Quantum conductance of 3D ballistic wires with idealy flat boundaries obeys
fluctuations with the properties quite distinguishable from those of universal
conductance fluctuations: Both their amplitude and the sensitivity to the
magnetic field flux Φ=HS penetrated into the sample cross-sectional area
S are different and depend on details of the cross-sectioanl shape of the
wire. When the latter is integrable, conductance fluctuations have the enlarged
amplitude δG∼[(e2/h)3G]1/4. When the cross-sectional
shape of a wire is non-integrable, the irregular part of a conductance has the
e2/h scale, whereas the correlation field is reduced to the value of
HS∼(λF/S)1/2(Φ0/S) and the correlation voltage of
the nonlinear conductance fluctuations has the scale of eVc∼ℏ2/mS∼EF/(S/λF), where λF=1/pF is the Fermi wavelength.Comment: 5 pages, no pictures, to be published in "Coulomb and Interference
Effects in Small Electronic Structures", ed. by D.Glattli, M.Sanquer and
J.T.T.Van