Will twisted superconducting flakes make better components for quantum computers?

Date:
September 28, 2021
Source:
University of Bath
Summary:
Researchers have found a way to make 'single-crystal flake' devices
that are so thin and free of defects, they have the potential to
outperform components used today in quantum computer circuits.



FULL STORY ========================================================================== Researchers at the University of Bath in the UK have found a way to make 'single-crystal flake' devices that are so thin and free of defects,
they have the potential to outperform components used today in quantum
computer circuits.


==========================================================================
The study is published this month in the journal Nano Letters.

The team from the university's Department of Physics made its discovery
while exploring the junction between two layers of the superconductor
niobium diselenide (NbSe?) after these layers had been cleaved apart,
twisted about 30 degrees with respect to one another, then stamped back together. In cleaving, twisting and recombining the two layers, the
researchers were able to build a Superconducting Quantum Interferometer
Device (SQUID) -- an extremely sensitive sensor used to measure incredibly
tiny magnetic fields.

SQUIDs have a wide range of important applications in areas that include healthcare (as seen in cardiology and magnetoencephalography -- a test
that maps brain function) and mineral exploration.

SQUIDS are also the building blocks of today's commercial quantum
computers - - machines that perform certain computational tasks much
more rapidly than classical computers. Quantum computing is still
in its infancy but in the next decade, it is likely to transform the problem-solving capacity of companies and organisations across many
sectors -- for instance by fast-tracking the discovery of new drugs
and materials.

"Due to their atomically perfect surfaces, which are almost entirely
free of defects, we see potential for our crystalline flakes to play
a significant role in building quantum computers of the future," said
Professor Simon Bending, who carried out the research together with
his PhD student Liam Farrar. "Also, SQUIDs are ideal for studies in
biology -- for instance, they are now being used to trace the path of magnetically-labelled drugs through the intestine - - so we're very
excited to see how our devices could be developed in this field too."
As Professor Bending is quick to point out, however, his work on SQUIDs
made using NbSe? flakes is very much at the start of its journey. "This
is a completely new and unexplored approach to making SQUIDs and a lot
of research will still have to done before these applications become a reality," he said.

Extremely thin single crystals The flakes from which the Bath
superconductors are fabricated are extremely thin single crystals
(10,000 times thinner than a human hair) that bend easily, which also
makes them suitable for incorporation into flexible electronics, as
used in computer keyboards, optical displays, solar cells and various automotive components.

Because the bonds between layers of NbSe? are so weak, cleaved flakes --
with their perfectly flat, defect-free surfaces -- create atomically sharp interfaces when pushed back together again. This makes them excellent candidates for the components used in quantum computing.

While this is not the first time NbSe₂ layers have been stamped
together to create a weak superconducting link, this is the first
demonstration of quantum interference between two such junctions patterned
in a pair of twisted flakes. This quantum interference has allowed the researchers to modulate the maximum supercurrent that can flow through
their SQUIDs by applying a small magnetic field, creating an extremely sensitive field sensor. They were also able to show that the properties
of their devices could be systematically tuned by varying the twist
angle between the two flakes.

========================================================================== Story Source: Materials provided by University_of_Bath. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Liam S. Farrar, Aimee Nevill, Zhen Jieh Lim, Geetha Balakrishnan,
Sara
Dale, Simon J. Bending. Superconducting Quantum Interference in
Twisted van der Waals Heterostructures. Nano Letters, 2021; 21
(16): 6725 DOI: 10.1021/acs.nanolett.1c00152 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210928102233.htm

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