New Simons Collaboration Explores Defects in Physics

For centuries, physicists have described how the universe functions based on observations of the natural world taken at a specific time and place. But increasingly, physicists have found that certain probes of the universe are not local to one place or time. Known as nonlocal observables or defects, these extend across regions of space-time of various dimensions and are ubiquitous in quantum mechanics and gravity. The Simons Foundation is pleased to announce the launch of the Simons Collaboration on the Virtues of Defects, a multidisciplinary community exploring nonlocal observables in physics.

Defects show up in all areas of theoretical physics, including quantum field theory, condensed matter and gravity. They even appear in pure mathematics. However, defects are often obscured in theories such as general relativity and quantum mechanics, which are usually described in terms of local variables.

“To find the nonlocal observables, you really have to look under the hood of the theory,” says Jaume Gomis of the Perimeter Institute, who directs the new collaboration. “But once you find them, you are able to diagnose new phenomena that local variables are not able to discern.”

For example, quantum entanglement occurs when two particles become linked, with the state of one reflecting the state of the other, no matter how far apart they are. This phenomenon, which Albert Einstein called “spooky action at a distance,” can be studied using local variables. But by describing it nonlocally, different aspects, such as the entanglement entropy, can be measured and studied more precisely. Using defects to gain a new perspective on old problems could also allow researchers to probe a system for new information, discover new phenomena and ask new questions.

“It’s like finding you have a new ingredient in your cupboard,” Gomis says. “It allows you to cook new things.”

The collaboration hopes to capitalize on recent successes in the field led by some of its principal investigators, including breakthroughs in computational methods, advances in theories of defects that revealed new phases of quantum systems, and progress in gauge theory, which describes some of the fundamental forces in the universe. Gomis believes that it may be possible to reformulate the theories of general relativity and quantum mechanics in terms of defects, revealing new phenomena in physics.

“Typically, big breakthroughs in physics happen when people from different backgrounds, traditions and cultures come together and make something new,” Gomis says. “That’s what I’m most excited about.”

Simons Collaborations in Mathematics and the Physical Sciences bring together groups of outstanding researchers to address topics of fundamental scientific importance. Collaborations receive up to $2 million per year for an initial four-year period, including indirect costs, and may be extended for an additional three years. The collaboration will be funded by grants from Simons Foundation International with administrative and scientific support from the Simons Foundation.

The members of the new collaboration are:

Jaume Gomis
Director; Perimeter Institute

Fakher Assaad
PI; University of Würzburg

Fiona Burnell
PI; University of Minnesota

Horacio Casini
PI; Bariloche Atomic Center

Meng Cheng
PI; Yale University

Gabriel Cuomo
PI; International School for Advanced Studies

Simone Giombi
PI; Princeton University

Yin-Chen He
PI; Perimeter Institute

Marina Huerta
PI; Bariloche Atomic Center

Anton Kapustin
PI; California Institute of Technology

Zohar Komargodski
PI; Simons Center for Geometry and Physics, Stony Brook University

Charlotte Kristjansen
PI; Niels Bohr Institute, University of Copenhagen

Marco Meineri
PI; University of Turin

Mat Metlitski
PI; Massachusetts Institute of Technology

Yifan Wang
PI; New York University