Prof. Andrew G. White Profile

Prof. Andrew G. White

at Univ of Queensland

SPIE Involvement:

Author

Proceedings Article | 28 June 2023 Paper

Educating decision makers on resource allocations for quantum technologies

Russell Manfield, Michael Harvey, Andrew White

Proceedings Volume 12723, 127232Y (2023) https://doi.org/10.1117/12.2668765

KEYWORDS: Quantum technologies, Online learning, Quantum science, Industry, Quantum computing, Video

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Proceedings Article | 27 August 2021 Open Access

Optimal imaging by measuring photon-number

Andrew White

Proceedings Volume 11918, 119180L (2021) https://doi.org/10.1117/12.2611217

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Transition-edge sensors (TES’s) are are extremely sensitive calorimeters able to measure energies of the order of a few electronvolts. They are now well-known in the quantum technology community because of their superb combination of high-efﬁciency— higher than 95% for photons in the near infrared range [1]—essentially zero dark counts, and photon-number resolution. One of the main challenges when working with TES’s is to extract the photon-number information from the continuous output signal of the detectors. The usual procedure is to accumulate signals over some time—typically ~2 GB per minuite—and then use post-processing techniques to obtain photon-number resolution from the recorded signals [2] Here we introduce an FPGA circuit that analyses TES signals in real-time—recording only speciﬁc characteristics such as signal area, height, and length—allowing near realtime photon-number resolution and reducing the memory requirements by orders-of-magnitude. Using this new capability, we are able to optimise the number-resolution of the detector to the range we are interested in for each new experiment. In a preliminary study, we calibrated the TES with a weakly-pulsed 820 nm diode laser, and using just the area data from the FPGA were able to discriminate up to 15 photons. We are able to accurately discriminate an n=2 photon Fock state with parts-per-billion precision, dropping to parts-per-hundred precision at n=15 [3]. It is well known that there are physical limits to the precision with which an image can be formed. There are ways in which this limit can be circumvented, for example using super-resolution techniques that exploit the physical structure of the object, or object illumination with entangled states of light. However, in many applications—for example when the object is very far away—we cannot directly interact with the object, or illuminate it with entangled light: the quantum state of the light field is all that is accessible to the observer. Given a finite size imaging system in the far field—i.e., systems with a finite effective numerical aperture—we show the best way to extract the spatial characteristics of the light source. We implement a general imaging method by measuring the complex degree of coherence using linear optics and our photon-number-resolving detectors. In the absence of collective or entanglement-assisted measurements, our method is optimal over a large range of practically relevant values of the complex degree of coherence [4]. We measure the size and position of a small distant source of pseudo-thermal light, and show that our method outperforms the traditional imaging method by an order of magnitude in precision. Additionally, we show that a lack of photon-number resolution in the detectors has only a modest detrimental effect on measurement precision, further highlighting the practicality of this method as a way to gain significant imaging improvements in a wide range of imaging applications. References [1] A. E. Lita, A. J. Miller, and S. W. Nam, Optics Express 16, 3032 (2008). [2] G. Brida, et al., New Journal of Physics 14, 085001, (2012). [3] L. Assis, et al., preprint (2020) [4] L. A. Howard, et al., Physical Review Letters 123, 143604 (2019).

Proceedings Article | 22 February 2018 Presentation + Paper

Spatial modes for testing indefinite causal order

Jacquiline Romero, Kaumudibikash Goswami, Christina Giarmatzi, Fabio Costa, Cyril Branciard, Andrew White

Proceedings Volume 10549, 1054908 (2018) https://doi.org/10.1117/12.2292732

KEYWORDS: Polarization, Prisms, Photon polarization, Quantum mechanics, Quantum communications, Superposition

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Proceedings Article | 13 September 2005 Paper

Using entanglement in photonic qubit measurements

G. Pryde, J. O'Brien, A. White, T. Ralph, S. Bartlett, H. Wiseman

Proceedings Volume 5893, 58930Y (2005) https://doi.org/10.1117/12.616166

KEYWORDS: Quantum communications, Polarization, Quantum physics, Beam splitters, Quantum information, Quantum computing, Nondestructive evaluation, Wave plates, Telecommunications, Optical circuits

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Proceedings Article | 3 February 2004 Paper

Investigation of two qubit quantum gates in linear optics

Timothy Ralph, Nathan Langford, Tamyka Bell, Jeremy O'Brien, Geoff Pryde, Andrew White, Gerard Milburn

Proceedings Volume 5161, (2004) https://doi.org/10.1117/12.505078

KEYWORDS: Beam splitters, Quantum communications, Photons, Polarization, Interferometers, Quantum computing, Quantum optics, Entangled states, Error analysis, Reflectivity

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Proceedings Article | 6 May 1996 Paper

Experiments and theory of laser noise: consequences for squeezing and injection locking

Hans-Albert Bachor, Matthew Taubman, Timothy Ralph, Charles Harb, A. White, David McClelland

Proceedings Volume 2799, (1996) https://doi.org/10.1117/12.239824

KEYWORDS: Second-harmonic generation, Nd:YAG lasers, Laser resonators, Systems modeling, Laser systems engineering, Semiconductor lasers, Resonators, Light, Sensors, Performance modeling

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Showing 5 of 6 publications

Conference Committee Involvement (1)

Quantum Communications Realized II

28 January 2009 | San Jose, California, United States

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