Quantum Point Contact (IMAGE) Joint Quantum Institute Caption Within the top gate barrier (which is otherwise an insulator), a very narrow passageway which conducts electrons normally (N), can link the superconducting (S) panels on either side of the top gate. The passage is known as a quantum point contact (QPC). Credit Stanford University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.