Colored artificial diamonds—especially the NV (nitrogen-vacancy) centers and SiV (silicon-vacancy) centers within them—do not just give crystals beautiful colors. Because their fluorescence emission features high monochromacy, photostability, and room-temperature operability, combined with diamond's excellent biocompatibility and chemical inertness, they exhibit indispensable and unique value in the field of quantum technology.
Their core applications are mainly concentrated in two major directions: Quantum Sensing (Precision Measurement) and Quantum Computing & Quantum Communication.
1. Quantum Sensing (Nanoscale Precision Measurement)
The ground state of the NV center's electron spin in diamond is a spin-triplet state, which is extremely sensitive to external physical field perturbations such as magnetic fields, electric fields, temperature, and pressure. Furthermore, its quantum state can be initialized and read out through optical methods, making it an excellent "atomic-scale sensor."
Highly Sensitive Magnetometers and Magnetic Field Imaging: Researchers have realized nanoscale magnetometers based on single NV centers, enabling high-precision magnetic field imaging under room temperature and extreme environments.
Biological and Neural Sensing (Non-invasive Detection): Utilizing NV quantum defects in diamond, scientists have achieved non-invasive, high spatio-temporal resolution detection of action potential magnetic fields in single neurons. This label-free and highly biocompatible technique provides a brand-new tool for studying neural conduction in complex physiological environments.
Single-Photon Source Preparation: High-purity and high-yield single-photon emitters can be produced using NV centers prepared efficiently in nanodiamonds through high-energy particle (such as proton) irradiation, offering a feasible pathway for nanoscale quantum sensing and biological imaging.
Breaking the Standard Quantum Limit: Utilizing multi-spin entangled states in diamond NV defects, scientists have successfully achieved phase measurement sensitivity that surpasses the standard quantum limit at room temperature.
Entanglement-Enhanced Single-Spin Detection: By preparing NV center pairs with a spacing of only 5 nm and constructing quantum entangled states, the contradiction between signal amplification and noise interference was successfully resolved, achieving entanglement-enhanced nanoscale single-spin detection in noisy environments for the first time.
Coherence Enhancement: Constructing a diamond-graphene heterojunction hybrid structure can increase the coherence time of NV centers by approximately two-fold, significantly enhancing the quantum coherence characteristics of nanoscale sensors.
2. Quantum Computing and Quantum Communication (Solid-State Quantum Information Processing)
Diamond color centers are among the core candidate systems for achieving scalable solid-state quantum computing. Their biggest advantage is the ability to operate at room temperature and possess millisecond-scale electron spin coherence times, providing a sufficient window for quantum logic operations.
Long-Distance Quantum Entanglement and "Quantum Teleportation": Scientists have successfully achieved quantum entanglement between two NV centers separated by more than 1.3 km, validating key components of quantum relays and quantum teleportation. This lays the foundation for developing modular quantum computing architectures connected by photons.
Quantum Repeaters: Based on SiV centers in nanophotonic diamond resonant cavities, an asynchronous Bell-state measurement based on quantum storage was experimentally demonstrated. Its key generation rate surpassed the ideal direct transmission limit, verifying core functions for quantum repeaters.
Micro-Nano Integrated Spin Manipulation: A hybrid structure of "tapered fiber-nanowire-electrode" was developed to achieve spatially selective, high-precision microwave manipulation of spin defects in diamond, opening up new pathways for developing compact, miniaturized solid-state quantum processors and sensors.