ORCID Profile
0000-0002-7209-9180
Current Organisations
Diraq
,
University of New South Wales
,
University of Tasmania
,
Tasmanian Audit Office
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Publisher: Wiley
Date: 02-11-2010
Publisher: Springer Science and Business Media LLC
Date: 14-11-2022
Publisher: American Physical Society (APS)
Date: 25-02-2022
Publisher: American Chemical Society (ACS)
Date: 17-05-2021
Publisher: American Physical Society (APS)
Date: 24-07-2023
Publisher: Springer Science and Business Media LLC
Date: 12-01-2023
Publisher: World Scientific Pub Co Pte Ltd
Date: 17-08-2022
DOI: 10.1142/S1094406022500159
Abstract: Synopsis The research problem Adding to the literature on audit market competition, this study examined how increasing competition affects audit pricing and audit quality in an emerging market where regulatory policies have resulted in increased competition (less market concentration) in the audit market, and Big 4 auditors are banned. The test hypotheses H 1 : Audit market concentration (competition) is positively (negatively) associated with audit fees. H 2 : Audit market competition is associated with audit quality. Target population Various stakeholders including regulators, auditors, firm managers, and users of financial reports. Adopted methodology Multivariate analysis using ordinary least squares and logit regressions. Analyses Using the Herfindahl index to measure competition in the audit market at the national level, we used a s le of listed firms from the emerging Iranian audit market, which is characterized by increase in audit market competition as a result of a regulatory change and a lack of market concentration because the audit market does not include Big 4 audit firms or any dominant local audit firms to examine the impact of competition on audit pricing and audit quality. Findings We found that higher (lower) levels of audit market competition measured using the Herfindahl index are associated with lower (higher) audit fees and higher (lower) levels of abnormal accruals. These results suggest that increased competition in audit markets in developing economies generates audit fee pressure, which negatively affects audit quality.
Publisher: Wiley
Date: 16-12-2022
Abstract: Quantum computers have the potential to efficiently solve problems in logistics, drug and material design, finance, and cybersecurity. However, millions of qubits will be necessary for correcting inevitable errors in quantum operations. In this scenario, electron spins in gate‐defined silicon quantum dots are strong contenders for encoding qubits, leveraging the microelectronics industry know‐how for fabricating densely populated chips with nanoscale electrodes. The sophisticated material combinations used in commercially manufactured transistors, however, will have a very different impact on the fragile qubits. Here some key properties of the materials that have a direct impact on qubit performance and variability are reviewed.
Publisher: American Chemical Society (ACS)
Date: 22-01-2021
Publisher: AIP Publishing
Date: 07-09-2015
DOI: 10.1063/1.4930909
Abstract: Achieving controllable coupling of dopants in silicon is crucial for operating donor-based qubit devices, but it is difficult because of the small size of donor-bound electron wavefunctions. Here, we report the characterization of a quantum dot coupled to a localized electronic state and present evidence of controllable coupling between the quantum dot and the localized state. A set of measurements of transport through the device enable the determination that the most likely location of the localized state is consistent with a location in the quantum well near the edge of the quantum dot. Our results are consistent with a gate-voltage controllable tunnel coupling, which is an important building block for hybrid donor and gate-defined quantum dot devices.
Publisher: American Physical Society (APS)
Date: 31-05-2022
Publisher: American Physical Society (APS)
Date: 15-03-2021
Publisher: Research Square Platform LLC
Date: 14-07-2023
DOI: 10.21203/RS.3.RS-3057916/V1
Abstract: Spins of electrons in CMOS quantum dots combine exquisite quantum properties and scalable fabrication. In the age of quantum technology, however, the metrics that crowned Si/SiO$_2$ as the microelectronics standard need to be reassessed with respect to their impact upon qubit performance. We chart spin qubit variability due to the unavoidable atomic-scale roughness of the Si/SiO$_2$ interface, compiling experiments across 12 devices, and develop theoretical tools to analyse these results. Atomistic tight binding and path integral Monte Carlo methods are adapted to describe fluctuations in devices with millions of atoms by directly analysing their wavefunctions and electron paths instead of their energy spectra. We correlate the effect of roughness with the variability in qubit position, deformation, valley splitting, valley phase, spin-orbit coupling and exchange coupling. These variabilities are found to be bounded, and they lie within the tolerances for scalable architectures for quantum computing as long as robust control methods are incorporated.
Publisher: American Physical Society (APS)
Date: 09-12-2021
Publisher: AIP Publishing
Date: 09-2022
DOI: 10.1063/5.0096467
Abstract: Quantum computing based on solid state spins allows for densely packed arrays of quantum bits. However, the operation of large-scale quantum processors requires a shift in paradigm toward global control solutions. Here, we report a proof-of-principle demonstration of the SMART (sinusoidally modulated, always rotating, and tailored) qubit protocol. We resonantly drive a two-level system and add a tailored modulation to the dressing field to increase robustness to frequency detuning noise and microwave litude fluctuations. We measure a coherence time of 2 ms, corresponding to two orders of magnitude improvement compared to a bare spin, and an average Clifford gate fidelity exceeding 99%, despite the relatively long qubit gate times. We stress that the potential of this work lies in the scalability of the protocol and the relaxation of the engineering constraints for a large-scale quantum processor. This work shows that future scalable spin qubit arrays could be operated using global microwave control and local gate addressability, while increasing robustness to relevant experimental inhomogeneities.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
No related grants have been discovered for Andre Saraiva.