ORCID Profile
0000-0002-6140-9323
Current Organisation
University of Adelaide
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Publisher: American Physical Society (APS)
Date: 28-08-2020
Publisher: American Physical Society (APS)
Date: 03-04-2018
Publisher: American Physical Society (APS)
Date: 23-09-2019
Publisher: The Optical Society
Date: 29-02-2016
DOI: 10.1364/OL.41.001014
Publisher: Optica Publishing Group
Date: 21-09-2023
DOI: 10.1364/OE.500278
Publisher: The Optical Society
Date: 07-08-2019
Publisher: Optica Publishing Group
Date: 30-09-2021
DOI: 10.1364/OL.435219
Abstract: Frequency combs play a crucial supporting role for optical clocks by allowing coherent frequency ision of their output signals into the electronic domain. This task requires stabilization of the comb’s offset frequency and of an optical comb mode to the clock laser. However, the two actuators used to control these quantities often influence both degrees of freedom simultaneously. This non-orthogonality leads to artificial limits to the control bandwidth and unwanted noise in the comb. Here, we orthogonalize the two feedback loops with a linear combination of the measured signals in a field-programmable gate array. We demonstrate this idea using a fiber frequency comb stabilized to a clock laser at 259 THz, half the frequency of the 1 S 0 → 3 P 0 Yb transition. The decrease in coupling between the loops reduces the comb’s optical phase noise by 20 dB. This approach could improve the performance of any comb stabilized to any optical frequency standard.
Publisher: American Physical Society (APS)
Date: 15-07-2013
Publisher: American Physical Society (APS)
Date: 18-05-2023
Publisher: American Physical Society (APS)
Date: 22-07-2015
Publisher: Springer Science and Business Media LLC
Date: 23-05-2013
Publisher: Springer Science and Business Media LLC
Date: 05-02-2020
DOI: 10.1038/S41586-020-1965-X
Abstract: The discovery of drivers of cancer has traditionally focused on protein-coding genes 1–4 . Here we present analyses of driver point mutations and structural variants in non-coding regions across 2,658 genomes from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium 5 of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). For point mutations, we developed a statistically rigorous strategy for combining significance levels from multiple methods of driver discovery that overcomes the limitations of in idual methods. For structural variants, we present two methods of driver discovery, and identify regions that are significantly affected by recurrent breakpoints and recurrent somatic juxtapositions. Our analyses confirm previously reported drivers 6,7 , raise doubts about others and identify novel candidates, including point mutations in the 5′ region of TP53 , in the 3′ untranslated regions of NFKBIZ and TOB1 , focal deletions in BRD4 and rearrangements in the loci of AKR1C genes. We show that although point mutations and structural variants that drive cancer are less frequent in non-coding genes and regulatory sequences than in protein-coding genes, additional ex les of these drivers will be found as more cancer genomes become available.
Publisher: American Physical Society (APS)
Date: 17-01-2013
Publisher: American Physical Society (APS)
Date: 09-2016
Publisher: American Physical Society (APS)
Date: 31-08-2018
Publisher: AIP Publishing
Date: 29-04-2013
DOI: 10.1063/1.4803703
Abstract: We demonstrate simultaneous phase and litude imaging of cold atoms using an intrinsically stable interferometer based on polarization beam-displacers. This method allows for the straight-forward retrieval of absorption and phase-shift experienced by an optical probe transmitted through an atomic s le. Furthermore, we show that our technique has a signal-to-noise ratio limited only by photon shot-noise.
Publisher: American Physical Society (APS)
Date: 09-05-2019
Publisher: AIP Publishing
Date: 24-10-2022
DOI: 10.1063/5.0119222
Abstract: Atomic magnetometry has spectacular magnetic field sensitivity at room temperature. Here, we theoretically and experimentally investigate the benefits of a multi-pass cell in magnetometers using nonlinear magneto-optical rotation interrogation. Our theoretical analysis shows that there is an improvement in the signal-to-noise ratio (SNR) and consequently on the magnetic field sensitivity by carefully choosing the number of passes through the medium. In our specific case, we experimentally demonstrate a 160% enhancement in the magnetometer sensitivity by using a triple-pass cell, and it is consistent with our analysis on the SNR. This work provides a pathway to evaluate the benefits of multi-pass cells in high-performance atomic magnetometers.
Publisher: American Physical Society (APS)
Date: 07-09-2018
Publisher: The Optical Society
Date: 07-01-2016
DOI: 10.1364/OE.24.000378
Publisher: Optica Publishing Group
Date: 15-08-2022
DOI: 10.1364/OE.467513
Abstract: Atomic vapour magnetometers sense the local magnetic field strength by measuring the resulting precession rate of a well-defined quantum state. An essential prerequisite for this approach is a requirement to drive the media into this quantum state, which is frequently achieved via optical pumping. In real-world alkali-metal atoms, with their multiplicity of ground states, the optical pumping process is necessarily lossy, with a large fraction of the atoms being lost to quantum states that do not contribute to the useful magnetically sensitive signal. This consequently reduces the sensitivity of all optically-pumped atomic sensors. Here we theoretically and experimentally study the population changes of the quantum ground states of 87 Rb during optical pumping. We use this understanding to develop a repumping scheme that allows us to increase the number of atoms that are contributing to the useful magnetic sensing output. Unlike prior schemes, our approach delivers this improved sensitivity with significantly suppressed fictitious magnetic fields associated with the repumping, which would otherwise reduce the accuracy of the sensor. When operated at Earth’s field strength (∼50 µ T), the repumped sensor shows a magnetic sensitivity of 200 fT/ Hz , that is nearly three times higher than the non-repumped version.
Publisher: American Physical Society (APS)
Date: 25-10-2016
Publisher: American Physical Society (APS)
Date: 27-11-2019
Publisher: The Optical Society
Date: 19-02-2016
DOI: 10.1364/OE.24.004088
Abstract: We demonstrate a scheme for coherent narrowband direct optical frequency comb spectroscopy. An extended cavity diode laser is injection locked to a single mode of an optical frequency comb, frequency shifted, and used as a local oscillator to optically down-mix the interrogating comb on a fast photodetector. The high spectral coherence of the injection lock generates a microwave frequency comb at the output of the photodiode with very narrow features, enabling spectral information to be further down-mixed to RF frequencies, allowing optical transmittance and phase to be obtained using electronics commonly found in the lab. We demonstrate two methods for achieving this step: a serial mode-by-mode approach and a parallel dual-comb approach, with the Cs D1 transition at 894 nm as a test case.
Publisher: American Physical Society (APS)
Date: 12-10-2018
Publisher: American Physical Society (APS)
Date: 23-12-2020
Publisher: IOP Publishing
Date: 30-11-2012
Publisher: American Physical Society (APS)
Date: 26-02-2020
Publisher: American Physical Society (APS)
Date: 11-04-2019
Publisher: Optica Publishing Group
Date: 14-01-2202
DOI: 10.1364/OL.416166
Abstract: In this Letter, we present Fourier-transform-limited, nanosecond scale optical pulses from a vertical cavity surface emitting laser (VCSEL) using injection locking with a narrow-band seed laser. We examine two different injection-locking architectures and show that we can achieve an effective injection-locking range of over 8 GHz with an extinction ratio of 20,000:1. These results indicate that injection-locked VCSELs could become a key component of large-scale photonic quantum networks.
Publisher: Springer Science and Business Media LLC
Date: 05-02-2020
DOI: 10.1038/S41586-019-1907-7
Abstract: Cancer develops through a process of somatic evolution 1,2 . Sequencing data from a single biopsy represent a snapshot of this process that can reveal the timing of specific genomic aberrations and the changing influence of mutational processes 3 . Here, by whole-genome sequencing analysis of 2,658 cancers as part of the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA) 4 , we reconstruct the life history and evolution of mutational processes and driver mutation sequences of 38 types of cancer. Early oncogenesis is characterized by mutations in a constrained set of driver genes, and specific copy number gains, such as trisomy 7 in glioblastoma and isochromosome 17q in medulloblastoma. The mutational spectrum changes significantly throughout tumour evolution in 40% of s les. A nearly fourfold ersification of driver genes and increased genomic instability are features of later stages. Copy number alterations often occur in mitotic crises, and lead to simultaneous gains of chromosomal segments. Timing analyses suggest that driver mutations often precede diagnosis by many years, if not decades. Together, these results determine the evolutionary trajectories of cancer, and highlight opportunities for early cancer detection.
Publisher: American Physical Society (APS)
Date: 26-02-2019
Publisher: American Physical Society (APS)
Date: 29-05-2018
Publisher: Springer Science and Business Media LLC
Date: 06-04-2014
Publisher: The Optical Society
Date: 11-06-2013
DOI: 10.1364/OL.38.002122
Publisher: American Physical Society (APS)
Date: 25-01-2012
No related grants have been discovered for Christopher Perrella.