重要成果  Key Achievements  
  • 太空自由下落原子演示为伽利略引力检验带来全新视角
  • Demonstration Free-falling atoms in space put a new twiston Galileo's Gravity test (2026)

 A test on a space station reaffirms a core part of Einstein's general theory ofrelativity

By Emily Conover
 
Two clouds of atoms on China’s Tiangong space station (rendering shown) fell with the same acceleration in a newexperiment.
 
An experiment made famous by Galileo has been shrunk down to theatomic level and shipped off to space.
To show that objects of different masses fall at the same rate, the 17thcentury Italian scientist is said — perhaps apocryphally — to havedropped weights off the Leaning Tower of Pisa. Now, scientists have re-created that experiment with atoms falling while orbiting Earth.Two clouds of atoms on China’s Tiangong space station fell withnearly identical accelerations, researchers report August 28 in Science Advances.
The researchers measured the relative accelerations of two clouds ofcold rubidium atoms. The atoms in each cloud had different masses,due to a difference in the number of neutrons in their atomic nuclei.Yet the accelerations of the two clouds matched with a precision of0.05 thousandths of a percent.
The matching accelerations confirm that two different ways ofdefining mass are equivalent. One, called gravitational mass,determines how an object responds to the pull of gravity. Another,called inertial mass, determines how much an object accelerateswhen pushed with a given amount of force. If the two definitions areequivalent, the effect of the mass cancels out in equations, and objectsof different masses will fall at the same rate in a vacuum. The conceptis known as the weak equivalence principle, and it’s a foundation ofAlbert Einstein's general theory of relativity, which describes gravityas the warping of spacetime.
Scientists have tested the weak equivalence principle by droppingobjects on Earth,including atoms. But objects on Earth can fall onlyso far, limiting the tests’ precision. In orbit, free fall can go onindefinitely. Space-based tests of falling metal cylinders on a satellite have previously confirmed the weak equivalence principle. But atoms,unlike larger objects, obey the rules of quantum physics, and it’sworth checking to see if they behave differently. Atoms in orbit takethe weak equivalence principle to a whole new level (D. F. Zhang, et al., Sci. Adv.12(35), eaeh4502,2026).

    Using a fiber array, we experimentally demonstrate the trapping and independent control of ten single atoms in two-dimensional optical tweezers, achieving individually addressed single-qubit gates with an average fidelity of 0.9966(3). More significantly, we perform simultaneous arbitrary single-qubit gates on four randomly selected qubits, resulting in an average fidelity of 0.9961(4)(X. Li et al., Nat. Commun. 16: 9728, 2025).

Experimental scheme. a Basic experimental setup for the trapping, rearrangement, manipulation, and detection of single-atomarrays.  b The cross-section of the fiber array. c Single-shot fluorescence image of an atomarraywith 50ms exposure time. d A schematic showing optical setup in the optical module. e Histogram of collected photons for one of the fiber traps during the initial loading process.

 

     Our team has developed a space-based dual-component rubidium isotope cold atom interferometer (npj Microgravity 9: 58, 2023). The device was launched aboard the Tianzhou-5 cargo spacecraft on November 12, 2022, and subsequently installed in the high microgravity science experiment cabinet of the Tianhe core module of the China Space Station. On December 30, 2024, the China Manned Space Engineering Office released the《China Space Station Science Research and Application Progress Report (2024)》to the public, selecting 34 representative research achievements and phased progress. Among them was the research on space cold atom interferometry gyroscope technology. This work marks the first demonstration of an in-orbit cold atom gyroscope utilizing an atom interferometer on the China Space Station (J. T. Li, et al., Natl. Sci. Rev. 12: nwaf012, 2025).

Physical image of the space cold atom interferometer in orbit

Astronauts conducting suspended cold atom interference experiments inside the Chinese Space Station

 

 Constructing the simplest molecule from two atoms and achieving coherent conversion between atoms and molecules represents the most fundamental step in matter control. However, limited by decoherence factors, this had not been realized until now. Our team proposed a novel method utilizing the coupling between atomic spin and the relative motional wave function. Ultimately, we achieved the coherent synthesis of individual ultracold 87Rb-85Rb molecules in the ground state of a trapping potential within an optical tweezer, observing long-lived coherent Rabi oscillations between the two-atom pair and the single molecule (X. D. He, et al., Science 370(6514), 331-335, 2020).

     

Schemes of SMC and molecular association in a tight OT.

  • 实现两原子系统
  • Realizaed two-atom sysytem (2015)

 

                 

Schematic diagram of inelastic collisions of heteronuclear diatomic molecules

 

    We successfully achieved controlled cold collisions between a 87Rb atom and a 85Rb atom in a micron-scale optical trap through laser manipulation(P. Xu, et al., Nat. Commun. 6: 7803, 2015).

 

 

  • 在E-8水平检验弱等效原理
  • Test weak equivalence principle at E-8 level (2015)

 

 

    

Schematic diagram of testing the equivalence principle using two-component atoms

 

   We made significant progress in testing the equivalence principle with microscopic particles. They proposed and realized a novel four-wave double Raman (4WDR) diffraction scheme for cold atom interferometry. Utilizing a dual-species atom interferometer, they conducted experiments to test the Weak Equivalence Principle, achieving a precision of 10⁻⁸ (L. Zhou, et al., Phys. Rev. Lett. 115, 013004, 2015).