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AP 483 seminar presents "Sensing beyond the conventional limits: vortices, viscosity and molecular vibrations"

Sensing beyond the conventional limits: vortices, viscosity and molecular vibrations
Monday, September 21, 2020 - 4:15pm
Prof. Warwick Bowen (University of Queensland, Australia)
Abstract / Description: 

It has been known for over a century that, in quantum physics, even the act of looking can have dramatic consequences. For instance, it kills the cat in Schrödinger’s famous thought experiment. However, it has proved extremely difficult to reach regimes where such effects play a role, let alone to use them as a tool to enhance measurement technologies. 


Over the past decade, however, advances in photonics and nanotechnology have allowed us to engineer both devices and states of light which exhibit this distinctive quantum behavior [1]. These “quantum optomechanical devices” consist of a nanoscale mechanical object – for example, a nanoparticle, molecule or cantilever – coupled to light via radiation pressure, often concentrated in a tiny optical cavity. In essence, they are miniature versions of the kilometer-scale interferometers that have enabled the extraordinary detection of gravitational waves from distant black hole collisions. Quite remarkably, they can allow measurements of motion at the sub-attometre level – more than a thousand times below the width of an atomic nucleus. At a fundamental level, this allows us to ask new questions of quantum physics for macroscopic systems consisting of trillions of atoms. It also provides a way to build precision optical sensors that far outperform the current state-of-the-art. 


In this talk, I will provide an overview of optomechanical sensors developed in my laboratory, with a particular focus on applications in the bioscience and in studying superfluid helium, a strongly interacting quantum liquid. This includes the observation of coherent vortex dynamics in two-dimensional superfluid helium [2]; the engineering of extreme Brillouin nonlinearities in superfluid thin-films [3]; a quantum-light microscope that provides absolute quantum advantage, allowing the observation of molecular vibrations of nanoscale biological structures that would otherwise be unresolvable [4]; and optical tweezers that allow tracking of the instantaneous

velocity of trapped particles, and through this orders-of-magnitude faster measurements of cell properties reaching microsecond timescales [5].

  1. Bowen and Milburn, Quantum Optomechanics, CRC Press (2016).
  2. Science 366 1480 (2019).
  3. Nature Physics 16 417 (2020); also Nature Physics 12 788 (2016).
  4. arXiv:2004.00178 (2020).
  5. arXiv:2007.03066 (2020); also Nature Photonics 11, 477-481 (2017); 9, 669-673 (2015); 7, 229-233 (2013)

This seminar is sponsored by the department of Applied Physics and the Ginzton Laboratory.

Organized by Prof. Amir Safavi-Naeini


Warwick Bowen's research focuses on the implications of quantum science on precision measurement, and applications of quantum measurement in areas ranging from quantum condensed matter physics to the biosciences. He is a Fellow of the Australian Institute of Physics, Director of the University of Queensland Precision Sensing Initiative, and a Theme Leader of the Australian Centre for Engineered Quantum Systems. His laboratory was the first to show the benefits of quantum-light in biological microscopy. This allowed the demonstration of quantum enhancement of biological measurements and of single molecule sensing with ultralow optical intensities, among other results. Prof Bowen's laboratory also has active research efforts on integrated photonics, quantum control of macroscopic mechanical devices, and superfluid helium physics. His research is supported by the Australian Research Council, the US Air Force Office of Scientific Research, Lockheed Martin, the US Army Research Office and the Australian Defence Science and Technology Group.