Detection and quantification of entanglement with measurement-device-independent and universal entanglement witness
Ke Zhi-Jin1, 2, Wang Yi-Tao1, 2, Yu Shang1, 2, Liu Wei1, 2, Meng Yu1, 2, Li Zhi-Peng1, 2, Wang Hang1, 2, Li Qiang1, 2, Xu Jin-Shi1, 2, Xiao Ya3, Tang Jian-Shun1, 2, †, Li Chuan-Feng1, 2, ‡, Guo Guang-Can1, 2
       

The scheme of extremal semiquantum nonlocal game. Players (Alice and Bob) share state ρ^AB , and then, they receive quantum questions τ^iA0 , ω^iB0 from referee (Charlie). After performimg local POVM on their own part of shared state and the quantum question state, they return classical answers x and y to Charlie. LOCC is allowed in this game. If the shared state is entangled, then Alice and Bob can always win this game (achieve payoff value larger than 0) as long as they perform suitable measurements.