ORCID Profile
0000-0002-9815-0968
Current Organisation
University of Queensland
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Quantum Information, Computation and Communication | Quantum Physics | Quantum Optics | Condensed Matter Physics | Nanoelectronics | Communications Technologies | Surfaces and Structural Properties of Condensed Matter | Electronic and Magnetic Properties of Condensed Matter; Superconductivity | Condensed Matter Modelling and Density Functional Theory | Quantum Physics not elsewhere classified | Microwave and Millimetrewave Theory and Technology | Condensed Matter Characterisation Technique Development | Particle Physics | Nanofabrication, Growth and Self Assembly
Expanding Knowledge in the Physical Sciences | Expanding Knowledge in Technology | Scientific Instruments | Expanding Knowledge in Engineering | Emerging Defence Technologies |
Publisher: IOP Publishing
Date: 06-03-2006
Publisher: American Physical Society (APS)
Date: 05-08-2010
Publisher: American Physical Society (APS)
Date: 17-09-2018
Publisher: American Physical Society (APS)
Date: 24-01-2008
Publisher: Springer Science and Business Media LLC
Date: 08-2013
DOI: 10.1038/NATURE12422
Abstract: Engineered macroscopic quantum systems based on superconducting electronic circuits are attractive for experimentally exploring erse questions in quantum information science. At the current state of the art, quantum bits (qubits) are fabricated, initialized, controlled, read out and coupled to each other in simple circuits. This enables the realization of basic logic gates, the creation of complex entangled states and the demonstration of algorithms or error correction. Using different variants of low-noise parametric lifiers, dispersive quantum non-demolition single-shot readout of single-qubit states with high fidelity has enabled continuous and discrete feedback control of single qubits. Here we realize full deterministic quantum teleportation with feed-forward in a chip-based superconducting circuit architecture. We use a set of two parametric lifiers for both joint two-qubit and in idual qubit single-shot readout, combined with flexible real-time digital electronics. Our device uses a crossed quantum bus technology that allows us to create complex networks with arbitrary connecting topology in a planar architecture. The deterministic teleportation process succeeds with order unit probability for any input state, as we prepare maximally entangled two-qubit states as a resource and distinguish all Bell states in a single two-qubit measurement with high efficiency and high fidelity. We teleport quantum states between two macroscopic systems separated by 6 mm at a rate of 10(4) s(-1), exceeding other reported implementations. The low transmission loss of superconducting waveguides is likely to enable the range of this and other schemes to be extended to significantly larger distances, enabling tests of non-locality and the realization of elements for quantum communication at microwave frequencies. The demonstrated feed-forward may also find application in error correction schemes.
Publisher: American Physical Society (APS)
Date: 07-06-2007
Publisher: Elsevier BV
Date: 07-2004
Publisher: American Physical Society (APS)
Date: 23-12-2021
Publisher: Springer Science and Business Media LLC
Date: 04-10-2016
DOI: 10.1038/NCOMMS12930
Abstract: Classical realism demands that system properties exist independently of whether they are measured, while noncontextuality demands that the results of measurements do not depend on what other measurements are performed in conjunction with them. The Bell–Kochen–Specker theorem states that noncontextual realism cannot reproduce the measurement statistics of a single three-level quantum system (qutrit). Noncontextual realistic models may thus be tested using a single qutrit without relying on the notion of quantum entanglement in contrast to Bell inequality tests. It is challenging to refute such models experimentally, since imperfections may introduce loopholes that enable a realist interpretation. Here we use a superconducting qutrit with deterministic, binary-outcome readouts to violate a noncontextuality inequality while addressing the detection, in idual-existence and compatibility loopholes. This evidence of state-dependent contextuality also demonstrates the fitness of superconducting quantum circuits for fault-tolerant quantum computation in surface-code architectures, currently the most promising route to scalable quantum computing.
Publisher: American Physical Society (APS)
Date: 21-12-2005
Publisher: American Physical Society (APS)
Date: 07-10-2013
Publisher: American Physical Society (APS)
Date: 20-02-2020
Publisher: American Physical Society (APS)
Date: 09-10-2019
Publisher: American Physical Society (APS)
Date: 25-07-2016
Publisher: American Physical Society (APS)
Date: 26-06-2013
Publisher: The American Association of Immunologists
Date: 11-2022
Abstract: α1-Antitrypsin (AAT), a serine protease inhibitor, is the third most abundant protein in plasma. Although the best-known function of AAT is irreversible inhibition of elastase, AAT is an acute-phase reactant and is increasingly recognized to have a panoply of other functions, including as an anti-inflammatory mediator and a host-protective molecule against various pathogens. Although a canonical receptor for AAT has not been identified, AAT can be internalized into the cytoplasm and is known to affect gene regulation. Because AAT has anti-inflammatory properties, we examined whether AAT binds the cytoplasmic glucocorticoid receptor (GR) in human macrophages. We report the finding that AAT binds to GR using several approaches, including coimmunoprecipitation, mass spectrometry, and microscale thermophoresis. We also performed in silico molecular modeling and found that binding between AAT and GR has a plausible stereochemical basis. The significance of this interaction in macrophages is evinced by AAT inhibition of LPS-induced NF-κB activation and IL-8 production as well as AAT induction of angiopoietin-like 4 protein, which are, in part, dependent on GR. Furthermore, this AAT-GR interaction contributes to a host-protective role against mycobacteria in macrophages. In summary, this study identifies a new mechanism for the gene regulation, anti-inflammatory, and host-defense properties of AAT.
Publisher: American Physical Society (APS)
Date: 28-06-2016
Publisher: IOP Publishing
Date: 18-10-2007
Publisher: American Association for the Advancement of Science (AAAS)
Date: 20-12-2013
Abstract: Quantum optics probes the interactions between light and matter. Building up from a simple, single-atom system, the exchange of virtual photons between systems of several (or many) atoms is expected to give rise to many exotic effects. Because controlling the separation of the atoms on the atomic scale is experimentally challenging, artificial atom systems may provide a more tractable route for systematic study, as described by van Loo et al. (p. 1494 , published online 14 November). Using a system of two separate superconducting qubits in a microwave transmission line, they show how the interaction between the two qubits can be controlled and mediated by electromagnetic modes. The results illustrate a feasible route to probing the complexity of many-body effects that may otherwise be difficult to realize.
Publisher: American Physical Society (APS)
Date: 19-11-2021
Publisher: SPIE
Date: 05-08-2003
DOI: 10.1117/12.487993
Publisher: American Physical Society (APS)
Date: 15-06-2020
Publisher: American Physical Society (APS)
Date: 11-12-2017
Publisher: Springer Science and Business Media LLC
Date: 14-12-2011
DOI: 10.1038/NATURE10713
Abstract: The Toffoli gate is a three-quantum-bit (three-qubit) operation that inverts the state of a target qubit conditioned on the state of two control qubits. It makes universal reversible classical computation possible and, together with a Hadamard gate, forms a universal set of gates in quantum computation. It is also a key element in quantum error correction schemes. The Toffoli gate has been implemented in nuclear magnetic resonance, linear optics and ion trap systems. Experiments with superconducting qubits have also shown significant progress recently: two-qubit algorithms and two-qubit process tomography have been implemented, three-qubit entangled states have been prepared, first steps towards quantum teleportation have been taken and work on quantum computing architectures has been done. Implementation of the Toffoli gate with only single- and two-qubit gates requires six controlled-NOT gates and ten single-qubit operations, and has not been realized in any system owing to current limits on coherence. Here we implement a Toffoli gate with three superconducting transmon qubits coupled to a microwave resonator. By exploiting the third energy level of the transmon qubits, we have significantly reduced the number of elementary gates needed for the implementation of the Toffoli gate, relative to that required in theoretical proposals using only two-level systems. Using full process tomography and Monte Carlo process certification, we completely characterize the Toffoli gate acting on three independent qubits, measuring a fidelity of 68.5 ± 0.5 per cent. A similar approach to realizing characteristic features of a Toffoli-class gate has been demonstrated with two qubits and a resonator and achieved a limited characterization considering only the phase fidelity. Our results reinforce the potential of macroscopic superconducting qubits for the implementation of complex quantum operations with the possibility of quantum error correction.
Publisher: American Physical Society (APS)
Date: 08-11-2017
Publisher: American Physical Society (APS)
Date: 05-03-2009
Publisher: WORLD SCIENTIFIC
Date: 10-2008
Publisher: American Physical Society (APS)
Date: 20-08-2021
Publisher: SPIE
Date: 05-05-2006
DOI: 10.1117/12.663366
Publisher: IOP Publishing
Date: 30-09-2008
Publisher: AIP Publishing
Date: 13-09-2021
DOI: 10.1063/5.0065011
Abstract: Neural networks have proven to be efficient for a number of practical applications ranging from image recognition to identifying phase transitions in quantum physics models. In this paper, we investigate the application of neural networks to state classification in a single-shot quantum measurement. We use dispersive readout of a superconducting transmon circuit to demonstrate an increase in assignment fidelity for both two and three state classifications. More importantly, our method is ready for on-the-fly data processing without overhead or need for large data transfer to a hard drive. In addition, we demonstrate the capacity of neural networks to be trained against experimental imperfections, such as phase drift of a local oscillator in a heterodyne detection scheme.
Publisher: American Physical Society (APS)
Date: 24-01-2012
Publisher: AIP Publishing
Date: 30-08-2021
DOI: 10.1063/5.0061078
Abstract: Superconducting quantum circuits are one of the leading quantum computing platforms. To advance superconducting quantum computing to a point of practical importance, it is critical to identify and address material imperfections that lead to decoherence. Here, we use terahertz scanning near-field optical microscopy to probe the local dielectric properties and carrier concentrations of wet-etched aluminum resonators on silicon, one of the most characteristic components of the superconducting quantum processors. Using a recently developed vector calibration technique, we extract the THz permittivity from spectroscopy in proximity to the microwave feedline. Fitting the extracted permittivity to the Drude model, we find that silicon in the etched channel has a carrier concentration greater than buffer oxide etched silicon and we explore post-processing methods to reduce the carrier concentrations. Our results show that near-field THz investigations can be used to quantitatively evaluate and identify inhomogeneities in quantum devices.
Publisher: American Physical Society (APS)
Date: 29-04-2011
Publisher: IOP Publishing
Date: 06-2022
Abstract: Substrate material imperfections and surface losses are one of the major factors limiting superconducting quantum circuitry from reaching the scale and complexity required to build a practical quantum computer. One potential path towards higher coherence of superconducting quantum devices is to explore new substrate materials with a reduced density of imperfections due to inherently different surface chemistries. Here, we examine two ternary metal oxide materials, spinel (MgAl 2 O 4 ) and lanthanum aluminate (LaAlO 3 ), with a focus on surface and interface characterization and preparation. Devices fabricated on LaAlO 3 have quality factors three times higher than those of earlier devices, which we attribute to a reduction in the interfacial disorder. MgAl 2 O 4 is a new material in superconducting quantum devices, and even in the presence of significant surface disorder, it consistently outperforms LaAlO 3 . Our results highlight the importance of materials exploration, substrate preparation, and characterization for identifying materials suitable for high-performance superconducting quantum circuitry.
Publisher: Springer Science and Business Media LLC
Date: 18-10-2016
Publisher: American Physical Society (APS)
Date: 17-03-2004
Publisher: Walter de Gruyter GmbH
Date: 03-04-2023
Abstract: Terahertz (THz) waves are a highly sensitive probe of free carrier concentrations in semiconducting materials. However, most experiments operate in the far-field, which precludes the observation of nanoscale features that affect the material response. Here, we demonstrate the use of nanoscale THz plasmon polaritons as an indicator of surface quality in prototypical quantum devices properties. Using THz near-field hyperspectral measurements, we observe polaritonic features in doped silicon near a metal-semiconductor interface. The presence of the THz surface plasmon polariton indicates the existence of a thin film doped layer on the device. Using a multilayer extraction procedure utilising vector calibration, we quantitatively probe the doped surface layer and determine its thickness and complex permittivity. The recovered multilayer characteristics match the dielectric conditions necessary to support the THz surface plasmon polariton. Applying these findings to superconducting resonators, we show that etching of this doped layer leads to an increase of the quality factor as determined by cryogenic measurements. This study demonstrates that THz scattering-type scanning near-field optical microscopy (s-SNOM) is a promising diagnostic tool for characterization of surface dielectric properties of quantum devices.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2005
Publisher: American Physical Society (APS)
Date: 07-06-2012
Publisher: American Scientific Publishers
Date: 09-2004
Publisher: American Physical Society (APS)
Date: 13-02-2012
Publisher: American Physical Society (APS)
Date: 20-01-2023
Publisher: American Physical Society (APS)
Date: 18-12-2015
Publisher: Springer Science and Business Media LLC
Date: 06-07-2008
DOI: 10.1038/NPHYS1019
Start Date: 2015
End Date: 12-2017
Amount: $613,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2023
End Date: 06-2026
Amount: $488,684.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2015
End Date: 12-2019
Amount: $768,369.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2018
End Date: 12-2018
Amount: $621,834.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2011
End Date: 12-2017
Amount: $24,500,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2018
End Date: 06-2025
Amount: $31,900,000.00
Funder: Australian Research Council
View Funded Activity