🔬 physics

First-in-human quantum entanglement imaging

This study presents the first in vivo imaging of the degree of quantum entanglement in annihilation photons from a human subject using the plastic-scintillator-based J-PET scanner, simultaneously mapping radiopharmaceutical uptake and entanglement levels in the liver and spleen to demonstrate a novel avenue for clinical diagnostics.

Original authors: Pawel Moskal, Deepak Kumar, Sushil Sharma, Ermias Y. Beyene, Neha Chug, Catalina Curceanu, Eryk Czerwiński, Atharva Dalvi, Manish Das, Alicja Hubalewska-Dydejczyk, Sharareh Jalali, Krzysztof Kacprzak

Published 2026-06-30

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CC BY 4.0

Original authors: Pawel Moskal, Deepak Kumar, Sushil Sharma, Ermias Y. Beyene, Neha Chug, Catalina Curceanu, Eryk Czerwiński, Atharva Dalvi, Manish Das, Alicja Hubalewska-Dydejczyk, Sharareh Jalali, Krzysztof Kacprzak, Tevfik Kaplanoglu, Łukasz Kapłon, Kamila Kasperska, Aleksander Khreptak, Grzegorz Korcyl, Tomasz Kozik, Sumit Kumar Kundu, Anoop Kunimmal Venadan, Bartosz Leszczyński, Edward Lisowski, Filip Lisowski, Justyna Mędrala-Sowa, Simbarashe Moyo, Wiktor Mryka, Szymon Niedźwiecki, Marta Opalińska, Anand Pandey, Piyush Pandey, Alessio Porcelli, Bartłomiej Rachwał, Magdalena Skurzok, Anna Sowa-Staszczak, Tomasz Szumlak, Satyam Tiwari, Pooja Tanty, Keyvan Tayefi Ardebili, Kavya Valsan Eliyan, Ewa Ł. Stepień

Original paper licensed under CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine you have a pair of magic dice. In the quantum world, when these dice are "entangled," they are connected in a way that defies normal logic: if you roll one and it lands on a six, the other one instantly knows to land on a specific matching number, no matter how far apart they are.

For decades, scientists knew that when a particle of matter (an electron) meets its antimatter twin (a positron) inside the human body, they vanish in a flash of light, creating two high-energy photons (particles of light). Theory said these two photons should be like those magic dice: perfectly entangled. However, until now, no one had ever been able to "see" this connection inside a living human.

This paper describes the first time scientists successfully took a picture of this quantum connection inside a person.

The Special Camera: The "Plastic" PET Scanner

Standard medical PET scanners (used for cancer detection) are like heavy, rigid cameras made of crystal blocks. They are great at telling where a flash of light happened, but they are terrible at figuring out how that light was spinning (its polarization).

The team used a new, lightweight scanner called J-PET, which is built from strips of plastic scintillators (think of it like a giant, flexible plastic tube made of thousands of glowing sticks).

The Analogy: Imagine throwing a ball at a wall of crystal; it bounces straight back. But if you throw it at a wall of plastic, it might bounce off at a weird angle.
Why it matters: When the light particles (photons) from the patient hit the plastic, they bounce (scatter) in a way that reveals their "spin" or polarization. This allowed the scientists to measure the relationship between the two photons, something standard crystal cameras cannot do.

The Experiment: A Patient with a "Quantum Tag"

A 48-year-old man, who had previously been scanned with a standard machine, was given a tiny amount of a radioactive tracer (a "quantum tag") that naturally gathers in the liver and spleen.

Inside his body, the tracer emitted positrons.
These positrons found electrons, annihilated, and created pairs of entangled photons.
The patient was then rolled into the plastic J-PET scanner.

The Discovery: Measuring the "Magic"

The scientists didn't just look for where the light came from; they looked at the angle between the two photons as they scattered inside the plastic scanner.

The Prediction: If the photons were perfectly "magic dice" (maximally entangled), they would scatter at specific angles in a very predictable pattern.
The Reality: The scientists found that the photons were entangled, but not perfectly. They were "somewhat" entangled.
- The Result: The degree of entanglement was about 0.79 for the liver and 0.76 for the spleen.
- What this means: A score of 1.0 would be perfect entanglement. A score of 0.5 would mean they are completely unrelated (like two people rolling dice in different rooms). The patient's organs scored somewhere in between.

Why Isn't It Perfect?

The paper suggests that the "magic connection" gets slightly diluted inside the body.

The "Pick-off" Effect: Sometimes, the positron doesn't just meet a random electron; it gets "stuck" in a temporary orbit around an atom (called positronium) before meeting an electron. If it meets an electron from a nearby molecule that isn't its partner, the "magic" connection is broken or weakened.
The Analogy: Imagine two dancers who are perfectly synchronized. But if they are dancing in a crowded room, sometimes they get bumped by other people, or they have to grab a random partner for a split second. This "crowd" (the tissue structure and oxygen levels) slightly messes up their perfect synchronization.

The Bottom Line

This paper proves that:

We can now take pictures of quantum entanglement inside a living human.
The entanglement in the liver and spleen is real but not perfect (it's weaker than the theoretical maximum).
This "weakness" might actually be useful information, as it seems to depend on the specific type of tissue and its molecular environment.

The study is a "proof of concept." It's like the first time someone took a photo of a ghost. They didn't prove ghosts can talk to us or cure diseases yet, but they proved that ghosts can be photographed, opening the door to studying them in new ways.

Technical Summary: First-in-Human Quantum Entanglement Imaging

Problem Statement
Standard Positron Emission Tomography (PET) relies on detecting pairs of 511 keV annihilation photons to reconstruct metabolic images based on tissue uptake of radiopharmaceuticals. While the annihilation of an electron-positron pair is theoretically predicted to produce photons that are maximally quantum-entangled in polarization, this property has not been exploited in clinical diagnostics. Previous studies suggested that the degree of entanglement ( $C_{QE}$ ) in matter might be reduced from the theoretical maximum ( $C_{QE}=1$ ) due to specific annihilation mechanisms, such as "pick-off" annihilation of ortho-positronium, which depends on tissue microstructure and oxygen concentration. However, no method existed to measure or image this degree of entanglement in vivo in a human subject.

Methodology
The study utilized the Jagiellonian Positron Emission Tomography (J-PET) scanner, a portable, modular system constructed from plastic scintillator strips rather than conventional inorganic crystals. This material choice is critical because 511 keV photons interact with plastic primarily via the Compton effect (rather than the photoelectric effect), allowing the detector to simultaneously record the interaction position, time, and the plane of polarization (determined by the scattering plane).

Subject and Protocol: A 48-year-old male patient, previously diagnosed with a pancreatic neuroendocrine tumor, was administered 145 MBq of the radiopharmaceutical [68Ga]Ga-DOTA-TATE. Following a routine diagnostic scan on a commercial GE PET/CT scanner, the patient was scanned on the J-PET system for 20 minutes (starting 90 minutes post-injection).
Event Selection: The analysis focused on "four-hit" events where both annihilation photons underwent at least one Compton scattering within the detector volume. This topology allowed for the reconstruction of the scattering planes for both photons.
Quantification: For each valid event, the angle $\varphi$ between the two scattering planes was calculated. The distribution of $\varphi$ is governed by the formula $F(\theta_1, \theta_2, \varphi) = 1 - C_{QE} \cdot A(\theta_1)A(\theta_2)\cos(2\varphi)$ , where $C_{QE}$ represents the degree of quantum entanglement.
Region of Interest (ROI): Using the reconstructed annihilation positions, events were spatially filtered to isolate those originating from the liver and spleen.
Corrections: The data were corrected for random coincidences (estimated at ~30.6%), scatter fractions, and detector efficiency using Monte Carlo simulations (Geant4) and time-of-flight (TOF) information.

Key Results
The study successfully reconstructed images of the radiopharmaceutical uptake (standard PET) and, simultaneously, images of the degree of quantum entanglement for the liver and spleen.

Entanglement Values: The measured degree of quantum entanglement ( $C_{QE}$ $C_{QE}$ ) was:
- Liver: $0.79 \pm 0.21$
- Spleen: $0.76 \pm 0.23$
Comparison to Theory: These values are significantly lower than the theoretical maximum for maximally entangled states ( $C_{QE}=1$ ) but higher than the value expected for separable (non-entangled) photons ( $C_{QE}=0.5$ ).
Consistency: The results align with recent theoretical predictions for organic tissues and liquids (e.g., adipose tissue, water, isopropanol), which suggest $C_{QE}$ values in the range of 0.78 to 0.89 due to the fraction of "pick-off" annihilations.
Image Correlation: The spatial distribution of the entanglement measurements correlated well with the standard metabolic uptake images, confirming the validity of the event selection and reconstruction.

Significance and Claims
The authors claim this work represents the first in vivo imaging of the degree of quantum entanglement of annihilation photons within a human subject.

Proof of Concept: The study demonstrates the feasibility of using plastic-scintillator-based PET scanners to extract quantum mechanical properties (polarization correlations) from clinical data without losing standard metabolic imaging capabilities.
New Biomarker Potential: The authors posit that $C_{QE}$ is sensitive to the tissue's molecular architecture and biochemical composition (specifically the fraction of pick-off annihilations). This suggests that quantum entanglement imaging could serve as a novel molecular biomarker, potentially distinguishing between tissue types or pathological states (e.g., tumors vs. healthy tissue) based on their micro-environment, independent of radiopharmaceutical uptake intensity.
Future Outlook: While the current statistics are limited, the authors note that next-generation total-body J-PET systems could achieve sensitivities comparable to standard PET, making quantum entanglement imaging a viable clinical tool. The work encourages the development of detectors capable of simultaneous annihilation and Compton-scattered photon registration to further explore this diagnostic modality.