The research of Prof. Chang and his Theoretical Quantum Nanophotonics group at ICFO is based upon a vision that quantum effects are at the forefront of future technologies and discoveries, and that nanophotonic systems will be a prominent platform for this frontier. Specifically, they aim to harness the unique configurability, large optical forces, and strong light-matter interaction strengths achievable in nanophotonic systems to produce new applications and phenomena involving matter and light, which have no analogue in macroscopic setups. The group also develops theoretical techniques that enable a better understanding of the complex phenomena at play. The work is highly inter-disciplinary, and the group explores the potential impact across atomic physics, quantum optics, nonlinear optics, nano-mechanics, low-dimensional materials, and quantum information science. They also collaborate with leading experimental groups to bring their theoretical ideas toward reality.