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22 results on '"Lingham, Marcus"'

1. Goldstone mode and pair-breaking excitations in atomic Fermi superfluids

Author

Hoinka, Sascha, Dyke, Paul, Lingham, Marcus G., Kinnunen, Jami J., Bruun, Georg M., and Vale, Chris J.

Subjects
Condensed Matter - Quantum Gases, Physics - Atomic Physics
Abstract

Spontaneous symmetry breaking is a central paradigm of elementary particle physics, magnetism, superfluidity and superconductivity. According to Goldstone's theorem, phase transitions that break continuous symmetries lead to the existence of gapless excitations in the long-wavelength limit. These Goldstone modes generally dominate the low-energy excitations, showing that symmetry breaking has a profound impact on the physical properties of matter. Here, we present the first comprehensive study of the elementary excitations in a homogeneous strongly interacting Fermi gas through the crossover from a Bardeen-Cooper-Schrieffer (BCS) superfluid to a Bose-Einstein condensate (BEC) of molecules using two-photon Bragg spectroscopy. The spectra exhibit a discrete Goldstone mode, associated with the broken symmetry superfluid phase, as well as pair breaking single-particle excitations. Our techniques yield a direct determination of the superfluid pairing gap and speed of sound in close agreement with a strong-coupling theory., Comment: Original version, full text published online in Nature Physics

Published
2017
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3. Precise determination of the structure factor and contact in a unitary Fermi gas

Author

Hoinka, Sascha, Lingham, Marcus, Fenech, Kristian, Hu, Hui, Vale, Chris J., Drut, Joaquín E., and Gandolfi, Stefano

Subjects
Condensed Matter - Quantum Gases
Abstract

We present a high-precision determination of the universal contact parameter in a strongly interacting Fermi gas. In a trapped gas at unitarity we find the contact to be $3.06 \pm 0.08$ at a temperature of 0.08 of the Fermi temperature in a harmonic trap. The contact governs the high-momentum (short-range) properties of these systems and this low temperature measurement provides a new benchmark for the zero temperature homogeneous contact. The experimental measurement utilises Bragg spectroscopy to obtain the dynamic and static structure factors of ultracold Fermi gases at high momentum in the unitarity and molecular Bose-Einstein condensate (BEC) regimes. We have also performed quantum Monte Carlo calculations of the static properties, extending from the weakly coupled Bardeen-Cooper-Schrieffer (BCS) regime to the strongly coupled BEC case, which show agreement with experiment at the level of a few percent., Comment: Replaced with accepted version

Published
2012
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5. Australia’s first laser guide star: design and telescope integration at Mount Stromlo Observatory

Author

Martínez Rey, Noelia, primary, d'Orgeville, Céline, additional, Ashworth, David, additional, Copeland, Michael, additional, Galla, Antony, additional, Grosse, Doris, additional, Hassan Krishna, Sowmya, additional, Lingham, Marcus, additional, Price, Ian, additional, Travouillon, Tony, additional, Fetzer, Greg, additional, Rako, Steve, additional, Baumgarten, Cory, additional, Webb, James, additional, Blundell, Mark, additional, Gao, Yue, additional, Gray, Andrew, additional, Ritchie, Ian, additional, Smith, Craig, additional, Wang, Yanjie, additional, Byrd, Olivia, additional, and Johnson, Robert L., additional

Published
2020
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6. Design concept for Pocket-GMT

Author

Lingham, Marcus, primary, Bouchez, Antonin H., additional, Gers, Luke, additional, Herrald, Nicholas, additional, Munro, Josephine, additional, and Travouillon, Tony, additional

Published
2020
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9. Adaptive optics tracking and pushing system for space debris manoeuvre

Author

Grosse, Doris, primary, Bennet, Francis, primary, Rigaut, François, primary, d'Orgeville, Céline, primary, Korkiakoski, Visa A., primary, Smith, Craig H., primary, Copeland, Michael, primary, Price, Ian, primary, Blundell, Mark, primary, Chan, Amy, primary, Ellis, Michael, primary, Galla, Antony, primary, Gers, Luke, primary, Hart, John, primary, Lingham, Marcus, primary, Gao, Yue, primary, Houston, Ellen, primary, Rees, Emily R., primary, Wang, Yanjie, primary, Ritchie, Ian, primary, Travouillon, Tony, primary, Vaccarella, Annino, primary, and Webb, James, primary

Published
2018
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11. Adaptive optics tracking and pushing system for space debris manoeuvre

Author

Laird Close, Laura Schreiber, Dirk Schmidt, Lingham, Marcus, Grosse, Doris, Bennet, Francis, Blundell, Mark, Chan, Amy, Copeland, Michael, d'Orgeville, Celine, Ellis, Michael, Galla, Tony, Gao, Yue, Gers, Luke, Hart, John, Houston, Ellen, Korkiakoski, Visa, Price, Ian, Rees, Emily, Rigaut, Francois, Ritchie, Ian, Smith, Craig, Travouillon, Tony, Vaccarella, Annino, Wang, Yanjie, Webb, James, Laird Close, Laura Schreiber, Dirk Schmidt, Lingham, Marcus, Grosse, Doris, Bennet, Francis, Blundell, Mark, Chan, Amy, Copeland, Michael, d'Orgeville, Celine, Ellis, Michael, Galla, Tony, Gao, Yue, Gers, Luke, Hart, John, Houston, Ellen, Korkiakoski, Visa, Price, Ian, Rees, Emily, Rigaut, Francois, Ritchie, Ian, Smith, Craig, Travouillon, Tony, Vaccarella, Annino, Wang, Yanjie, and Webb, James

Abstract

As space debris in lower Earth orbits are accumulating, techniques to lower the risk of space debris collisions must be developed. Within the context of the Space Environment Research Centre (SERC), the Australian National University (ANU) is developing an adaptive optics system for tracking and pushing space debris. The strategy is to pre-condition a laser launched from a 1.8 m telescope operated by Electro Optics Systems (EOS) on Mount Stromlo, Canberra and direct it at an object to perturb its orbit. Current progress towards implementing this experiment, which will ensure automated operation between the telescope and the adaptive optics system, will be presented.

Published
2018

12. High level adaptive optics supervision software for fast transition to optimal performance

Author

Laird M. Close, Laura Schreiber, Dirk Schmidt, Korkiakoski, Visa, Rigaut, Francois, Price, Ian, Cranney, Jesse, Bennet, Francis, Lingham, Marcus, Grosse, Doris, Namjouyan, Nima, Copeland, Michael, d'Orgeville, Celine, Laird M. Close, Laura Schreiber, Dirk Schmidt, Korkiakoski, Visa, Rigaut, Francois, Price, Ian, Cranney, Jesse, Bennet, Francis, Lingham, Marcus, Grosse, Doris, Namjouyan, Nima, Copeland, Michael, and d'Orgeville, Celine

Abstract

Space debris in low Earth orbit (LEO) below 1500 km is becoming an increasing threat to spacecrafts. To manage the threat, we are developing systems to improve the ground-based tracking and imaging of space debris and satellites. We also intend to demonstrate that it is possible to launch a high-power laser that modifies the orbits of the debris. However, atmospheric turbulence makes it necessary to use adaptive optics with such systems. When engaging with objects in LEO, the objects are available only a limited amount of time. During the observation window, the object has to be acquired and performance of all adaptive optics feedback loops optimised. We have implemented a high-level adaptive optics supervision tool to automatise time-consuming tasks related to calibration and performance monitoring. This paper describes in detail the current features of our software.

Published
2018

15. Australia’s first laser guide star: design and telescope integration at Mount Stromlo Observatory

Author

Schreiber, Laura, Schmidt, Dirk, Vernet, Elise, Martinez, Noelia, d'Orgeville, Céline, Ashworth, David, Copeland, Michael, Galla, Antony, Grosse, Doris, Hassan Krishna, Sowmya, Lingham, Marcus, Price, Ian, Travouillon, Tony, Fetzer, Greg, Rako, Steve, Baumgarten, Cory, Webb, James, Blundell, Mark, Gao, Yue, Gray, Andrew, Ritchie, Ian, Smith, Craig, Wang, Yanjie, Byrd, Olivia, and Johnson, Robert

Published
2020
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18. Adaptive optics tracking and pushing system for space debris manoeuvre

Author

Close, Laird M., Schreiber, Laura, Schmidt, Dirk, Lingham, Marcus, Grosse, Doris, Bennet, Francis, Blundell, Mark, Chan, Amy, Copeland, Michael, d'Orgeville, Celine, Ellis, Michael, Galla, Antony, Gao, Yue, Gers, Luke, Hart, John, Houston, Ellen, Korkiakoski, Visa, Price, Ian, Rees, Emily R., Rigaut, Francois, Ritchie, Ian, Smith, Craig, Travouillon, Tony, Vaccarella, Annino, Wang, Yanjie, and Webb, James

Published
2018
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