| 1. |
- Jack, C. R., et al.
(författare)
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Magnetic resonance imaging in Alzheimer's Disease Neuroimaging Initiative 2
- 2015
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 11:7, s. 740-756
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Alzheimer's Disease Neuroimaging Initiative (ADNI) is now in its 10th year. The primary objective of the magnetic resonance imaging (MRI) core of ADNI has been to improve methods for clinical trials in Alzheimer's disease (AD) and related disorders. Methods: We review the contributions of the MRI core from present and past cycles of ADNI (ADNI-1, -Grand Opportunity and -2). We also review plans for the future-ADNI-3. Results: Contributions of the MRI core include creating standardized acquisition protocols and quality control methods; examining the effect of technical features of image acquisition and analysis on outcome metrics; deriving sample size estimates for future trials based on those outcomes; and piloting the potential utility of MR perfusion, diffusion, and functional connectivity measures in multicenter clinical trials. Discussion: Over the past decade the MRI core of ADNI has fulfilled its mandate of improving methods for clinical trials in AD and will continue to do so in the future. (C) 2015 The Authors. Published by Elsevier Inc. on behalf of the Alzheimer's Association.
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| 2. |
- Alshaykh, Mohammed S., et al.
(författare)
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Optical dual-comb Vernier division of an octave-spanning Kerr microcomb
- 2021
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Ingår i: 2021 Conference on Lasers and Electro-Optics, CLEO 2021 - Proceedings.
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Konferensbidrag (refereegranskat)abstract
- We measure the repetition rate of a 900 GHz octave-spanning soliton microcomb based on Vernier dual-comb frequency division implemented with two silicon nitride microresonator combs fabricated on the same wafer.
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| 3. |
- Bao, Chengying, et al.
(författare)
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Observation of Breathing Dark Pulses in Normal Dispersion Optical Microresonators
- 2018
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 121:25
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Tidskriftsartikel (refereegranskat)abstract
- Breathers are localized waves in nonlinear systems that undergo a periodic variation in time or space. The concept of breathers is useful for describing many nonlinear physical systems including granular lattices, Bose-Einstein condensates, hydrodynamics, plasmas, and optics. In optics, breathers can exist in either the anomalous or the normal dispersion regimes, but they have only been characterized in the former, to our knowledge. Here, externally pumped optical microresonators are used to characterize the breathing dynamics of localized waves in the normal dispersion regime. High-Q optical microresonators featuring normal dispersion can yield mode-locked Kerr combs whose time-domain waveform corresponds to circulating dark pulses in the cavity. We show that with relatively high pump power these Kerr combs can enter a breathing regime, in which the time-domain waveform remains a dark pulse but experiences a periodic modulation on a time scale much slower than the microresonator round trip time. The breathing is observed in the optical frequency domain as a significant difference in the phase and amplitude of the modulation experienced by different spectral lines. In the highly pumped regime, a transition to a chaotic breathing state where the waveform remains dark-pulse-like is also observed, for the first time to our knowledge; such a transition is reversible by reducing the pump power.
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| 4. |
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| 5. |
- Fülöp, Attila, 1988, et al.
(författare)
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Frequency noise of a normal dispersion microresonator-based frequency comb
- 2017
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Ingår i: Optics InfoBase Conference Papers. - 2162-2701. - 9781943580231 ; , s. W2A.6-
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Konferensbidrag (refereegranskat)abstract
- Using delayed self-heterodyne coherent detection, we characterized the FM noise across the C-band of a widely spaced microresonator-based frequency comb. The resulting linewidth depends on both the pump laser and the comb line position.
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| 6. |
- Fülöp, Attila, 1988, et al.
(författare)
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Long-haul coherent communications using microresonator-based frequency combs
- 2017
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 25:22, s. 26678-26688
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Tidskriftsartikel (refereegranskat)abstract
- Microresonator-based frequency combs are strong contenders as light sources for wavelength-division multiplexing (WDM). Recent experiments have shown the potential of microresonator combs for replacing a multitude of WDM lasers with a single laser-pumped device. Previous demonstrations have however focused on short-distance few-span links reaching an impressive throughput at the expense of transmission distance. Here we report the first long-haul coherent communication demonstration using a microresonator-based comb source. We modulated polarization multiplexed (PM) quadrature phase-shift keying-data onto the comb lines allowing transmission over more than 6300 km in a single-mode fiber. In a second experiment, we reached beyond 700 km with the PM 16 quadrature amplitude modulation format. To the best of our knowledge, these results represent the longest fiber transmission ever achieved using an integrated comb source.
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| 7. |
- Fülöp, Attila, 1988, et al.
(författare)
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Long-haul coherent transmission using a silicon nitride microresonator-based frequency comb as WDM source
- 2016
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Ingår i: Conference on lasers and electro-optics (CLEO), San Jose, USA. - 9781943580118 ; , s. SM4F.2-
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Konferensbidrag (refereegranskat)abstract
- We demonstrated transmission of polarization-multiplexed quadrature phase-shift keying data over 6000 km using a low-noise silicon nitride microresonator frequency comb as light source. These results show the technology’s suitability for long-haul fiber communications.
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| 8. |
- Liu, Y., et al.
(författare)
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Bandwidth scaling of phase-modulated CW comb through four-wave mixing on silicon nano-waveguide
- 2013
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Ingår i: 2013 Conference on Lasers and Electro-Optics, CLEO 2013; San Jose, CA; United States; 9 June 2013 through 14 June 2013. - 9781557529725 ; , s. Art. no. 6833039-
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Konferensbidrag (refereegranskat)abstract
- We demonstrate a scheme to scale the bandwidth of a frequency comb generated by phase modulation of CW lasers using four-wave mixing in a silicon nano-waveguides, resulting in >100 comb lines spaced by 10-GHz within 5-dB bandwidth.
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| 9. |
- Lu, Hsuan Hao, et al.
(författare)
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Simulations of subatomic many-body physics on a quantum frequency processor
- 2019
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Ingår i: Physical Review A. - 2469-9934 .- 2469-9926. ; 100:1
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Tidskriftsartikel (refereegranskat)abstract
- Simulating complex many-body quantum phenomena is a major scientific impetus behind the development of quantum computing, and a range of technologies are being explored to address such systems. We present the results of the largest photonics-based simulation to date, applied in the context of subatomic physics. Using an all-optical quantum frequency processor, the ground-state energies of light nuclei including the triton (H3), He3, and the alpha particle (He4) are computed. Complementing these calculations and utilizing a 68-dimensional Hilbert space, our photonic simulator is used to perform subnucleon calculations of the two- and three-body forces between heavy mesons in the Schwinger model. This work is a first step in simulating subatomic many-body physics on quantum frequency processors - augmenting classical computations that bridge scales from quarks to nuclei.
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| 10. |
- Lu, Hsuan Hao, et al.
(författare)
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Subatomic many-body physics simulations on a quantum frequency processor
- 2019
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Ingår i: Optics InfoBase Conference Papers. - 2162-2701. ; Part F128-CLEO_QELS 2019
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Konferensbidrag (refereegranskat)abstract
- We demonstrate a photonic quantum simulation on a quantum frequency processor, computing the effective interaction potential between composite particles in the Schwinger model and determining the binding energies of three nuclei (3H, 3He, and 4He).
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