We propose a universal mechanism for the Josephson diode effect in short Josephson junctions. The proposed mechanism is due to finite Cooper pair momentum and is a manifestation of simultaneous breaking of inversion and time-reversal symmetries. The diode efficiency is up to 40%, which corresponds to an asymmetry between the critical currents in opposite directions $I_{c+}/I_{c-} \approx$ 230%. We show that this arises from both the Doppler shift of the Andreev bound state energies and the phase-independent asymmetric current from the continuum. Finally, we propose a simple scheme for achieving finite-momentum pairing, which does not rely on spin-orbit coupling and thus greatly expands existing platforms for the observation of supercurrent diode effects.
We propose a realization of the superconducting diode effect in flux biased superconducting circuits of Josephson junctions. So far the observation of the superconducting diode effect has been limited to rather exotic material platforms. In theoretical proposals, it relied on a non-sinusoidal form of the current phase relation of Josephson junctions. Here, we show how the diode effect can be engineered in superconducting circuits without any such requirements. The only necessary ingredients are standard sinusoidal Josephson junctions and flux bias lines that are readily available in scalable i…
It is necessary to break both time-reversal and parity symmetries to realize a Josephson, or superconducting, diode exhibiting nonreciprocal critical direct-currents (DC). In fact, these conditions are still insufficient. The dependencies of the free energy on the phase difference across the junction and the magnetic field are classified, exhibiting the current-reversion (JR), field-reversion, and field-current reversion conditions, respectively. To exhibit the DC Josephson diode effect, all symmetries satisfying the JR condition need to be broken. The relations of critical currents with respe…
Electric Control of Polarity in Spin-Orbit Josephson Diode
Pohang University of Science and Technology (POSTECH)（浦项科技大学）；Korea Advanced Institute of Science and Technology (KAIST)（韩国科学技术院）；Center for Theoretical Physics of Complex Systems, Institute of Basic Science (IBS)（基础科学研究院复杂系统理论物理中心）；University of Tennessee（田纳西大学）；Quantum Technology Institute, Korea Research Institute of Standards and Science (KRISS)（韩国标准科学研究所量子技术研究所）
Motivated by recent progress in the superconductivity nonreciprocal phenomena, we study the general theory of Josephson diodes. The central ingredient for Josephson diodes is the asymmetric proximity process inside the tunneling barrier. From the symmetry breaking point of view, there are two types of Josephson diodes, inversion breaking and time-reversal breaking. For the inversion breaking case, applying voltage bias could effectively tune the proximity process like the voltage-dependent Rashba coupling or electric polarization giving rise to $I_c(V)\neq I_c(-V)$ and $I_{r+}\neq I_{r-}$. For…
A Josephson diode is a non-reciprocal circuit element that supports a larger dissipationless supercurrent in one direction than in the other. In this work, we propose and theoretically study a class of Josephson diodes based on supercurrent interferometers containing mesoscopic Josephson junctions, such as point contacts or quantum dots, which are not diodes themselves but possess non-sinusoidal current-phase relations. We show that such Josephson diodes have several important advantages, like being electrically tunable and requiring neither Zeeman splitting nor spin-orbit coupling, only time-…
International Center for Quantum Design of Functional Materials (ICQD), University of Science and Technology of China（中国科学技术大学量子功能材料国际设计中心）；Hefei National Laboratory（合肥国家实验室）
Vortex-parity-controlled diode effect in Corbino topological Josephson junctions
Harvard University（哈佛大学）；Sungkyunkwan University（成均馆大学）；Institute for Basic Science（基础科学研究院）；John A. Paulson School of Engineering and Applied Sciences（约翰·保尔逊工程与应用科学学院）；Columbia University（哥伦比亚大学）；Cornell University（康奈尔大学）；Weizmann Institute of Science（魏茨曼科学研究所）；Princeton University（普林斯顿大学）；National Institute for Materials Science（国立材料研究所）
School of Science, Qingdao University of Technology（青岛理工大学理学院）；International Center for Quantum Materials, School of Physics, Peking University（北京大学物理学院量子材料科学中心）；Hefei National Laboratory（合肥国家实验室）
Josephson diode effect via a non-equilibrium Rashba system
Advanced Science Research Center, Japan Atomic Energy Agency（日本原子能机构先进科学研究中心）；RIKEN Center for Emergent Matter Science (CEMS)（理化学研究所 emergent matter 科学中心）
Vortex-Number-Controlled Josephson Diode Polarity in Corbino Junctions
Fudan University（复旦大学）；Shanghai Research Center for Quantum Sciences（上海量子科学研究中心）；Institute for Nanoelectronic Devices and Quantum Computing, Fudan University（复旦大学纳米电子器件与量子计算研究所）；Hefei National Laboratory（合肥国家实验室）
The simultaneous co-existence and gate-tuneability of the superconducting (SC), magnetic and topological orders in magic angle twisted bilayer graphene (MATBG) open up entirely new possibilities for the creation of complex hybrid Josephson junctions (JJ). Here we report on the creation of gate-defined, magnetic Josephson junctions in MATBG, where the weak link is gate-tuned close to the correlated state at a moiré filling factor of ν=-2. A highly unconventional Fraunhofer pattern emerges, which is phase-shifted and asymmetric with respect to the current and magnetic field directions, and shows…
Superconducting diodes are a recently-discovered quantum analogueue of classical diodes. The superconducting diode effect relies on the breaking of both time-reversal and inversion symmetry. As a result, the critical current of a superconductor can become dependent on the direction of the applied current. The combination of these ingredients naturally occurs in proximitized semiconductors under a magnetic field, which is also predicted to give rise to exotic physics such as topological superconductivity. In this work, we use InSb nanowires proximitized by Al to investigate the superconducting …
Pseudo-superconducting-diode effect in ferroelectric Josephson junctions
Kavli Institute of Nanoscience, Delft University of Technology（代尔夫特理工大学卡弗里纳米科学研究所）；Department of Quantum Nanoscience, Delft University of Technology（代尔夫特理工大学量子纳米科学系）；Department of Quantum Technology, Netherlands Organisation for Applied Scientific Research (TNO)（荷兰应用科学研究组织（TNO）量子技术部）
Many-body Josephson diode effect in superconducting quantum interferometers
Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences（中国科学院上海微系统与信息技术研究所）；School of Physical Science and Technology, ShanghaiTech University（上海科技大学物理科学与技术学院）；University of Chinese Academy of Sciences（中国科学院大学）；Department of Physics and Institute for Quantum Science and Technology, Shanghai University（上海大学物理系与量子科学技术研究院）；Shanghai Key Laboratory of High Temperature Superconductors, Shanghai University（上海大学高温超导上海市重点实验室）
We report evidence of non-reciprocal dissipation-less transport in single ballistic InSb nanoflag Josephson junctions, owing to a strong spin-orbit coupling. Applying an in-plane magnetic field, we observe an inequality in supercurrent for the two opposite current propagation directions. This demonstrates that these devices can work as Josephson diodes, with dissipation-less current flowing in only one direction. For small fields, the supercurrent asymmetry increases linearly with the external field, then it saturates as the Zeeman energy becomes relevant, before it finally decreases to zero a…
