Processing and distributing quantum information using photons through fibre-optic or free-space links are essential for building future quantum networks. The scalability needed for such networks can be achieved by employing photonic quantum states that are multiplexed into time and/or frequency, and light-matter interfaces that are able to store and process such states with large time-bandwidth product and multimode capacities. Despite important progress in developing such devices, the demonstration of these capabilities using non-classical light remains challenging. Here, employing the atomic frequency comb quantum memory protocol in a cryogenically cooled erbium-doped optical fibre, we report the quantum storage of heralded single photons at a telecom-wavelength (1.53 μm) with a time-bandwidth product approaching 800. Furthermore, we demonstrate frequency-multimode storage and memory-based spectral-temporal photon manipulation. Notably, our demonstrations rely on fully integrated quantum technologies operating at telecommunication wavelengths. With improved storage efficiency, our light-matter interface may become a useful tool in future quantum networks.
The quantum routing of single photons takes the central role in an optical quantum network. The matching between the routing probability and the selected frequency of single photons limits the robustness and universality of the quantum router. Here, we investigate how to implement the quantum routing of single photons within bandwidth frequencies by two cavities embedding atoms acting as quantum nodes. We show that the routing capabilities of the single photons and the range of the frequencies can be manipulated by properly designing the chiral coupling strengths and the channel boundaries. Also, we demonstrate that the incident single photons, within bandwidth frequencies, can be completely routed to the targeted output port. This is particularly important to construct optical quantum networks within bandwidth frequencies in the future.
We experimentally demonstrate frequency translation of a non-classical optical field by Bragg-scattering four-wave mixing, driven by orthogonally polarized pump pulses in a birefringent optical fiber. Heralded single photons are up- and down-translated by 6.8 THz between bands at 688.1 nm and 678.2 nm, each with efficiency > 97%. The input and output spectral shape and bandwidth show negligible modulation. Second-order auto-correlation measurements of the 678.2 nm and 688.1 nm fields at maximum conversion yield values of 0.0302 ± 0.0005 and 0.028 ± 0.001, respectively, compared with the input second-order correlation of 0.026 ± 0.001; this indicates that the frequency translation process preserves the non-classical nature of the field. The high efficiency, broad bandwidth, and low noise render this scheme useful for quantum networks and sources.