Entanglement swapping using integrated photonics

Quantum technology has already brought revolutionary applications in various areas, such as quantum communication, quantum computing, and quantum precision measurement. Among these, the most remarkable application is the quantum computer. For several specific problems, such as boson sampling, quantum computers can show extraordinary computational capabilities far beyond those of classical computers. To transmit quantum states between quantum computers globally, researchers have developed quantum networks based on quantum repeaters, which is also an important branch of quantum communication.

There are various platforms to realize the quantum information processing involved in quantum computing and quantum communication: superconducting quantum circuits, ion traps, neutral atoms, etc. Among these, integrated photonics has attracted considerable attention due to its scalability, high stability, low cost, and ability to operate at room temperature.

Chapter 1 of this thesis introduces the development and fundamental concepts of integrated quantum information processing. Chapters 2 to 4 demonstrates our efforts to realize entanglement swapping with integrated photonics as a step toward chip-based quantum repeaters. A quantum repeater consists of three classic experiments: quantum memory, quantum entanglement purification, and quantum entanglement swapping, which correspond to Chapter 2, Chapter 3, and Chapter 4, respectively.