Microscopic Origins Limit Diamond Quantum Sensors

New study identifies key mechanisms behind surface noise that degrades performance of nitrogen-vacancy centers in diamond.

Published on Feb. 6, 2026

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A new theoretical study led by researchers at the University of Chicago and Argonne National Laboratory has identified the microscopic mechanisms by which diamond surfaces affect the quantum coherence of nitrogen-vacancy (NV) centers - defects in diamond that underpin some of today's most sensitive quantum sensors. The findings provide clear, physics-based guidelines for engineering diamond surfaces that help preserve quantum coherence, a key requirement for quantum sensing and emerging quantum information technologies.

Why it matters

NV centers in diamond are a promising platform for quantum sensing, as they can detect extremely weak magnetic and electric signals from molecules, materials, and biological systems. However, when placed close to a diamond surface, NV centers are exposed to surface-related noise that rapidly degrades their quantum coherence and limits sensor performance. Understanding the microscopic origins of this surface noise is crucial for developing more advanced, powerful quantum sensors.

The details

The study combined density functional theory-based atomistic models of diamond surfaces with advanced quantum decoherence simulations to identify the dominant surface noise mechanisms. The researchers found that the way the surface is chemically terminated has a profound impact on NV coherence, with oxygen- and nitrogen-terminated surfaces largely preserving near-bulk coherence, while hydrogen- and fluorine-terminated surfaces introduce much stronger surface-related magnetic noise. Crucially, the researchers determined that it is surface-electron relaxation and hopping, driven by the laser pulses used to manipulate and read out the NV center, that dominate the coherence of shallow NVs.

  • The study was published in Physical Review Materials on February 7, 2026.

The players

Giulia Galli

Professor at the University of Chicago Pritzker School of Molecular Engineering (UChicago PME) and senior scientist at Argonne National Laboratory.

Jonah Nagura

UChicago PME PhD candidate and lead author of the study.

University of Chicago Pritzker School of Molecular Engineering (UChicago PME)

The institution where the lead researchers are affiliated.

Argonne National Laboratory

The national laboratory where the lead researcher Giulia Galli is a senior scientist.

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What they’re saying

“One long-standing challenge has been understanding why shallow NV centers lose coherence so quickly. By combining first-principles surface models with quantum dynamics simulations, we understood that the culprit of decoherence is not just which spins live at the diamond surface, but how they move: surface noise is dynamical!”

— Giulia Galli, Professor at the University of Chicago Pritzker School of Molecular Engineering (UChicago PME) and senior scientist at Argonne National Laboratory (Mirage News)

“In the literature the origins of surface noise have been often called 'X spins' or 'dark spins', because the precise microscopic nature of the noise was not understood, and it may stem from optically inactive sites. Our research helps pinpoint exactly what is noisy at the surface and sets a path for eliminating the noise so that one can create more advanced, powerful quantum sensors.”

— Jonah Nagura, UChicago PME PhD candidate and lead author of the study (Mirage News)

“However, while termination chemistry and facet orientation do matter, we found that it is surface-electron relaxation and hopping that dominate the coherence of shallow NVs. The electron spins present at the surface interact with the same laser pulses that are used to manipulate and read out the NV center. The laser light can drive changes in the surface charge state, causing unpaired electrons to hop between different atomic sites. That motion produces additional time-varying magnetic fields, that in turn generates extra noise.”

— Jonah Nagura, UChicago PME PhD candidate and lead author of the study (Mirage News)

What’s next

The findings of this study provide clear guidelines for engineering diamond surfaces to help preserve quantum coherence, which is a key requirement for advancing quantum sensing and quantum information technologies.

The takeaway

This study sheds light on the microscopic mechanisms that limit the performance of nitrogen-vacancy centers in diamond, a promising platform for quantum sensing. By identifying the dominant sources of surface noise, the researchers have paved the way for developing more robust and sensitive quantum sensors.