Quantum gas on China’s space station reaches 9.7 picokelvin, a record equivalent temperature

About 20,000 rubidium atoms held by laser light aboard the China Space Station spread out so slowly over 7 seconds that their motion matches a temperature of 9.7 trillionths of a kelvin, roughly four times below the previous lowest figure of 38 picokelvin.

Peer reviewed · Single experiment · Equivalent temperature (from expansion energy)

A team from Peking University and two Chinese Academy of Sciences institutes has made a Bose-Einstein condensate, an ultracold cloud of atoms behaving as one quantum object, inside a laser trap on the China Space Station. Released and left to drift for 7.0 seconds, the cloud reached an equivalent temperature of 9.7 picokelvin, reports the paper in Science. That is the lowest such figure reported for an ultracold atom platform, and the first time this kind of trap has made a quantum gas in microgravity. The catch: 9.7 pK measures how slowly the atoms spread, not a thermometer reading.

Evidence at a glance

Is this a big deal?

It is a solid technical step, not a change in physics. The lower number matters less than the two things behind it: a laser-based trap now works in orbit, and the team could follow the cloud for 7 seconds, more than three times the 2 seconds behind the previous record. Long, slow free fall is what space-based precision measurement has been waiting for.

What scientists found

The team reports a Bose-Einstein condensate of 2.0 × 10⁴ atoms. After the trap was switched off, the cloud expanded freely for 7.0 seconds, and its expansion energy corresponds to an equivalent temperature of 9.7 pK, with an uncertainty of +3.2 and −2.7 pK. A picokelvin is a trillionth of a kelvin, and the kelvin scale starts at absolute zero, so this is 0.0000000000097 degrees above the lowest temperature possible.

The abstract compares the result with the lowest equivalent temperature previously reported in such a system: 38 pK after 2 seconds of free expansion, made with atom-chip magnetic traps in microgravity. That earlier figure comes from a 2021 Physical Review Letters paper by Christian Deppner and colleagues, which Global Times reports was made in a drop tower at the University of Bremen in Germany. Dividing 38 by 9.7 gives about 3.9, so the new figure is roughly four times lower.

How they found it

The experiment runs in a cold-atom facility that flew to the station with the Mengtian laboratory module in 2022. According to CGTN, the project’s first assessment began in 2011, and a ground setup filling about 20 cubic metres and weighing about 10 tonnes was shrunk into a flight instrument of about 0.7 cubic metres and half a tonne that runs automatically in orbit.

Most earlier space and drop-tower condensates were made with magnetic traps on atom chips. This one uses an optical dipole trap: laser beams that pull atoms toward the brightest light. The abstract notes the advantages. Light leaves more room for laser probes, and it can hold atoms that do not respond to magnetic fields as well as those that do.

Getting there took several steps. Reporting by Phys.org and CGTN describes laser cooling, then evaporative cooling, which lets the most energetic atoms escape so the rest settle lower, much as steam carries heat away from a cup of tea. In microgravity that evaporation works less well, CGTN reports, so the team added a magnetic field gradient to help form the condensate. They then moved the atoms into a wider, weaker trap and let the cloud expand, which strips out more kinetic energy before release.

Weightlessness is the reason this works only in orbit. On the ground, a cloud left alone for 7 seconds falls under gravity. The arithmetic is simple: ½ × 9.81 m/s² × (7 s)² ≈ 240 metres. MIT physicist Wolfgang Ketterle made the same point to CGTN, putting the drop at about 250 metres and noting you would need a vacuum chamber that tall.

What “equivalent temperature” means

A thermometer reading assumes a gas whose atoms constantly collide and share energy. A released condensate is different: it is a drifting cloud whose atoms mostly fly apart. Physicists measure how fast the cloud grows and convert that expansion energy into the temperature a gas with the same energy would have. CGTN’s report makes the same distinction: the 9.7 pK figure describes the atoms’ extremely slow expansion, and it does not mean the equipment or its surroundings got that cold.

To make it concrete, SciQuest converted 9.7 pK into a speed. Using the relation ½mv² = ½k_BT for each direction, and assuming rubidium-87 (the isotope NASA’s Cold Atom Lab uses; the abstract we read does not name the isotope), the typical spread is about 30 micrometres per second. That is about 11 centimetres an hour. This is an illustration, not a number from the paper.

Show the maths: from 9.7 pK to a speed

1. Boltzmann constant k_B = 1.380649 × 10⁻²³ J/K, so k_BT = 1.380649 × 10⁻²³ × 9.7 × 10⁻¹² ≈ 1.34 × 10⁻³⁴ J.
2. Mass of one rubidium-87 atom: 86.909 u × 1.6605 × 10⁻²⁷ kg/u ≈ 1.443 × 10⁻²⁵ kg.
3. Speed spread along one direction: √(k_BT/m) = √(1.34 × 10⁻³⁴ ÷ 1.443 × 10⁻²⁵) ≈ 3.0 × 10⁻⁵ m/s, or about 30 µm/s.
4. Across the reported range of 7.0 to 12.9 pK, the same formula gives about 26 to 35 µm/s.
5. For the 38 pK record, it gives about 60 µm/s: twice the speed for four times the energy, because speed scales with the square root of temperature.

Why it matters to you

This won’t change anything in daily life this year. Its value is in measurement. Atom interferometers split and recombine atom clouds to measure acceleration and gravity, and their sensitivity grows with how long the atoms can fall freely. CGTN reports that the team sees future uses in mapping Earth’s gravity and testing fundamental physics; Global Times adds navigation and satellite orbit determination, all as goals rather than results. One related target is the equivalence principle, the idea that all objects fall the same way in gravity; we explained a recent quantum test of it in falling quantum atoms pass a new test of Einstein’s gravity.

What the evidence does not show

It does not show that matter anywhere reached a thermodynamic temperature of 9.7 pK. Headlines calling this the “coldest temperature ever” compress an equivalent temperature into a plain one. The distinction matters because different labs can lower expansion energy with different tricks, such as matter-wave lensing, and report it in different ways.

It also does not settle every comparison. Several reports state that NASA’s Cold Atom Lab on the International Space Station reached 52 pK. In that 2022 Nature Communications paper by Naceur Gaaloul and colleagues, 52 ± 10 pK is the expansion energy measured along one direction, with a similar value inferred for a second; the total 3D kinetic energy was “about 100 pK.” Measured that way, the new result is roughly ten times lower, not five.

Finally, it is one result from one instrument with a modest atom number. Twenty thousand atoms is small for precision sensors, which collect more signal from bigger clouds.

How this fits what we already knew

Space has been the obvious place for ultracold physics because nothing pulls the cloud to the floor. The Bremen drop tower gave about 2 seconds of free expansion for the 38 pK record, and Cold Atom Lab has run on the ISS since 2018, using atom-chip magnetic traps with rubidium-87. What changed in 2026 is the trap type and the length of observation. For scale, the cosmic microwave background, the leftover glow of the early universe, sits at 2.725 K; 2.725 ÷ 0.0000000000097 ≈ 2.8 × 10¹¹, so this cloud’s equivalent temperature is about 280 billion times lower. Liquid nitrogen, at about 77 K, is cold by kitchen standards and boiling hot by these.

What independent physicists told CGTN

Ketterle, who shared the 2001 Nobel Prize in Physics for Bose-Einstein condensates and was not an author, called the result “an excellent starting point to advance atomic thermometry and precision measurements” in comments to CGTN. Ernst Rasel of Leibniz University Hannover, a senior author of the 2021 38 pK paper, told CGTN that “Atom interferometers highly benefit from sources providing a large number of atoms,” a pointer to atom number as the next thing to grow. SciQuest did not interview either scientist, and no independent expert has yet commented on how the equivalent temperatures were compared.

How other headlines framed it

• Science news led with the coldest-temperature-ever angle, which is accurate only in the equivalent sense.
• CGTN framed it as a national cooling record but was the clearest on what the temperature does and does not describe.
• Global Times called it the coldest man-made matter and focused on the instrument’s miniaturisation and future uses.
• Interesting Engineering stressed the longer observation window and the possible experiments it could enable.

What happens next

The abstract points to new optical-trap experiments in quantum simulation and precision measurement. Phys.org’s account of the paper says the team hopes to build an atom interferometer in orbit and to use adjustable traps to raise atom numbers. Watch for a second, independent measurement and for interferometry results from the same facility. For how atoms already keep the world’s time, see how an atomic clock works.

In one sentence

A laser-trapped quantum gas on the China Space Station spread so slowly over 7 seconds that its motion matches 9.7 picokelvin, the lowest equivalent temperature reported, though that figure measures expansion energy rather than a true temperature.

Quick check: did it click?

1. What kind of trap made this condensate? An optical dipole trap, which holds atoms with laser light rather than magnets.
2. Why could this not be done the same way on the ground? In 7 seconds a released cloud would fall about 240 metres under Earth’s gravity.
3. Is 9.7 pK a thermometer reading? No. It is an equivalent temperature calculated from how fast the released cloud expands.

Read next

• Falling quantum atoms pass a new test of Einstein’s gravity: an atom-chip experiment on the equivalence principle, exactly the sort of test that slower, longer-falling clouds in orbit could one day make more precise.
• How does an atomic clock work? Atoms used as timekeepers, and why their ticking is so steady that whole systems rely on it.
• How cold is liquid nitrogen? 77 K.

Sources and disclosure

1. Xiong W., Li T., Jin S., Huang Q., Wang B., Li L., He Y., Li X., Chen D. et al. (22 authors, corresponding author Chen Xuzong). “Quantum gases below 10 picokelvin in space.” Science (2026), published online 5 November 2026. doi:10.1126/science.aea5324. Abstract and author list read via Crossref.
2. Deppner C. et al. “Collective-Mode Enhanced Matter-Wave Optics.” Physical Review Letters 127, 100401 (2021). doi:10.1103/PhysRevLett.127.100401.
3. Gaaloul N. et al. “A space-based quantum gas laboratory at picokelvin energy scales.” Nature Communications 13, 7889 (2022). doi:10.1038/s41467-022-35274-6; full text read via PubMed Central.
4. Fixsen D.J. “The Temperature of the Cosmic Microwave Background.” The Astrophysical Journal 707, 916 (2009), 2.72548 ± 0.00057 K. arXiv:0911.1955.
5. CGTN, “China’s space station sets new atomic cooling record,” 6 November 2026: news.cgtn.com.
6. Global Times, report on the CAS announcement, 6 November 2026: globaltimes.cn.
7. Phys.org, “Scientists achieve record-breaking low temperature on China’s space station,” 6 November 2026: phys.org.

Disclosure: This article was drafted with AI assistance and checked against the sources above. The full Science paper was blocked to us, so details beyond the abstract come from CGTN, Global Times and Phys.org and are attributed to them. Calculations by SciQuest: 38 ÷ 9.7 ≈ 3.9; 2.725 K ÷ 9.7 pK ≈ 2.8 × 10¹¹; ½ × 9.81 × 7² ≈ 240 m; √(k_BT/m) for rubidium-87 at 9.7 pK ≈ 30 µm/s. The graphic is a SciQuest original. Spotted an error? See our corrections policy.