Welcome, incoming MSPQC students! 

Bucky Badger in a lab coat holding a prism with a rainbow coming out, and Welcome to Physics! above

The UW–Madison Physics Department is pleased to welcome 18 students to the M.S. in Physics – Quantum Computing program. These students make up the third cohort to begin the program and are the largest entering class to date.  

“We are really pleased and proud that the MSPQC program continues to grow and prosper in its third year,” says Bob Joynt, MSPQC Program Director and professor of physics. “We look forward to providing a great experience for the class of 2021. A particular focus this year will be the formation of collaborative teams that will push forward research in quantum computing.” 

 Of note, three women are in the entering class, marking the first time that women have enrolled in MSPQC. Other facts and figures about this year’s cohort include: 

  • 11 students are coming directly from completing their Bachelors 
  • Three students have Master’s degrees 
  • Six students have at least four years of professional experience, and four of those students have over 10 years professional experience 
  • 15 are international students, and seven of those students have attended U.S. institutions for previous studies 
  • The students’ academic backgrounds include physics, astronomy, engineering, and business administration.  

The department is following University guidelines and is planning for students to join us in Madison this fall, with in-person instruction. Over the summer, students can attend optional virtual orientation sessions to prepare for the program.  

“The pandemic imposed restrictions on our admissions and recruitment activities which forced us to work virtually, but I believe these barriers made our programming more accessible and led to the most diverse and determined incoming cohort of MSPQC students to date,” says Jackson Kennedy, MSPQC coordinator. “Although I have been able to meet our incredibly talented students virtually, I cannot wait to greet them in-person this Fall as we celebrate a long-awaited return to campus.” 

In addition to Joynt, the department thanks the other faculty who serve on the MSPQC admissions committee — Alex Levchenko, Robert McDermott, Maxim Vavilov and Deniz Yavuz — for application review. We also thank Michelle Holland and Jackson Kennedy for organizing recruiting efforts.  

 The MSPQC program welcomed its first students in Fall 2019 – the first-ever class of students in the U.S. to enroll in a quantum computing M.S. degree program. The accelerated program was born out of a recognized need to rapidly train students for the quantum computing workforce and is designed to be completed in 12 months. It provides students with a thorough grounding in the new discipline of quantum information and quantum computing.  

names of students, UG institute and degree: Brooke Becker UW–Madison Computer Engineering Soyeon Choi Vanderbilt University Physics, Computer Science Manish Chowdhary Indian Institute of Technology Dhanbad Computer Application Hua Feng Dalian University of Technology Atomic and Molecular Physics Jacob Frederick University of Washington Computer Engineering Amol Gupta Delhi Technological University Computer Engineering Yucheng He Zhengzhou University Automation Xunyao Luo Lafayette College Physics and Neuroscience Arjun Puppala Indian Institute of Technology Roorkee Power Systems Engineering Evan Ritchie University of St Thomas - Minnesota Physics & Math Mubinjon Satymov New York City College of Technology - CUNY Applied Computational Physics Yen-An Shih National Cheng Kung University Computer Science Qianxu Wang University of Michigan Physics Jiaxi Xu UC-Berkeley Physics Anirudh Yadav Indian Institute of Technology Dhanbad Computer Science Yukun Yang Nanjing University Astronomy Jin Zhang UW–Madison Physics & Philosophy Lin Zhao UW–Madison Computer Science and Physics
The incoming 2021 class of MSPQC students

Flexible, easy-to-scale nanoribbons move graphene toward use in tech applications

greyscale scanning electron micrograph of graphene nanoribbons that looks like an intricate fingerprint. has also been described as a "zen garden"

From radio to television to the internet, telecommunications transmissions are simply information carried on light waves and converted to electrical signals.

Joel Siegel

Silicon-based fiber optics are currently the best structures for high-speed, long distance transmissions, but graphene — an all-carbon, ultra-thin and adaptable material — could improve performance even more.

In a study published April 16 in ACS Photonics, University of Wisconsin–Madison researchers fabricated graphene into the smallest ribbon structures to date using a method that makes scaling-up simple. In tests with these tiny ribbons, the scientists discovered they were closing in on the properties they needed to move graphene toward usefulness in telecommunications equipment.

“Previous research suggested that to be viable for telecommunication technologies, graphene would need to be structured prohibitively small over large areas, (which is) a fabrication nightmare,” says Joel Siegel, a UW–Madison graduate student in physics professor Victor Brar’s group and co-lead author of the study. “In our study, we created a scalable fabrication technique to make the smallest graphene ribbon structures yet and found that with modest further reductions in ribbon width, we can start getting to telecommunications range.”

For the full story, please visit: https://news.wisc.edu/flexible-easy-to-scale-nanoribbons-move-graphene-toward-use-in-tech-applications/

Searching for Sources of Gravitational Waves

a colorful graph showing degrees of sky on a graph's axes and plots of data indicating where gravitational waves may have come from

The entire astrophysical world was blown away by the first-ever binary neutron star collision seen in August 2017 (called ‘GW170817’). This event, identified as a kilonova, was the first to be seen in both gravitational waves, by the LIGO and Virgo detectors, as well as the electromagnetic spectrum, from gamma rays to radio waves (and covered previously in this Oct 2017 DArchive ). Since then, there have been dozens of new gravitational wave events.

A group of researchers in DES, the DESGW team, have focused on finding more electromagnetic counterparts to these gravitational wave events. Members of the Dark Energy Survey — including University of Wisconsin–Madison physics grad student Rob Morgan and postdoc Ross Cawthon, both in Prof. Keith Bechtol’s group —  look at two of the most intriguing events we have followed up with DECam since 2017.

For the full story, please visit The Dark Energy Survey post.

Introducing the Physics Ph.D. Class of 2021

Bucky Badger in a lab coat holding a prism with a rainbow coming out, and Welcome to Physics! above

After record-breaking application numbers and the most unique recruiting season yet, the Department of Physics is pleased to introduce the 30 students of the incoming Ph.D. class of 2021!   

“This year’s incoming Ph.D. class is a remarkably strong and diverse cohort who have overcome truly historic obstacles to join us,” says Ph.D. admissions committee chair, Prof. Shimon Kolkowitz. “I couldn’t be more excited to welcome them to our department and to witness the great work they will accomplish in their time here.” 

602 students applied for one of 91 admissions spots, the most applications the department has received in at least the past decade (based on available graduate school data). 

Some highlights of the incoming class include:   

  • Students coming from 18 U.S. states and three other countries (China, India, and Malaysia) 
  • 22 expressing a preference for experiment, with the rest expressing a preference for theory only, or either/undecided 
  • Eight women 
  • Three Advanced Opportunity Fellowship (AOF) eligible students 
  • Two students who were named 2021 NSF Graduate Research Fellows

This year’s incoming class is also the first to ever participate in “Virtual Visit Days,” thanks to the COVID-19 pandemic. Though perhaps not as exciting as visiting campus in person, admitted students could still meet with faculty to discuss research opportunities, participate in discussions and virtual games nights with current students, and watch videos — many newly-created just for these visits — about the University, the city of Madison, and research in our department. 

“Thank you to all the prospective students for their engagement and enthusiasm throughout the admissions and virtual visit process,” says Michelle Holland, graduate program coordinator. We are beyond thrilled to welcome the Class of 2021 to the Physics Ph.D. Program at UW–Madison as we find our new normal in being together on campus this fall.”   

The department would like to send a huge round of applause to everyone who participated in recruitment this year, especially current graduate students on the recruitment committeeTrevor Oxholm, Abigail Shearrow, Kunal SanwalkaSusmita Mondal, Winnie Wang. We also thank graduate program coordinators Michelle Holland and Jackson Kennedy for organizing and running the virtual visit days, Dan Bradley for once again providing IT solutions to help the admissions process and visit days run smoothly, and Sarah Perdue for website development and video production. 

The department also thanks the Ph.D. admissions committee for their thorough evaluation of the applicants. In addition to Kolkowitz, the committee members are Profs. Keith Bechtol, Stas Boldyrev, Victor Brar, Mark Eriksson, Ke Fang, and Jeff Parker.  

One student accepted our admissions offer but has deferred to 2022.  

  Name     Undergrad Institution   Major Zain Abhari Florida State University Physics Jared Benson University of Vermont Physics; Mathematics Emma Brann Michigan State University Physics Theodore Bucci Youngstown State University Physics/Mathematics Brighton Coe Illinois State University Physics/Computational Physics Caroline Doctor University of Georgia Physics Justin Edwards Texas Tech University Physics Carter Fox University of Michigan-Ann Arbor Physics; Astronomy/Astrophysics Syeda "Minhal" Gardezi Wellesley College Physics Daniel Heimsoth Yale University Astrophysics Tyler Kovach Case Western Reserve University Electrical Engineering; Engineering Physics Caroline "Carrie" Laber-Smith Massachusetts Institute Of Technology Physics Hong Ming Lim Nanyang Technological University Physics Yixiang "Ethan" Lu University of California-Berkeley Physics Justin Marquez Florida State University Physics Michael Martinez University of Chicago Astrophysics, Mathematics Stephen McKay Wheaton College Physics, Mathematics Trevor Nelson University of Massachusetts-Amherst Physics, Math, Astronomy Sam Norrell Indiana University Biology, Chemistry, Math Jesse Osborn University of Nebraska-Lincoln Physics and Mathematics Angelina Partenheimer Truman State University Physics Priyadarshini Rajkumar Texas Tech University Physics Zoe Rechav Truman State University Physics John "Jack" Reily University of Illinois Urbana-Champaign; University of Wisconsin-Madison (M.S.) Engineering Physics; Physics-Quantum Computing (M.S.) Faizah Siddique University of Massachusetts-Amherst Physics Matthew Snyder University of Missouri-Columbia Physics and Mathematics Gabriel Spahn University of Minnesota-Twin Cities Physics and Music Spencer Weeden Carleton College Physics Hongyi Wu University of Maryland-College Park Physics, Mathematics Perri Zilberman University of California-Santa Barbara Physics, Mathematics

Gage Bonner earns 2020 Teaching Award

profile picture of Gage Bonner
profile picture of Gage Bonner
Gage Bonner

Congrats to physics grad student Gage Bonner for earning a 2020 College of Letters & Sciences Continuation of Study teaching award!

This new award category recognizes graduate students in L&S who provided exceptional continuity of instruction support to their department or delivered exceptional student experience in a remote instructional setting during the COVID-19 pandemic.

Bonner was nominated for his work as a TA in Physics 109, Physics in the Arts, by one of the course’s instructors, Prof. Pupa Gilbert. Physics 109 is a quantitative-reasoning course offered to non-science majors, typically serving more than 200 students.

“The students are terrified of physics, and are not quantitative thinkers, thus it is especially important for Physics in the Arts TAs to be kind, friendly, and not intimidating,” Gilbert says. “Gage excels at all these challenges, and teaches masterfully. He is kind, intelligent, knowledgeable, and always in a good mood, making everyone feel comfortable and not intimidated.”

Gilbert nominated Bonner for the Continuation of Study award because of how effectively he adapted to the changes forced by the COVID-19 pandemic. For example, because in-person labs were no longer an option, Gilbert selected online labs, and asked the TAs to develop a series of interactive questions associated with each online experiment to help the students learn by doing. Bonner excelled at developing these questions. She also noted how well he interacts with students through the online Zoom lectures, helping to keep conversations going and being knowledgable, kind and effective with online instruction.

Based on course and TA evaluations, the students agree with Gilbert. Said one student in an evaluation:

“Gage has been a really awesome TA. He makes labs run so smoothly, responds to questions quickly and effectively, and reminds us [of] vital information. He was also super helpful in lectures. Letting the teachers know if there was a technical issue or question. He also made a really friendly and comfortable learning environment even with the restraints of BBC collaborate ultra.”

UW–Madison employs over 2,100 teaching assistants (TAs) across a wide range of disciplines. Their contributions to the classroom, lab, and field are essential to the university’s educational mission. To recognize the excellence of TAs across campus, the Graduate School supports the College of Letters & Science (L&S) in administering these awards.

Bonner has been a graduate student and TA in the department since Fall 2016.

Jimena González named Three Minute Thesis® finalist

Congrats to Jimena González, a physics graduate student in Keith Bechtol’s group, who is one of nine finalists for UW–Madison’s Three Minute Thesis® competition! Watch Jimena’s video on YouTube, and check out all nine finalists’ videos at the UW–Madison 3MT® website. The videos are only available through November 29. The finals will be held on February 3, 2021.

a still from a YouTube video of Jimena giving a presentation
Jimena González presents a virtual 3MT

Chuanhong (Vincent) Liu named to Fall 2020 cohort of the Quantum Information Science and Engineering Network (QISE-NET)

profile photo of Vincent Liu

Graduate student Chuanhong (Vincent) Liu (McDermott Group) has had his project awarded funding through QISE-NET, the Quantum Information Science and Engineering Network. Run through the University of Chicago, QISE-NET is open to any student pursuing an advanced degree in any field of quantum science. Liu and other students in his cohort earn up to three years of support, including funding, mentoring and training at annual workshops. All awardees are paired with a mentoring QISE company or national lab, at which they will complete part of their projects. Liu describes his project, below. Cecilia Vollbrecht, a grad student in Chemistry, also earned this honor. Both Liu and Volbrecht are students in the Wisconsin Quantum Institute.

The Single Flux Quantum (SFQ) digital logic family has been proposed as a scalable approach for the control of next-generation multiqubit arrays. With NIST’s strong track record in the field of SFQ digital logic and the expertise of McDermott’s lab in the superconducting qubit area, we expect to achieve high fidelity SFQ-based qubit control. The successful completion of this research program will represent a major step forward in the development of a scalable quantum-classical interface, a critical component of a fully error-corrected fault-tolerant quantum computer.

New study provides understanding of astrophysical plasma dynamics

plasma from a sun-like star in the upper left corner is coming out like a string that swirls like a whirlpool around a dot in the center of the image

Stars, solar systems, and even entire galaxies form when astrophysical plasma — the flowing, molten mix of ions and electrons that makes up 99% of the universe — orbits around a dense object and attaches, or accretes, on to it. Physicists have developed models to explain the dynamics of this process, but in the absence of sending probes to developing stars, the experimental confirmation has been hard to come by.

In a study published in Physical Review Letters September 25, University of Wisconsin–Madison physicists recreated an astrophysical plasma in the lab, allowing them to investigate the plasma dynamics that explain the accretion disk formation. They found that electrons, not the momentum-carrying ions, dominate the magnetic field dynamics in less dense plasmas, a broad category that includes nearly all laboratory astrophysical plasma experiments.

plasma from a sun-like star in the upper left corner is coming out like a string that swirls like a whirlpool around a dot in the center of the image
An artist’s conception of the accretion disk | Credit: P. Marenfeld/NOAO/AURA/NSF

Like water swirling around and down an open drain, plasma in an accretion disk spins faster nearer the heavy object in the center than further away. As the plasma falls inward, it loses angular momentum. A basic physics principle says that angular momentum needs to be conserved, so the faster rotating plasma must be transferring its momentum away from the center.

“This is an outstanding problem in astrophysics — how does that angular momentum get transported in an accretion disk?” says Ken Flanagan, a postdoctoral researcher with the department of physics at UW–Madison and lead author of the study.

The simplest explanation is friction, but it was ruled out when the corresponding accretion times, in some cases, would be longer than the age of the universe. A model developed by theoretical physicists posits that turbulence, or the chaotic changes in plasma flow speeds, can explain the phenomenon on a more realistic time scale.

“So ad hoc, astrophysicists say, ‘Okay, there’s this much turbulence and that explains it,’” Flanagan says. “Which is good, but you need to call in the plasma physicists to piece together where that turbulence comes from.”

Flanagan and colleagues, including UW­–Madison physics professor Cary Forest, wanted to build off an idea that the turbulence was coming from an intrinsic property of some plasmas known as magnetorotational instability. This instability is seen in plasmas that are flowing fastest near the center and are in the presence of a weak magnetic field.

“And it’s lucky because there are weak magnetic fields all around the universe, and the flow profile in the accretion disks is set by the gravitational force,” Flanagan says. “So, we thought this plasma instability could be responsible for turbulence, and it explains how accretion disks work.”

To investigate if this intrinsic plasma instability explained the observation, the researchers turned to the Big Red Ball (BRB), a three-meter-wide hollow sphere with a 3000 magnets at its inner surface and various probes inside. They activate a plasma by ionizing gas inside the BRB, then applying a current to drive its movement.

a 3-meter-diameter sphere, painted red and with tons of probes all around it
The Big Red Ball is one of several pieces of scientific equipment being used to study the fundamental properties of plasma in order to better understand the universe, where the hot, ionized gas is abundant. | Photo by Jeff Miller / UW–Madison)

Because they had previously been encountering problems in driving very fast flows, they tried a new technique to drive the flow across the entire volume of plasma, as opposed to just the edges. Fortuitously, the BRB had magnetic field probes from a previous experiment still attached, and when they activated the plasma under these conditions, they found that this new flow setup amplified the magnetic field strength with a peak at the center nearly twenty times the baseline strength.

“We didn’t expect to see that at all, because usually in plasma physics the simplest model is to think of plasmas as one fluid with the heavier ions dominating momentum,” Flanagan says. “The results suggested that the plasma is in the Hall regime, which means the electrons and their motion are entirely responsible for the plasma moving around magnetic fields.”

If they were correct in assuming it was the Hall effect that was driving magnetic field amplification, the equations governing magnetic fields and electric currents say that if you drive the current in the opposite direction, the strength of the magnetic field would be canceled out. So, they switched the current and measured the magnetic field strength: it was zero, supporting the Hall regime explanation.

While the results are not directly applicable to the plasma accretion disks around, say, a very dense black hole, they do directly impact the earth-bound experiments that attempt to recreate and study them.

“Nearly all plasma astrophysical experiments operate in the Hall regime, and so this sort of large qualitative effect is something you’re going to have to pay attention to when you make these sorts of flows in laboratory astrophysical plasmas,” Flanagan says. “In that sense, this work has a pretty broad impact for lots of different research areas.”

This research was supported in part by the National Science Foundation (#1518115) and by the U.S. Department of Energy (#DE-SC0018266).

Physics grad students share hands-on physics, art lessons with local fifth graders

picture of a computer screen showing a Zoom meeting where most of the individual boxes are where the students' kaleidoscopes are being held up to the camera
the 4 kits sent home with the students are laid out and opened up, revealing contents like worksheets, laser pointers, mirrors, and lenses
The at-home physics kits featured lessons on light, such as how it functions as both a particle and a wave, and how light changes as it passes through a prism. PHOTO: AEDAN GARDILL

UW–Madison physics grad student Aedan Gardill has been illustrating physics concepts with art for years, such as through his Instagram account, where he shares ink drawings. Earlier this year, he applied for a grant from the Madison Arts Commission to create hidden portraits of women in the physical sciences that could only be revealed by using polarized lenses. He also planned to visit local schools to explain the concept behind his art and help students make their own images based on his technique.

By the time Gardill learned he had been awarded the grant, the pandemic was in full force, and his plans had to change. While he could still present his portraits at the Wisconsin Science Festival, school visits were no longer in the cards.

“With the realization this summer that school was going to most likely be online in the fall, I had to rethink how I was going to use the funding from the grant,” Gardill explains. “And that has morphed into providing at-home, hands-on learning experiences that we’ll lead virtually.”

Hear more from Aedan and a Henderson Elementary School teacher and student he worked with, by reading the full story

Funding for Gardill’s work is provided by a grant from the Madison Arts Commission, with additional funds from the Wisconsin Arts Board, the Optical Society of America, the International Society for Optics and Photonics, and the UW­–Madison Department of Physics, with special thanks to Arts + Literature Laboratory. UW–Madison physics graduate student volunteers include Abby Bishop, Praful Gagrani, Jimena Gonzalez, Ben Harpt, Preston Huft, Brent Mode, Bryan Rubio Perez, Susan Sorensen, and Jessie Thwaites.