UMD Awarded $2 Million to Build a Quantum Biosensing Test Bed

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Category: Department News

Published: Monday, November 18 2024 10:07

Physics Professor Wolfgang Losert, Cell Biology and Molecular Genetics Professor Kan Cao, Chemistry and Biochemistry Professor John Fourkas, and Electrical and Computer Engineering Associate Professor Cheng Gong were awarded $2 million by the U.S. Air Force Office of Scientific Research to build a test bed to study how neural networks process information and develop new approaches to quantum computing and sensing inspired by the living brain. As principal investigator of this multidisciplinary and cross-institutional project, Losert will collaborate with both UMD faculty members as well as other academic and industry partners to better understand and recreate the brain’s unique capacity for learning and adapting quickly—abilities that far surpass traditional computer systems.Wolfgang Losert

“The human brain is remarkable in how efficiently it can learn and process information. For example, we only need to touch a hot stove once to learn not to do it again,” Losert explained. “But current artificial intelligence systems need more than just that. Typically, they require enormous amounts of data and computing power to learn new tasks through numerous rounds of trial and error.”

While traditional computers process information through individual components working in sequence, the brain distributes information across many networks of cells working in parallel. This fundamentally different approach allows for faster learning and adaptivity but with far less energy consumption than a computer. Losert and his team hope to identify the biological mechanisms behind this efficient method of learning in the brain.

For this research, a key focus is on astrocytes, a type of brain cell that makes up more than half of the cells in the human brain. Long considered mere support cells for neurons, astrocytes are now recognized as crucial to how the brain processes information. By engineering laboratory-based systems that incorporate both neurons and astrocytes, Losert’s team will closely observe how the two types of cells form living neural networks and react when exposed to various types of stress like ultrasound or electrical fields.

Recent discoveries by the neuroscientist on Losert’s team, assistant research scientist Kate O’Neill, and other researchers have already shown that astrocytes actively participate in brain signaling and may be essential to the brain’s ability to both learn and adapt to new situations quickly. Further observations could provide insights into how the brain maintains its performance under different conditions and may lead to more resilient forms of artificial intelligence (AI).

“Interestingly, one aspect that makes biocomputing so unique—the multitude of different signals in living neural networks, such as electro-magnetic, chemical and mechanical signals—also opens up another exciting aspect of our work. We can use living neural networks to test and improve quantum sensors for a range of biomedical applications,” said Losert, who is also an MPower Professor and interim associate dean for research in the College of Computer, Mathematical, and Natural Sciences with a joint appointment in the Institute for Physical Science and Technology.

Quantum sensors have the potential to measure minute physical changes like the presence of magnetic fields or electrochemical activity in cells in minimally invasive ways. Novel non-invasive biosensors could allow scientists and health care professionals to observe brain processes in patients that they couldn’t see before, potentially leading to better medical treatments and a more nuanced understanding of brain performance.

With this award, Losert’s team aims to bridge the gap between artificial and biological computing systems and help create new technologies that combine the best features of both.

“By understanding and replicating how brain cells work together, we hope to create more efficient and adaptable computing systems,” Losert said. “This project represents the start of a new paradigm in biocomputing that may help shape the future of both AI and neuroscience.”

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The grant will also facilitate collaborations with researchers from the U.S. Air Force Research Library, the National Quantum Laboratory (QLab), Lockheed Martin, the National Research Council of Italy (CNR) and the University of Bari Aldo Moro.

New Design Packs Two Qubits into One Superconducting Junction

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Category: Research News

Published: Monday, October 21 2024 00:01

Quantum computers are potentially revolutionary devices and the basis of a growing industry. However, their technology isn’t standardized yet, and researchers are still studying the physics behind the diverse ways to build these quantum devices. Even the most basic building blocks of a quantum computer—qubits—are still an active research topic.A superconducting circuit studied in Alicia Kollár’s lab. The middle of the three rectangles along the bottom are junctions that hold quantum states that may each be used as a qubit. A proposal to adjust the dimensions of the junctions would allow chips like this to host twice as many qubits.

In an article published September 23, 2024 in the journal Physical Review A, JQI researchers proposed a way to use the physics of superconducting junctions to let each function as more than one qubit. They also outlined a method to use the new qubit design in quantum simulations. While these proposed qubits might not immediately replace their more established peers, they illustrate the rich variety of quantum physics that remains to be explored and harnessed in the field.

Superconducting junctions are part of many diverse qubit designs, including those in the prototype quantum computers of IBM and Google. All the designs feature an island made of a superconductor joined to the rest of a superconducting circuit by a thin layer of insulator that forms the junction between the two sections. To cross the barrier, electrons in the circuit must quantum tunnel through the junction, influencing which quantum states the circuit can naturally hold.

JQI Fellow Mohammad Hafezi and JQI postdoctoral researcher Andrey Grankin, who is the first author of the paper, reviewed the research on junctions in superconducting circuits, and what they found left them wondering if the existing qubit designs were taking advantage of the full breadth of physics that can be realized in superconducting junctions. The design of a junction—the geography of the superconducting island—impacts which states it can host, and current designs have focused on small junctions and the simplest states.

In some qubit designs, the quantum states depend on the geography of the island because of how electrons in a superconductor are free to move around like a fluid. Like water in a small pool, the electrons can slosh back and forth and form waves that are influenced by their surroundings.

Certain electron waves isolated onto a superconducting island can be very stable and long lasting, which makes them useful for storing quantum information in a qubit. The waves that are stable are examples of a more general phenomenon, called standing waves, that occur when a wave isn’t interrupted during the slope of one of its hills or valleys; instead, its oscillations are perfectly completed at the edges (the walls of a pool, the points where a string is being held, etc.). A guitar string’s harmonics are also examples of standing waves. 

But just having a stable standing wave in the superconducting electrons isn’t enough to be useful for quantum calculations. To use a standing wave as a qubit, a quantum computer must be able to distinguish it from all other standing waves and individually target it. Current superconducting qubit designs circumvent this issue by using short junctions that host just a single standing wave; as long as a junction is sufficiently short, the physics governing the superconducting electrons effectively only allows a single standing wave on the superconducting island. Researchers have also studied junctions that meet along very long interfaces and found that they can easily host a vast array of standing waves. Unfortunately, the abundance of standing waves comes with a downside: The more standing waves there are, the more similar the waves become, which makes them difficult to tell apart and inconvenient for quantum computing. 

“Historically short and long junctions were researched quite extensively,” says Grankin, who is the first author of the paper. “But the intermediate junction lengths have not been studied.”

Hafezi—who is also a Minta Martin professor of electrical and computer engineering and physics at the University of Maryland (UMD) and a Senior Investigator at the National Science Foundation Quantum Leap Challenge Institute for Robust Quantum Simulation (RQS)—and Grankin became interested in this intermediate regime. The pair consulted with JQI Fellow Alicia Kollár, another author of the paper who works with superconducting qubits in her research.

“Andrey and Mohammad came to me with a creative new idea for how to make a junction host multiple qubit excitations,” says Kollár, who is also a Chesapeake Assistant Professor of Physics and a Co-Associate Director of Research for RQS. “Our main challenge was coming up with a design that would yield practical device parameters and a device that is actually within reach of current state-of-the-art fabrication techniques.”

Together, the group explored the behaviors of electrons in the intermediate case and if it is practical to produce multiple excitations that can be easily distinguished and separately manipulated. Since the pool of electrons is within a solid superconductor, setting them into motion isn’t as simple as plucking a string. To push and pull on electrons you need an electric field. One way that physicists like to push electrons around is using a special reflective chamber—or resonator—that is full of electric and magnetic fields in the form of light. 

Light in a resonator can form its own standing waves that act on the electrons. Similar to a guitar string vibrating due to the sound waves from another string—or more dramatically the sound of a singer’s voice shaking a glass until it shatters—the right light waves inside a resonator can excite electrons in a superconducting junction into a standing wave, which physicists call a mode of the junction. 

The team analyzed how medium-sized junctions should behave inside a resonator and found promising results. The various modes of a junction each respond more or less strongly to particular frequencies of light, so light can be selected to target a specific mode. The response of a mode to a standing wave of light in a resonator also depends on whether the symmetries of the mode and the light match. If the waves of light in the resonator are symmetrical across the center of a junction, they naturally push electrons into waves with a similar symmetry. For instance, if the light waves crossing the junction form a hill on one side and a valley on the other, they can’t push the electrons into a simple hill reflected across the center of the device, but they might be able to excite a similarly lopsided mode of the junction. 

So, light that creates one mode in the superconducting electrons may be ignored by another mode. In the paper, the team described a method of exploiting these two effects to excite or manipulate only a targeted mode. The researchers proposed a design where two distinct modes are targeted so that a single junction functions as two independent qubits. They also described a method to use a one-dimensional line of junctions to simulate interactions between two-dimensional grids of quantum particles. However, they haven’t yet tackled fabricating the junctions and demonstrating the feasibility of their proposal.

“This project started from a fundamental interest in the electrodynamics of extended junctions,” Grankin says. “Then it turned out to be also useful from the quantum information and simulation perspective.”

Original story by Bailey Bedford: https://jqi.umd.edu/news/new-design-packs-two-qubits-one-superconducting-junction

HAWC Finds High-Energy Gamma-Ray Emissions from Microquasar V4641 Sagittarii

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Category: Research News

Published: Wednesday, October 16 2024 00:01

A new study in Nature, “Ultra-high-energy gamma-ray bubble around microquasar V4641 Sgr,"   has  revealed a groundbreaking discovery by researchers from the High Altitude Water Cherenkov (HAWC) observatory:  TeV gamma-ray emissions from V4641 Sagittarii (V4641 Sgr), a binary system composed of a black hole and a main sequence B-type companion star. This discovery provides fresh insights into particle acceleration in large-scale jets emitted from microquasars, which serve as natural laboratories for studying high-speed jets produced by matter falling onto spinning black holes. The findings show that V4641 Sgr's gamma-ray emissions occur at similar distances from the black hole as those observed in another well-known microquasar, SS 433. This makes V4641 Sgr stand out for its super-Eddington accretion and one of the fastest superluminal jets in the Milky Way. With a gamma-ray spectrum that ranks among the hardest of any known TeV sources, the emissions are detected at energies exceeding 200 TeV. Schematic illustration of the V4641 Sgr region.

The study's results indicate that the gamma rays are likely produced by extremely high-energy protons. While studies of SS 433 indicate that the emission from this object is likely electrons, the high energy emission at large distances from V4641 argue against electrons due to their rapid energy loss at high energies. The implications are profound: the environment around the microquasar may play a critical role in determining whether the emission from the large-scale jets comes from electrons or protons, and they could play a significant role as a source of Galactic cosmic rays. These observations open new avenues for understanding particle acceleration in extreme environments and contribute to the broader study of high-energy astrophysics. 

 "At a zenith angle of 46° from HAWC's field of view, the microquasar V4641 Sgr has accelerated particles to the knee of the cosmic-ray spectrum, pushing the boundaries of our understanding of particle acceleration and transport in such extreme environments," said Dr. Dezhi Huang, a Post-Doctoral researcher at the University of Maryland. "HAWC observatory continues to deliver exceptional performance, providing valuable insights into these high-energy processes that were previously beyond our reach. "

“The HAWC survey has discovered for the first time very high energy gamma rays from the extended 100 pc jet of the microquasar V4641 Sgr. This proves that jets launched in accreting systems can accelerate particles up to PeV energies, and therefore that microquasars are potentially significant contributors to the Galactic cosmic ray population at high energies," saidDr. Sabrina Casanova, Professor from Institute of Nuclear Physics of the Polish Academy of Sciences. "Furthermore, although very high energy protons are strongly suspected to exist in the kpc jets of active galactic nuclei (AGN), the associated hundred TeV emission has never been observed from an extended region from an AGN jet due to strong gamma-ray absorption over the long distances to Earth.”Differential spectrum weighted by E2 for the northern and southern sources in a model with two point sources and for the asymmetric extended source in a model with a single asymmetric extended source. The shaded regions indicate the best-fit spectra and 1σ statistical uncertainties when fitting a single-power-law model to the data from 10 to >200 TeV. The markers correspond to the best-fit values and their 1σ statistical uncertainties obtained when fitting a single-power-law model to data in individual energy bins. The chosen energy range for plotting the spectrum is specified in the Methods.

This study was supported by the collaborative efforts of multiple institutions, with major contributions from the University of Maryland. Distinguished University Professor Jordan Goodman, a member of the collaboration's internal editorial board, played a key role in guiding the publication. Dr. Dezhi Huang, one of the corresponding authors, led significant aspects of the analysis, while Dr. Kristi Engel helped refine the paper. Additional support came from UMD HAWC group members Research Scientist Dr. Andrew Smith, Project Engineer Michael Schneider, Dr. Zhen Wang, Dr. Jason Fan and graduate students Sohyoun Yun-Cárcamo.

More on the finding: https://www.nature.com/articles/d41586-024-03191-x

Sasha Philippov Awarded 2024 Packard Fellowship

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Category: Department News

Published: Tuesday, October 15 2024 09:01

Assistant Professor Sasha Philippov has been named one of 20 members of the 2024 class of Packard Fellows for Science and Engineering. Sponsored by the David and Lucile Packard Foundation, the $875,000, five-year award for early-career researchers provides “flexible funding and the freedom to take risks and explore new frontiers in their fields of study,” according to the foundation.

Philippov is the seventh UMD faculty member—and the second from UMD’s Department of Physics—to receive this competitive award since its launch in 1988.

“I am delighted to see the recognition Sasha is receiving with the awarding of the Packard Fellowship,” said UMD Physics Chair Steven Rolston. “His outstanding work places our excellent plasma theory group at the center of multi-messenger astronomy, with multiple connections to efforts in physics and astronomy both within and beyond the university.”

Each year, the Packard Foundation invites 50 universities to nominate two faculty members for a Packard Fellowship, which is ultimately narrowed down to 20 recipients. Previous UMD awardees include Janice Reutt-Robey (chemistry and biochemistry) in 1990, William Pugh (computer science) in 1991, Victor Yakovenko (physics) in 1995, Victor Muñoz (formerly chemistry and biochemistry) and Sarah Tishkoff (formerly biology) in 2001, and Vedran Lekić (geology) in 2014.Sasha Philippov

Funding from the Packard Fellowship will enable Philippov to develop new computational codes capable of running on the world’s biggest supercomputers. In his research, Philippov uses computational astrophysics to study some of the most mysterious objects in the universe, including neutron stars and black holes. He is particularly interested in discovering how hot, magnetized gas—known as plasma—produces the light we see around exotic objects, such as the ring of light captured in the first image of a black hole in galaxy M87.

His new simulations would shed light on “how plasma shines around black holes,” as well as fast radio bursts—mysterious flashes of radio waves that are extremely bright and short-lived, lasting for mere milliseconds. Some of these extremely bright signals travel for billions of years before reaching Earth, but their exact origin remains an open question in astrophysics.

“Remarkable recent observational discoveries, including fast radio bursts and silhouettes of black holes, make it breathtaking and timely to work in this field,” Philippov said. “The common theoretical challenge to explaining stunning observations of neutron stars and black holes is understanding the behavior of relativistic plasma, the hot, magnetized, collisionless gas of charged particles producing the observed light under extreme conditions that we cannot explore on Earth.”

Simulations can complement images captured by the Event Horizon Telescope and other observatories, enabling researchers like Philippov to explore the physics of the highly energized electrons in plasma. He expressed gratitude to the Packard Foundation for supporting “high-risk, high-reward” research like the development of his new codes that could—if successful—yield much more realistic simulations.

“It could allow us to run three-dimensional kinetic simulations of black hole accretion, which we were not able to run before,” Philippov said.

Graduate students and postdoctoral researchers in Philippov’s lab will also play a hands-on role in developing this code, running and analyzing simulations, and constructing theoretical models of plasma phenomena.

Since joining UMD in 2022, Philippov has received a 2024 Sloan Research Fellowship, which provided him with $75,000 to study the production of neutrinos (weakly interacting particles) around black holes and magnetars (neutron stars with the strongest magnetic fields in the universe). He was also awarded a 2024 Thomas H. Stix Award for Outstanding Early Career Contributions to Plasma Physics Research for his “seminal contributions to the theory and simulation of collisionless astrophysical plasmas, especially compact objects.”

Although Philippov is excited to receive a Packard Fellowship, it is also bittersweet. Rolston and UMD Physics Professor Bill Dorland helped deliver the fellowship news to Philippov over a Zoom call last month, which ended up being the last time he and Dorland spoke.

Dorland, who was a mentor and friend to Philippov, died in September following a 20-year battle with chordoma, a rare cancer. In many ways, Philippov’s research will carry on Dorland’s legacy in computational plasma physics.

“Bill was a remarkable, kind and generous person. His passing left a giant void in all who had the privilege of knowing and working with him,” Philippov said. “He often mentioned that writing code is not just his job but a part of his very being. We will continue forging ahead in his memory.”

Original story by Emily C. Nunez: https://cmns.umd.edu/news-events/news/sasha-philippov-awarded-2024-packard-fellowship