Science & Technology (Commonwealth Union) – A team led by researchers from the California NanoSystems Institute at UCLA has developed a novel material derived from a traditional superconductor, which allows electrons to move through it without resistance under specific conditions, such as extremely low temperatures. This experimental material exhibits properties that make it promising for use in quantum computing, an emerging technology that surpasses the capabilities of classical digital computers.
While conventional superconductors typically fail when exposed to magnetic fields of a certain strength, the new material maintains its superconducting properties under much higher magnetic fields than the theoretical limit for traditional superconductors. Additionally, the team measured the maximum electrical current the new material can carry before losing its superconductivity, by applying electricity from one direction and then from the opposite direction. They discovered that the material could carry significantly higher current in one direction compared to the other, demonstrating the superconducting diode effect. In contrast, conventional superconductors lose their zero-resistance property when subjected to equal current from either direction.
Quantum computers function according to the counterintuitive principles that dictate subatomic particle interactions. In quantum computing, the fundamental unit of information is the qubit, which can exist in multiple states simultaneously. In contrast, the bit, the basic unit in classical computing, can only be either 0 or 1.
Researchers of the study indicated that quantum computers have the potential to solve problems beyond the reach of traditional computers, but the technology is still nascent, with significant challenges to be addressed. One major challenge is the delicate nature of qubits. Even slight environmental changes can cause qubits to lose their quantum characteristics, which typically last only for microseconds.
Scientists have proposed that a unique type of superconductor, known as a chiral superconductor, might enhance qubits’ ability to retain accuracy during computations.
Both chiral and conventional superconductors rely on quantum mechanics. In these materials, pairs of electrons form a state called entanglement, which imposes specific constraints on their properties. In conventional superconductors, entangled electrons move and spin in opposite directions to comply with these constraints. However, in chiral superconductors, entangled electrons may spin in the same direction, and they must follow complex rules governing their motion. This complexity could enable new ways to control current flow or process information.
As a result of this distinction, the behavior of electrons in conventional superconductors exhibits symmetries that are disrupted in chiral superconductors, which prefer unidirectional flow, as demonstrated by the superconducting diode effect. Currently, only a few materials are considered candidates for chiral superconductivity, and they are exceedingly rare. In the present study, the researchers discovered a method to modify their material, encouraging a conventional superconductor to behave like a chiral one.
The UCLA-led team engineered a lattice with alternating layers. One layer, formed with tantalum disulfide, which is a conventional superconductor, as thin as three atoms. The subsequent layer was composed of a “left-handed” or “right-handed” molecular layer of a different compound. The researchers tested tiny nanoscale devices constructed from their lattice to determine if the material exhibited the properties of a chiral superconductor.
Quantum computing has the potential to bring about innovations such as unbreakable cybersecurity, enhanced artificial intelligence, and high-fidelity simulations of various phenomena, from drug interactions in the body to city traffic flow to financial market fluctuations. To achieve these applications, quantum computers need to significantly improve their ability to function despite potential disturbances to delicate qubits. Superconducting circuits are fundamental to many quantum computing approaches, and the superconducting diode effect produced by chiral superconductors is expected to be beneficial for creating more efficient and stable qubits.
Superconducting qubits are at the forefront of superconductor quantum technology, playing a pivotal role in the development of quantum computers. These qubits, which utilize the unique properties of superconductors, can achieve remarkable coherence times and operational stability, making them ideal candidates for quantum computation.
