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Bose polarons near quantum criticality
Zoe Z Yan1, Yiqi Ni1, Carsten Robens1
1MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Science (New York, N.Y.)
|April 11, 2020
Summary
Researchers studied Bose polarons near quantum criticality. They observed well-defined quasiparticles far below the critical temperature, but their behavior broke down near the critical point, signaling a loss of quasiparticle existence.
Area of Science:
- Quantum physics
- Condensed matter physics
- Atomic physics
Background:
- Quasiparticles are fundamental to understanding interacting matter.
- The behavior of quasiparticles near quantum critical points is not fully understood.
- Bose-Einstein condensates (BECs) provide a platform to study quantum phenomena.
Purpose of the Study:
- To investigate the existence and properties of quasiparticles near a quantum critical point.
- To probe the behavior of Bose polarons in a BEC under varying temperatures.
- To determine the conditions under which the quasiparticle picture breaks down.
Main Methods:
- Creation of Bose polarons by immersing atomic impurities in a BEC.
- Radiofrequency spectroscopy to measure impurity energy, spectral width, and correlations.
- Systematic variation of temperature to observe changes in quasiparticle properties.
Main Results:
- Well-defined quasiparticles were observed far below the superfluid critical temperature.
- The inverse lifetime (spectral width) of impurities increased linearly with temperature at the Planckian scale, indicating quantum critical behavior.
- Near the BEC critical temperature, the spectral width surpassed the impurity binding energy, signifying a breakdown of the quasiparticle description.
Conclusions:
- The study provides experimental evidence for quantum critical behavior in Bose polarons.
- The findings challenge the universal validity of the quasiparticle concept near quantum criticality.
- This work offers insights into the fundamental nature of matter at extreme quantum conditions.
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