Researchers from the Massachusetts Institute of Technology (MIT) have found a way to observe fermions better, building a microscope that allows a thousand particles to be viewed at the same time.

Fermions, like protons, electrons, neutrons, atoms and quarks, are the building blocks of matter. They contain an odd number of elementary particles, and it's because of this that they are difficult to observe and understand. To address this problem, MIT researchers tried using ultracold gases of fermionic atoms, creating stand-ins for other kinds of fermions.

However, this presented another challenge: atoms are highly sensitive to light. A single photon strike could knock a particle out of place, making capturing an image of one fermionic atom next to impossible. To address this other problem, researchers used a laser-based technique, trapping and freezing fermions in place and imaging the particles at the same time.

The technique employs two laser beams targeting a fermionic atom cloud set within an optical lattice. Of different wavelengths, the laser beams cool the cloud, bringing the fermions to their lowest possible energy states. This makes the fermions stable enough to stay in place. Every fermion also releases light, and this is captured as well by the microscope. The captured light is then used to image the exact position of a fermion in the lattice, the result of which is more accurate than a light wavelength.

This technique has allowed the cooling and imaging of more than 95 percent of fermionic atoms in a potassium gas cloud, but MIT researchers also discovered that it could keep fermions cool well after imaging.

According to Martin Zwierlein, a physics professor from MIT and one of the authors of the study published in the journal Physical Review Letters, simultaneous high-resolution imaging of fermionic atoms will enhance the scientific community's understanding of how other fermions behave in nature, most especially electrons.

"The Fermi gas microscope, together with the ability to position atoms at will, might be an important step toward the realization of a quantum computer based on fermions," he said.

Around the same time that Zwierlein and colleagues released the results of their study, teams from the University of Strathclyde and Harvard University also reported imaging fermionic atoms individually, hinting at the potential that fermion microscopes have.

The study received funding support from the David and Lucille Packard Foundation, the Army Research Office, the Office of Naval Research, the Air Force Office of Scientific Research and the National Science Foundation. Other authors include Lawrence Cheuk, Thomas Lompe, Matthew Nichols, Waseem Bakr, Melih Okan, Vinay Ramasesh and Thomas Gersdorf.

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