The coherence of wave-packet-tunable photons (2312.15687v1)

Abstract: The wave-packet-tunable photons [Optics Express 30, 2792-2802 (2022)] generated by spontaneous Raman scattering (SRS) based on atomic ensemble lay a foundation for the hybrid quantum network to successfully connect quantum nodes with different bandwidths, but the coherence time of wave-packet photons becomes the key factor limiting the distance of entanglement distribution. The coherence of photons deteriorates with the propagation distance of the entanglement distribution. So far, the coherence of wave-packet-tunable photons entangled with an atomic memory has remained unexplored. An unequal arm fiber interferometer is constructed to measure the interference visibility of 150 ns-1.06 {\mu}s pulse width wave-packet-tunable photons. The coherence time and bandwidth of the photons can be directly derived from the decay of the visibility in the interferogram as the wave-packet photons length increases. The measured results show that the coherence time of write laser is 2.36 {\mu}s and bandwidth is 78 KHz, which interact onto atoms can generate Stokes photons with the coherence time is 1.14{\mu}s and bandwidth is 156 KHz. The measurement of coherence of wave-packet-tunable photons lays the foundation for establishing the distribution of entanglement between spatially separated memories in hybrid quantum networks, and for establishing a baseline telescope of arbitrary length through wave-packet-tunable photon interference.