In a groundbreaking leap toward the realization of the quantum internet, a collaborative effort between researchers at MIT and the University of Cambridge has yielded a minuscule yet revolutionary device designed to facilitate the swift and efficient transmission of quantum information across vast distances.
Central to this innovation is a tiny “microchiplet” crafted from diamond, where select carbon atoms are substituted with tin atoms. This ingenious device, equipped with waveguides to convey quantum information, resolves a longstanding paradox that has hindered the development of large-scale, deployable quantum networks.
The delicate nature of quantum information, encoded in quantum bits (qubits), renders it susceptible to environmental disturbances, such as magnetic fields, which can obliterate the integrity of the information. Thus, there exists a delicate balance: while it’s advantageous for qubits to remain isolated from environmental interference, they must also effectively interact with light, or photons, which serve as the carriers of this information across extensive distances.
The joint effort by MIT and Cambridge researchers achieves this delicate equilibrium by co-integrating two distinct types of qubits, harmonizing their functions to preserve and transmit information seamlessly. Furthermore, the team reports exceptional efficiencies in the transfer of quantum information, marking a significant milestone in the field.
Dirk Englund, an associate professor in MIT’s Department of Electrical Engineering and Computer Science (EECS) and leader of the MIT team, emphasizes the critical nature of this achievement: “This is a critical step as it demonstrates the feasibility of integrating electronic and nuclear qubits in a microchiplet. This integration addresses the need to preserve quantum information over long distances while maintaining strong interaction with photons. This was possible through the combination of the strengths of the University of Cambridge and MIT teams.”
Professor Mete Atatüre, leader of the Cambridge team, underscores the collaborative spirit driving this accomplishment: “The results are an outcome of a strong collaborative effort between the two research teams over the years. It is great to see the combination of theoretical prediction, device fabrication, and the implementation of novel quantum optical controls all in one work.”
The work was published in Nature Photonics.
Working at the quantum scale
In the realm of computing, a fundamental unit of information, known as a bit, typically manifests in two distinct physical states, such as “on” and “off,” representing binary values of zero and one. However, delving into the esoteric domain of quantum mechanics, the concept of a qubit emerges, endowed with a remarkable property: the ability to exist not only in one of the two states but also in a simultaneous superposition of both states.
As explained by Martínez, a qubit can occupy a state of “on” and “off” concurrently, unlocking unprecedented potential in information processing. Unlike traditional computing bits, qubits, especially when entangled, can convey a wealth of information, showcasing the intrinsic power of quantum computing.
Among the myriad variations of qubits, two prevalent types stem from spin properties, specifically the rotational dynamics of electrons or nuclei. The innovative device in question integrates both electronic and nuclear qubits, leveraging their unique characteristics.
An electronic qubit, embodied by the spin of an electron, exhibits a propensity for interaction with its environment, whereas a nuclear qubit, residing within the spin of an atom’s nucleus, remains notably isolated, preserving information over extended durations. By harmonizing these distinct qubits, researchers anticipate harnessing the complementary strengths of each, thereby optimizing performance.
Harris elaborates on the operational mechanism: “The electron [electronic qubit] traversing within the diamond can become trapped at the tin defect.” Subsequently, this electronic qubit facilitates the transmission of its encoded information to the spinning tin nucleus, housing the nuclear qubit.
This novel approach not only bridges disparate qubit functionalities but also holds promise for enhanced quantum information processing capabilities. Through the fusion of electronic and nuclear qubits, scientists endeavor to unlock new frontiers in quantum computing, pushing the boundaries of what is conceivable in information technology.
Source: Materials Research Laboratory, Massachusetts Institute of Technology