Quantum

A transition-metal qubit in diamond with all-optical control and millisecond quantum memory

I. M. Morris, T. Alberth, L. Crooks, T. Lühmann, D. J. Twitchen, S. Pezzagna, J. Meijer, S. S. Nicley, J. N. Becker

Featured July 9, 2026

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Simply

Scientists found a new tiny diamond flaw, a nickel-vacancy, that can store quantum information for over a millisecond using only light, making it a promising building block for future quantum networks.

In depth

The paper introduces the nickel-vacancy (NiV$^{-}$) center in diamond as a novel spin-photon interface, overcoming the limitations of previous diamond qubits. This defect leverages transition-metal $d$-orbital hybridization to achieve intrinsic spin-orbit protection and an orbital-singlet excited state, enabling direct all-optical coherent control and millisecond quantum memory at accessible cryogenic temperatures.

Key Takeaways

1
The study identifies the nickel-vacancy (NiV$^{-}$) center in diamond as a new spin-photon interface, intrinsically combining efficient optical access, coherent control, and long-lived quantum memory.
2
The authors demonstrate all-optical coherent control of the NiV $^{-}$ spin qubit through Raman Rabi oscillations and Ramsey interferometry, eliminating the need for microwave control or strain engineering.
3
The paper achieves millisecond quantum memory (1.27 ms) at 1.65 K using all-optical dynamical decoupling, significantly extending coherence times for diamond qubits in compact cryogenic systems.

Conceptual Flow

HIGH LEVEL

Methodology: How the New Qubit Works

The paper uses a special defect in diamond, a nickel-vacancy, that can be controlled and read out using only light, unlike older methods that needed microwaves.

Diamond with Defect

Laser Light

Control Spin State

Quantum Information

Results: Longer Memory with Light

This new diamond defect can remember quantum information for a much longer time than previous ones, even at warmer temperatures, by using clever light pulses to protect it.

Old Diamond Qubit

New Diamond Qubit

Compare Memory Time

Much Longer Memory