Quantum Computing and Communications: An Engineering Approach

4

Two Simple Quantum Algorithms

The majority of this book focuses on quantum algorithms which are significantly more efficient than their best-known classical alternatives. There are no magic formulas about designing appropriate quantum algorithms to solve a certain problem. As we will see later several often used and fairly useful tools can be attained when studying available quantum algorithms systematically. However, before staring this interesting but time-consuming process we present two simple algorithms that can be understood without effort based on our (at this point) limited available skills in quantum computing. They typically excite beginners and give enough stimulation to get through some hard topics. We show how to use quantum communication channels to achieve higher information transfer rates by means of superdense coding in Section 4.1. Next the dream of all science fiction fans will be fulfilled when we design a quantum-based teleportation device in Section 4.2.

4.1 SUPERDENSE CODING

The science that is responsible among others for investigating theoretical limits of communication over an erroneous channel is called information theory. It was founded by Claude Shannon [136] in the 1940s. This science has since been flourishing not only in terms of theory but also the results have been transplanted into equivalent everyday practice and built in all communication devices. The corresponding quantum equivalent – called quantum information theory – forms the backbone ...