A flux transformer, consisting of a superconducting primary loop (pick-up loop) in series with a superconducting secondary loop on which measurement is done, is considered to optimize the approach and sensitivity of the Superconducting QUantum Interference Device (SQUID). Performance of such a pick-up loop placed above a magnetic particle is investigated using the numerical Ginzburg-Landau (GL) simulations. By solving 3D GL equations, static properties of the device such as the distribution of Cooper-pair density and the screening current in the secondary coil have been investigated as a function of the dimensions of the primary loop. Dynamic properties, such as current-voltage characteristics and flux-dependent critical current of the device have also been addressed, all leading to conclusion that smaller size pick-up loop is the first requirement for its optimal sensitivity.

磁通变压器由一个超导初级回路（拾取回路）和一个进行测量的超导次级回路串联组成，被认为可以优化超导量子干扰装置（SQUID）的方法和灵敏度。使用数值Ginzburg-Landau（GL）模拟研究了放置在磁性粒子上方的此类拾波环的性能。通过求解3D GL方程，已经研究了设备的静态特性，例如库珀对密度的分布和次级线圈中的屏蔽电流，这些特性是初级环路尺寸的函数。还解决了器件的动态特性，例如电流-电压特性和与磁通有关的临界电流，