Researchers from the University of Copenhagen and Ruhr University have made a significant breakthrough by figuring out how to control two quantum light sources instead of just one. This new technology has the potential to be developed in order to create a universal error-corrected quantum computer, which is frequently referred to as the holy grail of quantum computing. Although a small step up from one to two may sound too anticlimatic to be termed a breakthrough, it is possible that it will be.
The University of Copenhagen reports that researchers all over the world have been working for years to create stable quantum light sources in order to achieve what is referred to as quantum mechanical entanglement. Entanglement is a term used in photonic quantum computing to describe situations in which two light sources can have instantaneous effects on one another, possibly even over vast geographical distances. The creation of an effective quantum computer is fundamentally dependent on the concept of entanglement.
When two light sources are entangled, one will have an immediate effect on the other if you control one of them. After that, this technology can be scaled up to create an entire network of interconnected quantum light sources that can be used to carry out "quantum bit operations," which are similar to what are done with regular bits in computers.
Due to their extreme noise sensitivity, researchers were unable to create two entangled light sources. The issue is primarily caused by spectral jitter caused by carriers' "charge noise" in the vicinity of the quantum emitter. “We overcome this by employing ultra-clean materials and applying a low-noise bias voltage across the quantum dot emitter,” indianexpress.com was informed via email by co-author Peter Lodahl of the research paper that was published in the journal Science.
Researchers used a nanochip the size of a human hair to accomplish this feat. This nanochip has been developed by the team over the past five years, eventually enhancing its performance.
"We start with extremely clean materials that our colleagues in Bochum, Germany, grew in a UHV molecular-beam epitaxy chamber. After that, we use our specialized and extensively tested etching procedures to create small chip devices. Finally, Lodahl explained, "We fabricate electrical contact on the samples and shield the experiment from picking up excessive electrical noise."
The researchers claim that this technology can be modified to make use of 20 to 30 entangled quantum light sources, which could be put to use in the construction of a "universal error-corrected quantum computer," a project into which technology companies are investing billions of dollars.
According to the EU Research and Innovation Magazine, the primary distinction between a classical computer and a quantum computer is their distinct rule sets. Quantum computers, in contrast to conventional ones and zeros, do not employ "bits." Instead, they use "qubits" in their work.
Bits can be compared to a light switch, which can be either on or off, indicating one or zero. Qubits possess a unique property that enables them to exist in both zero and one states. Theoretically, quantum computers will be able to perform tasks previously unimaginable for them.
I believe that hard quantum problems would be the primary application for quantum computers. For instance, in the context of comprehending intricate chemical reactions, such as those in a pipeline for drug discovery or the engineering of new materials. Lodahl said, referring to the various quantum technologies, "quantum computers are not yet very mature, and around the world, different qubit platforms are being researched, each having its own pros and cons."
“Photonics is becoming a more and more serious contender, primarily due to the fact that it appears to be simpler to scale up to large processors than some of the competing approaches. Lodahl added, "Our work is an important first step toward using deterministic single-photon sources for photonic quantum computing."
A university cannot afford to construct a system that can control ten, fifteen, or more light sources, according to the researchers. Therefore, it is now up to other actors, such as laboratories and private businesses, to advance the research and discover potential uses for the technology.