Stimulated Emission as a Result of Multiphoton Interference

By performing an experiment on stimulated emission by two photons in the parametric amplification process and comparing it to a three-photon interference scheme, we present evidence in support of the idea that the underlying physics of stimulated emission is simply the constructive interference due to photon indistinguishability. So the observed signal enhancement upon the input of photons can be interpreted as a result of multiphoton interference of the input photons and the otherwise spontaneously emitted photon from the amplifier.

Figure 1

Comparison between (a) the stimulated emission and (b) the multiphoton interference with a beam splitter. The empty circle is the photon from the excited atom in (a).

Figure 2

Schematics for studying the stimulated emission of an input of $N$-photon state with parametric amplification. SMF: single-mode fiber; IF: interference filter; $H$, $V$: horizontal and vertical polarizations; $T_H$: adjustable delay.

Figure 3

(a) Four-photon coincidence of $ABCD$ detectors in 100 s and (b) three-photon coincidence of $ABD$ detectors in 10 s as a function of the delay $c{T}_H$.

Figure 4

A simple scheme for interference of $N$ photons and one photon with a beam splitter. Same notations as Fig. 2.

Figure 5

Same as Fig. 2 but with data obtained from Fig. 4.