Physicists probe quantum world with billion dollar laser


Adrian Feiguin (left), associate professor of physics at Northeastern, and Arun Bansil (right), professor emeritus of physics at the university. Photo by Matthew Modoono / Northeastern University

Suppose you are a budding physicist probing the quantum world to better understand the fundamental nature of reality.

There are two ways to conduct your science odyssey, but both involve very expensive machinery. One way is to smash a bunch of atoms together, revealing their subatomic innards; another is to launch them under a ray of light, illuminating a nanoscopic trajectory through space.

A group of theoretical physicists from Northeastern are preparing to do the latter, with millions in new funding. They are part of a multi-institutional team that received a $ 2.7 million grant from the Department of Energy for a project to develop a set of machine learning tools and related software that will help students. researchers to better interpret the quantum images produced by one of the largest and most powerful particle accelerators, the billion dollars Stanford linear accelerator.

Funding for the project will be split more or less evenly between Northeastern University, Howard University – the lead institution involved – and the Stanford Linear Accelerator Center (SLAC).

Photo by Matthew Modoono / Northeastern University

Particle accelerators are large, complicated machines, but do exactly what their name suggests – they accelerate charged particles, such as protons and electrons that make up atoms, to incredibly high speeds, often crushing them against others. particles in magnificent acts of quantum destruction.

But Stanford’s Particle Accelerator, also known as Linac Coherent Light Source (LCLS), with its upgrade, the LCLS-II, is not designed to atomize atoms. Researchers involved in the project plan to use the LCLS to film high-energy X-rays on a range of different materials to observe how light scatters when it interacts with material that has simply been “disturbed” , not shattered into pieces, says Arun Bansil, distinguished university professor in the Department of Physics at Northeastern.

LCLS machines can take “x-ray snapshots of atoms and molecules at work” at “super-fast timescales,” according to SLAC website. The Stanford laser can deliver 120 x-ray pulses per second, each lasting “quadrillionths of a second” or femtoseconds. At such an incomprehensibly fast timescale, researchers will also develop a set of technological tools to model and interpret the data.

“These are snapshots of material in its excited state,” Bansil says. “It’s a bit like what happens when you throw a stone in water.”

It’s the resulting splash, to complement the quantum metaphor, that researchers seek to capture at specific times and in sequence, Bansil says.

Here’s another way of looking at it: if you’ve ever been in a sports arena when the “Mexican wave” is riding, you might not be paying attention to people – their facial expressions, what they’re wearing and the like. such characteristics — which make up the wave, only that they are part of a larger process.

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Here, the fans would represent groups of electrons in their “excited state”.

“It’s much easier to describe the Mexican wave to someone than the behavior of 19,000 people,” says Adrien Feiguin, associate professor at the College of Sciences, who is also part of the research team.

But what’s so complicated about this delicate molecular film is that it’s not observed in what’s called real space, or by direct means, Bansil says.

Rather, the “image” produced by the laser is a set of data points from which researchers use to infer the behavior of electrons and other small particles in materials. The software platforms will give them the ability to interpret LCLS data in real time, Bansil says.

“So in this sense, machines, which are actually computers, are used to examine large amounts of data in order to get physical information about the data and help develop new theoretical models,” Bansil explains. .

The goal of the overall project is to better understand the properties and states of certain magnetic materials, says Bansil.

“The materials we are going to focus on are indeed magnetic materials,” Bansil said. “Magnetism is attracting more and more attention because of the activity it offers.”

For media inquiries, please contact [email protected].

About Mark A. Tomlin

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