An experiment conducted by a team from the University of New South Wales (UNSW) demonstrates that two atomic nuclei can be entangled through the mediating action of electrons. This work, published in Science, paves the way for quantum microprocessors using the same fabrication scale as the silicon chips in our phones or computers.
When atomic nuclei start talking
The idea of using atomic nuclei as computing platforms is not new, but it faced a major obstacle. These nuclei, being extremely well isolated, proved very difficult to connect to each other.
Until now, the only way to establish contact was to place several nuclei within the same electron space. This configuration allowed for clear communication but could not be scaled up.
The researchers circumvented this limitation by relying on a unique property of the electron: its ability to delocalize. By linking each nucleus to a distinct electron and then allowing these electrons to interact with each other, they succeeded in establishing a novel communication channel.
An electronic gateway for entanglement
The protocol used, called a "geometric gate," had already been validated for precisely manipulating qubits in silicon. For the first time, it was applied to two nuclei separated by about 20 nanometers.
This figure corresponds to less than forty silicon atoms side by side. On a human scale, the researchers point out that such a distance would be comparable to that between Sydney and Boston.
A convergence with the semiconductor industry
Most remarkably, this scale of 20 nanometers is exactly the scale of transistors integrated into current electronic circuits. In other words, nuclear qubits can now coexist with traditional microelectronics.
This technical compatibility opens up the possibility of a future where semiconductor industry processes could be directly applied to the fabrication of quantum processors.
The researchers are already considering extending entanglement to even greater distances by moving the electrons or forcing their spatial extension. The approach could then link an increasing number of qubits without loss of precision.
To go further: what is quantum entanglement?
Entanglement links two particles so that their states become interdependent, even if they are far apart. A measurement performed on one immediately influences the other.
This phenomenon, experimentally validated for decades, has revolutionized our view of reality. Today, entanglement is no longer just a theoretical object. It is the central ingredient of emerging technologies like quantum cryptography and quantum computing.
Article author: Cédric DEPOND