A partitioned system of fermions is mathematically equivalent to an assembly of two-level atoms described by spin operators. A number-phase uncertainty relation can therefore be derived to describe the noise properties of divided electrons. We examine both the number (or electron flux) and phase (or electron wave phase) decorrelation introduced by electron branching in mesoscopic circuits. Initially Poissonian, this electron number partition noise is increasingly suppressed by inelastic scattering in the transition from ballistic to dissipative electron division. Graphical results from our model show a trend from a coherent spin state in the ballistic regime toward a number-squeezed spin state in the dissipative regime, even when detrimental elastic scattering is present.

• Received 25 October 1993

DOI:https://doi.org/10.1103/PhysRevB.49.10520