The First Experimental Observation of a 'Quantum Boomerang' Has Been Reported

The First Experimental Observation of a 'Quantum Boomerang' Has Been Reported

The first experimental observation of a "Quantum Boomerang" has been reported in an incredible new study from the University of California, Santa Barbara.

Physicists at UC Santa Barbara have become the first to observe a peculiar quantum behavior: the "quantum boomerang" effect, which occurs when particles in a disordered system are thrown out of their positions. Instead of landing elsewhere, as one might expect, they turn around and come back to where they started and stop there.

"It's really a fundamentally quantum mechanical effect," said atomic physicist David Weld, whose lab created and documented the effect in a paper published in Physical Review X. "There's no classical explanation for this phenomenon."

The boomerang effect is based on a phenomenon predicted roughly 60 years ago by physicist Philip Anderson, a disorder-induced behavior known as Anderson localization that prevents electrons from moving to another location.

They become stuck in place, unable to travel very far from where they began. The pinned-down electrons prevent the material from conducting electricity, transforming it from a metal to an insulator. This localization is also required for the boomerang effect.

"This type of disorder will keep them from basically dispersing anywhere," says lead author Roshan Sajjad of the University of California-Santa Barbara, US.

This phenomenon has been poorly understood (until now) because it is nearly impossible to track every electron.

However, David Weld and colleagues demonstrated this effect by substituting 100,000 ultracold lithium atoms for electrons. Rather than looking for atoms returning to their original positions, the team investigated the analogous situation for momentum, which was relatively easy to create in the lab. The atoms were initially stationary, but after being given laser kicks to give them momenta, they returned to their original standstill states on average, creating a momentum boomerang.

The quantum particles must not be of pristine material and made up of orderly arranged atoms for the experiment to work but must have many defects, such as atoms that are missing or misaligned or other types of atoms sprinkled throughout, according to the researchers.

The team also figured out how to break the boomerang. The boomerang effect requires time-reversal symmetry to work, which means that the particles should behave the same when time runs forward as they do when time is rewinded. The researchers broke time-reversal symmetry by changing the timing of the first kick from the lasers, causing the kicking pattern to be off-kilter and the boomerang effect to disappear, as predicted.

Eventually, this experiment strongly indicates that periodic kicks with time-reversal symmetry cause the boomerang effect; however, random kicks destroy this symmetry, canceling out the boomerang effect.

1 Response to "The First Experimental Observation of a 'Quantum Boomerang' Has Been Reported"

  1. This could be used for a quantum computer using the boomerang effect & periodic/aperiodic momentum kicks to go between conductor & insulator, like current transistors, & a quantum entangler to entangle enough qubits to perform multiple simultaneous calculations.