Abstract
We demonstrate distribution of polarization entangled photon-pairs across multiple channels in a 6 km loop of deployed fiber. We use an all-optical networking switch to route Bell-state photons in three different wavelength pairs and verify entanglement distribution in all channel pairs by measuring two-photon interference fringes.
| Original language | English (US) |
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| Title of host publication | 2023 Conference on Lasers and Electro-Optics, CLEO 2023 |
| Publisher | Institute of Electrical and Electronics Engineers Inc. |
| ISBN (Electronic) | 9781957171258 |
| State | Published - 2023 |
| Event | 2023 Conference on Lasers and Electro-Optics, CLEO 2023 - San Jose, United States Duration: May 7 2023 → May 12 2023 |
Publication series
| Name | 2023 Conference on Lasers and Electro-Optics, CLEO 2023 |
|---|
Conference
| Conference | 2023 Conference on Lasers and Electro-Optics, CLEO 2023 |
|---|---|
| Country/Territory | United States |
| City | San Jose |
| Period | 5/7/23 → 5/12/23 |
Funding
Photon Source (EPS-1000-W), which consists of a periodically poled lithum niobate waveguide that generates quantum-correlated photon-pairs. The waveguide is pumped by a pulsed laser with a 250 MHz repetition rate at 1550.1 nm (ITU Channel 34). The polarization entangled state generated by the EPS is aligned to the |HH〉+|VV〉 Bell state at the receivers using two NuCrypt Polarization Analyzers (model PA-1000) and appropriate alignment signals. The output photons are filtered and divided into six channels that represent three sets of entangled photon-pairs in different 100 GHz ITU channel bands (i.e., C22/C46, C23/C45, and C24/C44). The EPS also generates a classical alignment signal, in the H and D bases [5]. The EPS is interfaced with the PAs and a NuCrypt Remote Correlation System (RCS) as shown in Fig. 1. The RCS uses the alignment signal generated by the EPS to compensate for any polarization drift in the network and align the PAs with the EPS H/D bases. This process helps us to rapidly align the polarizations for the two-photon interference measurement. Each channel pair of the EPS is connected to an input port on a Polatis Series 6000 16×16 all-optical SDN switch, while two output ports of the Polatis switch are connected to the circulators. We use Polatis’ web-based interface to select the pair to be propagated on each experiment. After counterpropagating the photon-pairs across the fiber loop, the photons are routed from the circulator to the PAs. We use the PAs to select the desired basis state for measurement after aligning it with the EPS bases using the alignment signal [5]. All instruments are controlled by NuCrypt software to synchronize measurements. Finally, the photon-pairs projected by the PA on a specific basis are measured by a Quantum Opus detector composed of two superconducting nanowire single photon detectors (SNSPD) for coincidence counting, from which electrical pulses are recorded by the RCS. With the idler PA fixed at a specific basis of H, R, V, L on the Poincaré sphere, the other PA is programmed to rotate about the S2 axis of the Poincaré sphere, and coincidence counts are measured at each setting, thus generating interference fringes. We verify the entanglement by calculating the fringe visibility, defined as (CCmax−CCmin)/(CCmax+CCmin), where CC refers to the coincidence counts, the maximum and minimum of which are extracted by fitting the fringes to sinusoids. We observe interference fringes in the coincidence counts as a function of the retardance of the waveplate of the signal PA with a visibility that is well above 71% in all bases across all three pairs as shown in Fig. 2, thus demonstrating entanglement between the signal and idler pairs and its distribution across the loop in the Q-LAN. In conclusion, we have demonstrated a topology to distribute polarization entanglement selectively using an SDN all-optical switch and deployed fiber, which can be used to distribute various Bell states to separate measurement nodes. Acknowledgments: This work is funded by the the U.S. Department of Energy’s Advanced Scientific Computing Research Transparent Optical Quantum Networks for Distributed Science program, but no government endorsement is implied. We would like to thank Daniel Reilly and Paul Moraw at NuCrypt LLC for help with measurements. We also thank Rick Krasuski and Michael Monczynski at Argonne National Laboratory for help in setting up the deployed fiber. GK and PK disclose their financial interest in NuCrypt LLC. This work is funded by the the U.S. Department of Energy's Advanced Scientific Computing Research Transparent Optical Quantum Networks for Distributed Science program, but no government endorsement is implied. We would like to thank Daniel Reilly and Paul Moraw at NuCrypt LLC for help with measurements. We also thank Rick Krasuski and Michael Monczynski at Argonne National Laboratory for help in setting up the deployed fiber. GK and PK disclose their financial interest in NuCrypt LLC.
ASJC Scopus subject areas
- Artificial Intelligence
- Computer Science Applications
- Electronic, Optical and Magnetic Materials
- Instrumentation
- Atomic and Molecular Physics, and Optics