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Mesoscopic behaviour of the neutral Fermi gas He-3 confined in quantum wires

Research output: Contribution to journalJournal article

Published

Journal publication date8/10/1998
JournalNature
Journal number6702
Volume395
Number of pages3
Pages578-580
Original languageEnglish

Abstract

The behaviour of electron gases in restricted geometries provides a means to explore the fundamental quantum-mechanical properties of fermion gases at mesoscopic length scales(1). But the existence of Coulomb repulsion between electrons unavoidably complicates the physics. Quantum gases of neutral fermions-such as He-3 quasiparticles in a dilute solution of He-3 in He-4, cooled to millikelvin temperatures(2)-therefore offer a means of probing regimes completely inaccessible to electronic systems. Here we demonstrate the quantum exclusion of a He-3 fermion gas from a network of narrow channels, connected to a reservoir of He-3/He-4 solution. The effect is expected from simple quantum-mechanical arguments, which predict that the He-3 atoms cannot enter the channels when their wavelength exceeds root 2 times the channel width. By adjusting the temperature of the solution, the energy of the particles and hence their average wavelength can be controlled. In this way, we observe temperature-dependent changes in the penetration of the 3He quasiparticles into the channels. Our results demonstrate the macroscopic response of an atomic gas to basic quantum-mechanical restrictions at the mesoscopic level.