Fig. 1: Experimental realization of temporal Wheeler’s delayed-choice experiment.
From: Temporal Wheeler’s delayed-choice experiment based on cold atomic quantum memory
a Energy level diagram. MOT A, B and C represent three magneto-optical traps. Single photons S 1 and S 2 are generated from MOT A using the SFWM process with single-photon detuning Δ/2π = 50 MHz. The MOT B/C acts as QM based on Raman storage protocol. States \(\left|1\right\rangle\), \(\left|2\right\rangle\), \(\left|3\right\rangle\) and \(\left|4\right\rangle\) correspond to 85Rb atomic levels of 5S1/2(F = 2), 5S1/2(F = 3), 5P1/2(F = 3) and 5P3/2(F = 3) respectively. b Simplified experimental setup. Pump 1/2 is pump light beam. Coupling 1/2 represents the coupling light beam. EOM is an electro-optic modulator to introduce a phase shift, and 200-m fiber is aimed for an optical delay of 1 μs. D 1/D 2, avalanche diode 1/2. c Schematic of the evolution of single-photon pulse in the delayed-choice experiment. d The wave-particle duality of single photons. When the M-BS 2 is inserted, the red experimental data dots are obtained and the interference curve is fitted with a sine function, which is a wave-like phenomenon. The black line is fitted with a constant function while M-BS 2 is moved out, the interference is vanished, revealing a particle-like phenomenon. The error bars in the experimental data are estimated from Poisson statistics and represent one standard deviation.
