ITS A QUANTUM UNIVERSE
Chiral phonons create orbital current via their own magnetism
In a new study, an international group of researchers has found that chiral phonons can create orbital current without needing magnetic elements – in part because chiral phonons have their own magnetic moments. Additionally, this effect can be achieved in common crystal materials. The work has potential for the development of less expensive, energy-efficient orbitronic devices for use in a wide array of electronics.
All electronic devices are based upon the charge of an electron, and electrons have three intrinsic properties: spin, charge and orbital angular momentum. While researchers have long explored the use of spin as a more efficient way to create current, the field of orbitronics – based upon using an electron’s orbital angular momentum, rather than its spin, to create a current flow – is still relatively new.
“Traditionally it has been technically challenging to generate orbital current,” says Dali Sun, co-corresponding author on the study. Sun is a professor of physics and member of the Organic and Carbon Electronics Lab (ORaCEL) at North Carolina State University.
“The generation of orbital currents traditionally necessitates the injection of charge current into specific transition metals, and many of these elements are now classified as critical materials – substances that the U.S. government identifies as essential to energy technologies, economic and national security, and the manufacture of key products. But this work shows that we can use a heat gradient to drive out chiral phonons in a quartz (i.e., SiO2) substrate, and the chiral phonons can be converted into orbital current.”
“There are other ways to generate orbital angular momentum, but this method allows for the use of cheaper, more abundant materials,” Sun says.
The new paper builds upon previous work that found spin current can be created and controlled by applying a thermal gradient to non-magnetic hybrid semiconductors that contain chiral phonons.
Chiral phonons are groups of atoms that move in a circular direction when excited by an energy source such as heat. As the phonons move through a material, they propagate that circular motion, or angular momentum, through it.
“In this work we show that we can use that angular momentum from the chiral phonon and convert it to orbital current instead of spin,” says Jun Liu, associate professor of mechanical and aerospace engineering at NC State and member of ORaCEL. “And we can do it in very simple non-magnetic insulators containing chiral phonons, because the rotation of the chiral phonon generates magnetism.” Liu is a co-corresponding author of the research.
The researchers hope that the work can pave the way toward cost-effective orbitronic applications.
“The work also answers fundamental questions around the interplay between structural chirality and orbital currents, which will hopefully help expand the field of orbitronics further,” Sun says.
The work appears in Nature Physics. Jun Zhou, a physicist at Nanjing Normal University, is a co-corresponding author. Yoji Nabei, a postdoc in Sun’s group, is the first author. Sun was supported in part by the Department of Energy under award number DE-SC0020992 and the Air Force Office of Scientific Research, Multidisciplinary University Research Initiatives (MURI) Program under award number FA9550-23-1-0311.
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Note to editors: An abstract follows.
“Orbital Seebeck effect induced by chiral phonons”
DOI: 10.1038/s41567-025-03134-x
Authors: Yoji Nabei, Cong Yang, Hana Jones, Andrew H. Comstock, Ziqi Wang, Benjamin Ewing, John Bingen, Rui Sun, Jun Liu, Dali Sun; North Carolina State University; Hong Sun, Jun Zhou, Nanjing Normal University; Thuc Mai, Rahul Rao, Air Force Research Laboratory; Tian Wang, Xiaosong Li, University of Washington; Rikard Bodin, Binod Pandey, Z.
Valy Vardeny, University of Utah; Yuzan Xiong, Wei Zhang, University of North Carolina at Chapel Hill; Dmitry Smirnov, National High Magnetic Field Laboratory; Axel Hoffmann, University of Illinois at Urbana-Champaign; Ming Hu, University of South Carolina; Binghai Yan, Pennsylvania State University
Published: Jan. 21, 2026 in Nature Physics
Abstract:
The orbital angular momentum of electrons presents exciting opportunities for developing energy efficient, low-power magnetic devices. Typically, the generation of orbital currents is driven by the transfer of orbital angular momentum from 3d transition metal magnets, either through the application of an electric field using the orbital Hall effect or through magnetization dynamics. Chiral phonons are quantized lattice vibrations that carry nonzero angular momentum due to the circular motion of the atoms. An interplay of chiral phonon dynamics and electrons would enable the direct generation of orbital angular momentum, even without the need for magnetic elements. Here, we experimentally demonstrate the generation of orbital currents from chiral phonons activated in the chiral insulator α-quartz under an applied magnetic field and a temperature gradient. We refer to this phenomenon as the orbital Seebeck effect. The generated orbital current is selectively detected in tungsten and titanium films deposited on quartz through the inverse orbital Hall effect. Our findings hold promises for orbitronics based on chiral phonons in nonmagnetic insulators and shed light on the fundamental understanding of chiral phonons and their interaction with electron orbitals.
Journal
Nature Physics
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Orbital Seebeck effect induced by chiral phonons
Article Publication Date
21-Jan-2026
Using magnetic frustration to probe new quantum possibilities
UC Santa Barbara Professor Stephen Wilson’s lab group has established an innovative way to use a phenomenon referred to as frustration to engineer unconventional magnetic states with potential relevance for quantum technologies
image:
A researcher in the lab of Stephen Wilson, whose group studies how magnetic interactions can produce unusual states of matter relevant to quantum research.
view moreCredit: Matt Perko
Research in the lab of UC Santa Barbara materials professor Stephen Wilson is focused on understanding the fundamental physics behind unusual states of matter and developing materials that can host the kinds of properties needed for quantum functionalities.
In a paper published in the journal Nature Materials, Wilson’s lab group reports on an innovative way to use a phenomenon referred to as frustration of long-range order in a material system to engineer unconventional magnetic states with potential relevance for quantum technologies. At the same time, Wilson emphasized, “This is fundamental science aimed at addressing a basic question. It’s meant to probe what physics may be possible for future devices.”
The paper, “Interleaved bond frustration in a triangular lattice antiferromagnet,” explores how several types of frustration can come into play in this realm. One is geometric frustration, which refers to when the magnetic moments of a material are unable to settle in a single ordered arrangement, leaving them in a fluctuating state, or frustrated.
“You can think of magnetism as being derived from tiny bar magnets sitting at the atomic sites in a crystal lattice,” Wilson said. “Those bar magnets are what we call magnetic dipole moments, and they can interact and orient themselves relative to one another in specific ways, depending on the details of a material, to minimize their energy or, said another way, to realize their ground state.” That is the lowest energy state for any system, and any system at absolute zero temperature exists in its ground state.
“If those magnetic moments interact in a way that wants them to point antiparallel to one another, we call that antiferromagnetism,” Wilson added. “If they want to interact in this antiferromagnetic way, and if they are sitting on atoms forming a square network, then each moment can be antiparallel to its neighbors. The moments are ‘happy,’ and that is the ground state. In a different network, however, such as a triangle, not every moment can point opposite to its neighbors. They compete with one another, or are ‘frustrated,’ because they don’t know which way to point to realize the ground state of the system. The moments seek equilibrium but are frustrated from achieving it by the geometry of the space they occupy.”
It turns out that a similar type of frustration can occur with other aspects of the electron, its charge, for instance. In particular, if two neighboring ions try to share an electron across a bond, they can form what is called an atomic dimer. Similar to the case of antiferromagnetism, the formation of these dimers can be frustrated in certain lattice geometries, such as triangular lattices or honeycomb networks. What can then result is a frustrated bond network that is highly susceptible to strain, which can act to relieve the frustration of the bond network. Wilson’s paper examines an extremely rare system of materials where both of these types of frustration were found to coexist.
Wilson describes this advance as “exciting” because it opens a window into functional control over one frustrated system via a perturbation that impacts the other. Over the past six or seven years, researchers have found that they can engineer a frustrated magnetic state by using materials built from triangular networks of lanthanides, a group of elements located at the bottom of the periodic table.
“In principle, this triangular lattice network of properly chosen lanthanide moments can cause a special kind of intrinsically quantum disordered state to arise,” Wilson said. “One thing we tried to do in this project was to functionalize that exotic state by embedding it in a crystal lattice that has an additional degree of bond frustration.”
While there are many different “flavors” of quantum disordered magnetism, in principle, Wilson noted, “Some states can host long-range entanglement of spins, which is of interest in the realm of quantum information. Gaining control over those states via applying a strain in the frustrated bond network would be exciting.”
If you have two highly frustrated layers that are both very sensitive to perturbations, like strain, or, in the magnetic case, a magnetic field, then the question is whether you can couple the two together, because when one is biased and decides to order, it can potentially couple to the second one and alter it.
“It’s a way of imparting in things a functionality or response to other things to which it would otherwise not respond,” Wilson explained. “So, in principle, one can engineer large ferroic responses.You can apply a bit of strain, which induces magnetic order, or you can apply a bit of magnetic field and induce changes to the structure.
“Again, in principle, if you can find a quantum disordered ground state that hosts long-range entanglement, the question then becomes whether you can access that entanglement by, for instance, coupling to another layer, such as bond frustration.”
Wilson also wants to discover whether, through this process, it is possible to realize different types of intertwined order. “Basically, you could have different types of order that get nucleated because of the proximity of these two frustrated lattices,” he said. “That’s the big-picture idea.”
Journal
Nature Materials
Article Title
Interleaved bond frustration in a triangular lattice antiferromagnet
New insight into light–matter thermalization could advance neutral-atom quantum computing
Simulation of Rydberg arrays inside optical cavity shows photons and atoms don’t always rapidly settle at same temperature and destroy quantum information
University at Buffalo
BUFFALO, N.Y. — Light and matter can remain at separate temperatures even while interacting with each other for long periods, according to new research that could help scale up an emerging quantum computing approach in which photons and atoms play a central role.
In a theoretical study published in Physical Review Letters, a University at Buffalo-led team reports that interacting photons and atoms don’t always rapidly reach thermal equilibrium as expected.
Thermal equilibrium is the process by which interacting particles exchange energy before settling at the same temperature, and it typically happens quickly when trapped light repeatedly interacts with matter. Under the right circumstances, however, physicists found that photons and atoms can instead settle at different — and in some cases opposite — temperatures for extended periods.
These so-called prethermal states are fleeting on human timescales, but they can last long enough to matter for neutral-atom quantum computers, which rely on interactions between photons and atoms to store and process information.
“Thermal equilibrium alters quantum properties, effectively erasing the very information those properties represent in a quantum computer,” says the study’s lead author, Jamir Marino, PhD, assistant professor of physics in the UB College of Arts and Sciences. “So delaying thermal equilibrium between photons and atoms — even for a matter of milliseconds — offers a temporal window to preserve and process useful quantum behavior.”
All quantum computers store and process information using qubits — the most basic units of quantum information and analogous to the binary bits used in classical computers. While classical bits can exist either as a 1 or a 0, qubits have the ability to exist in a superposition of two states at once, allowing for infinitely more complex calculations.
Qubits can take many forms. In superconducting quantum computers, a qubit is a collective quantum state involving many electrons flowing together through a superconducting circuit, such as a Josephson junction.
In neutral-atom quantum computers, each qubit is a single atom — often alkali metal atoms excited into so-called Rydberg states.
Their major advantage is simpler hardware. Instead of the complex wiring required for superconducting qubits, atomic qubits can be trapped, controlled and connected via light beams.
However, this has raised concerns that the light will immediately thermally equilibrate with the atoms and disrupt the fragile quantum behavior required for computation.
To date, most neutral-atom quantum computing research has focused on building large arrays of Rydberg atoms. In those systems, brief laser pulses are used to trap and entangle atoms within the arrays. The light is a fleeting control tool and escapes quickly, leaving little opportunity for it to thermalize with the atoms and interfere with their delicate quantum behavior.
But looking to the future, researchers expect that truly powerful neutral-atom quantum computers will require many Rydberg arrays linked together by light. In that architecture, photons would linger and repeatedly interact with atoms, increasing the risk of rapid thermalization.
“This would mean the light essentially destroys the very quantum information it was meant to carry,” says the study’s first author, Aleksandr Mikheev, PhD, a postdoc who worked in Marino’s lab during Marino’s time at Johannes Gutenberg University Mainz in Germany, and is now a postdoc at the University of Konstanz.
To explore whether that outcome is inevitable, Marino and his collaborators used theoretical models to simulate the quantum dynamics of photons and atoms. In their calculations, a neutral-atom array is placed inside an optical cavity — a pair of mirrors that trap light and force it to repeatedly interact with the atoms.
As the atoms interact and decay, they emit photons that become confined within the cavity. The simulations show that, after an initial burst of energy exchange, the atoms and photons can sometimes stop efficiently sharing energy, allowing them to maintain separate temperatures. In some cases, the atoms even settle at negative temperatures while the photons settle at positive temperatures.
Eventually, as photons gradually leak out of the cavity, this prethermal state breaks down and the atoms and photons reach thermal equilibrium.
“The modeling demonstrates it may indeed be feasible to use light to link larger neutral-atom arrays without washing away the quantum information," says co-author Hossein Hosseinabadi, PhD, a former graduate student in Marino’s lab who will soon start as an independent distinguished postdoctoral scholar at the Max Planck Institute for the Physics of Complex Systems in Germany.
“Additionally, the same light emitted by the atoms could eventually serve as the very light that connects the arrays in a full-scale neutral-atom quantum computer,” Marino adds. “This is crucial because you wouldn’t have to continuously intervene. Once the system is set up, it can naturally remain out of thermal equilibrium for a long time.”
The study was supported by the German Research Foundation and the European Union.
Journal
Physical Review Letters
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
Prethermalization of Light and Matter in Cavity-Coupled Rydberg Arrays
