振動運動:超流体ヘリウム-4で量子笛を吹いている
E Hoskinson1, R E Packard, Thomas M Haard
1Physics Department, University of California, Berkeley, California 94720, USA.
Nature
|January 28, 2005
まとめ
科学者たちは,ナノメートルのサイズの開口を使用して,超流動的ヘリウム-4 (4He) に量子振動を誘導しました. 2Kでのこの発見は,非常に正確な回転センサーにつながる可能性があります.
科学分野:
- 量子流体力学とは
- 凝縮物質物理学 凝縮物質物理学
背景:
- 超流体や超伝導体と同様に,マクロスケールの量子システムは,閉じ込められたときに振動運動を示すことが予測されています.
- これらの量子現象を理解することは,先進技術の開発に不可欠です.
研究 の 目的:
- 超流体ヘリウム-4 (4He) の振動運動をナノメートルサイズの開口孔を通して実験的に誘導し観察する.
- これらの振動の特徴とその潜在的な応用を調査する.
主な方法:
- ナノメートルのサイズのアパートルの配列を用いて,超流体ヘリウム-4 (4He) を圧縮物を通す.
- 誘発された振動を,可聴な口笛の音として検知する.
主要な成果:
- 2Kの超流体ヘリウム-4 (4He) でコヒーレントの振動を成功裏に誘導した.
- 振動がジョセフソンの周波数関係に従っていることが観察されました.
- 聴覚可能な音として振動を検知し,マクロスコプの量子行動を示しています.
結論:
- 実験的観測は,量子流体力学の基本的な予測を検証する.
- 比較的高い温度である2Kでの4Heの現象は,実用的な応用のための有望なプラットフォームを提供します.
- この発見は,新しい高精度回転センサーの開発につながる可能性があります.
関連する概念動画
Forced Oscillations
When an oscillator is forced with a periodic driving force, the motion may seem chaotic. The motions of such oscillators are known as transients. After the transients die out, the oscillator reaches a steady state, where the motion is periodic, and the displacement is determined.
Standing Waves
Sometimes waves do not seem to move; rather, they just vibrate in place. Unmoving waves can be seen on the surface of a glass of milk kept in a refrigerator, which is one example of standing waves. Vibrations from the refrigerator motor create waves on the milk that oscillate up and down but do not seem to move across the surface. These waves are formed or created by the superposition of two or more identical moving waves in opposite directions. The waves move through each other, with their...
Standing Waves in a Cavity
A household microwave and lasers are examples of standing electromagnetic waves in a cavity. When two conducting metal plates are placed parallel at the nodal planes, it creates a cavity where standing waves are formed. The cavity between the two planes is analogous to a stretched string held at the points x = 0 and x = L. Here, the distance 'L' between the two planes must be an integer multiple of half of the wavelength. The wavelengths that satisfy this condition are given by:
Sound as Pressure Waves
Sound waves, which are longitudinal waves, can be modeled as the displacement amplitude varying as a function of the spatial and temporal coordinates. As a column of the medium is displaced, its successive columns are also displaced. As the successive displacements differ relatively, a pressure difference with the surrounding pressure is created. The gauge pressure varies across the medium.
The pressure fluctuation depends on the difference in displacements between the successive points in the...
The pressure fluctuation depends on the difference in displacements between the successive points in the...
Deriving the Speed of Sound in a Liquid
As with waves on a string, the speed of sound or a mechanical wave in a fluid depends on the fluid's elastic modulus and inertia. The two relevant physical quantities are the bulk modulus and the density of the material. Indeed, it turns out that the relationship between speed and the bulk modulus and density in fluids is the same as that between the speed and the Young's modulus and density in solids.
The speed of sound in fluids can be derived by considering a mechanical wave propagating...
The speed of sound in fluids can be derived by considering a mechanical wave propagating...
Conservation of Mass in Moving, Nondeforming Control Volume
Stormwater detention basins are essential in managing runoff during heavy rainfall, particularly in urban areas where impervious surfaces increase the risk of flooding. Understanding the conservation of mass in these systems allows engineers to optimize basin performance, balancing inflow, outflow, and water storage.
In the context of a detention basin, the conservation of mass states that the total mass of water entering the basin must equal the mass leaving the basin plus any accumulation of...
In the context of a detention basin, the conservation of mass states that the total mass of water entering the basin must equal the mass leaving the basin plus any accumulation of...


