Jigang Wang gave a brief overview of a novel kind of microscope that could aid in the understanding and eventual development of the underlying workings of quantum computing.
Professor Wang of physics and astronomy at Iowa State University, who is also connected to the Ames National Laboratory of the U.S. Department of Energy, explained how the instrument operates at extremely small scales of space, time, and energy, such as billionths of a meter, quadrillionths of a second, and trillions of electromagnetic waves per second.
The control systems, laser source, maze of mirrors that creates an optical path for light pulsing at trillions of cycles per second, superconducting magnet surrounding the sample space, custom-built atomic force microscope, and bright yellow cryostat that lowers sample temperatures to the equivalent of liquid helium, or about -450 degrees Fahrenheit, were all pointed out and described by Wang.
Cryogenic Magneto-Terahertz Scanning Near-Field Optical Microscope is how Wang refers to the device. (That is short for cm-SNOM.) It is situated northwest of Iowa State University’s campus in the Sensitive Instrument Facility of the Ames National Laboratory.
The instrument’s construction took five years and cost $2 million, including $1.3 million from the Los Angeles-based W.M. Keck Foundation and $700,000 from Iowa State University and Ames National Laboratory. It has been participating in trials and accumulating data for less than a year.
Wang stated of the extreme-scale nanoscope, “No one has it.” It’s the first of its kind in the world.
It can function at temperatures below those of liquid helium and in intense Tesla magnetic fields, with a focus of around 20 nanometers, or 20 billionths of a meter. That’s tiny enough to detect the superconducting characteristics of substances in these harsh conditions.
Superconductors are substances that, often at very low temperatures, conduct electricity—or electrons—without resistance or heat. There are several uses for superconducting materials, notably in the medical field for MRI scans and as magnetic racetracks for charged subatomic particles whizzing around accelerators like the Large Hadron Collider.
For quantum computing, the new generation of computing power based on the physics and energy at the atomic and subatomic scales of the quantum world, superconducting materials are now being investigated. Qubits, or superconducting quantum bits, are the brains of the novel technology. Using powerful light-wave pulses is one method of managing supercurrent flows in qubits.
Wang stated that a key area of focus for quantum computing is superconducting technology. We must thus comprehend and characterize superconductivity, as well as how light affects it.
That task is being carried out by C-SNOM equipment.Wang and a group of researchers are making the first ensemble average measurements of supercurrent flow in iron-based superconductors at terahertz (trillions of waves per second) energy scales and the first cm-SNOM action to detect terahertz supercurrent tunneling in a high-temperature, copper-based cuprate superconductor, as described in a study that was just published in the journal Nature Physics and a preprint paper that was posted to the arXiv.
According to Wang, the response of superconductivity to light wave pulses can now be measured in a new way. During terahertz cycles, we are leveraging our technologies to provide a fresh perspective on this quantum state at nanometer-length scales.
We can create sophisticated tomography techniques for observing quantum entangled states in superconductors controlled by light by analyzing the new experimental datasets, according to Ilias Perakis, professor and chair of physics at the University of Alabama at Birmingham and a collaborator on this project.
The interactions that can cause these supercurrents, according to the researchers’ publication, “are currently poorly understood, in part due to the paucity of data.”
Wang is planning the next steps to use the cm-SNOM to simultaneously measure supercurrent existence at nanometer and terahertz scales now that such measurements are being made at the ensemble level. His team is looking for ways to make the new device even more accurate with assistance from the Superconducting Quantum Materials and Systems Center run by the Illinois-based Fermi National Accelerator Laboratory of the US Department of Energy. Could measurements allow for the precise visualization of supercurrent tunneling—the passage of electrons through a barrier between two superconductors—at single Josephson junctions?
To have an impact on the optimization of qubits for quantum computers, he said, “we really need to measure down to that level.” “What a lofty objective! And for now, this is only a tiny step in that direction. “The process is step-by-step.”
