Related Experiment Video
Updated: Jun 16, 2025

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators
Published on: May 30, 2014
Phantom energy in the nonlinear response of a quantum many-body scar state
Kangning Yang1,2, Yicheng Zhang3,4, Kuan-Yu Li2,5
1Department of Physics, Stanford University, Stanford, CA 94305, USA.
Abstract:
Quantum many-body scars are notable as nonthermal, low-entanglement states that exist at high energies. In this study, we used attractively interacting dysprosium gases to create scar states that are stable enough to be driven into a strongly nonlinear regime while retaining their character. We measured how the kinetic and total energies evolve after quenching the confining potential. Although the bare interactions are attractive, the atoms behave as if they repel each other: Their kinetic energy paradoxically decreases as the gas is compressed. The missing "phantom" energy is quantified by benchmarking our experimental results against generalized hydrodynamics calculations. We present evidence that the missing kinetic energy is carried by undetected, very high momentum atoms.
Related Concept Videos
The Quantum-Mechanical Model of an Atom
The de Broglie Wavelength
Energy Associated With a Charge Distribution
Free Energy Changes for Nonstandard States
where R is the gas constant (8.314 J/K·mol), T is the absolute temperature in kelvin, and Q is the reaction quotient. This equation may be used to predict the spontaneity of a process under any given set of conditions.
Reaction Quotient...
Energy Carried By Electromagnetic Waves
The Bohr Model

