Shared in Quantum Science in Space · Labbook
Slowing an atom cloud for a test of free fall in space
Magnetic lensing of a rubidium condensate on an atom chip: from the first condensate to what a satellite test needs.
- Author
- Jonas Weber, Example Institute for Space Quantum Science (fictional)
Started 2026-09-29 · Last step 2026-10-11 · 5 steps
Updated 6 days ago
Steps
- 1
A condensate to start from
2026-09-29 · A Bose–Einstein condensate of 1.2 × 10⁵ rubidium atoms on the chip
- 2
When to switch the lens off
2026-10-01 · A model of the cloud after release: the residual magnetic push and the best lens duration
- 3
The lens works
2026-10-05 · A 0.9 ms magnetic lens slows the cloud's expansion about seven-fold
- 4
Longer is not stronger
2026-10-08 · A longer lens is not a stronger one: at 1.8 ms the cloud expands as fast as without
- 5
Good enough for space?
2026-10-11 · One lens is not enough for a 10⁻¹⁵ test of free fall in space; two would be
Where things stand
One magnetic lens slows the cloud about seven-fold, to 76 ± 10 pK (A 0.9 ms magnetic lens slows the cloud's expansion about seven-fold), at the duration our model predicted (A longer lens is not a stronger one: at 1.8 ms the cloud expands as fast as without). That is not yet enough for a 10⁻¹⁵ test in space; a second lens is predicted to be (One lens is not enough for a 10⁻¹⁵ test of free fall in space; two would be).
Open points
- Rerun the two-lens simulation with the cloud displaced as in orbit (Lena's review).
- Measure the second lens on the chip.
- Ask the authors of Müller et al. whether an erratum for Tab. II is planned.