Description:
Hybrid quantum networks are a key step towards realizing distributed quantum computing and quantum communications, two areas that promise to fundamentally change the way information is processed, delivered and secured. Hybrid quantum networks consist of quantum components that operate at different optical wavelengths. This is necessary since different functions of the network are best performed by different technologies (e. g. trapped ions, Rydberg atoms, nitrogen-vacancy color centers, etc.) that operate at incompatible wavelengths. Quantum interfaces are needed to make the different nodes compatible. Ideally, these interfaces are optical frequency converters that convert photons of one wavelength to another with 100% conversion efficiency and no additional noise. In practice, up to 86% internal conversion efficiency has been demonstrated [1] using periodically poled lithium niobate (PPLN) waveguides, and when coupling and collection losses are included, external conversion efficiencies between 51% [2] and 65% [1] have been shown. Furthermore, these devices have been developed by academic institutions and to our knowledge, no commercial vendors exist that can achieve this level of performance.
An unmet need exists for a commercial source of high-efficiency, high-performance optical frequency converters. Efficient, low-loss converters are needed for both up- and down-conversion. Devices must be able to efficiently convert between far-separated wavelengths, which requires on-chip mode conditioning and directional coupling [3]. Attention to packaging and fiber coupling is needed to make the devices robust and easy to use. NIST is interested in these devices to further efforts in realizing a hybrid quantum network. We are seeking proposals from US industry to develop reliable, high-efficiency devices and demonstrate a path towards commercialization.
The goal of this project is to develop commercial facilities and capabilities to manufacture, characterize and test high-performance optical frequency converters. High performance includes high conversion efficiency, low noise, robust packaging, good long-term stability and performance free of photorefractive damage. High external conversion efficiency requires excellent waveguide quality, low propagation losses and high coupling efficiency. On-chip filters and couplers are likely needed to achieve high launching and coupling efficiencies.
Phase I expected results:
Demonstration of expertise and capability in fabricating high-efficiency waveguides. Design and verification via modeling for high conversion efficiency, high efficiency input and output coupling (likely utilizing on-chip filters) for (a) upconversion between 1892 nm + 1550 nm ® 852 nm and (b) down-conversion between 852 nm + 1892 nm ® 1550 nm.
Phase II expected results:
Demonstrate packaged, fiber-coupled optical frequency converters for upconversion and downconversion. Fiber-coupling should enable high launching efficiencies of both pump and signal beams, which will likely requires two separate input fibers and on-chip beam combining. Develop waveguides with at least 80% internal conversion efficiency and 50% external conversion efficiency using a continuous-wave (CW) pump. The devices should achieve maximum conversion with input CW pump power below 1W. Demonstrate capability to characterize (a) internal and external conversion efficiencies, (b) waveguide propagation losses, (c) input coupling efficiency, accounting for facet, fiber-pigtailing and mode-matching losses, and (d) output coupling efficiency. Demonstrate fabricated waveguides for both processes mentioned in phase I and show the designs can be adapted and executed at other wavelengths, for instance processes having pump longer than 2100 nm.
It is expected that NIST researchers will be available for consultation and input.
References:
[1] Pelc, J.S., Ma, L., Phillips, C.R., Zhang, Q., Langrock, C., Slattery, O., Tang, X. and Fejer, M.M. “Long-wavelength-pumped upconversion single-photon detector at 1550 nm: performance and noise analysis”, Opt. Express 19, 21445-21456 (2011).
[2] Kuo, P.S., Pelc, J.S., Slattery, O., Kim, Y.S., Fejer, M.M. and Tang, X. “Reducing noise in single-photon-level frequency conversion”, Opt. Lett. 38, 1310-1312 (2013).
[3] Pelc, J.S., Yu, L., De Greve, K., McMahon, P.L., Natarajan, C.M., Esfandyarpour, V., Maier, S., Schneider, C., Kamp, M., Höfling, S., Hadfield, R.H., Forchel, A., Yamamoto, Y. and Fejer, M.M. “Downconversion quantum interface for a single quantum dot spin and 1550-nm single-photon channel”, Opt. Express 20, 27510-27519 (2012).
