CN Center Solves Silicon Quantum Devices Hydrogen Fragility
University of California, Santa Barbara (UCSB) quantum information science researchers found a new, highly robust silicon qubit that could form the basis of scalable quantum technology. The hydrogen-free CN center solves silicon-based quantum emitter manufacturing problems.
The team, led by Materials Professor Chris Van de Walle, has found a stable defect that is compatible with industrial processes, suggesting a way to link laboratory quantum research with large-scale semiconductor-based quantum device manufacturing.
The Silicon Advantage
For the perfect qubit, the quantum equivalent of a classical computer bit, materials that are easy to create in vast quantities have been sought. Silicon, the core of the trillion-dollar semiconductor industry, is best for this transformation. Because silicon chip production infrastructure exists, researchers can employ this material without adopting new manufacturing paradigms.
Quantum technologies require “fab-friendly” physical systems with desirable quantum characteristics. Researchers have struggled to find silicon faults that are physically durable and can communicate across long distances using present infrastructure. CN center discovery solves communication and stability difficulties.
T Center “Hydrogen Fragility” Resolved
Before the CN center was discovered, the T center dominated scientific interest. The T center, a silicon imperfection consisting of carbon and hydrogen atoms, can store quantum information for long periods of time, like diamonds' NV center.
But hydrogen is the T center's "Achilles' heel". In a crystal lattice, hydrogen atoms are notoriously unstable because they are “slippery” and migrate easily during high-temperature heating and chemical processing for chip production. This sensitivity makes it difficult for engineers to create millions of identical T centers on a silicon wafer, which is needed for scalable quantum processors.
CN Center: Strong Alternative
To address this dependability issue, the UCSB Computational Materials Group used powerful first-principles computer simulations to find a hydrogen-free replacement. Their analysis revealed the CN center, a one-carbon (C)-one-nitrogen (N) compound.
The CN core is stronger than the hydrogen center because carbon and nitrogen produce stronger and more stable silicon lattice connections. While overseeing the experiment, UCSB postdoctoral scholar Kevin Nangoi noted, “This defect will be more robust and easier to realize in actual devices because it does not contain hydrogen like the T center does.”
The simulation findings reveal that the CN center duplicates the T center's electrical and optical features without fabrication concerns. According to project postdoctoral researcher Mark Turiansky, the core is solid and stays stable even under rigorous heat processing conditions used in conventional semiconductor manufacturing.
Transitioning to the Quantum Internet
The CN center is stable and communicatively gifted. For a global “Quantum Internet” to exist, qubits must produce light in the telecom band, which may pass via fiber-optic cables with little signal loss.
These telecom photons are naturally emitted by the CN center. A stable “spin” that serves as quantum memory can be directly coupled to a quantum communication unit, a “photon,” by building a spin-photon interface. Due to its compatibility with global fiber-optic networks, the CN center is a strong candidate for long-distance quantum networking.
Simulation of Future Hardware
First-principles computer simulations enabled this discovery. These advanced models allow researchers to predict the properties of material systems that have not yet been developed in a lab. Theoretical models guide technical efforts to create novel quantum devices, saving time and money.
Professor Van de Walle noted that if the CN center is experimentally proven, it might be used as a building block for electronics that use the same silicon material as modern computers and cellphones.
Moving Forward: Experimental Validation
This research will proceed to experimental validation. To study the CN core physically, scientists worldwide will “plant” carbon and nitrogen atoms into silicon lattices.
The CN center may become the industry standard for future quantum hardware if experiments match UCSB calculations. This suggests that a fault-tolerant quantum computer that can simulate new drugs or crack complex encryptions may require a precise silicon technology enhancement rather than a manufacturing revolution.
The DOE-funded study at the National Energy Research Scientific Computing Center showed how teamwork may enhance quantum physics. The CN center shows how computational materials science can unlock the promise of trusted materials as the industry evolves.