One of the many scientific and
engineering challenges to realizing the prospects of quantum
computing—which involves the use of quantum phenomena, like entanglement,
to perform complex calculations—is creating a device that can
electrically generate a single photon to be used for carrying data in a quantum
network. One method for producing these single photons is the use of complex
multiple laser arrangements that have been precisely set up
with optical components to produce these single photons. Lately, layered
materials that serve as quantum
emitters have begun to show a way forward. But even these
layered materials require some kind of light source to trigger the emission of
a single photon.
Now researchers at the University of
Cambridge in England have constructed devices made from thin layers of
graphene, boron nitride, and transition metal dichalcogenides (TMDs) that generate a
single photon entirely electrically. The combination of these
three types of two-dimensional (2D) materials produces devices that are
essentially all-electrical ultrathin quantum light-emitting diodes (LEDs).
In research described in the journal Nature Communications, the
U.K.-based researchers demonstrated that the TMDs of
tungsten diselenide and tungsten disulfide, which are both known for
being optically active semiconductors, can serve as a platform for producing
quantum-light generating devices.
The TMD layers provide a tightly confined
area in two dimensions where electrons fill in holes. When an electron
moves into one of these holes that reside at a lower energy, the difference in
energy produces a photon. In the quantum LEDs produced by the U.K. researchers,
a voltage pushes electrons through the device and fill holes, producing single
photons when they do.
The researchers believe that this ultrathin
platform run entirely electrically will bring on-chip single-photon emission
for quantum communication closer to reality.
“Ultimately, we need fully integrated
devices that we can control by electrical impulses, instead of a laser that
focuses on different segments of an integrated circuit,” said Professor Mete
Atatüre of Cambridge’s Cavendish Laboratory, one of the paper’s senior authors,
in a press release. “For quantum communication with single photons, and quantum
networks between different nodes, we want to be able to just drive current and
get light out. There are many emitters that are optically excitable, but only a
handful are electrically driven.”
This research demonstrated that tungsten
diselenide can operate electrically as a quantum emitter. But the researchers
also showed that tungsten disulfide is an entirely new class of quantum
emitter and offers all-electrical single-photon generation in the visible
spectrum.
Atatüre added: “We chose tungsten disulfide
because we wanted to see if different materials offered different parts of the
spectra for single photon emission. With this, we have shown that the
quantum emission is not a unique feature of tungsten disulfide, which suggests
that many other layered materials might be able to host quantum dot-like
features as well.”
Keywords:quantum communications,tungsten dislenide,quantum
computing,lasers,tungsten disulfide,LEDs, graphere, transition metal
dichalcogenides, quantum emitters
Source:IEEE
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