Electrical currents in nanostructures of any nature exhibit unusual 1/f noise. They are in the transition region between two radically different components of the fundamental quantum 1/f noise. This transition region between the coherent and conventional quantum 1/f effects displays a plateau on which the spectral density of 1/f current noise remains practically constant, while aH changes its value. Along that plateau, it is possible to reduce the cross section Q of the device without incurring an increased 1/f noise penalty. However, this implies that in this transition region the corresponding quantum 1/f coefficient aH increases when the number of carriers per unit length of the device increases. This represents a peculiar coherent magnetic interaction between the current carriers.
The question arises then: How far does one need to physically distance two longitudinal halves of the sample, mentally separated along the center plane parallel to the current flow, in order to preclude the influence of the carriers from either half on the aH of those in the other half?
This coherent magnetic interaction which increases the 1/f noise is hereby named žInduced 1/f NoiseÓ, or Quantum 1/f Proximity Effect. The effect is proportional to the mutual inductance L between the two parallel halves, or between two parallel currents at a distance d, in general. The coherent magnetic field causes the coherent quantum 1/f effect. There is a similarity between noise power and the magnetic energy term in the hamiltonian. The total magnetic energy is not a sum of the contributions of individual carriers, but rather proportional to the square of such a coherent sum, i.e., to the squared magnetic field.
In conclusion, we expect the induced 1/f noise effect to vary with the distance d between two parallel elements of current proportional to the mutual induction coefficient. This is applicable, e.g., to bundles of doped strands of DNA, used as conductors. (See full paper)
 P.H. Handel, "Noise, low frequency" in the Wiley Encyclopedia of Electrical and Electronics Engineering, Vol. 14, pp. 428-449 (1999); Eq. (119)
Peter H. Handel
Department of Physics and Astronomy
University of Missouri - St. Louis
8001 Natural Bridge Rd.
St. Louis, MO 63121, USA