.G. Truscott, Optics and Photonics News: Optics in 2011, 22(12), 37 (2011).

"Direct measurement of long-range third-order coherence in Bose-Einstein condensates", S.S. Hodgman, R.G. Dall, A.G. Manning, K. G. H. Baldwin, and A.G. Truscott, Science 331, 1046 - 1049 (2011).

"Observation of atomic speckle and Hanbury Brown - Twiss correlations in guided matter waves", R.G. Dall, S.S. Hodgman, A.G. Manning, M.T. Johnsson, K.G.H. Baldwin and A.G. Truscott, Nature Communications 2:291 doi:10.1038/ncomms1292 (2011).

"Cold and trapped metastable noble gases", W. Vassen, C. Cohen-Tannoudji, M. Leduc, D. Boiron, C.I. Westbrook, A.G. Truscott, K.G.H. Baldwin, G. Birkl, P. Cancio and M. Trippenbach, Reviews of Modern Physics 84, 175 - 210 (2012).

"Metastable helium: Atom optics with nano-grenades", K.G.H. Baldwin, Contemporary Physics 46 (2), 105 - 120 (2005).

Publications

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Updated:  23 August 2017 / Responsible Officer:  Director (Research Services Division) / Page Contact:  Researchers