超导体Superconductivity

1957 年巴丁、库珀和施里弗提出 BCS 理论：电子通过晶格振动（声子）的媒介产生微弱吸引，自旋和动量相反的两个电子结合成库珀对，大量库珀对凝聚到同一量子态，能隙使其不受散射，从而零电阻流动。三人获 1972 年诺贝尔物理学奖。铜氧化物和铁基高温超导体的配对机制至今尚未完全阐明，通常认为与自旋涨落有关。

In 1957 Bardeen, Cooper and Schrieffer proposed BCS theory: electrons attract each other weakly through lattice vibrations (phonons), forming Cooper pairs of opposite spin and momentum, and vast numbers of pairs condense into a single quantum state whose energy gap protects them from scattering, so they flow without resistance. The three shared the 1972 Nobel Prize in Physics. The pairing mechanism of cuprate and iron-based high-temperature superconductors is still not fully understood and is usually linked to spin fluctuations.

1911 年昂内斯用液氦冷却汞，发现在 4.2 K 时电阻突然消失（1913 年诺贝尔物理学奖）。1933 年迈斯纳和奥克森菲尔德发现完全抗磁性。1986 年贝德诺尔茨和米勒发现镧钡铜氧在约 35 K 超导（1987 年诺贝尔物理学奖），1987 年朱经武、吴茂昆以及中国科学院赵忠贤等发现钇钡铜氧（YBCO）T_c 约 93 K，首次高于液氮温度 77 K。2008 年细野秀雄发现铁基超导体；2015 年高压硫化氢在约 203 K 超导。

In 1911 Kamerlingh Onnes cooled mercury with liquid helium and saw its resistance vanish abruptly at 4.2 K (Nobel Prize in Physics 1913). Meissner and Ochsenfeld discovered perfect diamagnetism in 1933. In 1986 Bednorz and Müller found superconductivity near 35 K in lanthanum barium copper oxide (Nobel Prize in Physics 1987), and in 1987 Paul Chu and Maw-Kuen Wu, and independently Zhao Zhongxian's group in China, found yttrium barium copper oxide (YBCO) with T_c near 93 K, the first above liquid nitrogen's 77 K. Hosono discovered iron-based superconductors in 2008, and in 2015 hydrogen sulfide under high pressure was found to superconduct near 203 K.

铌钛和铌三锡超导线绕制的磁体用于医院磁共振成像、粒子加速器（大型强子对撞机）和核聚变装置；超导量子干涉器件（SQUID）可测量极微弱的磁场；超导量子比特是量子计算机的主流方案之一；高温超导电缆、磁悬浮列车和限流器也在发展中。

Magnets wound from niobium–titanium and niobium–tin wire are used in hospital MRI scanners, particle accelerators such as the Large Hadron Collider and fusion devices; superconducting quantum interference devices (SQUIDs) measure tiny magnetic fields; superconducting qubits are a leading approach to quantum computing; and high-temperature superconducting cables, maglev trains and fault-current limiters are being developed.