Unlike photons, which are conveniently handled by mirrors and optical fibres without loss of coherence, atoms lose their coherence via atom–atom and atom–wall interactions. This decoherence of atoms deteriorates the performance of atomic clocks and magnetometers, and also hinders their miniaturization. Here we report a novel platform for precision spectroscopy. Ultracold strontium atoms inside a kagome-lattice hollow-core photonic crystal fibre are transversely confined by an optical lattice to prevent atoms from interacting with the fibre wall. By confining at most one atom in each lattice site, to avoid atom–atom interactions and Doppler effect, a 7.8-kHz-wide spectrum is observed for the 1S0−3P1(m=0) transition. Atoms singly trapped in a magic lattice in hollow-core photonic crystal fibres improve the optical depth while preserving atomic coherence time.

Unravelling superradiance, also known as superfluorescence, relies on an ensemble of phase-matched dipole oscillators and the suppression of inhomogeneous broadening. Here we report on a novel superradiance platform that combines an optical lattice free from the ac Stark shift and a hollow-core photonic crystal fibre, enabling an extended atom-light interaction over 2 mm free from the Doppler effect. This system allows controlling the

We have demonstrated the continuous outcoupling of ultracold 88Sr atoms using a moving optical lattice. While Sr atoms are Zeeman-slowed and magneto-optically trapped on the 1S0 − 1P1 transition, the atoms relaxed to the 5s5p 3P2 metastable state are agnetically-trapped and Doppler cooled on the 5s5p 3P2 − 5s4d 3D3 transition at 2.92 μm. By optically pumping the atoms to the 5s5p 3P0 state, we outcouple the atoms by a moving optical lattice. Such a continuous atomic source enables superradiant lasers and the zero-dead-time operation of atom interferometers and optical lattice clocks.