Secure quantum communications require an entanglement‐preserving photo‐detector in which quantum information is transmitted by photon polarization through an mid infrared optical fiber system and then transferred to electron spin in a optoelectronic semiconductor device. Using interpolation scheme we have investigated the electron g‐factor in bulk Ga1−xInxAsySb1−y quaternary alloy matched to GaSb as a function of Indium and Arsenic concentration on the complete range 0≤x,y≤1. A specific g‐factor as a function of the radius in a spherical GaSb/Ga1−xInxAsySb1−y/GaSb quantum dot heterostructure is calculated. Furthermore, we present calculations of the energy states including the Zeeman effect on the electrons confined in quaternary heterostructure quantum dots, with a parabolic confining potential under applied magnetic fields. Our calculations have been worked out by using interpolating methods to find the band gap as a function of the Indium concentration in order to determine the conduction band‐offset at room temperature in GaSb/Ga1−xInxAsySb1−y/GaSb heterostructure, within the effective‐mass approximation. Experimental or theoretical electron g‐factor, spin‐orbit splitting Δso, and coupling matrix elements Ep = (2/m0)|〈S|px|X〉|2 value between the states of the lowest conduction band Γ6 and the upper valence bands Γ8 for Ga1−xInxAsySb1−y/GaSb quaternary alloy are not readily available. Our predictions show that electron g‐factor values are in the range between the electron g‐factor measured in bulk GaSb when x→0 (g = −9.25) and that measured in InAs when x→1 (g = −18.08), but there is a remarkable minimum in the g‐factor value (g≃−23.14) at x≃0.67.