Publications

You can also find my articles on Google Scholar.

Bubblewrap: Online tiling and real-time flow prediction on neural manifolds

Published in Advances in Neural Information Processing Systems 34, 2021

We present a method that combines fast, stable dimensionality reduction with a soft tiling of the resulting neural manifold, allowing dynamics to be approximated as a probability flow between tiles. This method can be fit efficiently using online expectation maximization, scales to tens of thousands of tiles, and outperforms existing methods when dynamics are noise-dominated or feature multi-modal transition probabilities. The resulting model can be trained at kiloHertz data rates, produces accurate approximations of neural dynamics within minutes, and generates predictions on submillisecond time scales. It retains predictive performance throughout many time steps into the future and is fast enough to serve as a component of closed-loop causal experiments.

Draelos, A., Gupta, P., Jun, N. Y., Sriworarat, C., and Pearson, J. (2021). "Bubblewrap: Online tiling and real-time flow prediction on neural manifolds." Advances in Neural Information Processing Systems 34 (accepted; also at arXiv:2108.13941)

https://arxiv.org/pdf/2108.13941.pdf

improv: A flexible software platform for adaptive neuroscience experiments

Published in bioRxiv (preprint), 2021

We introduce improv, a software platform that allows users to flexibly specify and manage adaptive experiments to integrate data collection, preprocessing, visualization, and user-defined analytics. Using improv for streaming data analysis for two-photon calcium imaging and behavior, we demonstrate how access to online information can be used for automated, integrated experimentation.

Draelos, A., Nikitchenko, M., Sriworarat, C., Sprague, D., Loring, M. D., Pnevmatikakis, E., Giovannucci, A., Naumann, E. A., and Pearson, J. M. (2021). "improv: A flexible software platform for adaptive neuroscience experiments." bioRxiv:10.1101/2021.02.22.432006

https://www.biorxiv.org/content/10.1101/2021.02.22.432006v1.full.pdf

Online Neural Connectivity Estimation with Noisy Group Testing

Published in Advances in Neural Information Processing Systems (NeurIPS), 2020

We describe a method based on noisy group testing to infer functional connections in large networks of neurons. By stimulating small ensembles of neurons, we show that it is possible to recover binarized network connectivity with a number of tests that grows only logarithmically with population size under minimal statistical assumptions. We extend our method to the streaming setting, where continuously updated posteriors allow for optional stopping, and demonstrate the feasibility of inferring connectivity for networks of up to tens of thousands of neurons online.

Draelos, A., Pearson, J. M. (2020). "Online Neural Connectivity Estimation with Noisy Group Testing." Advances in Neural Information Processing Systems 33.'

https://proceedings.neurips.cc/paper/2020/file/531d29a813ef9471aad0a5558d449a73-Paper.pdf

Interference of chiral Andreev edge states

Published in Nature Physics, 2020

We explore the interface between a quantum Hall insulator and an s-wave superconductor in graphene Josephson junctions and find clear signatures of hybridized electron and hole states similar to chiral Majorana fermions, called chiral Andreev edge states.

Zhao, L., Arnault, E.G., Bondarev, A., Seredinski, A., Larson, T.F., Draelos, A.W., Li, H., Watanabe, K., Taniguchi, T., Amet, F., Baranger, H.U., Finkelstein, G. (2020). "Interference of chiral Andreev edge states." Nat. Phys., pp. 1-6.

Anomalous periodicity of magnetic interference patterns in encapsulated graphene Josephson junctions

Published in Physical Review Research, 2019

We investigate supercurrent interference patterns measured as a function of magnetic field in ballistic graphene Josephson junctions and find anomalous interferences that are close to the periodicity predicted for topological Andreev bound states carrying a charge of e, not 2e.

Ke, C.T., Draelos, A.W., Seredinski, A., et. al. (2019). "Anomalous periodicity of magnetic interference patterns in encapsulated graphene Josephson junctions." Phys. Rev. Research 1(3), p. 033084.

Quantum Hall–based superconducting interference device

Published in Science Advances, 2019

We present a study of a graphene-based Josephson junction in the quantum Hall regime with dedicated side gates carved from the same sheet of graphene as the junction itself and observe a supercurrent localized along that edge of the junction.

Seredinski, A., Draelos, A.W., Arnault, E., Wei, M.T., Li, H., Fleming, T., Watanabe, K., Taniguchi, T., Amet, F., Finkelstein, G. (2019). "Quantum Hall–based superconducting interference device." Sci. Adv. 5(9), eaaw8693.

Chiral quasiparticle tunneling between quantum Hall edges in proximity with a superconductor

Published in Physical Review B, 2019

We study a two-terminal graphene Josephson junction with contacts shaped to form a narrow 100 nm constriction and observe enhanced conductance through a wide range of magnetic fields and gate voltages.

Wei, M.T., Draelos, A.W., Seredinski, A., Ke, C.T., Li, H., Mehta, Y., Watanabe, K., Taniguchi, T., Yamamoto, M., Tarucha, S., Finkelstein, G., Amet., F., Borzenets, I.V. (2019). "Chiral quasiparticle tunneling between quantum Hall edges in proximity with a superconductor." Phys. Rev. B 100(12), p. 121403.

Subkelvin lateral thermal transport in diffusive graphene

Published in Physical Review B, 2019

We report on hot carrier diffusion in graphene across large enough length scales that the carriers are not thermalized across the crystal at low temperatures and thus observe a thermal gradient.

Draelos, A.W., Silverman, A., Eniwaye, B., Arnault, E.G., Ke, C.T., Wei, M.T., Vlassiouk, I., Borzenets, I.V., Amet, F., Finkelstein, G. (2019). "Subkelvin lateral thermal transport in diffusive graphene." Phys. Rev. B 99(12), p. 125427.

Supercurrent flow in multiterminal graphene Josephson junctions

Published in Nano Letters, 2019

We present the first investigation of the electronic properties of ballistic planar Josephson junctions with multiple superconducting terminals and find that superconducting and dissipative currents coexist within the same region of graphene.

Draelos, A.W., Wei, M.T., Seredinski, A., Li, H., Mehta, Y., Watanabe, K., Taniguchi, T., Borzenets, I.V., Amet, F., Finkelstein, G. (2019). "Supercurrent flow in multiterminal graphene Josephson junctions." Nano Lett. 19(2), pp. 1039-1043.

Supercurrent in Graphene Josephson Junctions with Narrow Trenches in the Quantum Hall Regime

Published in MRS Advances, 2018

We report on low-temperature transport measurements in devices constructed with a narrow trench perpendicular to the contacts in a Josephson junction, which create counterpropagating quantum Hall edge channels tens of nanometres from each other.

Seredinski, A., Draelos, A., Wei, M.T., et. al. (2018). "Supercurrent in Graphene Josephson Junctions with Narrow Trenches in the Quantum Hall Regime." MRS Advances 3(47-48), pp. 2855-2864.

Investigation of Supercurrent in the Quantum Hall Regime in Graphene Josephson Junctions

Published in Journal of Low Temperature Physics, 2018

We examine multiple encapsulated graphene Josephson junctions to determine which mechanisms may be responsible for supercurrent observed in the quantum Hall regime.

Draelos, A.W., Wei, M.T., Seredinski, A., Ke, C.T., Mehta, Y., Chamberlain, R., Watanabe, K., Taniguchi, T., Yamamoto, M., Tarucha, S., Borzenets, I.V., Amet, F., Finkelstein, G. (2018). "Investigation of supercurrent in the quantum Hall regime in graphene Josephson junctions." J. Low Temp. Phys. 191(5-6), pp. 288-300.

Ballistic graphene Josephson junctions from the short to the long junction regimes

Published in Physical Review Letters, 2016

We present low-temperature transport measurements on ballistic graphene-based Josephson junctions and find a crossover from the short to the long junction regimes as the length of the device increases.

Borzenets, I.V., Amet, F., Ke, C.T., Draelos, A.W., Wei, M.T., Seredinski, A., Watanabe, K., Taniguchi, T., Bomze, Y., Yamamoto, M., Tarucha, S., and Finkelstein, G. (2016). "Ballistic graphene Josephson junctions from the short to the long junction regimes." Phys. Rev. Lett. 117(23), p. 237002.

Critical current scaling in long diffusive graphene-based Josephson junctions

Published in Nano Letters, 2016

We present low-temperature transport measurements on long, diffusive, graphene-based Josephson junctions and examine the relationship between critical current and the Thouless energy for different junction lengths.

Ke, C.T., Borzenets, I.V., Draelos, A.W., Amet, F., Bomze, Y., Jones, G., Craciun, M., Russo, S., Yamamoto, M., Tarucha, S., Finkelstein, G. (2016). "Critical current scaling in long diffusive graphene-based Josephson junctions." Nano Lett. 16(8), pp. 4788-4791.

Plasmonics in the UV range with Rhodium nanocubes

Published in Proceedings of SPIE 9884, 2016

We study the electromagnetic behaviour of isolated Rh nanocubes of different sizes through numerical simulations and compare with experimental measurements.

Zhang, X., Gutiérrez, Y., Li, P., Barreda, Á.I., Watson, A.M., de la Osa, R.A., Finkelstein, G., González, F., Ortiz, D., Saiz, J.M., Sanz, J.M. (2016). "Plasmonics in the UV range with Rhodium nanocubes." In Nanophotonics VI (Vol. 9884, p. 98841E), International Society for Optics and Photonics.

Rhodium Nanoparticles for Ultraviolet Plasmonics

Published in Nano Letters, 2015

We present for the first time the use of rhodium nanoparticles for ultraviolet plasmonics, demonstrating essential steps toward plasmonically enhanced ultraviolet photocatalysis.

Watson, A.M., Zhang, X., Alcaraz de La Osa, R., Sanz, J.M., González, F., Moreno, F., Finkelstein, G., Liu, J., Everitt, H.O. (2015). "Rhodium nanoparticles for ultraviolet plasmonics." Nano Lett. 15(2), pp.1095-1100.

Topographic measurement of buried thin-film interfaces using a grazing resonant soft x-ray scattering technique

Published in Physical Review B, 2014

We demonstrate that grazing resonant soft x-ray scattering (GRSoXS), a technique measuring diffusely scattered soft x rays from grazing incidence, can reveal the statistical topography of buried thin-film interfaces.

Gann, E., Watson, A., Tumbleston, J.R., Cochran, J., Yan, H., Wang, C., Seok, J., Chabinyc, M., Ade, H. (2014). "Topographic measurement of buried thin-film interfaces using a grazing resonant soft x-ray scattering technique." Phys. Rev. B 90(24), p. 245421.

Surface-enhanced Raman scattering plasmonic enhancement using DNA origami-based complex metallic nanostructures

Published in Nano Letters, 2014

We use DNA origami templates to engineer surface-enhanced Raman scattering substrates and show a significant Raman signal enhancement from molecules covalently attached to the assemblies.

Pilo-Pais, M., Watson, A., Demers, S., LaBean, T.H., Finkelstein, G. (2014). "Surface-enhanced Raman scattering plasmonic enhancement using DNA origami-based complex metallic nanostructures." Nano Lett. 14(4), pp.2099-2104.

JLIFE: The Jefferson Lab Interactive Front End For The Optical Propagation Code

Published in 35th International Free Electron Laser Conference, 2013

We present the design and construction of a graphical interface for the open source software program Optical Propagation Code (OPC) to model wave propagation in FEL oscillators.

Watson, A.M., Shinn, M.D. (2013). "JLIFE: The Jefferson Lab Interactive Front End For The Optical Propagation Code." In 35th International Free-Electron Laser Conference. (pp. 149-151).

A New Approach to Improving the Efficiency of FEL Oscillator Simulations

Published in 34th International Free Electron Laser Conference, 2012

We compare 2D, 3D, and 4D free-electron laser (FEL) oscillator simulation codes against the measured performances of three oscillator FELs.

Shinn, M.D., Benson, S.V.,Watson, A.M., van der Slot, P.J., Freund, H.P. and Nguyen, D.C. (2012). "A new approach to improving the efficiency of fel oscillator simulations." In 34th International Free-Electron Laser Conference (pp. 225-228).

Demonstration of 3D Effects with High Gain and Efficiency in a UV FEL Oscillator

Published in 2011 Particle Accelerator Conference, 2011

We report on the performance of a high gain UV FEL oscillator operating on an energy recovery linac at Jefferson Lab and find 3D simulations do predict the performance with reasonable precision.

Benson, S., Biallas, G., Blackburn, K., [et. al., including Watson, A.], (2011). "Demonstration of 3D Effects with High Gain and Efficiency in a UV FEL Oscillator." In 2011 Particle Accelerator Conference (pp. 2429-2431).