One Particle of Antimatter, Held for Months
Physicists at Northwestern University have held a single positron, the electron's antimatter twin, in a magnetic trap for months. They can now watch it climb one energy step at a time.
Physicists at Northwestern University have caught a single particle of antimatter and kept it for months. It floats in a vacuum inside a magnetic trap chilled to about 0.3 kelvin.
What happened
A team in the Gabrielse group at Northwestern reported in Physical Review Letters that "a single positron has been trapped for months". The paper, "One-Positron Quantum Cyclotron", is by Myers, Soucy, Sukra, Sinha and Gabrielse, and it is open access.[1]
The university's own news page describes the storage time as "an entire month". This article follows the paper's wording.[4]
A positron is the electron's antimatter twin. When it meets ordinary matter, the two annihilate.[4]
Why it's surprising
Single positrons are not new in a trap. Dehmelt's group trapped single positrons in the 1980s. What is new, according to Physics World, is "the first time a single positron has been trapped so its lowest-energy quantum states can be fully resolved".[3][1]
Our readIn our reading, the achievement is less about holding antimatter at all and more about holding one particle so calmly that its smallest energy steps become visible.[3]
How it works
Because a positron vanishes on contact with matter, it cannot rest against a wall. Instead it is held in the vacuum of a cryogenic Penning trap by a 5.6-tesla magnetic field, cooled by a dilution refrigerator to about 300 mK. Loading one positron takes 8–11 hours.[1]
The magnetic field makes the positron move in tiny circles. The team holds it in its lowest cyclotron state, then uses microwaves to raise it one quantum at a time. The cyclotron frequency is about 156 GHz.[1][2]
Each step is detected without disturbing the particle, a method known as quantum nondemolition detection.[1]
Why it matters
The goal is a test of CPT symmetry: comparing how strongly the positron and the electron act like tiny magnets. The paper aims to make that comparison more than 30 times more precisely than before. The best current comparison is 2.1 parts per trillion, from 1987.[1][2]
Our readIf nature treats matter and antimatter the same, the two magnetic moments should match. A precise comparison is a direct way to check that idea.[1][2]
What's confirmed and what isn't
Confirmed in the paper: one positron held for months, a 5.6-tesla field, a temperature of about 300 mK, and microwave steps of one quantum at a time, each detected without disturbing it.[1]
Not yet done: the APS Physics Viewpoint notes that the work does not yet give a high-precision measurement. The comparison with the electron has not been made.[2]
ScienceAlert reports that the team expects to make the measurement "early next year". That is a plan, not a result.[5]
- Not claimedThis is not the first antimatter ever trapped.
- Not claimedThis is not the first positron trapped; Dehmelt's group trapped single positrons in the 1980s.
- Not claimedThis is not claimed to be the longest antimatter storage.
- Not claimedNo difference between the positron and the electron has been measured.
- Not claimedNo energy or weapon applications are claimed.
- Not claimedNo firm date for the measurement is claimed; "early next year" is ScienceAlert's report only.
Sources
- Physical Review Letters (American Physical Society) — One-Positron Quantum Cyclotron, 2026-10-21Primary
- APS Physics — A Quantum Cyclotron for AntimatterIndependent
- Physics World — Physics World report by Sam Jarman, 2026-10-20Independent
- Northwestern University Physics — Gabrielse lab traps a single antimatter particle for a month, 2026-10-23Primary
- ScienceAlert — ScienceAlert report on the single-positron trapIndependent
7 claims checked against these sources; 6 confirmed.
Spot an error? Request a correction.
Video transcript
Physicists at Northwestern University have caught a single particle of antimatter, and kept it for months.
It's a positron, the electron's antimatter twin. Touch ordinary matter, and it vanishes.
So it floats in empty space, held by a strong magnetic field inside a trap chilled to a fraction of a degree above absolute zero.
The magnet makes the positron move in tiny circles. Microwaves lift it up one energy step at a time, and the team can watch each step.
Next, they want to measure how strongly the positron acts like a tiny magnet, and compare it with the electron.
If nature treats matter and antimatter the same, the two should match. That measurement hasn't been made yet.
Production note: All visuals are original Blender renders labelled schematic; they are not images of the real trap, and no Northwestern, APS or paper imagery is used. The narration is a synthetic voice.
What else changed
Space & Science2 min readNº 007Moon Trash Could Become Tomorrow's Spare PartsAn MIT student team won first prize in NASA's LunaRecycle Challenge with a system that grinds discarded packaging and molds it into composite parts. The foam usually thrown out becomes part of the material.Read story 
Space & Science2 min readNº 002Japan Is Going to Mars's Moon Phobos — and Plans to Bring a Piece BackJAXA's MMX spacecraft has launched toward Phobos, one of Mars's two moons. The plan is to bring at least 10 grams of it back to Earth by 2031.Read story 
Space & Science2 min readNº 003A Dark-Universe Telescope Just Found a New CometEuclid was built to map the dark universe, not to hunt comets. In September 2026 its images caught a previously unknown one, now named C/2026 S1 (Euclid).Read story