Nonlinear frequency conversion of photons for quantum networks

Alex S. Clark, L. G. Helt, Matthew J. Collins +4 more

Surajit Bose, Alí M. Angulo M., Stefanus Wijaya +8 more

Light manipulation in waveguides has proven to be an important technology in the classical and quantum regimes. The frequency conversion in the quantum domain was proposed to change the photon's frequency distribution without affecting photons statistics [1] and is important for quantum networks, as well as creating superposition in frequency-encoded states [2]. Scalable quantum networks need noiseless conversion. A common approach for noiseless frequency conversion is electro-optical phase-shift-induced sideband creation. However, the magnitude of the frequency shift in this technology is rather restricted, limiting their processing bandwidth to sub-THz levels [2]. This necessitates a thorough design of the nonlinear interaction to utilize a deterministic approach to reshape single photons. Here, we demonstrate the use of Kerr-nonlinear refractive index fronts [3], [4] to optically manipulate the frequency of a single-photon wave packet.

Tong Xiang, Qi-Chao Sun, Yuanhua Li +2 more

Frequency conversion of single photons is an important technology for quantum interface and quantum communication networks. Here, single-photon frequency conversion in the telecommunication band is experimentally demonstrated via cascaded quadratic nonlinear processes. Using cascaded quasi-phase-matched sum and difference frequency generation in a periodically poled lithium niobate waveguide, the signal photon of a photon pair from spontaneous down-conversion is precisely shifted to identically match its counterpart, i.e., the idler photon, in frequency to manifest a clear nonclassical dip in the Hong-Ou-Mandel interference. Moreover, quantum entanglement between the photon pair is maintained after the frequency conversion, as is proved in time-energy entanglement measurement. The scheme is used to switch single photons between dense wavelength-division multiplexing channels, which holds great promise in applications in realistic quantum networks.

Yu A Il'inskiĭ, Vera M. Petnikova

Sidarth Raghunathan

Susanne Blum, G. A. Olivares-Rentería, Carlo Ottaviani +2 more

Frequency conversion of single photons in a nonlinear crystal is theoretically discussed. Losses and noise are included within a Heisenberg-Langevin formalism for the propagating photon field. We calculate the first- and second-order correlation functions of the frequency-converted light when the input is a train of single-photon pulses. This model allows one to identify the requirements on the nonlinear device so that it can be integrated in a quantum network.