Quantum causality explores the fundamental principles governing cause-and-effect relationships in quantum systems, where traditional notions of causality are challenged by quantum superposition and entanglement. It seeks to understand how quantum events influence each other and redefine the flow of information in complex quantum networks.

Quantum communications leverage the principles of quantum mechanics, such as entanglement and superposition, to enable ultra-secure data transmission. This field aims to develop unbreakable encryption methods and establish global quantum networks for instantaneous and tamper-proof information exchange.

Multiphoton experiments study interactions involving multiple photons to explore quantum phenomena such as entanglement, interference, and nonlinear optics. These experiments advance our understanding of light-matter interactions and are crucial for quantum computing, communication, and metrology.

Integrated quantum photonics is an advanced field that combines quantum mechanics and photonic technologies on compact chip-scale platforms. It focuses on manipulating and integrating quantum states of light for complex applications.