Researchers Spy Finish Line in Race for Majorana Qubits

Our computer age is built on a foundation of semiconductors. As researchers and engineers look toward a new generation of computers that harness quantum physics, they are exploring various foundations for the burgeoning technology.

Almost every computer on earth, from a pocket calculator to the biggest supercomputer, is built out of transistors made from a semiconductor (generally silicon). Transistors store and manipulate data as “bits” that can be in one of two possible states—the ones and zeros of binary code. Many other things, from vacuum tubes to rows of dominos, can theoretically serve as bits, but transistors have become the dominant platform since they are convenient, compact and reliable.Researchers have been working to demonstrate that devices that combine semiconductors and superconductors, like this one made by Microsoft, have the potential to be the basis for a new type of qubit that can open the way to scalable quantum computers. (Credit: John Brecher, Microsoft)Researchers have been working to demonstrate that devices that combine semiconductors and superconductors, like this one made by Microsoft, have the potential to be the basis for a new type of qubit that can open the way to scalable quantum computers. (Credit: John Brecher, Microsoft)

Quantum computers promise unprecedented computational capabilities by replacing bits with quantum bits—qubits. Like normal bits, qubits have two states used to represent information. But they have additional power since they can simultaneously explore both possibilities during calculations through the phenomenon of quantum superpositions. The information stored in superpositions, along with other quantum effects like entanglement, enables new types of calculations that can solve certain problems much faster than normal computers.

All quantum objects sometimes enter a superposition, but that doesn’t mean they all make practical qubits. A qubit needs certain traits to be useful. First, it must have states that are easy to identify and manipulate. Then, the superposition of those states must last long enough to perform calculations. Physicists typically think about the stability of a quantum state in terms of its coherence, and how long a quantum state can remain coherent is a critical metric for judging its suitability as a qubit.

So far, no platform has emerged as the default for making qubits the way silicon-based transistors did for bits. As researchers and companies build the early generations of quantum computers, many options are being used, including superconducting circuits, trapped ions, and even particles of light. 

Some researchers, including Professor and JQI Fellow Sankar Das Sarma and Professor and JQI Co-Director Jay Sau, have been exploring the possibility that semiconductors might prove to be a good foundation for quantum computing as well. In 2010, Das Sarma, Sau and JQI postdoctoral researcher Roman Lutchyn proposed that a strong magnetic field and a nanowire device made from the combination of a semiconductor with a superconductor could be used to create a particle-like quantum object—a quasiparticle—called a Majorana. Nanowires hosting Majorana quasiparticles should be able to serve as qubits and come with an intrinsic reliability enforced by the laws of physics. However, no one has definitively demonstrated even a single Majorana qubit while some quantum computers built using other platforms already contain more than 1,100 qubits.

Fifteen years after Das Sarma and Sau opened the door to experiments searching for Majorana quasiparticles, they are optimistic that the proof of Majorana-based qubits is now on the horizon. In an article published on June 18 in the journal Physical Review B, Das Sarma and Sau used theoretical simulations to analyze cutting-edge experiments hunting for Majoranas and proposed an experiment to finally demonstrate Majorana qubits.

“I think that we're at the point where we can at least see where we are in terms of qubits,” says Sau, who is also professor of physics at UMD. “It might still be a long road. It's not going to be easy, but at least we can see the goal now.”

The Tortoise and the Hare?

Since quantum computers are already being built from other types of qubits, Majoranas are behind in the race. But they have some advantages that proponents, including Das Sarma and Sau, hope will let them make up for lost time and become the preferred foundation for quantum computers. 

One advantage Majorana qubits potentially have is the extensive infrastructure that already exists around semiconductors. The established knowledge and fabrication techniques from the computer industry might allow large quantum computers with many interacting qubits to be built using Majoranas (which is a goal all the competition is currently working to achieve). If Majorana-based quantum computers prove easier to scale up than their competition that might allow them to make up for lost time and be a competitive technology.

But the thing that really sets Majorana qubits apart from the competition is that their properties should protect from errors that would derail calculations. In general, the superpositions of quantum states are easily disrupted by outside influence, which makes them useless for quantum computing. However, Majorana quasiparticles are a type of topological state, which means they have traits that the rules of physics say can only be altered by a dramatic change to the whole system and are impervious to minor influences. This “topological protection” might be harnessed to make Majorana qubits more stable than their competition.

Pursuing these potential advantages, Microsoft has been trying to develop a Majorana-based quantum computer, and in February of this year, Microsoft researchers shared new results in the journal Nature where they described their observations of the two distinct quantum states of their device designed to create Majorana quasiparticles. At the same time, they also announced additional claims of having Majorana-based qubits, which has sparked controversy. In July, Microsoft researchers posted an article on the arXiv preprint server that elaborates on their claims of creating a Majorana qubit using their device. They observe results consistent with creating a short-lived Majorana qubit, but they acknowledge in the article that the type of experiment they performed cannot prove that Majoranas are the explanation.

The experiment described in the Nature article opened new measurement opportunities by introducing an additional component, called a quantum dot, that connects to the nanowire. The quantum dot serves as a bridge that quantum particles can travel across but never stop on—a process called quantum tunneling. This development allowed them, for the first time, to hunt for Majorana quasiparticles that might be useful in making qubits. Their experiment demonstrated that they could observe two distinct states where they expect Majoranas to reside in the device, which hints at the necessary ingredients of a qubit, but didn’t prove that Majorana quasiparticles were successfully created. 

In their new article, Das Sarma and Sau analyzed Microsoft’s published data and found that the measurements described in the paper could not prove if they had an ideal Majorana quasiparticle with its guaranteed stability or if the presence of impurities in the device resulted in imperfect Majoranas that produce only some of the signs of a topological state. The imperfect Majoranas could still offer some improved stability but don’t carry the ironclad guarantee of topological protection. Even if the device didn’t hold ideal Majoranas, it still might be able to function as a qubit with useful properties. 

“We were excited that they're now actually getting into a qubit regime,” Sau says. “One of the things we wanted to do in our analysis is be agnostic to whether it's Majoranas or not. You have this device. Let's just ask ‘What kind of a qubit coherence would one get from a qubit made out of this device?’ And that's really the important question in this field.”

The Road Forward

To investigate the coherence of potential Majorana qubits, Das Sarma and Sau created a basic theoretical model of Microsoft’s device and used it to simulate nanowires that harbored various amounts of disorder—disorder that might disrupt the formation of Majoranas. Their simulations indicate that Microsoft’s device is likely plagued by a level of disorder that would prevent it from having a competitively long coherence time. However, the simulations also indicate that if enough disorder is eliminated then the device could see a dramatic jump in how long it maintains its coherence. A clear measurement of coherence is likely to be the smoking gun that leads many researchers to accept that a Majorana qubit has been fabricated. 

As researchers attempt to demonstrate the coherence of a Majorana qubit, there are two ways they can respond to the presence of disorder in their devices: eliminate it or work around it. 

In the article, Das Sarma and Sau used their simulation to describe experiments that require devices with fewer defects and that could clearly demonstrate the coherence of the Majorana quasiparticle. The experiment would require researchers to use two nanowires that can each contain a Majorana and that are connected via quantum tunneling. The tunneling would allow researchers to create a superposition where the Majorana is in a mixture of the two possible locations. When there is a superposition between the two states, the researchers can make the probability of the Majorana being in each spot oscillate so it goes from more to less likely in each location. This back and forth is predicted to provide a clear sign of how long the quantum state remains coherent but requires work in improving the nanowire quality to achieve the results.

The pair also discussed an alternative approach using simpler experiments that are similar to the one published in Nature. This approach continues to focus on measuring if a particle exists in a particular wire. The simulations Das Sarma and Sau performed suggest that if the measurement techniques were improved sufficiently the technique could give an estimate of the coherence, but it will be trickier to pick out the signature from the noise than using their proposed experiment. And the effort improving the measurement would likely not translate into making the nanowire into a Majorana qubit with a competitive coherence time.

“We can now start to see the finish line,” Sau says. “The experiments don't tell us quite where we are; that's where simulations are useful. It’s telling us that disorder is one of the key bottlenecks for this. There are various options of which path you can take, and the harder and more rewarding path is to just work on improving disorder.” 

Original story by Bailey Bedford: jqi.umd.edu/news/researchers-spy-finish-line-race-majorana-qubits

 

Superconductivity’s Halo: Physicists Map Rare High-field Phase

 A puzzling form of superconductivity that arises only under strong magnetic fields has been mapped and explained by a research team of UMD, NIST and Rice University including  professor of physics and astronomy at Rice University. Their findings,  published in Science July 31, detail how uranium ditelluride (UTe2) develops a superconducting halo under strong magnetic fields. 

Traditionally, scientists have regarded magnetic fields as detrimental to superconductors. Even moderate magnetic fields typically weaken superconductivity, while stronger ones can destroy it beyond a known critical threshold. However, UTe2 challenged these expectations when, in 2019, it was discovered to maintain superconductivity in critical fields hundreds of times stronger than those found in conventional materials. Image by Sylvia Klare Lewin, Nicholas P Butch/ NIST & UMDImage by Sylvia Klare Lewin, Nicholas P Butch/ NIST & UMD

“When I first saw the experimental data, I was stunned,” said Andriy Nevidomskyy, a member of the Rice Advanced Materials Institute and the Rice Center for Quantum Materials. “The superconductivity was first suppressed by the magnetic field as expected but then reemerged in higher fields and only for what appeared to be a narrow field direction. There was no immediate explanation for this puzzling behavior." 

Superconducting resurrection in high fields

This phenomenon, initially identified by researchers at the University of Maryland Quantum Materials Center and the National Institute of Standards and Technology (NIST), has captivated physicists worldwide. In UTe2, superconductivity vanished below 10 Tesla, a field strength that is already immense by conventional standards, but surprisingly reemerged at field strengths exceeding 40 Tesla. 

This unexpected revival has been dubbed the Lazarus phase. Researchers determined that this phase critically depends on the angle of the applied magnetic field in relation to the crystal structure. 

In collaboration with experimental colleagues at UMD and NIST, Nevidomskyy decided to map out the angular dependence of this high-field superconducting state. Their precise measurements revealed that the phase formed a toroidal, or doughnutlike, halo surrounding a specific crystalline axis. 

“Our measurements revealed a three-dimensional superconducting halo that wraps around the hard b-axis of the crystal,” said Sylvia Lewin of NIST, a co-lead author on the study. “This was a surprising and beautiful result.”

Building theory to fit halo

To explain these findings, Nevidomskyy developed a theoretical model that accounted for the data without relying heavily on debated microscopic mechanisms. His approach employed an effective phenomenological framework with minimal assumptions about the underlying pairing forces that bind electrons into Cooper pairs. 

The model successfully reproduced the nonmonotonic angular dependence observed in experiments, offering insights into how the orientation of the magnetic field influences superconductivity in UTe2. 

Deeper understanding of interplay

The research team found that the theory, fitted with a few key parameters, aligned remarkably well with the experimental features, particularly the halo’s angular profile. A key insight from the model is that Cooper pairs carry intrinsic angular momentum like a spinning top does in classical physics. The magnetic field interacts with this momentum, creating a directional dependence that matches the observed halo pattern. 

This work lays the foundation for a deeper understanding of the interplay between magnetism and superconductivity in materials with strong crystal anisotropy like UTe2. 

“One of the experimental observations is the sudden increase in the sample magnetization, what we call a metamagnetic transition,” said NIST’s Peter Czajka, co-lead author on the study. “The high-field superconductivity only appears once the field magnitude has reached this value, itself highly angle-dependent.” 

The exact origin of this metamagnetic transition and its effect on superconductivity is hotly debated by scientists, and Nevidomskyy said he hopes this theory would help elucidate it. 

“While the nature of the pairing glue in this material remains to be understood, knowing that the Cooper pairs carry a magnetic moment is a key outcome of this study and should help guide future investigations,” he said.

Co-authors of this study include Corey Frank and Nicholas Butch from NIST; Hyeok Yoon, Yun Suk Eo, Johnpierre Paglione and Gicela Saucedo Salas from UMD; and G. Timothy Noe and John Singleton from the Los Alamos National Laboratory. This research was supported by the U.S. Department of Energy and the National Science Foundation.

 Original article: https://news.rice.edu/news/2025/superconductivitys-halo-rice-theoretical-physicist-helps-map-rare-high-field-phase

New Protocol Demonstrates and Verifies Quantum Speedups in a Jiffy

While breakthrough results over the past few years have garnered headlines proclaiming the dawn of quantum supremacy, they have also masked a nagging problem that researchers have been staring at for decades: Demonstrating the advantages of a quantum computer is only half the battle; verifying that it has produced the right answer is just as important.

Now, researchers at JQI and the University of Maryland (UMD) have discovered a new way to quickly check the work of a quantum computer. They proposed a novel method to both demonstrate a quantum device’s problem-solving power and verify that it didn’t make a mistake. They described their protocol in an article published March 5, 2025, in the journal PRX Quantum.

“Perhaps the main reason most of us are so excited about studying large interacting quantum systems in general and quantum computers in particular is that these systems cannot be simulated classically,” says JQI Fellow Alexey Gorshkov, who is also a Fellow of the Joint Center for Quantum Information and Computer Science (QuICS), a senior investigator at the National Science Foundation Quantum Leap Challenge Institute for Robust Quantum Simulation (RQS) and a physicist at the National Institute of Standards and Technology. “Coming up with ways to check that these systems are behaving correctly without being able to simulate them is a fun and challenging problem.”Researchers have proposed a new way to both demonstrate and verify that quantum devices offer real speedups over ordinary computers. Their protocol might be suitable for near-term devices made from trapped ions or superconducting circuits, like the one shown above. (Credit: Kollár Lab/JQI)Researchers have proposed a new way to both demonstrate and verify that quantum devices offer real speedups over ordinary computers. Their protocol might be suitable for near-term devices made from trapped ions or superconducting circuits, like the one shown above. (Credit: Kollár Lab/JQI)

In December 2024, Google announced its newest quantum chip, called Willow, accompanied by a claim that it had performed a calculation in five minutes that would have taken the fastest supercomputers 10 septillion years. That disparity suggested a strong demonstration of a quantum advantage and hinted at blazing fast proof that quantum computers offer exponential speedups over devices lacking that quantum je ne sais quoi.

But the problem that the Willow chip solved—a benchmark called random circuit sampling that involves running a random quantum computation and generating many samples of the output—is known to be hard to verify without a quantum computer. (Hardness in this context means that it would take a long time to compute the verification.) The Google team verified the solutions produced by their chip for small problems (problems with just a handful of qubits) using an ordinary computer, but they couldn’t come close to verifying the results of the 106-qubit problem that generated the headlines.

Fortunately, researchers have also discovered easy-to-verify problems that can nevertheless demonstrate quantum speedups. Such problems are hard for a classical (i.e., non-quantum) computer but easy for a quantum computer, which makes them prime candidates for showing off quantum prowess. Crucially, these problems also allow a classical computer to quickly check the work of the quantum device.

Even so, not every problem with these features is practical for the quantum computers that exist right now or that will exist in the near future. In their new paper, the authors combined two key earlier results to construct a novel protocol that is more suitable for demonstrating and verifying the power of soon-to-be-built quantum devices.

One of the earlier results identified a suitable problem with the right balance of being difficult to solve but easy to verify. Solving that problem amounts to preparing the lowest energy state of a simple quantum system, measuring it, and reporting the outcomes. The second earlier result described a generic method for verifying a quantum computation after it has been performed—a departure from standard methods that require a live back-and-forth while the computation is running. Together, the two results combined to significantly cut down the number of repetitions needed for verification, from an amount that grows as the square of the number of qubits down to a constant amount that doesn’t grow at all.

“We combined them together and, somewhat unexpectedly, this also reduced the sample complexity to a really low level,” says Zhenning Liu, the lead author of the new paper and a graduate student at QuICS.

The resulting protocol can run on any sufficiently powerful quantum computer, but its most natural implementation is on a particular kind of device called an analog quantum simulator.

Generally, quantum computers, which process information held by qubits, fall into two categories. There are digital quantum computers, like Google’s Willow chip, that run sequences of quantum instructions and manipulate qubits with discrete operations, similar to what ordinary digital computers do to bits. And then there are analog quantum computers that initialize qubits and let them evolve continuously. An analog quantum simulator is a special-purpose analog quantum computer. 

Liu and his colleagues—inspired by the kinds of quantum devices that are already available and driven by one of the primary research goals of RQS—focused on demonstrating and verifying quantum advantage on a subset of analog quantum simulators.

In particular, their protocol is tailored to analog quantum simulators capable of hosting simple nearest-neighbor interactions between qubits and making quantum measurements of individual qubits. These capabilities are standard fare for many kinds of experimental qubits built out of trapped ions or superconductors, but the researchers required one more ingredient that might be harder to engineer: an interaction between one special qubit—called the clock qubit—and all of the other qubits in the device.

“Quantum simulators will only be useful if we can be confident about their results,” says QuICS Fellow Andrew Childs, who is also the director of RQS and a professor of computer science at UMD. “We wanted to understand how to do this with the kind of simulators that can be built today. It's a hard problem that has been a lot of fun to work on.”

Assuming an analog quantum simulator with all these capabilities could be built, the researchers described a protocol to efficiently verify its operation by following a classic two-party tale in computer science. One party, the prover, wants to convince the world that their quantum device is the real deal. A second party, the verifier, is a diehard skeptic without a quantum computer who wants to challenge the prover and ascertain whether they are telling the truth.

In the future, a practical example of this kind of interaction might be a customer accessing a quantum computer in a data center that can only be reached via the cloud. In that setting, customers might want a way to check that they are really using a quantum device and aren’t being scammed. Alternatively, the authors say the protocol could be useful to scientists who want to verify that they’ve really built a quantum simulator in their lab. In that case, the device would be under the control of a researcher doing double duty as both verifier and prover, and they could ultimately prove to themselves and their colleagues that they’ve got a working quantum computer.

In either case, the protocol goes something like this. First, the verifier describes a specific instance of the problem and an initial state. Then, they ask the prover to use that description to prepare a fixed number of final states. The correct final state is unknown to the verifier, but it is closely related to the original problem of finding the lowest energy state of a simple quantum system. The verifier also chooses how certain they want to be about whether the prover has a truly quantum device, and they can guarantee a desired level of certainty by adjusting the number of final states that they ask the prover to prepare.

For each requested state, the verifier flips a coin. If it comes up heads, the verifier’s goal is to collect a valid solution to the problem, and they ask the prover to measure all the qubits and report the results. Based on the measurement of the special clock qubit, the verifier either throws the results away or stores them for later. Measuring the clock qubit essentially lets the verifier weed out invalid results. The results that get stored are potentially valid solutions, which the verifier will publish at the end of the protocol if the prover passes the rest of the verification.

If the coin comes up tails, the verifier’s goal is to test that the prover is running the simulation correctly. To do this, the verifier flips a second coin. If that coin comes up heads, the verifier asks the prover to make measurements that check whether the input state is correct. If the coin comes up tails, the verifier asks the prover to make measurements that reveal whether the prover performed the correct continuous evolution. 

The verifier then uses all the results stemming from that second coin flip to compute two numbers. In the paper, the team calculated thresholds for each number that separate fraudulent provers from those with real quantum-powered devices. If the two numbers clear those thresholds, the verifier can publish the stored answers, confident in the fact that the prover is telling the truth about their quantum machine.

There is a caveat to the protocol that limits its future use by a suspicious customer of a quantum computing cloud provider. The protocol assumes that the prover is honest about which measurements they make—it assumes that they aren’t trying to pull one over on the verifier and that they make the measurements that the verifier requests. The authors describe a second version of the protocol that parallels the first and relaxes this element of trust. In that version, the prover doesn't measure the final states but instead transmits them directly to the verifier as quantum states—a potentially challenging technical feat. With the states under their control, the verifier can flip the coins and make the measurements all on their own. This is why the protocol can still be useful for researchers trying to put their own device through its paces and demonstrate near-term quantum speedups in their labs.

Ultimately the team would love to relax the requirement that the prover is trusted to make the right measurements. But progress toward this more desirable feature has been tough to find, especially in the realm of quantum simulation.

“That's a really hard problem,” Liu says. “This is very, very nontrivial work, and, as far as I know, all work that has this feature relies on some serious cryptography. This is clearly not easy to do in quantum simulations.”

Original story by Chris Cesare: https://jqi.umd.edu/news/new-protocol-demonstrates-and-verifies-quantum-speedups-jiffy

In addition to Gorshkov, Zhenning Liu, and Childs the paper had several other authors: Dhruv Devulapalli, a graduate student in physics at UMD; Dominik Hangleiter, a former QuICS Hartree Postdoctoral Fellow who is now a Quantum Postdoctoral Fellow at the Simons Institute for the Theory of Computing at the University of California, Berkeley; Yi-Kai Liu, who is a QuICS Fellow and a senior investigator at RQS; and JQI Fellow Alicia Kollár, who is also a senior investigator at RQS.

 

Work on 2D Magnets Featured in Nature Physics Journal

University of Maryland Professor Cheng Gong (ECE), along with his postdocs Dr. Ti Xie, Dr. Jierui Liang and collaborators in Georgetown University (Professor Kai Liu group), UC Berkeley (Professor Ziqiang Qiu), University of Tennessee, Knoxville (Professor David Mandrus group) and UMD Physics (Professor Victor M. Yakovenko), have made a new discovery on controlling the magnetic domain behaviors in two-dimensional (2D) quantum magnet, with a paper published in 2025 July issue of Nature Physics. Titled “High-efficiency optical training of itinerant two-dimensional magnets”, the work developed a new approach to using ultralow-power optical incidence to control the size and spin orientations of the formed magnetic domains. Prof. Victor Yakovenko, Dr. Ti Xie, and Prof. Cheng Gong. Photo credit: Shanchuan Liang and Dhanu ChettriProf. Victor Yakovenko, Dr. Ti Xie, and Prof. Cheng Gong. Photo credit: Shanchuan Liang and Dhanu Chettri

Generally, nature likes to evolve towards lower energy for the sake of stability. For example, water flows from mountains down to valleys. However, we often see that water puddles are trapped on the hillside, instead of sliding all the way down to the valleys due to the physical barriers that prevent the stream’s continuous drop. In a nutshell, even though a physical system tends to develop itself into the lowest energy state (i.e., ground state), it can be trapped at many local energy minima (i.e., metastable states). Controlling the kinetic process can guide a system into numerous previously unexplored metastable configurations.

In the recent Nature Physics article, Gong’s team sheds light on 2D magnets to control their magnetic phase transition kinetics, easily weaving a plethora of distinct metastable spin textures onto the atomically thin magnetic flatlands. “The stereotype notion is that a material’s properties are set once its atomic composition and structure are set,” Gong explained, “this is not always the case. The electron spins can arrange themselves in distinct spatial patterns on top of an atomic lattice. Each spin pattern corresponds to the series of associated physical properties magnetically, electrically, optically, and even thermally. This means that one can create numerous quantum materials by magnetic dressing, without the need of changing the material’s compositional skeleton at all."

“The idea is out of the box, yet easily understandable.” Gong further introduced their design, “we implant optically excited spin polarized electrons as tiny magnetic seeds throughout the 2D magnet, by shining a circularly polarized light during the cooling process. When a large-size 2D magnet flake is cooled down across its magnetic phase transition temperature, the electron spins will be aligned to form many domains of either up or down orientation, usually with 50% by 50% populations. However, with the help of magnetic seeds, all the spins nearby can be aligned towards the same orientation following the seeds, resulting in enlarged domain size or even single magnetic domain across the whole material. The orientation of the single magnetic domain can be dictated by the handedness of the circular light”. Their research article includes details on using optical helicity and ultralow optical power density (approximately 20 microwatts per micrometer square) to control the size and orientation of the formed domains. “Well, clearly, this is a non-chemical, reconfigurable method to create artificial quantum materials with arbitrarily designed spin textures, with hopefully on-demand properties,” Gong added.

“The work of the Gong group developed the innovative, non-synthetic method to create artificial quantum magnets by magnetically dressing 2D materials with designed spin textures, potentially reshaping the landscape of quantum materials. This advance is a valuable contribution to the ongoing Quantum Information Science initiatives in the U.S.,” remarked UMD Professor and Quantum Technology Center (QTC) Founding Director Ronald Walsworth.

The novel strategy of optical training of 2D magnets may lead to energy-efficient technology innovations at large. Don Woodbury, Director of Innovation and Partnerships, Clark School of Engineering at University of Maryland, said “The technology developed in the Gong group represent state-of-the-art innovations in 2D spintronic and opto-spintronic devices in ultracompact footprint, with wide implications in integrated nanoelectronics, nanophotonics and magnetoelectric sensors that could find use in both defense and civilian domains.”

Professor Sennur Ulukus, Chair of Department of Electrical and Computer Engineering, University of Maryland, summarized, “The original research led by Professor Gong lies at the intersection of quantum materials and spintronic devices, resonating with the U.S. Quantum Information Science legislation and CHIPS and Science Act. Gong’s sustained high-profile research achievements featured by prestigious journals are successful testimonies of UMD’s quantum and microelectronic workforce.” 

The research work published in this Nature Physics article is primarily supported by the grants from the Air Force Office of Scientific Research under award no. FA9550-22-1-0349 and National Science Foundation under award nos. DMR-2340773, FuSe-2425599, DMR-2326944, ECCS-2429994, DMR-2005108 and ECCS-2429995.

 Original story: https://ece.umd.edu/news/story/discovery-led-by-professor-cheng-gong-featured-in-nature-physics-journal

NASA’s Parker Solar Probe Reveals a Key Particle Accelerator Near the Sun

Flying closer to the sun than any spacecraft before it, NASA’s Parker Solar Probe uncovered a new source of energetic particles near Earth’s star, according to a new study co-authored by University of Maryland researchers. 

Published in The Astrophysical Journal Letters on May 29, 2025, the paper suggests that a process linked to magnetic reconnection—the explosive merging and realigning of magnetic field lines—could propel particles near the sun to extremely high energy. The data sheds light on processes that were impossible to observe in such a harsh environment before Parker launched in 2018, according to study co-author and University of Maryland researcher James Drake.As NASA’s Parker Solar Probe (trajectory shown in green) crossed the heliospheric current sheet, it encountered merging magnetic islands (areas shown in blue) and protons accelerated toward the sun, establishing reconnection as their source. Image credit: JHUAPL. As NASA’s Parker Solar Probe (trajectory shown in green) crossed the heliospheric current sheet, it encountered merging magnetic islands (areas shown in blue) and protons accelerated toward the sun, establishing reconnection as their source. Image credit: JHUAPL.

“We now, for the first time, have a spacecraft that is going through an enormous magnetic reconnection event and can directly measure everything, and that's simply never happened before,” said Drake, a Distinguished University Professor in UMD’s Department of Physics and Institute for Physical Science and Technology (IPST).

Study co-author and Parker Solar Probe project scientist Nour Rawafi, who is also a heliophysicist at the Johns Hopkins Applied Physics Laboratory, added that Parker is enabling researchers to see unexplored regions of the sun.

“Parker Solar Probe was designed to solve some of the sun’s biggest mysteries and uncover hidden processes we couldn’t detect from afar,” Rawafi said, “and this discovery hits right at the heart of that mission.”

Drake and Marc Swisdak, a research scientist in UMD’s Institute for Research in Electronics & Applied Physics (IREAP), were tapped to help analyze Parker Solar Probe data because of their expertise in magnetic reconnection. The two UMD researchers previously identified the mechanism driving the sun’s fast wind and have now interpreted data from a massive magnetic reconnection event measuring four times the size of the sun, according to Drake. 

This data was collected during Parker’s fourteenth swing by the sun in December 2022, when the probe crossed the heliospheric current sheet (HCS), an undulating structure invisible to human eyes. Like a twirling flamenco skirt, the sheet separates regions where the sun’s magnetic field points in opposite directions.

Ripples in the current sheet cause the magnetic fields to merge and rearrange through magnetic reconnection. This releases energy explosively, catapulting a jet of charged particles away as an “exhaust” of energized particles. That same phenomenon affects the Earth-space environment, creating auroral shows at Earth’s poles and geomagnetic storms capable of disrupting satellite communications and causing blackouts.

For nearly four hours in late 2022, Parker passed through the exhaust generated by these reconnection events in the HCS. There, it encountered protons being accelerated, unexpectedly, toward the sun—quashing any doubt over where this energy came from.

“These findings indicate that magnetic reconnection in the HCS is an important source of energetic particles in the near-sun solar wind,” said the study’s lead author Mihir Desai, a solar physicist at the Southwest Research Institute.

Some of the protons that Parker measured had nearly 1,000 times more energy than what could have been transferred by the available magnetic energy. To help pinpoint the mechanism for this surprising energy gain, Drake, Swisdak and IREAP Faculty Assistant Zhiyu Yin (Ph.D. ’24, physics) ran a simulation using a computational model that had been in development for several years at UMD. This study marks the first time their model has been used to directly simulate an observable event. 

“From that simulation, we calculated the spectrum of energetic particles and then compared that with what was seen in the Parker data, and we were able to get a pretty good match,” Drake explained.

Their simulations also confirmed earlier studies, including a 2006 paper co-authored by Drake and Swisdak, which identified “magnetic islands”—loops of the magnetic field that pinch off like water droplets when field lines merge—as the source of this extra energy boost. Particles trapped within the loops get an additional kick as the islands merge and shed their own energy, accelerating some particles nearly to the speed of light. 

“The mechanisms we saw in this study seem consistent with what we have been working on for nearly 20 years, but what surprised me is that these particles gain so much energy,” Drake said. “One important thing about this set of observations is that it demonstrates that magnetic energy can get focused into a small number of extremely energetic particles.”

In addition to demystifying energy exchanges near the sun, learning more about magnetic reconnection—and any resulting solar flares—can help astronauts stay safe.

“These energetic particles are a threat to astronauts if they're out in space,” Drake said. “In a solar flare, you can get some dangerous particles that reach extremely high energies.”

As researchers continue to explore these problems through Parker Solar Probe data, Drake hopes that future observations will chart the spectra of electrons in magnetic reconnection events—a missing piece of the puzzle.

“Our simulations show that the electrons have a lot of energy, but the data we published in this paper don't show the electron spectrum at all,” Drake explained. “One of the important questions is, ‘What carries more energy: the protons or the electrons undergoing acceleration?’ That's one important aspect that we would really like to follow up on.”

###

This article was adapted from text provided by the Johns Hopkins Applied Physics Lab and the Southwest Research Institute. 

Their paper, “Magnetic Reconnection–driven Energization of Protons up to ∼400 keV at the Near-Sun Heliospheric Current Sheet,” was published May 29, 2025, in The Astrophysical Journal Letters.

This research was supported by NASA's Parker Solar Probe Mission (Contract No. NNN06AA01C), NASA grants (Nos. 80NSSC20K1815, 80NSSC18K1446, 80NSSC21K0112, 80NSSC20K1255, 80NSSC21K0971 and 80NSSC21K1765), the U.S. National Science Foundation (Grant No. PHY2109083) and Princeton University. This article does not necessarily reflect the views of these organizations.