The quantum internet, by providing the underlying communication infrastructure required for many quantum information applications, is of high strategic importance. As a result, countries such as China, the United States and members of the European Union are investing heavily in both terrestrial and space-based quantum communication networks. The prototype systems currently being deployed lack the essential hardware required to “regenerate” and route quantum information across a network. The technology being developed at the ANU is a leading contender to form the basis of this quantum networking hardware.

The ANU technology is based on quantum memories using rare-earth doped crystals. The focus to date has been to develop the technology for terrestrial applications. This project will evaluate key issues in operating rare-earth quantum technology on a satellite platform and gauge its suitability for potential future space missions. The work will be conducted in collaboration with researchers at the NASA Goddard Space Flight Center.

This project will apply the concepts and techniques of distributed receive beamforming to achieve higher throughput at low signal-to-noise (SNR) values. This project will also explore general methods for satellite applications.

Driven by the booming amount of transmission information, modern communication systems have developed to the fifth generation, and are expected to integrate different radio access technologies, including the satellite component. As outlined in the 3GPP, the future integrated satellite and terrestrial architectures will lead to manifold advantages and make satellite communications essential to the evolution fo the 5G network. Thus, the future 5G satellite network is required to have low latency, high capacity, and strong adaptability to complex environments, and these requirements are aligned to our research objectives, “developing advanced communication networks which are efficient and stable”.

However, the traditional satellite communication systems only have a limited ability to face challenges in 5G scenarios, including high attenuation, the complex and unreliable communication environment and resulting transmission errors. Though there are some existing solutions for satellite communications to combat these channel impairments, they cannot work well enough for 5G. To ensure the accuracy, efficiency and reliability of the future wireless communications system, our research aims to develop DL based wireless physical layer frameworks (i.e., leveraging deep-learning to redesign the module of the conventional communication system) for performance improvement, which can also be used to implement 5G satellite communications.

The CHORUS project aims to build on existing world leading Australian technology in compact RF tactical terminals and optical communication to develop “leap-frogging” technology that exploits bearer diversity through a highly integrated hybrid Optical-RF tactical terminal. If successful, this will place Australia in a leading position to create new capabilities for compact, high data rate, high availability satellite earth terminals for commercial and national security markets.

Phase 1 of CHORUS, now successfully completed (Apr 2019-Apr 2020), was a high-risk, high-payoff research activity to develop concepts for, and explore the feasibility of, a highly integrated, tactical satellite communications terminal combining radio frequency and optical frequency capabilities into a single compact terminal.

Phase 2, proposed to the CRC in December 2020, is for the development of a full size engineering model of one of the candidate terminal concepts. The Phase 2 objectives are to validate the intellectual property created in Phase 1 and to build knowledge and confidence in the manufacturability and performance of the terminal.

The project overall plans to demonstrate a system that will enable optical fibre-like data transfer rates for atmospheric free-space communication links, including over 10 km⁺ ground-to-ground links, as well as space-to-ground links.

P1-01: The precursor to this project involved the initial development and deployment of a phase-stabilised system, finally demonstrating the feasibility of coherent free-space optical communications over a horizontal 2km link.

P1-18: Following Phase 1, in this next stage of the project we will further develop an advanced optical communications system that has been shown to support optical fibre-like data transfer rates over atmospheric free-space communication links.

This communication system is based on the combination of optical terminals using active optics technology, and a free-space coherent phase-stabilisation system. In the precursor to this project, these systems were successfully demonstrated over 2.4 km and 10 km horizontal free-space links.

This research project will focus on deploying this technology and thereby demonstrating optical fibre-like data transfer rates for free-space optical communications over a series of vertical links through Earth’s turbulent atmosphere, starting with low-altitude targets, progressing to light aircraft and stratospheric vehicles.

A Chip-based frequency comb FSOC system as a basis for super channel architecture that can utilize coherent processing due to the fixed phase relationship between all comb laser lines.

Optical frequency combs (f-combs) are an emerging disruptive laser technology capable of replacing 10s to 100s of individual CW lasers to produce densely packed optical superchannel transmitters. For free-space optical communication (FSOC) applications, a more profound advantage over arrays of independent laser transmitters (ie. ‘dumb’ lasers), is that frequency combs have an intrinsic phase relationship between the channels which allows ‘pilot’ channels to be allocated that can be digitally and coherently processed at the receiver end. A further advantage of using a frequency-comb based transmitter is the potential for a signal processing mechanism to compensate for atmospheric distortion for all comb lines. This proposed architecture could in the future be evolved towards a completely smart and reconfigurable software driven transmitter.

Our proposed FSOC transmitter is a unique and stable chip laser frequency comb architecture that is at an early TRL for this application but has already been demonstrated to produce a world-leading stable frequency comb, and to date only been applied to spectroscopic applications.