SB141-004 TITLE: *Portable Microwave Cold Atomic Clock*
TECHNOLOGY AREAS: Materials/Processes, Sensors, Electronics This topic is eligible for the DARPA Direct to Phase II Pilot Program. Please see section 4.0 of the DARPA instructions for additional information. To be eligible, offerors are required to provide information demonstrating the scientific and technical merit and feasibility of a Phase I project. DARPA will not evaluate the offeror's related Phase II proposal where it determines that the offeror has failed to demonstrate the scientific and technical merit and feasibility of the Phase I project. Offerors must choose between submitting a Phase I proposal OR a Direct to Phase II proposal, and may not submit both for the same topic. OBJECTIVE: Develop a laser-cooled microwave atomic clock with small volume (< 1 L) and weight (< 1 kg), low power consumption (< 5 W), and the stability (10^-12 at 1 s) of a primary atomic frequency standard. DESCRIPTION: Frequency and timing devices are essential components in modern military systems. The stability and accuracy of these devices impact the performance of communication, navigation, surveillance, and missile guidance systems. Atomic clocks are at the cores of many of these systems, either directly or via time-transfer from a master clock. By employing techniques used in current laboratory atomic clocks, military clocks can be improved by orders-of-magnitude. Such clocks will enable secure data routing, communication systems that are insensitive to jamming, higher resolution coherent radar, and more reliable and robust global positioning. Laser-cooled optical lattice atomic clocks are currently the world's most stable clocks, with stability below 10^-18 at 6 hours of averaging [1]. DARPA's QuASAR program aims to miniaturize and ruggedize such high-performance optical atomic clocks for deployment in the field [2]. While this work could enable widespread adoption of optical clock technology, many applications cannot tolerate the size, weight, and power (SWaP) of these first generation portable optical clocks (S > 50 L, W > 50 kg, P > 150 W). DARPA's Chip Scale Atomic Clock (CSAC) program has developed miniature microwave atomic clocks with extremely low SWaP values (S ~ 16 cm^3, W ~ 35 g, P ~ 125 mW) and good short-term stability (10^-10 at 1 sec) [3]. However these clocks drift over long timescales making them unsuitable for many applications. The goal of this SBIR is to bridge the gap between these extremes by developing an atomic frequency standard with long term stability (< 5x10^-15 at 1 day), approaching that of laboratory frequency standards such as the NIST F1 microwave Cs fountain clock [4] but with reasonable SWaP values (S < 1 L, W < 1 kg, P < 5 W). To achieve these goals, this SBIR will combine aspects of the two extreme clock architectures mentioned above: laser cooling (as used in QuASAR optical clocks) and microwave hyperfine transitions (as used in CSAC). Alternative strategies will also be considered if sufficiently justified. Special attention will need to be focused on reducing the power requirements of the requisite lasers, microwave sources, and local oscillators. Furthermore, the final device should be robust to environmental fluctuations (e.g. temperature, magnetic field, vibration) in a relevant operating environment. PHASE I: Develop an initial design and model key elements of the proposed clock. The chosen work must be compatible with a fractional frequency stability of < 10^-12 at 1 second averaging and < 5x10^-15 for 1 day of averaging. It should have a size < 1 L, weight < 1 kg, and power consumption < 5 W. Develop a detailed analysis of the predicted performance in a relevant environment accounting for expected environmental fluctuations such as temperature, magnetic field, and vibration fluctuations. Exhibit the feasibility of the approach through a laboratory demonstration of critical components. Phase I deliverables will include a design review including expected device performance and a report presenting the plans for Phase II. DIRECT TO PHASE II - Offerors interested in submitting a Direct to Phase II proposal in response to this topic must provide documentation to substantiate that the scientific and technical merit and feasibility described in the Phase I section of this topic has been met and describes the potential commercial applications. Documentation should include all relevant information including, but not limited to: technical reports, test data, prototype designs/models, and performance goals/results. Read and follow Section 4.0 of the DARPA Instructions PHASE II: Construct and demonstrate a prototype device validating the device performance outlined in Phase I. The Transition Readiness Level to be reached is 5: Component and/or bread-board validation in relevant environment. PHASE III: The low SWaP of the clock developed in this program should enable widespread deployment of clocks with stability comparable to primary frequency standards. Such clocks could lead to more reliable and robust global positioning, synchronization and time-keeping in GPS-denied environments, secure data routing, communication systems that are insensitive to jamming, higher resolution coherent radar, and precision timekeeping. Potential commercial applications include precise synchronization of telecommunication networks for high-bandwidth communications, next-generation satellite atomic clocks for global positioning, and local clocks for very long-baseline interferometry. REFERENCES: 1. Hinkley, N. et al. An atomic clock with 10^-18 instability. arXiv:1305.5869 (2013), http://arxiv.org/abs/1305.5869 2. QuASAR: Quantum Assisted Sensing and Readout: https://www.fbo.gov/index?s=opportunity&mode=form&id=9c912ae0743a9da465a18618bdc4d2a8&tab=core&_cview=0 3. Knappe, S. et al. A chip-scale atomic clock based on 87Rb with improved frequency stability. Opt. Express 13, 1249-1253 (2005). 4. NIST Primary Frequency Standards and the Realization of the SI Second. NCSL International Measure, Vol 2, No 4, 74 (2007) ( http://tf.nist.gov/general/pdf/2039.pdf) _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
