Related Experiment Video
Updated: Jan 4, 2026
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
8.9K
Measuring the Hydrodynamic Linear Response of a Unitary Fermi Gas
Lorin Baird1, Xin Wang1, Stetson Roof1
1Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA.
Physical Review Letters
|November 9, 2019
Summary
We directly observed the hydrodynamic response of a unitary Fermi gas. Thermal conductivity influences temperature gradients and compression responses in this quantum gas.
Area of Science:
- Quantum physics
- Thermodynamics of quantum gases
Background:
- Unitary Fermi gases exhibit quantum hydrodynamic behavior.
- Understanding thermal transport is crucial for characterizing quantum fluid dynamics.
Purpose of the Study:
- To directly observe the hydrodynamic linear response of a unitary Fermi gas.
- To investigate the influence of thermal conductivity on the gas's dynamic response.
Main Methods:
- Confining a unitary Fermi gas in a box potential.
- Applying a spatially periodic optical potential translated at various speeds (subsonic to supersonic).
- Measuring the time-dependent change of the density profile.
Main Results:
- The hydrodynamic linear response was directly observed.
- Density profile changes were sensitive to thermal conductivity.
- Thermal conductivity was shown to control relaxation rates of temperature gradients.
Conclusions:
- The study provides direct experimental evidence of hydrodynamic linear response in a unitary Fermi gas.
- Thermal conductivity plays a key role in the dynamic response to compression, affecting adiabatic and isothermal processes.
Related Concept Videos
01:16Measurement of Fluid Pressure
545
Fluid pressure is commonly measured using devices called manometers, which rely on liquid columns to indicate pressure differences. The height of a liquid column in a manometer reflects the pressure exerted by the fluid, providing a simple yet effective means of measurement. Different types of manometers serve specific purposes based on their configurations and the type of fluids involved.
A basic form of manometer is the piezometer, a vertical tube open at the top and filled with the same...
A basic form of manometer is the piezometer, a vertical tube open at the top and filled with the same...
545
01:12Fermi Level Dynamics
610
The vacuum level denotes the energy threshold required for an electron to escape from a material surface. It is usually positioned above the conduction band of a semiconductor and acts as a benchmark for comparing electron energies within various materials.
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
610
01:12Kinetic Theory of an Ideal Gas
4.6K
A mole is defined as the amount of any substance that contains as many molecules as there are atoms in exactly 12 grams of carbon-12. An Italian scientist Amedeo Avogadro (1776–1856) formed the hypothesis that equal volumes of gas at equal pressure and temperature contain equal numbers of molecules, independent of the type of gas. Later, the hypothesis was developed to form the SI unit for measuring the amount of any substance.
The number of molecules in one mole is called...
The number of molecules in one mole is called...
4.6K
01:20Maxwell-Boltzmann Distribution: Problem Solving
2.8K
Individual molecules in a gas move in random directions, but a gas containing numerous molecules has a predictable distribution of molecular speeds, which is known as the Maxwell-Boltzmann distribution, f(v).
This distribution function f(v) is defined by saying that the expected number N (v1,v2) of particles with speeds between v1 and v2 is given by
This distribution function f(v) is defined by saying that the expected number N (v1,v2) of particles with speeds between v1 and v2 is given by
2.8K
04:01Real Gases: Effects of Intermolecular Forces and Molecular Volume Deriving Van der Waals Equation
38.6K
Thus far, the ideal gas law, PV = nRT, has been applied to a variety of different types of problems, ranging from reaction stoichiometry and empirical and molecular formula problems to determining the density and molar mass of a gas. However, the behavior of a gas is often non-ideal, meaning that the observed relationships between its pressure, volume, and temperature are not accurately described by the gas laws.
38.6K
01:05Estimation of the Physical Quantities
7.1K
On many occasions, physicists, other scientists, and engineers need to make estimates of a particular quantity. These are sometimes referred to as guesstimates, order-of-magnitude approximations, back-of-the-envelope calculations, or Fermi calculations. The physicist Enrico Fermi was famous for his ability to estimate various kinds of data with surprising precision. Estimating does not mean guessing a number or a formula at random. Instead, estimation means using prior experience and sound...
7.1K