One of the biggest hurdles in building a functional quantum computer is 'noise'—interference from the environment that disrupts the delicate state of quantum bits (qubits). To solve this, scientists use the nucleus of a phosphorus atom implanted inside a silicon chip. The phosphorus nucleus is exceptionally good at isolating itself from external noise, making it a stable vessel for quantum information. However, this stability creates a paradox: the better a qubit is at hiding from noise, the harder it is for it to 'talk' or interact with other qubits, which is necessary for computation.
Australian research institutions are global leaders in silicon-based quantum computing, specifically utilizing phosphorus atoms.
To perform calculations, qubits must communicate. Previously, phosphorus nuclei had to be placed extremely close together to interact. A new breakthrough allows them to communicate over much larger distances—relative to their size, comparable to the distance between Sydney and Boston. This is achieved by attaching an electron to each nucleus, acting as an 'electronic telephone.' In quantum physics, electrons are not just particles but exist as 'clouds of probability.' These clouds can stretch far from the nucleus. By allowing the probability clouds of two distinct electrons to touch slightly, the information from one nucleus can be transmitted to another, creating an entangled state even when the nuclei are physically far apart.
Universities and research centres in Australia often publish findings on electron spin resonance and quantum interconnects.
The ability to entangle nuclei that are not immediately adjacent is a game-changer for manufacturing quantum computers. If atoms must be placed with atomic precision right next to each other, building a chip with millions of qubits is nearly impossible. By using the 'electronic telephone' method, the atoms can be spaced further apart, making the architecture scalable. This spacing allows for the insertion of intermediate couplers and control lines necessary to manage the qubits. This development is a critical step toward creating large-scale quantum processors capable of solving complex problems beyond the reach of today's supercomputers.
Commercial entities and government bodies in Australia are actively investing in the manufacturing and scaling of quantum hardware.