The field of quantum condensed-matter physics continues to amaze and intrigue researchers around the world. One of the recent discoveries in this field that has captivated the attention of scientists is the superconducting diode effect. This fascinating phenomenon allows for dissipationless supercurrent to flow in only one direction, opening up new possibilities for superconducting circuits. In a collaboration between researchers from the University of Wollongong and Monash University, the superconducting diode effect was carefully reviewed, shedding light on its potential applications in both classical and quantum computing.
Superconductivity, characterized by zero resistivity and perfect diamagnetic behavior, enables dissipationless transport and magnetic levitation. The traditional understanding of superconductors is well-explained by the Bardeen-Cooper-Schrieffer (BCS) theory proposed in 1957. However, the world of superconductivity goes beyond these conventional materials.
In recent years, researchers have delved into unconventional superconductivity, where superconducting order can be stabilized in functional materials such as magnetic superconductors, ferroelectric superconductors, and helical or chiral topological superconductors. This exploration has led to the discovery of new phenomena and opened up exciting possibilities for quantum technologies.
One of these exciting phenomena is the superconducting diode effect, where nonreciprocal supercurrent transport leads to diode effects in various superconducting materials with different geometric structures and designs. This effect has been observed in single crystals, thin films, heterostructures, nanowires, and Josephson junctions, among others.
The FLEET research team conducted a comprehensive review of the theoretical and experimental progress in the superconducting diode effect. The study not only highlighted the materials hosting this effect but also delved into device structures, theoretical models, and symmetry requirements for different physical mechanisms leading to the superconducting diode effect.
Unlike conventional semiconducting diodes, the efficiency of the superconducting diode effect is widely tunable through various extrinsic stimuli, including temperature, magnetic field, gating, device design, and intrinsic quantum mechanical functionalities. This tunability opens up new possibilities for novel device applications in superconducting and semiconducting-superconducting hybrid technologies.
One of the key findings of this research is that the direction of the supercurrent can be controlled either with a magnetic field or a gate electric field. This gate-tunable diode functionality in field-effect superconducting structures has the potential to revolutionize device applications, paving the way for advancements in superconducting and semiconducting-superconducting hybrid technologies.
The superconducting diode effect has been observed in a wide range of superconducting structures, including conventional superconductors, ferroelectric superconductors, twisted few-layer graphene, van der Waals heterostructures, and helical or chiral topological superconductors. These observations highlight the enormous potential and wide usability of superconducting diodes, significantly diversifying the landscape of quantum technologies.
With their review of the superconducting diode effect, the FLEET research team has provided valuable insights into this fascinating phenomenon. The tunability, versatility, and wide usability of superconducting diodes offer exciting possibilities for the development of future ultra-low energy superconducting and semiconducting-superconducting hybrid quantum devices. As researchers continue to explore the potential applications of the superconducting diode effect, we can look forward to groundbreaking advancements in both classical and quantum computing.
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