A two-particle state can be sensitive to a magnetic flux through exchange even if it is composed of single-particle states which on the average are statistically uncorrelated and exhibit no direct interference. Consequently, two-particle observables can be sensitive to a flux even if all single-particle observables are flux insensitive. We investigate exchange effects in current cross correlations of small conductors subject to a magnetic field.

• Received 19 August 1991

DOI:https://doi.org/10.1103/PhysRevLett.68.843