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Researchers at the University of Pennsylvania have developed a method to entangle diamond qubits ten times faster than previous techniques while operating at room temperature. The study, published in *Nature Nanotechnology*, focuses on nitrogen-vacancy centers, which are tiny defects in diamond where a nitrogen atom sits next to a missing carbon atom. These systems typically use an electron at the defect and nearby carbon-13 nuclei as qubits.

Previously, scientists linked qubits using sequential gates that operated one pair at a time. This slow process often caused crosstalk errors, where operations affected unintended qubits. The new approach uses a single gate to interact with multiple qubits simultaneously. By applying a precisely timed sequence of controls, the electron interacts with three nuclear qubits in parallel to create a four-qubit Greenberger–Horne–Zeilinger state.

The team verified the entanglement by varying quantum phases and measuring light emitted from the diamond defect. They found that their parallel gate completed the task in 14.8 microseconds, which is ten times faster than sequential methods. The operation also achieved a fidelity of 0.92(4), significantly higher than the 0.69(3) fidelity of the sequential approach. The authors state this method lays the foundation for scalable entanglement generation in practical quantum devices.