Application of quantum-limited optical time transfer to space-based optical clock comparisons and coherent networks

Abstract

With the demonstration of quantum-limited optical time transfer capable of tolerating the losses associated with long ground-to-space links, two future applications of free-space time transfer have emerged: intercontinental clock comparisons for time dissemination and coherence transfer for future distributed sensing in the mm-wave region. In this paper, we estimated the projected performance of these two applications using quantum-limited optical time transfer and assuming existing low-size, low-weight, and low-power hardware. In both cases, we limit the discussion to the simplest case of a single geosynchronous satellite linked to either one or two ground stations. One important consideration for such future space-based operations is the choice of reference oscillator onboard the satellite. We find that with a modestly performing optical reference oscillator and low-power fiber-based frequency combs, quantum-limited time transfer could support intercontinental clock comparisons through a common-view node in geostationary orbit with a modified Allan deviation at the 10−16 level at 10-s averaging time, limited primarily by residual turbulence piston noise. In the second application of coherence transfer from ground-to-geosynchronous orbit, we find the system should support high short-term coherence with ∼10 millirad phase noise on a 300 GHz carrier at essentially unlimited integration times.

Mathieu-Hill Equation Stability Analysis for Trapped Ions. Anharmonic Corrections for Nonlinear Electrodynamic Traps

“…Furthermore, it is anticipated that the use of compound atomic clocks can enhance the stability of single ion clocks with long clock transition lifetimes to levels comparable to that of optical lattice clocks [80,106]. For ion species with shorter lifetimes, the stability can be improved directly by increasing the number of ions, but this approach requires special care in the selection of the atomic transition and offers the potential for a stability beyond the SQL , which could be a viable method to further improve the stability of optical clocks [109] and provide quantum-limited optical time transfer [87,146] to achieve intercontinental clock comparisons through a common-view node in geostationary orbit (GEO). Several missions such as NASA's Deep Space Atomic Clock (DSAC) or several European Space Agency (ESA) missions are based on deploying optical clocks in space.…”

Mathieu–Hill Equation Stability Analysis for Trapped Ions: Anharmonic Corrections for Nonlinear Electrodynamic Traps

“…For ion species characterized by shorter lifetimes, the stability can be improved directly by increasing the number of ions. Nevertheless, this approach requires special care in the selection of the atomic transition and offers the potential for a stability beyond the SQL, which could represent a viable approach to further improve the stability of optical clocks [91] and provide quantum-limited optical time transfer [82,92], with an aim to achieve intercontinental clock comparisons through a common-view node in geostationary orbit (GEO). Several missions such as NASA's Deep Space Atomic Clock (DSAC) or the Atomic Clock Ensemble in Space (ACES), along with ongoing or future European Space Agency (ESA) missions are based on deploying optical clocks in space.…”