A research team at the University of New South Wales has achieved a major milestone in quantum computing by creating entangled quantum states between two phosphorus atoms embedded in a silicon chip. This breakthrough could bring quantum technology closer to integration with existing semiconductor manufacturing.
What makes this achievement special
Entanglement is a phenomenon where two particles become so deeply linked that the state of one instantly influences the other, even when separated. For quantum computers, entanglement is a key ingredient for performing complex calculations.
In this experiment, the scientists placed two phosphorus atoms about 20 nanometers apart—a distance that current silicon chip technology can easily fabricate. Each atom carried an electron, and those electrons acted like “bridges,” allowing the atomic nuclei to interact and become entangled.
Key results
- The team successfully performed a two-qubit controlled-Z gate, one of the fundamental operations in quantum logic.
- They created and measured a nuclear Bell state, achieving a fidelity of around 76%—a strong indicator that the entanglement was robust.
- The method showed that nuclear spins, which are naturally well-protected from outside noise, can still be linked over practical distances through electron mediation.
Why it matters
This work tackles one of the biggest challenges in quantum hardware: balancing isolation with connectivity. Qubits need to be shielded from interference to preserve their fragile states, but they also need to interact to perform useful computations. By linking nuclear spins via electrons, the researchers managed to achieve both.
Even more promising, the scale of these interactions aligns with current semiconductor manufacturing processes. That means the technology could, in theory, be scaled up using industry-standard chip-making tools, potentially reducing cost and complexity.
Challenges ahead
While the results are groundbreaking, scaling beyond two qubits remains difficult. Maintaining entanglement across larger systems introduces noise, cross-talk, and error rates that are not yet solved. Researchers will also need to refine electron control so that it facilitates entanglement without introducing instability.
The bigger picture
This experiment demonstrates that quantum computing might not remain confined to exotic lab setups forever. By showing that entangled states can be engineered in silicon—a material that underpins nearly all modern electronics—scientists have taken another step toward building practical, scalable quantum computers.
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