Dr. Leo Hollberg, Physics Department, Stanford University

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An advanced atomic clock in a well-defined orbit, combined with laser links between ground and space could serve as a Space-Time Reference frame that can provide time-transfer uncertainties of < 1 ps, range uncertainties of < 1 mm worldwide. It would enable new capabilities of high-speed data transfer with PNT referencing, secure communications, and additional atmospheric science. Potential applications include worldwide synchronization of time scales (e.g. optical clocks at national standards labs), high accuracy geodetic referencing, and perhaps added value in characterizing GNSS atomic frequency references and orbits without ionospheric uncertainties. Worldwide several new atomic clocks are being studied/developed for space and might sever in this role. We have analyzed a model system with particular focus on achievable performance of time-transfer, precise orbit determination, and ranging for two-way laser links between ground and space and addressing various limitations due to atmospheric turbulence, scintillation, beam wonder and optical group delay. Professor Physics (research) Stanford University. Previously CTO at AOSense, and 20+ years at NIST. PhD University of Colorado and postdoc Bell Laboratory. Research in laser-atomic physics and precision measurements.