Scientists at the University of Pennsylvania have pulled off a four-qubit entangled state in diamond at room temperature in just 14.8 microseconds. That’s roughly 10 times faster than the classic sequential approach using paired gates. Instead of chaining together multiple two-qubit gates, the team went with a single multi-qubit gate, leveraging the natural interactions between an NV center’s electron spin and three nearby carbon-13 nuclei. The operation’s fidelity jumped from 0.69 to 0.92.

Four Qubits in 14.8 Microseconds

The entangled state was created on a solid-state diamond platform at room temperature, clocking in at just 14.8 μs. Compared to the old-school sequential setup, this gives about a tenfold speed boost.

One Multi-Qubit Gate Beats a Long Gate Chain

The game-changer here is using a multi-qubit gate directly. By tapping into the natural interactions between the NV center’s electron spin and three neighboring carbon-13 nuclei, the researchers skipped the need for a long series of two-qubit operations.

Big Jump in Operation Fidelity

Along with faster entanglement, the team also improved fidelity—from 0.69 up to 0.92. That means it’s now much more reliable to generate the target four-qubit entangled state in this setup.