Nuclear magnetic resonance for quantum computing: Techniques and recent achievements
Xin Tao1, Wang Bi-Xue1, Li Ke-Ren1, Kong Xiang-Yu1, Wei Shi-Jie1, Wang Tao1, Ruan Dong1, Long Gui-Lu1, 2, 3,
       

(color online) Quantum circuit for implementing the HHL algorithm in NMR with r=2 and . Single-qubit operations S and H are respectively phase gate and Hadamard gate. , . is the rotation operation around y axis. . The vertical segment with × means an SWAP operation.