New! Sign up for our free email newsletter.
Science News
from research organizations

To kill a quasiparticle: A quantum whodunit

Date:
September 28, 2020
Source:
ARC Centre of Excellence in Future Low-Energy Electronics Technologies
Summary:
Quasiparticles die young, lasting far, far less than a second. Why? A new Monash University study finds a culprit beyond the usual suspect (decay into lower energy states). Identification of the new villain--many-body dephasing--may be key to controlling quantum effects such as superconductivity and superfluidity.
Share:
FULL STORY

What causes quasiparticle death?

In large systems of interacting particles in quantum mechanics, an intriguing phenomenon often emerges: groups of particles begin to behave like single particles. Physicists refer to such groups of particles as quasiparticles.

Understanding the properties of quasiparticles may be key to comprehending, and eventually controlling, technologically important quantum effects like superconductivity and superfluidity.

Unfortunately, quasiparticles are only useful while they live. It is thus particularly unfortunate that many quasiparticles die young, lasting far, far less than a second.

The authors of a new Monash University-led study published today in Physical Review Letters investigate the crucial question: how do quasiparticles die?

Beyond the usual suspect -- quasiparticle decay into lower energy states -- the authors identify a new culprit: many-body dephasing.

MANY BODY DEPHASING

Many-body dephasing is the disordering of the constituent particles in the quasiparticle that occurs naturally over time.

As the disorder increases, the quasiparticle's resemblance to a single particle fades. Eventually, the inescapable effect of many-body dephasing kills the quasiparticle.

Far from a negligible effect, the authors demonstrate that many-body dephasing can even dominate over other forms of quasiparticle death.

This is shown through investigations of a particularly 'clean' quasiparticle -- an impurity in an ultracold atomic gas -- where the authors find strong evidence of many-body dephasing in past experimental results.

The authors focus on the case where the ultracold atomic gas is a Fermi sea. An impurity in a Fermi sea gives rise to a quasiparticle known as the repulsive Fermi polaron.

The repulsive Fermi polaron is a highly complicated quasiparticle and has a history of eluding both experimental and theoretical studies.

Through extensive simulations and new theory, the authors show that an established experimental protocol -- Rabi oscillations between impurity spin states -- exhibits the effects of many-body dephasing in the repulsive Fermi polaron.

These previously unrecognised results provide strong evidence that many-body dephasing is fundamental to the nature of quasiparticles.


Story Source:

Materials provided by ARC Centre of Excellence in Future Low-Energy Electronics Technologies. Note: Content may be edited for style and length.


Journal Reference:

  1. Haydn S. Adlong, Weizhe Edward Liu, Francesco Scazza, Matteo Zaccanti, Nelson Darkwah Oppong, Simon Fölling, Meera M. Parish, Jesper Levinsen. Quasiparticle Lifetime of the Repulsive Fermi Polaron. Physical Review Letters, 2020; 125 (13) DOI: 10.1103/PhysRevLett.125.133401

Cite This Page:

ARC Centre of Excellence in Future Low-Energy Electronics Technologies. "To kill a quasiparticle: A quantum whodunit." ScienceDaily. ScienceDaily, 28 September 2020. <www.sciencedaily.com/releases/2020/09/200928093738.htm>.
ARC Centre of Excellence in Future Low-Energy Electronics Technologies. (2020, September 28). To kill a quasiparticle: A quantum whodunit. ScienceDaily. Retrieved October 11, 2024 from www.sciencedaily.com/releases/2020/09/200928093738.htm
ARC Centre of Excellence in Future Low-Energy Electronics Technologies. "To kill a quasiparticle: A quantum whodunit." ScienceDaily. www.sciencedaily.com/releases/2020/09/200928093738.htm (accessed October 11, 2024).

Explore More

from ScienceDaily

RELATED STORIES