Lead
Researchers are adapting familiar fluorescent proteins into quantum-capable sensors that could detect magnetic and chemical signals inside living cells. In laboratory demonstrations, engineered enhanced yellow fluorescent protein (EYFP) showed quantum behaviour at room temperature and its fluorescence changed by about 30% in response to magnetic fields. The work, led by teams at the University of Chicago and collaborators, builds on prior molecular-qubit demonstrations from 2020 and tests in living bacterial cells. If made robust and sensitive, protein-based quantum sensors could place quantum probes exactly where biology needs them—inside cells and next to specific molecules.
Key takeaways
- Fluorescent proteins such as EYFP can be prepared in a coherent triplet spin state and manipulated with lasers and microwaves, enabling qubit-like behaviour demonstrated in 2020 and in recent lab work.
- In proof-of-principle experiments, EYFP’s emitted light varied by roughly 30% under external magnetic influence, and the sensor functioned in living bacterial cells at room temperature.
- Compared with nitrogen-vacancy (NV) diamond sensors, protein sensors are ~10 times smaller and can be genetically targeted to precise cellular locations, offering a potential gain in spatial specificity.
- NV diamond centres remain highly sensitive, versatile and stable at room temperature and have driven advances such as nanoscale MRI and an experimental HIV test claimed to be 100,000× more sensitive than standard diagnostics.
- Major initiatives supporting biomedical quantum sensing include the US National Science Foundation boost in 2023 and the UK Quantum Biomedical Sensing Research Hub launched in December 2024.
- Key technical challenges include photodegradation of fluorescent proteins under illumination and the need to increase dwell time in the triplet state to improve sensitivity.
- Laboratories report that many candidate proteins are off‑the‑shelf and that required optics and microwave hardware are standard in physics and some biology labs, lowering entry barriers for further development.
Background
The modern fluorescent-protein toolkit began with green fluorescent protein from jellyfish and has since expanded into multicolour labels used to tag, track and sense molecular events inside cells. These markers revolutionized cell biology by allowing researchers to localize proteins, monitor signalling such as calcium fluxes, and evaluate drug-target engagement. Traditionally, fluorescent labels are classical optical reporters — they change brightness or colour with biochemical conditions but are not sensitive to magnetic fields.
Quantum sensing uses controllable quantum states to detect environmental variables with extreme precision; unlike qubits for computing, quantum sensors are intentionally influenced by external fields so those influences can be read out. NV centres in diamond are a leading quantum sensor technology: a nitrogen substitution adjacent to a lattice vacancy creates electron-spin states that respond predictably to magnetic fields, temperature and strain at room temperature. Translating this capability into biological settings has been challenging because living systems are warm, chemically complex and spatially crowded.
Main event
Teams led by researchers at the Chicago Quantum Institute and collaborators revisited the idea that molecular systems could host quantum states useful for sensing. Following organometallic-molecule qubit demonstrations in 2020, researchers focused on biological fluorophores that are already widely used in biology, notably enhanced yellow fluorescent protein (EYFP). From a quantum-physics perspective, EYFP’s electronic energy-level architecture supports a metastable triplet state that can host coherent spin superpositions.
In the experiments, researchers used laser excitation and microwave pulses to place EYFP into the desired superposition and then monitored fluorescence output. The team observed that fluorescence intensity changed by about 30% when exposed to external magnetic fields, consistent with the triplet-state spin being affected by the environment. Crucially, the effect was measurable in living bacterial cells at room temperature, indicating the approach can survive a biological milieu at least in initial tests.
Researchers emphasize that not all fluorescent proteins are equally suitable: many have been engineered to minimise time spent in the triplet state to avoid blinking and photobleaching, a property that is disadvantageous for the quantum-sensing approach. Current work therefore includes re-engineering or selecting variants that dwell longer in the triplet state, plus efforts to reduce photodegradation under the illumination regimes needed for sensing.
Analysis & implications
Placing quantum sensors on proteins rather than on micron-scale diamond particles changes the trade-offs. Proteins can be produced inside cells from genetic instructions and targeted to interact with specific biomolecules, offering subcellular placement that NV diamonds struggle to match. That proximity could greatly increase effective sensitivity for local signals, such as magnetic changes caused by ion flows or neuronal action potentials.
However, protein-based quantum sensors currently face limits in robustness and longevity: fluorescent proteins photobleach under repeated excitation and their quantum-state lifetimes are shorter than those of solid-state defects. Overcoming these limitations will require directed evolution, protein engineering and careful optical protocols to balance signal extraction against damage. If those hurdles are addressed, applications could include mapping electromagnetic activity in tissues, early detection of oxidative stress via free-radical sensing, and remotely switchable molecular probes for imaging or therapeutics.
From a translational perspective, protein quantum sensors could lower barriers to in vivo application because they do not require introducing inorganic nanoparticles and can leverage genetic delivery techniques. That said, regulatory and safety evaluation would be essential before cell- or organism-level deployment. Commercialisation timelines are uncertain: lab demonstrations exist, but scaling to robust, validated tools for preclinical or clinical use will likely take several years.
Comparison & data
| Property | NV diamond centre | Fluorescent-protein quantum sensor (EYFP) |
|---|---|---|
| Typical size | ~10× protein scale (microns to nanosheets) | protein scale (nanometres) |
| Room-temperature operation | Yes | Yes (demonstrated in bacteria) |
| Reported magnetic-response change | Highly sensitive; context-dependent | ~30% fluorescence variation in tests |
| Targeting precision | Difficult to place precisely inside cells | Genetically targetable to specific proteins/locations |
| Current maturity | Commercial/experimental use in physical sciences | Proof-of-principle; early-stage biological demonstrations |
The table highlights complementary strengths: NV diamonds are mature and extremely sensitive in physical settings, whereas protein sensors offer unmatched biological targeting and smaller form factor. Integrating both approaches could address different use cases, from nanoscale MRI to intra‑cellular electromagnetic readouts.
Reactions & quotes
“These fluorescent labels can actually be turned into a qubit — it sounds science fiction, but the physics is real,” remarked Peter Maurer, a quantum engineer at the University of Chicago, summarising the conceptual leap from labels to quantum probes.
Peter Maurer, University of Chicago (quantum engineer)
“Sensitivity has long been a bottleneck for fluorescent labels,” said Jin Zhang of UC San Diego, noting that quantum variants may unlock previously impractical biological measurements.
Jin Zhang, University of California, San Diego (biosensor developer)
“What once seemed unlikely is now entering an application-ready phase,” observed Ania Jayich of UC Santa Barbara, reflecting on the broader momentum behind quantum sensing for biology.
Ania Jayich, University of California, Santa Barbara (physicist)
Unconfirmed
- No peer-reviewed, repeatable demonstration yet shows protein quantum sensors detecting neuronal action potentials in intact neural tissue; current claims are limited to bacterial cells and controlled lab conditions.
- The long-term stability and photobleaching resistance of engineered triplet‑enhanced fluorescent proteins remain to be validated under repeated imaging conditions typical of biological experiments.
- Comparative sensitivity metrics between optimized protein sensors and best-in-class NV diamonds for specific biological signals have not been established across independent labs.
Bottom line
Converting familiar fluorescent proteins into quantum-capable sensors is a promising route to bring quantum measurement into living systems. Early experiments demonstrate room-temperature quantum behaviour and measurable responses to magnetic fields in bacteria, and the approach benefits from genetic targeting and small size. Nonetheless, substantial engineering is required to improve photostability, increase triplet-state dwell times and validate sensitivity in complex tissues.
If these challenges are overcome, protein-based quantum sensors could enable new types of intracellular imaging and diagnostics that are difficult or impossible with current probes. The field has momentum — supported by funding initiatives and interdisciplinary hubs — but practical biological and clinical applications will need rigorous validation, standardisation and safety assessment before widespread adoption.
Sources
- Nature (news) — original report summarising recent demonstrations and interviews.
- Chicago Quantum Institute, University of Chicago (academic centre) — centre involved in molecular and biological quantum sensing work.
- University of California, San Diego (academic) — laboratories developing fluorescent biosensors and commenting on implications.
- US National Science Foundation (official) — provided funding support for quantum-bioscience initiatives in 2023.
- UK Quantum Biomedical Sensing Research Hub (research hub) — launched December 2024, focused on quantum biomedical sensing.