Trinity team builds device that could speed up quantum tech development

7 Jul 2020

Image: © Ocelia_Mg/

Researchers unveiled a device that emits single particles of light which could have a ‘striking effect’ on quantum technologies.

Researchers at CRANN and the School of Physics in Trinity College Dublin (TCD) believe they have made a significant improvement on previous designs of photonic systems used to develop quantum computers and other similar technologies.

Unlike a traditional computer that uses binary ‘bits’ that can be either one or zero, a quantum bit (qubit) can be one, zero or both at the same time. In order to make quantum computing a viable reality, some researchers are looking at how to make use of the quantum properties of light at the nanoscale as qubits.

Writing in Nano Letters, the Trinity team detailed a new device that emits single particles of light, or photons, in a controlled fashion in time and space from quantum emitters. The photons are emitted from nanoscale materials known as quantum dots and, 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 occurs when a pair or group of particles are quantum-mechanically linked in such a way that the quantum state of each particle cannot be described independently of the state of the others.

A tip excited by light

“The device works by placing a metal tip within a few nanometres of a surface containing the quantum dots,” said Prof John Donegan of the research team.

“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 team also said that the device is much simpler than current systems that attempt to fix a metal tip in close proximity to a quantum dot.

According to Prof Ortwin Hess, it’s expected the device and its operation “will have a striking effect on research in quantum emitters for quantum technologies”.

Last April, CRANN researchers were involved in another quantum computing breakthrough. These experimental researchers were able to observe the vibrations of molecular qubits for the first time, taking science one step closer to a more efficient quantum computer.

Colm Gorey was a senior journalist with Silicon Republic