Scientists create new device to light up the way for quantum
technologies

Date:
July 7, 2020
Source:
Trinity College Dublin
Summary:
Researchers have created an innovative new device that will emit
single particles of light, or photons, from quantum dots that are
the key to practical quantum computers, quantum communications,
and other quantum devices.



FULL STORY ========================================================================== Researchers at CRANN and the School of Physics at Trinity College Dublin
have created an innovative new device that will emit single particles
of light, or photons, from quantum dots that are the key to practical
quantum computers, quantum communications, and other quantum devices.


==========================================================================
The team has made a significant improvement on previous designs in
photonic systems via their device, which allows for controllable,
directional emission of single photons and which produces entangled
states of pairs of quantum dots.

Qubits and the promise of quantum computing The promise of quantum
computers leverages the properties of quantum bits - - "qubits" -- to
execute computations. Current computers process and store information in
bits of either 0s or 1s whereas qubits can be 0 and 1 simultaneously. That means quantum computers will have much greater computational powers over
and above classical computers.

Scientists are exploring different options and designs to make quantum computing a viable reality. One proposed idea utilises photonic systems,
making use of quantum properties of light at the nanoscale, as qubits. The Trinity team explores such a system in their recently published paper
in the high- profile journal Nano Letters.

Their system utilises single photons of light emitted in a controlled
fashion in time and space from quantum emitters (nanoscale materials
known as quantum dots). For applications such as quantum computing,
it is necessary to control emissions from these dots and to produce
quantum entanglement of emission from pairs of these dots.

Quantum entanglement is a fundamental property of quantum mechanics and
occurs when a pair or group of particles are quantum-mechanically linked
in a way such that the quantum state of each particle of the pair cannot
be described independently of the state of the others. Essentially,
two entangled quantum dots can emit entangled photons.

Professor John Donegan, CRANN and Trinity's School of Physics, said: "The device works by placing a metal tip within a few nanometers of a surface containing the quantum dots. The tip is excited by light and produces an electric field of such enormous intensity that it can greatly increase
the number of single photons emitted by the dots. This strong field
can also couple emission from pairs of quantum dots, entangling their
states in a way that is unique to quantum emitters of light." The other significant advantage is the mechanism by which the device works over
current state-of-art photonic devices for quantum computing applications.

Professor Ortwin Hess, Professor of Quantum Nanophotonics in Trinity's
School of Physics and CRANN, added: "By scanning the metal tip over the
surface containing the quantum dots, we can generate the single photon
emission as required. Such a device is much simpler than current systems
that attempt to fix a metal tip, or a cavity, in close proximity to a
quantum dot. We now expect that this device and its operation will have a striking effect on research in quantum emitters for quantum technologies."

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


========================================================================== Journal Reference:
1. Frank Bello, Nuttawut Kongsuwan, John F. Donegan, Ortwin
Hess. Controlled
Cavity-Free, Single-Photon Emission and Bipartite Entanglement
of Near- Field-Excited Quantum Emitters. Nano Letters, 2020; DOI:
10.1021/ acs.nanolett.0c01705 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200707113318.htm

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