Researchers have identified a two-dimensional material that could be used to
store quantum information at room temperature.
Quantum memory is a major building block to be addressed in the building of
a quantum internet, where quantum information is securely stored and sent
via photons, or particles of light.
Researchers from the Cavendish Laboratory at the University of Cambridge, in
collaboration with colleagues from UT Sydney in Australia, have identified a
two-dimensional material, hexagonal boron nitride, that can emit single
photons from atomic-scale defects in its structure at room temperature.
The researchers discovered that the light emitted from these isolated
defects gives information about a quantum property that can be used to store
quantum information, called spin, meaning the material could be useful for
quantum applications. Importantly, the quantum spin can be accessed via
light and at room temperature.
The finding could eventually support scalable quantum networks built from
two-dimensional materials that can operate at room temperature. The results
are reported in the journal Nature Communications.
Future communication networks will use single photons to send messages
around the world, which will lead to more secure global communication
technologies.
Computers and networks built on the principles of quantum mechanics would be
both far more powerful and more secure than current technologies. However,
in order to make such networks possible, researchers need to develop
reliable methods of generating single, indistinguishable photons as carriers
of information across quantum networks.
"We can send information from one place to another using photons, but if
we're going to build real quantum networks, we need to send information,
store it and send it somewhere else," said Dr. Hannah Stern from Cambridge's
Cavendish Laboratory, the study's co-first author, along with Qiushi Gu and
Dr. John Jarman. "We need materials that can hold onto quantum information
for a certain amount of time at room temperature, but most current material
platforms we've got are challenging to make and only work well at low
temperatures."
Hexagonal boron nitride is a two-dimensional material that is grown by
chemical vapor deposition in large reactors. It's cheap and scalable. Recent
efforts have revealed the presence of single photon emitters and the
presence of a dense ensemble of optically accessible spins, but not
individually isolated spin-photon interfaces operating under ambient
conditions.
"Usually, it's a pretty boring material that's normally used as an
insulator," said Stern, who is a Junior Research Fellow at Trinity College.
"But we found that there are defects in this material that can emit single
photons, which means it could be used in quantum systems. If we can get it
to store quantum information in spin, then it's a scalable platform."
Stern and her colleagues set up a hexagon boron nitride sample near a tiny
gold antenna and a magnet of set strength. By firing a laser at the sample
at room temperature, they were able to observe lots of different magnetic
field-dependent responses on the light being emitted from the material.
The researchers found that when they shone the laser on the material, they
were able to manipulate the spin, or inherent angular momentum, of the
defects, and use the defects as a way of storing quantum information.
"Typically, the signal is always the same in these systems, but in this
case, the signal changes depending on the particular defect we're studying,
and not all defects show a signal, so there is a lot to still discover,"
said co-first author Qiushi Gu. "There's a lot of variation across the
material, like a blanket draped over a moving surface—you see lots of
ripples, and they're all different."
Professor Mete Atature, who supervised the work, adds "now that we have
identified optically accessible isolated spins at room temperature in this
material, the next steps will be to understand their photophysics in detail
and explore the operation regimes for possible applications including
information storage and quantum sensing. There will be a stream of fun
physics following this work."
Reference:
Hannah L. Stern et al, Room-temperature optically detected magnetic
resonance of single defects in hexagonal boron nitride, Nature
Communications (2022).
DOI: 10.1038/s41467-022-28169-z
Tags:
Physics