Superdense coding step by step

Abstract

Scholars of quantum computing all become familiar with Alice and Bob when learning about superdense coding and entanglement. However, in every research book and video that we found, the assumption is made that the student will automatically understand how those two classical bits at the end come to their values when they started as two qubits. This vagueness was unavoidable when quantum computers were purely theoretical. After exhaustive search of every quantum superdense coding Bob and Alice example in the research literature since late 2017, we found not one that presented evidence from a real quantum computer. However, moving from theory to practice is necessary. Today, using results from a real IBM Q Experience quantum computer, we illustrate each step of the Bob and Alice qubit journey and make it all crystal clear.