Low-frequency Gravitational Wave Detection via Double Optical Clocks in Space

TL;DR

This paper proposes a space-based Doppler tracking system using double optical clocks to detect low-frequency gravitational waves with high sensitivity, surpassing previous radio-based methods.

Contribution

It introduces a novel optical clock-based Doppler tracking system in space for gravitational wave detection, achieving higher sensitivity and noise reduction compared to traditional radio methods.

Findings

Achieves sensitivity of 5 x 10^{-19} over 2 years

Detects gravitational waves in 10^{-4} to 10^{-2} Hz range

Reduces noise effects from Earth's atmosphere and ground-based systems

Abstract

We propose a Doppler tracking system for gravitational wave detection via Double Optical Clocks in Space (DOCS). In this configuration two spacecrafts (each containing an optical clock) are launched to space for Doppler shift observations. Compared to the similar attempt of gravitational wave detection in the Cassini mission, the radio signal of DOCS that contains the relative frequency changes avoids completely noise effects due for instance to troposphere, ionosphere, ground-based antenna and transponder. Given the high stabilities of the two optical clocks (Allan deviation $\sim 4.1\times 10^{-17}$ @ 1000 s), an overall estimated sensitivity of $5 \times 10^{-19}$ could be achieved with an observation time of 2 years, and would allow to detect gravitational waves in the frequency range from $\sim 10^{-4}$ Hz to $\sim 10^{-2}$ Hz.