Abstract
We have designed and implemented a photon-pair source, based on the spontaneous four wave mixing (SFWM) process in a few-mode fiber, in a geometry which permits multiple, simultaneous SFWM processes, each associated with a distinct combination of transverse modes for the four participating waves. In our source: i) each process is group-velocity-matched so that it is, by design, nearly-factorable, and ii) the spectral separation between neighboring processes is greater than the marginal spectral width of each process. Consequently, there is a direct correspondence between the joint amplitude of each process and each of the Schmidt mode pairs of the overall two-photon state. Our approach permits hybrid entanglement in discrete frequency and in transverse mode, whereby control of the number of supported fiber transverse modes allows scalability to higher dimensions while spectral filtering may be used for straightforward Schmidt mode discrimination.
Highlights
We have shown previously that a few-mode, birefringent fiber can permit multiple spontaneous four wave mixing (SFWM) processes, each involving a different phasematched combination of transverse modes for pumps 1 and 2, signal, and idler[8]
In this paper we extend our earlier work, exploiting the observation that if: i) each joint amplitude, taken individually, is made factorable, and ii) the spectral separation between neighboring SFWM processes is greater than the marginal spectral width of each process, each joint amplitude constitutes a Schmidt mode pair for the overall two-photon state
The two-photon state produced by this source includes contributions from three separate SFWM processes, each corresponding to a phasematched combination of transverse modes and frequencies of the participating waves
Summary
We have shown previously that a few-mode, birefringent fiber can permit multiple SFWM processes, each involving a different phasematched combination of transverse modes for pumps 1 and 2, signal, and idler[8]. In this paper we discuss a scheme which permits the emission of photon pairs with hybrid entanglement between frequency and transverse mode, implemented through the SFWM process in a few-mode fiber. Note that this type of entanglement may in principle be faithfully transmitted over long distances utilizing few-mode fibers engineered for the suppression of coupling between the supported modes[20]. Our goal is to generate photon pairs involving multiple SFWM processes, so that the JSA for each process is factorable, i.e. so that it can be written as fj(ωs, ωi) =Sj(ωs)Ij(ωi) In this case, the state which exhibits discrete hybrid entanglement in frequency and transverse mode can be written as follows
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
