Zero Sound

a special kind of wave that can be propagated in quantum fluids or, more precisely, Fermi fluids, such as liquid He³, at temperatures very close to absolute zero. It is associated with the departure of the distribution function of the elementary excitations, or quasiparticles, existing in a Fermi fluid from the equilibrium value. The speed of zero sound c₀ is not the same as the speed of ordinary sound c, which is dependent on the compressibility of the fluid, and indeed c₀ > c. The existence of zero sound was predicted by L. D. Landau in 1957 on the basis of the general theory of Fermi fluids. Zero sound was observed experimentally in liquid He³ by the American physicists W. Abel, A. Anderson, and J. Wheatly in 1966. In the temperature range from 0.002° to 0.1° K at a pressure of 0.32 atmosphere, the average value of c was 187.9 m/sec, while c₀ was 194.4 m/sec (at frequencies of 15.4 and 45.5 megahertz). Under certain conditions, zero sound can also exist in metals where the electrons form a charged Fermi fluid.

REFERENCE

Abel, W. R., A. C. Anderson, and J. C. Wheatly. “Rasprostranenie nulevogo zvuka v zhidkom He³ pri nizkikh temperaturakh.” Uspekhi fizicheskikh nauk, 1967, vol. 91, issue 2.

单词	zero sound
释义	Zero Sound Zero Sound a special kind of wave that can be propagated in quantum fluids or, more precisely, Fermi fluids, such as liquid He³, at temperatures very close to absolute zero. It is associated with the departure of the distribution function of the elementary excitations, or quasiparticles, existing in a Fermi fluid from the equilibrium value. The speed of zero sound c₀ is not the same as the speed of ordinary sound c, which is dependent on the compressibility of the fluid, and indeed c₀ > c. The existence of zero sound was predicted by L. D. Landau in 1957 on the basis of the general theory of Fermi fluids. Zero sound was observed experimentally in liquid He³ by the American physicists W. Abel, A. Anderson, and J. Wheatly in 1966. In the temperature range from 0.002° to 0.1° K at a pressure of 0.32 atmosphere, the average value of c was 187.9 m/sec, while c₀ was 194.4 m/sec (at frequencies of 15.4 and 45.5 megahertz). Under certain conditions, zero sound can also exist in metals where the electrons form a charged Fermi fluid. REFERENCE Abel, W. R., A. C. Anderson, and J. C. Wheatly. “Rasprostranenie nulevogo zvuka v zhidkom He³ pri nizkikh temperaturakh.” Uspekhi fizicheskikh nauk, 1967, vol. 91, issue 2.
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