Ultrafast switching snapshots in quantum electronics could lead to faster computing devices

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A team of researchers has devised a new way to capture the ultra-fast atomic motions inside the tiny switches that control the flow of current in electronic circuits. Pictured is Aditya Sood (left) and Aaron Lindenberg (right). Credit: Greg Stewart/SLAC National Accelerator Laboratory

Scientists take raw snapshots of ultrafast switching in a quantum electronic device

They discover a short-lived state that could lead to faster, more energy-efficient computing devices.

The electronic circuits that compute and store information contain millions of tiny switches that control the flow of electric current. A deeper understanding of how these tiny switches work could help researchers push the boundaries of modern computing.

Scientists have now made the first snapshots of the atoms moving inside one of those switches as it turns on and off. Among other things, they discovered a short-lived state inside the switch that could one day be exploited for faster, more energy-efficient computing devices.

The research team from the Department of Energy’s SLAC National Accelerator Laboratory, Stanford University, Hewlett Packard Laboratories, Penn State University and Purdue University describe their work in a paper published in Science today (July 15, 2021).

“This research is a breakthrough in ultra-fast technology and science,” says SLAC scientist and collaborator Xijie Wang. “It is the first time that researchers have used ultrafast electron diffraction, which can detect minute atomic motions in a material by scattering a strong beam of electrons from a sample, to observe an electronic device in action.”

The team used electrical pulses, shown here in blue, to turn the switches on and off on demand multiple times. They timed these electrical pulses to arrive before the electron pulses produced by the SLAC MeV-UED’s ultrafast electron diffraction source, which captured the atomic motions that occur inside these switches as they turned on and off. Credit: Greg Stewart/SLAC National Accelerator Laboratory

session capture

For this experiment, the team’s custom-designed miniature electronic switches made of vanadium dioxide, a model quantum material whose ability to change back and forth between insulating and electrically conducting states near room temperature could be harnessed as a key to future computing. The material also has applications in brain-inspired computing due to its ability to create electronic impulses that mimic nerve impulses fired in the human brain.

The researchers used electrical pulses to toggle these switches back and forth between the insulating state and the conducting state while taking snapshots showing tiny changes in the arrangement of their atoms over a billionth of a second. These snapshots, captured with SLAC’s ultra-fast electron diffraction camera, MeV-UED, were stitched together to create a molecular film of atomic motions.

Lead researcher Aditya Sood discusses new research that could lead to a better understanding of how small switches work within electronic circuits. Credit: Olivier Bonin/SLAC National Accelerator Laboratory

“This ultrafast camera can actually look inside a material and take fast images of how its atoms move in response to a sharp pulse of electrical excitation,” said collaborator Aaron Lindenberg, an investigator at the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC. He is a professor in the Department of Materials Science and Engineering at Stanford University. “At the same time, it also measures how the electronic properties of that material change over time.”

Using this camera, the team discovered a new intermediate state within the material. It is created when a material responds to an electrical pulse by switching from an insulating state to a conductive state.

“The insulating and conducting states have slightly different atomic arrangements, and it usually takes energy to go from one to the other,” said SLAC scientist and collaborator Xiaozhe Shen. “But when the transition occurs through this intermediate state, the switch can occur without any changes in the atomic arrangement.”

Opening a window on atomic motion

Although the intermediate state is present for a few millionths of a second, it stabilizes due to imperfections in the material.

To continue this research, the team is looking at how to engineer these defects in the materials to make this new state more stable and longer-lasting. This would allow them to make devices in which electronic switching could occur without any atomic motion, which would run faster and require less power.

“The results demonstrate the robustness of electrical switching over millions of cycles, and define potential limits for switching speeds for such devices,” said collaborator Shriram Ramanathan, a professor at Purdue University. “The research provides invaluable data on microscopic phenomena that occur during device operations, which is critical for the design of future circuit models.”

The research also offers a new method for synthesizing materials not found in natural conditions, allowing scientists to monitor them on ultrafast time scales and then fine-tune their properties.

“This method gives us a new way to watch devices in action, and opens a window for looking at how atoms move,” said SIMES lead author and researcher Aditya Sood. “It is exciting to bring together ideas from traditionally privileged fields of electrical engineering and ultra-fast science. Our approach will enable the creation of next-generation electronic devices that can meet the world’s growing needs for intelligent, data-intensive computing.”

MeV-UED is a tool for the LCLS User Facility, operated by SLAC on behalf of the Department of Energy’s Office of Science, which funded this research.

SLAC is a vibrant multi-program laboratory that explores how the universe operates at the largest, smallest, and fastest scales and creates powerful tools used by scientists around the world. Through research that includes particle physics, astrophysics, cosmology, materials, chemistry, biosciences, energy, and scientific computing, we help solve real-world problems and advance the interests of the nation.

SLAC is operated by the Stanford University Office of Science of the US Department of Energy. The Office of Science is the largest supporter of basic research in the physical sciences in the United States and works to address some of the most pressing challenges of our time.

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