Low Size, Weight, and Power (SWAP), High Electrical Efficiency Microwave and/or Radiofrequency (RF) Generator or Amplifier for Atomic or Molecular Spectroscopy Applications

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Microelectronics; Quantum Science OBJECTIVE: Low Size, Weight, and Power (SWaP), high electrical efficiency microwave and/or radiofrequency (RF) generator or amplifier for atomic or molecular spectroscopy applications. DESCRIPTION: Quantum computing and quantum information science use qubits (quantum bits) to store information. These qubits can be implemented in many ways, frequently by manipulating the energy state of the qubit to change between two levels. For atomic, atomic ion[1,2], molecular ion, and other physical implementations of qubits, these levels can be separated by microwave-scale energy differences. For example, trapped ion qubits can have level differences ranging from 0.8 to 41 GHz (listed as hyperfine splittings in [3]). Additionally, radio frequency can be utilized with acousto-optic or electro-optic modulation to place sidebands on lasers, allowing them address additional structure within the qubits. Microwave spectroscopy is not limit to single atoms or ions, but can extend to molecular polar ions [4] where microwaves are able to identify and manipulate the rotational state of the ions. This need places good quality microwave and radiofrequency sources and amplifiers among the critical components of many quantum information science-related experiments. In particular these devices need good amplitude, frequency, and phase noise characteristics for the final, post-amplification signal at delivered to the qubit. While most of these experiments take place in laboratory environment, increased electrical efficiency remains important. In addition to their contributions to operating costs, electrical inefficiencies will add to the overall thermal load of the laboratory making temperature stability a greater challenge and restricting the locations of the equipment relative to temperature-sensitive equipment. Additionally, for efforts looking to transition these quantum technologies outside of pristine laboratory environments, the Size, Weight, and Power (SWaP) of these devices will limit the locations in which they can be deployed. Mobile platforms are a particular challenge due to their strict SWaP limitations; on these platforms any gain in efficiency or reduction in SWaP either allows additional capabilities to be included or enables longer time-in-service. For example (although not used for spectroscopy in this instance), microwave sources were deployed to the International Space Station as part of a ultracold atomic physics experiment package [5]. PHASE I: Phase I will determine the technical feasibility of radiofrequency and/or microwave sources and/or amplifiers, suitable for the uses described in the objective and description above. Because this topic covers a wide range of frequencies and applications, no uniform set of metrics will apply to all situations. As such, the proposer should identify one or more comparable research laboratory-grade device(s) as the benchmark for comparison during Phase I and any following Phase efforts. A successful effort will include a detailed analysis of predicted performance, including both improvements on relevant microwave and/or radiofrequency signal metrics (e.g. linearity, gain, response flatness, phase noise, amplitude noise, frequency noise, etc.) and overall electrical efficiency of the system compared to identified performance benchmarks. Phase I Base amount must not exceed $295,000 for a 12-month period of performance. PHASE II: Using the results from Phase I, develop, test, and demonstrate the operation of a prototype system. This should include a direct laboratory comparison to the identified benchmark system in Phase I, if feasible. Phase II Base amount must not exceed $1,300,000 for a 24-month period of performance and the Option amount must not exceed $650,000 for a 12-month period of performance. PHASE III DUAL USE APPLICATIONS: The quantum information science industry extends well beyond DoD research settings, with many existing laboratories in DoD, academic, and private industry contexts (for example, [6] contains a listing of trapped ion research groups around the world). These laboratories have uses for microwaves beyond those considered in this SBIR, for example [7-8]. Any gains in performance under Phase I or Phase II could be utilized by any of these laboratories. Additionally, microwaves are used broadly throughout the telecommunications industry, where improvement in efficiency could provide immediate benefits to interested parties. REFERENCES: 1. Colin D. Bruzewicz, John Chiaverini, Robert McConnell, and Jeremy M. Sage , "Trapped-ion quantum computing: Progress and challenges", Applied Physics Reviews 6, 021314 (2019) https://doi.org/10.1063/1.5088164 2. Leibfried, D., Blatt, R., Monroe, C., & Wineland, D. (2003). Quantum dynamics of single trapped ions. Reviews of Modern Physics, 75(1), 281 324. doi:10.1103/RevModPhys.75.281 3. Quantum Computing with Trapped Ions, Duke University. (2023). Trapped Ion Periodic Table. Retrieved March 10, 2023, from https://iontrap.duke.edu/resources/ion-periodic-table/ 4. Shi, M., Herskind, P. F., Drewsen, M., & Chuang, I. L. (2013). Microwave quantum logic spectroscopy and control of molecular ions. New Journal of Physics, 15(11), 113019. doi:10.1088/1367-2630/15/11/113019 5. Frye, K., Abend, S., Bartosch, W. et al. The Bose-Einstein Condensate and Cold Atom Laboratory. EPJ Quantum Technol. 8, 1 (2021). https://doi.org/10.1140/epjqt/s40507-020-00090-8 6. Air Force Research Laboratory, Quantum Information Science Branch. (2022). AFRL/RITQ - ion references and useful links. AFRL/RITQ - Ion References and Useful Links. Retrieved March 10, 2023, from https://www.afrl.af.mil/About-Us/Fact-Sheets/Fact-Sheet-Display/Article/3040329/afrlritq-ion-references-and-useful-links/ 7. Lekitsch, B., Weidt, S., Fowler, A. G., M lmer, K., Devitt, S. J., Wunderlich, C., & Hensinger, W. K. (2017). Blueprint for a microwave trapped ion quantum computer. Science Advances, 3(2), e1601540. doi:10.1126/sciadv.1601540 8. Piltz, C., Sriarunothai, T., Ivanov, S. S., W lk, S., & Wunderlich, C. (2016). Versatile microwave-driven trapped ion spin system for quantum information processing. Science Advances, 2(7), e1600093. doi:10.1126/sciadv.1600093 KEYWORDS: Microwave Oscillators; Microwave Amplifiers; Radio Frequency Generators; Radio Frequency Amplifiers; Radio Frequency Spectroscopy; Atomic Spectroscopy; Molecular Spectroscopy; Quantum Information