Zhang Song-Bo, Trauzettel Björn
Institute for Theoretical Physics and Astrophysics, University of Würzburg, D-97074 Würzburg, Germany.
Würzburg-Dresden Cluster of Excellence ct.qmat, Germany.
Phys Rev Lett. 2019 Jun 28;122(25):257701. doi: 10.1103/PhysRevLett.122.257701.
Perfect crossed Andreev reflection (CAR) is striking for high-efficiency Cooper pair splitting, which bears promising applications in quantum communication. Recent experimental advances have disclosed the way to explore CAR in Dirac fermion systems under ultrastrong magnetic fields. We develop a scattering approach to study quantum-Hall-superconductor-quantum-Hall junctions formed by a two-dimensional time-reversal symmetric Dirac semimetal. We propose two different setups of the hybrid junction in the quantum limit, where only zeroth Landau levels are involved in transport to exploit perfect CAR. In both setups, the CAR probability can reach unity without applying bias voltage and is controllable by the magnetic field strength, the junction width, the length, and the doping of the superconductor. CAR dominates the nonlocal transport and is directly measurable by the differential conductances. We also identify a quantized spin injection per CAR event in one of the two setups. Our proposal is experimentally feasible and will be helpful for exploring high-efficiency Cooper pair splitting and spin injection in Dirac materials.
完美交叉安德烈夫反射（CAR）对于高效库珀对分裂而言十分显著，这在量子通信中具有广阔的应用前景。近期的实验进展揭示了在超强磁场下狄拉克费米子系统中探索CAR的方法。我们开发了一种散射方法来研究由二维时间反演对称狄拉克半金属形成的量子霍尔-超导体-量子霍尔结。我们提出了量子极限下混合结的两种不同设置，其中只有零阶朗道能级参与输运以利用完美CAR。在这两种设置中，CAR概率无需施加偏置电压即可达到1，并且可通过磁场强度、结宽度、长度和超导体的掺杂来控制。CAR主导非局域输运，并且可通过微分电导直接测量。我们还在两种设置之一中确定了每个CAR事件的量子化自旋注入。我们的提议在实验上是可行的，将有助于探索狄拉克材料中的高效库珀对分裂和自旋注入。
