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Events During the Week of December 16th through December 23rd, 2018

Monday, December 17th, 2018

R. G. Herb Condensed Matter Seminar
Rays-based learning and auto-tuning of devices in quantum dot experiments
Time: 3:00 pm
Place: ***5280 Chamberlin Hall***
Speaker: Justyna Zwolak
Abstract: Over the past decade, machine learning techniques have revolutionized how scientific research is done, from designing new materials to finding significant events in particle physics to assisting drug discovery. Recently, we added to this list by showing how a machine learning algorithm, combined with optimization routines, can assist experimental efforts in tuning semiconductor quantum dot devices. In particular, we demonstrated that deep convolutional neural networks can be used to characterize the state and charge configuration of single and double quantum dots devices based on measurements of a current-gate voltage transport characteristics or via the conductance of a nearby charge sensor [1]. Our approach provides a paradigm for fully-automated experimental initialization through a closed-loop system that does not rely on human intuition and experience. Here I expand upon our prior work to show how a machine learning-based approach can be applied for pattern recognition to higher-dimensional systems. Given the recent progress in the physical construction of systems with N >> 3 gates to create a large number of dots, in both one and two dimensions [2,3], it is imperative to have a reliable method to find a stable, desirable electron configuration in the dot array. I will present a preliminary approach that differs from the conventional machine learning literature, in which we consider the benefit of using a “fingerprint” of state space. Rather than working with full-sized sweeps of the gate voltage space, we train a machine-learning algorithm using use 1D traces (“rays”) of fixed length in multiple directions to recognize relative position of the features characterizing given state (i.e., to “fingerprint”) in order to differentiate between various state configurations. We use a double dot device as a toy model to compare with our existing, CNN approach, and then show how this fingerprinting can extend to higher-dimensional systems. Our approach not only allows to automate the recognition of states, but also to reduce the number of measurements required for tuning. [1] S.S. Kalantre, J.P. Zwolak, S. Ragole, X. Wu, N. M. Zimmerman, M.D. Stewart, Jr., J.M. Taylor, arXiv:1712.04914 (2017). [2] D.M. Zajac, T.M. Hazard, X. Mi, E. Nielsen, J.R. Petta, Phys. Rev. Appl. 6, 054013 (2016). [3] U. Mukhopadhyay, J. P. Dehollain, C. Reichl, W. Wegscheider, L. M. K. Vandersypen, Appl. Phys. Lett. 112, 183505 (2018).
Host: Eriksson
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Tuesday, December 18th, 2018

No events scheduled

Wednesday, December 19th, 2018

Atomic Physics Seminar
Update on the GNOME Experiment
Time: 10:00 am - 11:00 am
Place: 5310 Chamberlin
Speaker: Ibrahim Sulai (for the GNOME collaboration), Bucknell University
Abstract: The Global Network of Optical Magnetometers for Exotic physics (GNOME) comprises an array of atomic
magnetometers used for searching for beyond the standard model spin interactions. It presently
consists of 12 active magnetometer stations spread around the globe with gps-time stamped data being
continuously streamed to a central server for analysis. Of special interest is the search for dark matter in
the form of interactions with axion - like particles (ALPs) which may form ALP domain walls and ALP
stars. Such interactions will have the signature of temporally coincident transients occurring in multiple
sensors in the network. I will in this talk describe the experimental details of the network and review some
data analysis ideas.
Host: Thad Walker
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NPAC (Nuclear/Particle/Astro/Cosmo) Forum
Invisible Worlds: Rare Event Searches for Physics Beyond the Standard Model
Time: 2:00 pm
Place: 5280 Chamberlin Hall
Speaker: Danielle Speller, Wright Laboratory, Yale University
Host: Baha Balantekin
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Thursday, December 20th, 2018

No events scheduled

Friday, December 21st, 2018

No events scheduled