The paper by van Wees et al. (1988) investigates the quantized conductance of ballistic point contacts in a two-dimensional electron gas (2DEG) within a GaAs-AlGaAs heterostructure. The conductance changes in quantized steps of \( e^2/\pi \hbar \) as the width of the point contact, controlled by a gate voltage, is varied. Up to sixteen steps are observed when the point contact is widened from 0 to 360 nm. The authors propose an explanation based on the assumption of quantized transverse momentum in the point-contact region. They derive a formula for the conductance that agrees with the experimental observations, showing that the conductance is quantized in units of \( e^2/\pi \hbar \). This finding suggests that the system closely approximates the behavior of idealized mesoscopic systems. The study highlights a novel quantum effect in ballistic transport through point contacts in 2DEGs.The paper by van Wees et al. (1988) investigates the quantized conductance of ballistic point contacts in a two-dimensional electron gas (2DEG) within a GaAs-AlGaAs heterostructure. The conductance changes in quantized steps of \( e^2/\pi \hbar \) as the width of the point contact, controlled by a gate voltage, is varied. Up to sixteen steps are observed when the point contact is widened from 0 to 360 nm. The authors propose an explanation based on the assumption of quantized transverse momentum in the point-contact region. They derive a formula for the conductance that agrees with the experimental observations, showing that the conductance is quantized in units of \( e^2/\pi \hbar \). This finding suggests that the system closely approximates the behavior of idealized mesoscopic systems. The study highlights a novel quantum effect in ballistic transport through point contacts in 2DEGs.