Quantum Communication

Quantum communication is the most advanced field of quantum information processing. Commercial quantum key distribution (QKD) systems are readily available, and significant efforts to build large-scale quantum communication networks are under way in China and across Europe. 

The goal of this course is to provide the students with a thorough description of the hardware required for building quantum networks. Starting with a brief review of the underpinning theoretical aspects of quantum information (14P030), and building on quantum optics (14P020), we will discuss the creation and measurement of quantum bits and entangled quantum bits—both encoded into different degrees of freedom of photons as well as into individual atoms—and detail different possibilities of QKD over optical fiber.

We will then move on to discuss current efforts into the creation of quantum networks, including networks based on long-lived entangled nodes containing single atoms, and networks across quantum repeaters that include atomic-ensemble-based quantum memories.

To round off the course, we will briefly describe some approaches to quantum computing that are based on photonic qubits and linear optics, or on optically mediated qubit interrogation and qubit-qubit entanglement.

The course will be based on a combination of teaching at the whiteboard, student presentations followed by in-class discussions, as well as supervised exercises. The final grade will be established based on presentations (including short quizzes) as well as on an oral exam.