Over the course of numerous years, a dedicated group of scientists and engineers have persevered in their efforts to develop quantum computing systems, albeit with limited success. Despite significant advancements in hardware capabilities, fundamental challenges persist in processing and accessing data within quantum systems. However, a recent study from Imperial College London may have brought us closer to realizing the potential of quantum technology. The research marks a significant milestone as it demonstrates the successful transmission of quantum data between two machines, along with the ability to interpret the output. This achievement presents a promising advancement towards the realization of an ultra-secure and ultra-fast quantum internet.
Quantum computing seeks to leverage the unique properties of matter at the smallest scales, where peculiar quantum effects such as superposition and entanglement emerge. Scientists believe that harnessing these effects could lead to faster and more secure computing. Nevertheless, quantum systems require meticulous protection from interference, which can compromise their integrity. Consequently, the transmission of quantum data has posed a longstanding challenge for researchers.
In conventional communication, repeaters are utilized to amplify signals and ensure their successful delivery. However, the storage and, more importantly, the retrieval of data are essential for this process. Quantum information, typically encoded using photons of light, presents a significantly greater challenge. Any attempt to extract information from a quantum system results in its destruction, underscoring its potential for high security. The research team, led by Dr. Sarah Thomas and Lukas Wagner, utilized standard fiber optic cabling to implement a novel form of "quantum memory" capable of assimilating and retaining the quantum state of light for subsequent retrieval.
The study reveals that this system is based on the generation of photons using semiconductor quantum dots. However, integrating this system with the new quantum memory posed a formidable challenge. The memory, known as ORCA (Off-Resonant Cascaded Absorption), employs a cloud of rubidium atoms to store quantum information. The photons emitted by quantum dots lack the appropriate wavelength for seamless absorption by the atoms, necessitating several adjustments to enable this groundbreaking achievement.
Initially, the researchers modified the quantum dot architecture to emit light at a wavelength of 1529.3 nm, compatible with standard fiber optic telecom lines. Subsequently, they devised a series of filters and modulators to adjust the wavelength of the emitted photons until they could interact with the atomic quantum memory. A laser was employed to activate and deactivate the memory by altering the absorption properties of the rubidium atoms. Dr. Sarah Thomas, the lead author, expressed immense enthusiasm, stating that interfacing two key devices together is a crucial step forward in allowing quantum networking, and we are really excited to be the first team to have been able to demonstrate this.
While this achievement is remarkable, it is important to note that it does not signify an imminent transformation of the internet as we currently know it. The research team reported an efficiency of 12.9% in storing photonic states in the atomic memory and successfully retrieving them later. The retrieved photons maintained their original quantum states, indicating the potential for storing and recalling quantum information without compromising its integrity. Despite this significant progress, there are still substantial obstacles to overcome before quantum computing can become an integral part of our daily lives. Nevertheless, this accomplishment represents a significant stride in that direction.
