The proposed quantum internet could transmit data over much longer distances than previously thought, thanks to the creation of an exceptionally bright light source that was developed by innovating a combination of existing technologies. (Image credit: Pitris/Getty Images)
Researchers have developed an “exceptionally bright” light source capable of generating quantum-entangled photons (light particles) that could be used to securely transmit data in a future high-speed quantum communications network.
A future quantum internet could transmit information using pairs of entangled photons — meaning particles exchange data across time and space, regardless of distance. Based on the counterintuitive principles of quantum mechanics, information encoded in these entangled photons could be transmitted at high speeds, while their “quantum coherence” — the state in which the particles are entangled — provides protection against data interception.
However, one of the key challenges in creating a quantum internet is that the intensity of these photons can decrease as they travel; light sources have not been bright enough. For a quantum internet capable of transmitting data over long distances to succeed, the photons must be powerful enough to avoid “decoherence,” a process in which entanglement is lost and the information they contain disappears.
In a study published July 24 in the journal eLight, scientists from Europe, Asia and South America have developed a new type of quantum signal source using existing technology that produces very high brightness.
This was achieved by combining a photon dot emitter (a generator of single photons or light particles) with a quantum resonator (a device for amplifying a quantum signature), which made it possible to create a new powerful quantum signal.
What is particularly interesting is that the individual technologies have been independently tested in laboratories, but have only been used individually. This study is the first example of their combined use.
The researchers combined a photonic point emitter with a circular Bragg resonator (a reflector for directing electromagnetic waves) on a piezoelectric actuator (a device that generates electricity when exposed to heat or voltage). The result was an improved version of the photonic point emitter that could fine-tune the emitted photons to achieve maximum polarized entanglement. This was controlled using a piezoelectric actuator.
The photon pairs generated by the device demonstrated high entanglement fidelity and extraction efficiency, meaning that each photon was bright enough for practical applications and retained its “quantum signature” (a valuable quantum property) well. Previously, achieving both the desired level of brightness and high entanglement fidelity was difficult, as each required a separate technology and was difficult to combine in a scalable way.
This is a significant advance in practical quantum technologies, demonstrating how they can be combined to create a more powerful and efficient light source.
Unfortunately, we shouldn’t expect a quantum internet anytime soon, as the various technologies are still in the experimental and developmental stages. The photonic emitter used in the study also required the use of toxic materials, including arsenic, which must be handled with care. There are also safety concerns associated with gallium arsenide, which is the material from which the photonic point emitter was made. Fisher Scientific, a company that supplies laboratory equipment and chemicals for scientific research, considers gallium arsenide to be dangerous for several reasons, including its carcinogenic properties.
Safety issues associated with the use of these materials may limit the scalability of the proposed methodology. Therefore, it may be necessary to find viable alternative materials for generating bright, entangled photons for the upcoming quantum communication network.
The next step in the development process will be to integrate the diode-like structure into the piezoelectric actuator. This will allow the creation of an electric field through the quantum dots to prevent decoherence and therefore improve the degree of entanglement.
Sourse: www.livescience.com
