Curator's Take
This breakthrough addresses one of quantum computing's most persistent infrastructure challenges by demonstrating that diamond NV centers can directly interface with standard telecommunications networks without costly frequency conversion. While NV centers typically emit light in the visible spectrum that requires complex downconversion to reach telecom wavelengths, these researchers discovered that the "dark" infrared transition at 1042 nm can carry the same quantum spin information with high fidelity. The ability to read quantum states directly in the telecommunications window (1300-1600 nm) could dramatically simplify quantum network architectures and reduce costs, potentially accelerating the development of distributed quantum computing systems that leverage existing fiber optic infrastructure. This work represents a significant step toward making quantum sensing networks more practical and economically viable by eliminating a major technical bottleneck.
— Mark Eatherly
Summary
Nitrogen-vacancy (NV) centers in diamond are a leading platform for solid-state quantum sensing and quantum information processing. While most optical studies rely on the visible fluorescence associated with the triplet transitions, the infrared singlet transition near $1042$ nm, which is typically considered dark within the singlet manifold of the NV optical cycle, provides an alternative optical channel. Here, we report wavelength-resolved optically detected magnetic resonance (ODMR) measurements of this infrared emission. We directly observe ODMR contrast in the $1042$ nm emission and analyze its dependence on the magnetic field. The field-dependent spectral dispersion of the ODMR signal demonstrates that the spin-state information encoded in the NV center is transcribed to the infrared singlet emission through the spin-selective intersystem crossing, in close analogy to the visible fluorescence readout. These results establish infrared ODMR as a high-fidelity optical readout pathway. Crucially, by extending spin-state transcription directly into the $1300-1600$ nm range, this work demonstrates a direct, conversion-free interface between diamond spin-qubits and standard telecommunication infrastructure, bypassing the efficiency bottlenecks of active frequency conversion and benefiting from the already well-developed technologies in this range of the electromagnetic spectrum.