A Diamond Defect Steered by Light Remembers a Quantum Secret ⚡ экспресс
Transition metals in diamond offer an alternative path to quantum bits combining spin coherence protected by spin-orbit coupling, all-optical control, and near-infrared emission. At a single nickel-vacancy (NiV⁻) center, an all-optically controlled qubit was demonstrated with coherence time exceeding a millisecond at 1.65 K, under conditions compatible with compact closed-cycle cryostats. Raman Rabi oscillations and Ramsey interferometry were implemented; using all-optical dynamical decoupling (CPMG-4), coherence was boosted from T₂* = 371 ns to T₂^CPMG-4 = 1.27 ms. These results establish NiV⁻ as a practical spin-photon interface for scalable quantum networks.
Quantum networks need particles that obey light and have a long memory. Such a particle was found in diamond—it's a single nickel atom embedded in a crystal with empty spaces around it. Its spin can be controlled solely by light pulses, like a conductor leading an orchestra without touching the instruments.
In the experiment, this rhythm was sustained with a series of flashes using the Rabi method, extending quantum memory. The lifetime jumped from 0.4 microseconds to 1.3 milliseconds—a factor of 3400. In that time, a infrared photon could travel from a city center to its suburbs, and the qubit could perform hundreds of operations. And it works at –271°C in a standard lab fridge.
The secret is not diamond's purity, but its deliberate defect. Such centers can be mass-produced by bombarding diamond with nickel ions. They need no magnets, emit in the fiber-optic range, and promise simple nodes for quantum communication.
🎯 If an ordinary qubit forgot information at the same rate, it would lose it a thousand times per second. This one manages to send a message across city districts in a single millisecond.
🎬 Such long-lived qubits bring us closer to a quantum internet reminiscent of the ansible from Ursula Le Guin's Hainish Cycle—a device for instant communication across any distance.