Detectors for extreme luminosity: Belle II

We describe the Belle II detector at the SuperKEKB electron-positron accelerator. SuperKEKB operates at the energy of the ϒ(4S) resonance where pairs of B mesons are produced in a coherent quantum mechanical state with no additional particles. Belle II, the first Super B factory detector, aims to achieve performance comparable to the original Belle and BaBar B factory experiments, which first measured the large CP violating effects in the B meson system, with much higher luminosity collisions and larger beam-induced backgrounds.