ASU welcomes new leader of groundbreaking compact X-ray laser project

To Arvinder Sandhu, the compact X-ray free electron laser (CXFEL) is not just a groundbreaking machine to allow us to see particles at an unprecedented level — it's a passion project he has nurtured from its start.

Previously a University of Arizona professor in physics and optical sciences, Sandhu has long worked with Arizona State University on state-of-the-art lasers. He was also a key player in helping ASU land the university’s biggest National Science Foundation grant totaling $90.8 million in 2023 to build this unique facility. 

The CXFEL will generate ultrafast pulses of X-rays that allow scientists to probe the inner workings of biomolecules, materials and chemical processes. In contrast to the existing large-scale, multibillion-dollar X-ray lasers, the compact size of CXFEL enables it to be housed in universities, hospitals and fabrication facilities, increasing the accessibility and usage in interdisciplinary science, health care and the semiconductor industry.

In this Q&A, Sandhu details his history with the project, its future and his vision. 

Question: How did you get involved with CXFEL?

Answer: My involvement started with a serendipitous meeting with Bill Graves, the previous director of the CXFEL project, just as he had joined ASU. I was fascinated by the implications of a compact X-ray machine and jumped at the opportunity of helping with the early work on laser systems. As a first step towards CXFEL, we started with the construction of a compact X-ray light source (CXLS). We employed an ultraviolet laser to produce electrons that are quickly accelerated using sophisticated microwave fields. Then a second high-power laser beam is made to collide with those electrons to produce hard X-rays.

While CXLS was being built, I was keen to get started on CXFEL so that we could make attosecond X-ray pulses, which are incredibly fast pulses lasting less than a millionth of a billionth of a second. We worked hard to speed up our efforts by writing grants to earn funding for the CXFEL. I was a co-PI on several successful grant proposals, and we were elated when we landed the big one for the construction of the CXFEL.

Q: How do you think your background can provide insight and a new perspective to the CXFEL project?

A: Even as a graduate student, I worked extensively with high-intensity lasers, and such lasers are a key component of this project. A bit later in my career, I developed sources of attosecond X-rays and employed them to investigate the real-time motion of electrons. My experience with the field of laser physics, ultrafast imaging of molecules and materials, and the applications of X-ray science in general translates nicely to where we want to go with this project.

Q: What excites you about becoming the director of the CXFEL project?

A: When I had the opportunity to come on board and lead this project, it was like a dream come true. We have a combination of such amazing technologies in the form of novel accelerators and powerful lasers here that they offer endless possibilities. The likes of these machines do not exist anywhere else in the world. So, sure, we want to build a CXFEL to disrupt the way X-rays are currently generated and fuel new discoveries, but we can keep going and think bigger to make powerful accelerators for medical therapies, open new paths to nuclear fusion energy and so on. There is no limit to scientific applications of the technologies we are developing.

I just think that we have a perfect combination of scientific and engineering talent here at CXFEL, and everyone is eager to advance this project further. It just made sense to join because I'm so engaged in this effort that it's one of my most, I would say, passionate involvements in science. I am thoroughly energized about the prospects of what we can achieve.

Q What are your priorities in your new position?

A: My priority is to make this project a shining example of innovation at universities, which will make ASU stand out in the world. We want to build a user facility here, so that scientists from national labs and universities from all over the world can come here, bring their samples and do cutting-edge research.

I should point out that the CXFEL is being developed in tandem with the ongoing commissioning of a hard X-ray CXLS machine that generated its first electrons in 2021 and is now ready to investigate the dynamic structure of proteins and materials.

Q: What are some of the impacts of this technology to everyday people?

A: The CXFEL will produce ultrashort pulses of coherent X-ray light, which will create new applications with tremendous impact on society. One of the nearest examples lies in understanding proteins. Proteins are vital to the functioning of our body, so understanding their structures and how they change is the key to discovering new drugs and devising lifesaving medical therapies.

The instrument will also allow us to advance medical imaging, unlock the secrets of historical and cultural artifacts, and advance the development of artificial intelligence and quantum materials.

Then, of course, the fundamental goal is to keep on pushing the frontiers of time and energy. Right now, most X-ray facilities are limited to the femtosecond timescales. A femtosecond is a thousandth of a trillionth of a second. We want to go beyond that into a regime of attoseconds — the shortest duration that humans can explore in a lab currently.

Studying quantum physics on those timescales has implications for everything that happens around us, be it in improving light harvesting for energy generation, making efficient chemical catalysts, creating new phases of matter, controlling quantum processes to make new ultrafast devices and so on. As history has shown, exploring the unknown and seeking new knowledge often leads to amazing breakthroughs in science, medicine and technology.