Fig. 1

Overview of experiment. a The relevant energy level diagram. Write and Read represent write-laser pulse and read-laser pulse respectively; S1 and S2 are Signal 1 photon and Signal 2 photon. States \(\vert 1\rangle,\vert 2\rangle,\vert 3\rangle\), and \(\vert 4\rangle\) correspond to \({}^{85}{\mathrm{Rb}}\) atomic levels of \(5{S}_{1/2}(F=2)\), \(5{S}_{1/2}(F=3)\), \(5{P}_{1/2}(F=3)\), and \(5{P}_{3/2}(F=3)\), respectively. \(\Delta\) represents the detuning of write-laser pulse, which is set to be \(+2\pi \times 70\ {\rm{MHz}}\). The part in below is the time sequence of experiment. b Experimental setup. MOT is magneto-optical trap, \({\rm{L}}1-{\rm{L}}8\) represent a series of lenses, \({\rm{\lambda }}/4\) is quarter-wave plate, \({\rm{\lambda }}/2\) is half-wave plate and PBS is polarization beam splitter. SLM \(1 \sim 4\) are spatial light modulators