In the world of quantum condensed-matter physics, the superconducting diode effect has emerged as one of the most captivating phenomena, captivating the minds of FLEET researchers from the University of Wollongong and Monash University. This effect allows for dissipationless supercurrent to flow in a single direction, presenting exciting possibilities for superconducting circuits and paving the way for future advancements in ultra-low energy superconducting and semiconducting-superconducting hybrid quantum devices. The potential of this discovery extends to both classical and quantum computing, showcasing the versatility and power of the superconducting diode.
Understanding the underlying principles of superconductivity is crucial in comprehending the significance of the superconducting diode effect. Superconductivity is defined by zero resistivity and perfect diamagnetic behavior, enabling transport without energy loss and magnetic levitation. The conventional understanding of superconductors, as explained by the Bardeen-Cooper-Schrieffer (BCS) theory proposed in 1957, emphasizes their characteristic properties. However, the realm of unconventional superconductivity has opened up possibilities for superconducting order in various functional materials, including magnetic superconductors, ferroelectric superconductors, and topological superconductors.
Recent breakthroughs have witnessed the emergence of nonreciprocal supercurrent transport, leading to the discovery of diode effects within different superconducting materials. From single crystals and thin films to heterostructures, nanowires, and Josephson junctions, researchers have observed the manifestation of the superconducting diode effect. The diverse geometric structures and designs of these materials have shed light on the immense scope for advancements in this field.
The FLEET research team sought to delve into the theoretical and experimental progress surrounding the superconducting diode effect (SDE). Through their comprehensive review, they uncovered crucial insights regarding materials hosting SDE, device structures, theoretical models, and the symmetry requirements that enable different physical mechanisms leading to SDE. This in-depth analysis serves as a guiding light for future research and paves the way for further exploration into the possibilities of the superconducting diode.
What sets the superconducting diode effect apart from its conventional semiconducting counterparts is its remarkable tunability. External factors such as temperature, magnetic field, gating, and device design, along with intrinsic quantum mechanical functionalities like Berry phase, band topology, and spin-orbit interaction, offer a wide range of possibilities to manipulate and enhance the efficiency of SDE. With the ability to control the direction of supercurrent through magnetic fields or gate electric fields, novel device applications for superconducting and semiconducting-superconducting hybrid technologies become achievable, as highlighted by co-author Prof Michael Fuhrer of Monash University.
The superconducting diode effect has made its mark in various structures, spanning from conventional superconductors to ferroelectric superconductors, twisted few-layer graphene, van der Waals heterostructures, and topological superconductors. This wide range of applications and materials demonstrates the vast potential and versatility of superconducting diodes, revolutionizing the landscape of quantum technologies. Prof Xiaolin Wang of the University of Wollongong, who is a Chief Investigator of FLEET, aptly captures the essence of this dynamic field by emphasizing its enormous potential and wide usability.
The superconducting diode effect has emerged as a groundbreaking phenomenon in quantum condensed-matter physics. The collaborative efforts of FLEET researchers have shed light on the intricacies and possibilities of this effect, opening pathways for future advancements in quantum technologies. The tunability and versatility of the superconducting diode offer new horizons for superconducting and semiconducting-superconducting hybrid devices, imparting a promise of innovation and progress that will shape the future of classical and quantum computing.