Cooperative Classical and Quantum Communications Systems

According to Moore's law, the number of transistors on a micro-chip doubles every two years. Hence, the transistor size is expected to approach atomic scale in the near future due to our quest for miniaturization and more processing power. However, atomic level behaviour is governed by the laws of quantum physics, which are significantly different from those of classical physics. More explicitly, the inherent parallelism associated with quantum entities allows a quantum computer to carry out operations in parallel, unlike conventional computers. More significantly, quantum computers are capable of solving challenging optimization problems in a fraction of the time required by a conventional computer. However, the major impediment in the practical realization of quantum computers is the sensitivity of the quantum states, which collapse when they interact with their environment. Hence, powerful Quantum Error Correction (QEC) codes are needed for protecting the fragile quantum states from undesired influences and for facilitating the robust implementation of quantum computers. The inherent parallel processing capability of quantum computers will also be exploited to dramatically reduce the detection complexity in future generation communications systems.

In this work, we aim for jointly designing and ameliorating classical and quantum algorithms to support each other in creating powerful communications systems. More explicitly, the inherent parallelism of quantum computing will be exploited for mitigating the high complexity of classical detectors. Then, near-capacity QEC codes will be designed by appropriately adapting algorithms and design techniques used in classical Forward Error Correction (FEC) codes. Finally, cooperative communications involving both the classical and quantum domains will be conceived. The implementation of a quantum computer purely based on quantum-domain hardware and software is still an open challenge. However, a classical computer employing some quantum chips for achieving efficient parallel detection/processing may be expected to be implemented soon. This project is expected to produce a 'quantum-leap' towards the next-generation Internet, involving both classical and quantum information processing, for providing reliable and secure communications networks as well as affordable detection complexity.

Telecommunications systems have evolved from first generation (1G) narrowband communications to fourth generation (4G) broadband communications that can support ubiquitous multimedia transmissions. The advances in telecommunications have transformed all aspects of our lives and the next major milestone in human history would be the realisation of quantum systems. This is a wide open field and the proposed research would produce further scientific advances in both classical and quantum systems in order to yield further economical and societal benefits for the UK. More specifically, 50 billion devices are anticipated to be connected to broadband connections by 2020, according to the 'Future Internet Report' by the 'UK Future Internet Strategy Group'. The proposed quantum-aided classical detector is the ideal technology for processing this huge data traffic. The same report also identified that the future Internet conveying machine/man-to-machine/man (M2M) communications is capable of providing £50-£100 Billion/year of realisable benefits to the UK. The proposed cooperative schemes would contribute further significant economic benefits to the UK and also globally by stimulating the device-design community due to its efficient and fast processing capability. Note that an efficient detector would allow the transmitters to reduce their transmit power. Hence, the battery recharge-time of each transmitter can be extended. This is ideal for wireless sensor networks (WSNs) used for example in environmental monitoring. Light-weight sensor node implants could also be supported for monitoring the human body, hence providing a better health care.

Furthermore, the proposed joint classical and quantum encoded scheme could offer secure transmission due to the transmission of qubits across quantum channels (with the aid of quantum superdense coding) as well as near-capacity performance due to the employment of powerful iterative joint classical-and-quantum decoding. Secure and robust communications are essential for cyber-security and for countering terrorism. Hence, the individuals' quality of life may be further enhanced and government policies may be affected by our findings. The research would make a substantial impact on the wider research community, as detailed in the Academic Beneficiaries section. This would help the UK to play a leading role in these transformative research areas. It would also help the School of Electronics and Computer Science (ECS) at the University of Southampton to maintain its world-class research reputation, as well as further developing the expertise and project leadership skills of the Principal Investigator (PI), who undertakes this role for the first time in an EPSRC project. The experience obtained under this EPSRC project would enable the PI to undertake more ambitious projects in the future, for making an even wider impact and contributions. Valuable networking opportunities would be provided for the PI, via academic visits to/from world-renowned research centres.

This research addresses key EPSRC priorities in the "Information and Communication Technologies" theme http://www.epsrc.ac.uk/ourportfolio/themes/ict and the "Quantum Optics and Information" research area http://www.epsrc.ac.uk/ourportfolio/researchareas/Pages/quantum.aspx. In particular, the topic on coding, transmission and detection is related to the "digital signal processing'' and "RF and microwave communications" research areas, which the EPSRC intends to grow. This research paves the way for collaborations between the classical and quantum research communities, which aligns with EPSRC's "working together" priority. Classical and quantum algorithms are also investigated in the context of hardware implementation of quantum devices, which is an example of working together between the 'hardware- and software-oriented areas'.