Network Theory and Discrete Calculus – Quantized Conductance
This post is part of a series
The Graph Operator
In my last post, I mentioned the graph operator
and the fact the exterior derivative of a discrete 0-form can be expressed as a commutator
I then let myself speculate that the graph conductance 1-form
could be nothing more than the graph operator. In this post, I hope to explain a bit more how that might work.
Recall that the discrete Ohm’s Law
gives the total current
If we did not need to probe the current in any one of the individual parallel directed edges, it would be tempting to replace them with a single effective directed edge representing the total current flowing them, i.e.
In doing so, we could also replace the conductances with a single effective conductance
Could it be that ?
Let denote a partition of the set of directed edges from node to node and express the graph operator as
and is the number of directed edges in the subset . This would only make sense if we were not going to probe into any single directed edge within any element of the partition.
Comparing this to the conductance
we see that the graph conductance can be interpreted as the graph operator where each directed edge of our electric network is actually composed of a number of fundamental directed edges, i.e. conductance is simply counting the number of sub-paths within each directed edge.
As before, thinking about this (as time allows) raises more questions than answers. For example, if the above makes any sense and is in any way related to nature, this would imply a fundamental unit of conductance and that conductance should be quantized, i.e. come in integer multiples of the fundamental unit. For completely unrelated (?) reasons, conductance is observed to be quantized due to the waveguide like nature of small, e.g. nano, wires and the fundamental unit of conductance is given by
where is the electron charge and is Planck constant.
This also makes me think of the geometric origin of inhomogeneous media. In vacuum, I would expect there to be just a single directed edge connecting any two nodes. Hence, I would expect in vacuum. In the presence of matter, e.g. components of an electrical network, there should be bunches of directed edges between any two nodes.