Abstract
Recently, a method of engineering the quantum states with a nonlinear interferometer was proposed to achieve precise state engineering for near-ideal single-mode operation and near-unity efficiency (L. Cui et al., Phys. Rev. A 102, 033718 (2020)), and the high-purity bi-photon states can be created without degrading brightness and collection efficiency. Here, we study the coarse or fine tunability of the nonlinear interference method to match constructive interference patterns into a transmission window of standard 100-GHz DWDM channels. The joint spectral intensity spectrum is measured for various conditions of the nonlinear interference effects. We show that the method has coarse- and fine-tuning ability while maintaining its high spectral purity. We expect that our results expand the usefulness of the nonlinear interference method. The photon-pair generation engineered via this method will be an excellent practical source of the quantum information process.
Highlights
Modal purity or indistinguishability is an essential factor in achieving high visibility of quantum interference for quantum photonic applications such as quantum teleportation [1] and linear optical quantum computing [2]
Spectrally uncorrelated photon pairs with a factorable joint spectral amplitude (JSA) can induce high visibility of quantum interference [4,6] with high indistinguishability and high spectral purity
For the case of using single-mode fiber (SMF) as a dispersive medium, only one constructive island can be matched on the ITU grid as ∆kSMF of SMF is quadratically dependent on the detuning of pairs from the pump frequency (∆ωs(i) = |ωp − ωs(i)|) [18,21]
Summary
Modal purity or indistinguishability is an essential factor in achieving high visibility of quantum interference for quantum photonic applications such as quantum teleportation [1] and linear optical quantum computing [2]. For the case of using single-mode fiber (SMF) as a dispersive medium, only one constructive island can be matched on the ITU grid as ∆kSMF of SMF is quadratically dependent on the detuning of pairs from the pump frequency (∆ωs(i) = |ωp − ωs(i)|) [18,21]. Ignoring the propagation loss of fibers and pump chirping, the bi-photon state amplitude through an N-stage NLI system can be calculated by [18], N. n=1 where FDSF(ωs, ωi) is the JSA at the signal (ωs) and idler (ωi) frequency generated by SFWM in a single DSF section, ∆kDSF (∆kSMF) is the phase mismatch between signal, idler, and two pump fields in DSF (SMF), LDSF (LSMF) is the length of DSF (SMF), respectively. That 100-GHz DWDM filters, whose center frequency spacing from the pump is ±400 GHz were the target filters for reducing the Raman noise through the NLI optical fiber system
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