Physicists Overcome Decades-Long Hurdle in Fundamental Physics: Control Two Quantum Light Sources Simultaneously

The University of Copenhagen, in partnership with Ruhr University Bochum, has achieved a significant milestone in quantum research, which has long been a challenging issue. Researchers can now manipulate two quantum light sources instead of just one, enabling them to generate quantum mechanical entanglement, a crucial phenomenon in quantum physics.

Although this may not appear to be a significant development for those unfamiliar with quantum mechanics, it has enormous implications for businesses and other entities that want to capitalize on this technology. While going from one to two may seem insignificant in most fields, it is a critical accomplishment in the realm of quantum physics.

For many years, researchers worldwide have worked tirelessly to create steady quantum light sources and accomplish quantum mechanical entanglement, a phenomenon with nearly science fiction-like qualities in which two light sources can instantaneously affect each other, even across vast distances. Entanglement serves as the foundation for quantum networks and is a key component in developing an effective quantum computer.

Controlling Two Quantum Light Sources

The Niels Bohr Institute researchers have recently achieved this breakthrough and published their findings in the prestigious journal Science. According to Professor Peter Lodahl, one of the researchers involved in the study, this achievement is a significant advancement towards elevating the development of quantum technology to the next level, and eventually "quantizing" the internet, computers, and encryption utilized by society.

According to Professor Peter Lodahl, who has been conducting research in the field since 2001, they have made a significant breakthrough by controlling two quantum light sources and linking them to each other, despite it seeming like a minor accomplishment. This achievement has been built upon the last two decades of work and has uncovered the key to scaling up the technology, which is essential for developing groundbreaking quantum hardware applications. This breakthrough has been made possible using a nanochip, which the researchers have also developed in recent years, and is only slightly larger than the width of a human hair.

Peter Lodahl's team is focusing on a particular kind of quantum technology that utilizes photons, or light particles, as microcarriers to transfer quantum information. Despite being a leading group in this area of quantum physics, they were only capable of controlling one light source at a time due to the high sensitivity of light sources to external noise, making replication highly challenging. However, in their recent breakthrough, the research team was successful in generating two indistinguishable quantum light sources instead of just one.

An Entanglement that Leads to Immediate Impact

Postdoctoral researcher Alexey Tiranov, the lead author of the article, clarifies that entanglement leads to the immediate impact of one light source by controlling another, allowing for the creation of an entire network of entangled quantum light sources, which can interact with one another and perform quantum bit operations more powerfully than traditional computer bits. The reason behind this enhanced processing power is the ability of a quantum bit to represent both 1 and 0 simultaneously, which is impossible with today's computer technology. Professor Lodahl also adds that a single quantum light source emitting just 100 photons contains more information than the world's most significant supercomputer can process.

A universal error-corrected quantum computer, which is the ultimate "holy grail" of quantum technology, can potentially be built by utilizing 20-30 entangled quantum light sources. This goal has attracted massive investments from large IT companies. According to Lodahl, the most significant challenge has been moving from controlling one to two quantum light sources, requiring the development of ultra-quiet nanochips and precise control over each light source. With this new research development, the basic research groundwork in quantum physics is now in place, paving the way for other entities to apply the research and use it in a variety of technologies such as computers, the internet, and encryption.

Professor Lodahl notes that it is cost-prohibitive for a university to construct a system that controls 15-20 quantum light sources. Therefore, now that they have contributed to the fundamental understanding of quantum physics and taken the initial step, the focus will be on further scaling up, which is primarily a technological challenge, as reported by SciTech Daily.

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