Skip to main content

Quantised current steps observed in superconducting nanowires

Quantised current steps observed in superconducting nanowires

  • Date16 Jan 2023
  • Reading time 1min

Superconducting nanotechnology is a rapidly developing field with a series of promising applications. Recently, a joint team of researchers from the Royal Holloway University of London (RHUL) in collaboration with the National Physical Laboratory, the Leibniz Institute of Photonic Technology in Jena, and Aalto University in Espoo, has demonstrated photon assisted coherent tunnelling of magnetic fluxes through a superconducting nanowire.

RaisImg1Edit.jpg

The researchers at Royal Holloway who carried out the experiment.

The effect is seen as quantized current steps on the current-voltage characteristic subject to high frequency microwave radiation. It is dual to the well-known voltage Shapiro steps in Josephson junctions.

The coherent tunneling of magnetic fluxes and the formation of current steps have been theoretically predicted more than thirty years ago. A superconducting nanowire made of thin films of high-quality niobium nitride allowed researchers to observe sharp and clearly visible quantization of electric current, In = 2efn where 2e is the electric charge of a Cooper pair, f is the frequency of microwave radiation, and n is an integer number, denoting the step order. The phenomenon resembles that of the well-known voltage Shapiro steps in Josephson junctions, which are currently used in voltage standards. Similarly, the main potential application of the observed effect is the development of the current standard: each current step corresponds to integer number of Cooper pairs transferred through the nanowire per one period of microwave radiation.

The article about this exciting breakthrough has been published in Nature. The achievement is based on state-of-the-art sample fabrication at RHUL SuperFab and a series of low temperature experiments carried out by the RHUL Nanophysics&Nanotechnology group in collaboration with the NPL Quantum Metrology Institute. High-quality niobium nitride films for devices were grown in Jena. The theoretical analysis has been done at Aalto University.

Related topics

Explore Royal Holloway

Get help paying for your studies at Royal Holloway through a range of scholarships and bursaries.

There are lots of exciting ways to get involved at Royal Holloway. Discover new interests and enjoy existing ones.

Heading to university is exciting. Finding the right place to live will get you off to a good start.

Whether you need support with your health or practical advice on budgeting or finding part-time work, we can help.

Discover more about our academic departments and schools.

Find out why Royal Holloway is in the top 25% of UK universities for research rated ‘world-leading’ or ‘internationally excellent’.

Royal Holloway is a research intensive university and our academics collaborate across disciplines to achieve excellence.

Discover world-class research at Royal Holloway.

Discover more about who we are today, and our vision for the future.

Royal Holloway began as two pioneering colleges for the education of women in the 19th century, and their spirit lives on today.

We’ve played a role in thousands of careers, some of them particularly remarkable.

Find about our decision-making processes and the people who lead and manage Royal Holloway today.