In a recent breakthrough, researchers at the University of Würzburg have developed an innovative method to enhance the performance of quantum resistance standards. This method is based on a quantum phenomenon known as the Quantum Anomalous Hall effect. The precise measurement of electrical resistance holds significant importance in various industries such as industrial production and electronics, especially in the manufacturing of high-tech sensors, microchips, and flight controls.
The Quantum Anomalous Hall effect eliminates the need for an external magnetic field to determine resistance measurements accurately. This is a notable advantage as even the smallest deviations can have a significant impact on complex systems. Professor Charles Gould from the Institute for Topological Insulators at the University of Würzburg emphasizes the importance of precise measurements in such systems. Through this new method, the accuracy of resistance measurements can be greatly improved.
Many may be familiar with the classic Hall effect from their physics lessons. When a current flows through a conductor in the presence of a magnetic field, a voltage is generated, known as the Hall voltage. The Hall resistance obtained from dividing this voltage by current increases as the strength of the magnetic field increases. In thin layers and at sufficiently large magnetic fields, this resistance begins to exhibit discreet steps with values of exactly h/ne2, where h is Planck’s constant, e is the elementary charge, and n is an integer number.
Advancements in Quantum Anomalous Hall Effect
The Quantum Anomalous Hall effect can exist even at zero magnetic field, simplifying experiments. This is particularly beneficial when determining physical quantities such as the kilogram. The QAHE allows for the measurement of electrical resistance in the absence of a magnetic field. However, until now, QAHE measurements were limited to low currents due to an electric field that disrupted the effect at higher currents. The Würzburg physicists have addressed this challenge by neutralizing the electric field using two separate currents in a multi-terminal Corbino device.
Feasibility Study and Future Goals
In a feasibility study, the researchers demonstrated that the new measurement method matches the precision level of basic DC techniques. Their future goal is to evaluate the practicality of this method with more precise metrological tools by collaborating with specialized institutions such as the Physikalisch-Technische Bundesanstalt (PTB), the German National Metrology Institute. Professor Gould emphasizes that this method extends beyond the QAHE, offering broader applications in the field of metrology and quantum research.
This innovative approach to quantum resistance standards marks a significant advancement in the field of metrology and offers promising opportunities for enhancing the accuracy and reliability of resistance measurements in various industrial and technological applications.