Wireless-powered Optical System Achieves Coherent Transmission Using M-ary Phase Shift Keying

Wireless power transfer and quantum communication are rapidly evolving fields, and a new study explores their powerful combination, creating a system that transmits quantum information without traditional batteries. Ioannis Krikidis from the University of Cyprus and colleagues demonstrate a wireless-powered optical system where a transmitter harvests radio-frequency energy to send quantum states, specifically using a method called M-ary phase shift keying. This research significantly advances the potential for secure and sustainable communication networks, as it establishes a fundamental performance limit using the Helstrom bound and proposes a method to optimise the system for maximum data transmission rate. By jointly optimising both the measurement strategy and the energy-harvesting duration, the team paves the way for practical, energy-efficient quantum communication systems that do not rely on conventional power sources.

Wireless Power Fuels Quantum Communication Networks

Scientists have engineered a novel wireless-powered optical communication system, addressing the growing need for sustainable power in emerging technologies. The study pioneers a method where a transmitter, free from batteries, harvests energy from a conventional radio-frequency source to transmit information using quantum states. This approach leverages coherent states and M-ary phase shift keying (M-PSK) modulation over an optical channel, while accounting for thermal noise that degrades signal quality. The fundamental limits of detection performance were evaluated using established theoretical principles, providing a benchmark for system design.

To maximize data transmission rates, the team developed an optimization framework that simultaneously determines the best quantum measurement strategy and the duration of the energy harvesting phase. This framework aims to maximize the effective rate of information transfer within a fixed time constraint, carefully balancing energy collection and data transmission. Analytical solutions were derived for simplified scenarios, specifically Binary Phase Shift Keying (BPSK) and noiseless M-PSK modulation, providing valuable insights into system behavior. For more complex scenarios, scientists employed powerful computational techniques to address the challenges of optimization.

The effectiveness of this approach is demonstrated through extensive numerical results, which validate the unimodal nature of the effective rate function and reveal the impact of key design parameters. These simulations confirm that there is an optimal balance between energy harvesting time and modulation order for achieving peak performance. The system delivers a practical architecture for applications such as quantum IoT, low-power quantum sensing, and secure short-range communication, where energy-constrained quantum transmitters can be powered via radio-frequency signals for optical transmission. This innovative methodology enables the creation of sustainable and batteryless quantum communication networks, paving the way for future advancements in secure and energy-efficient data transfer.

RF Power Drives Sustainable Quantum Communication

The research centers on a “harvest-then-transmit” protocol, where the transmitter first collects radio-frequency (RF) energy and then uses this stored power to transmit data via an optical channel, maximizing the effective rate under a fixed time constraint. An optimization framework was designed to jointly determine the optimal quantum measurement and the duration of energy harvesting, ultimately maximizing data transmission efficiency. Closed-form expressions were derived for Binary Phase Shift Keying (BPSK) and noiseless M-PSK scenarios, simplifying analysis and providing foundational results. For more general scenarios, the team employed powerful computational techniques, enabling them to address complex challenges and optimize performance.

Numerical results confirm the unimodal relationship between the effective rate function and energy harvesting time, demonstrating a clear relationship between these factors. The findings reveal crucial trade-offs between energy harvesting duration, modulation order, and detection performance, providing valuable insights for system design. This architecture unlocks emerging applications such as quantum IoT, low-power quantum sensing, and secure short-range communication, where energy-constrained quantum transmitters can be powered wirelessly via RF signals for quantum optical transmission.

Optimised Wireless Power and Optical Communication

This research investigates a novel wireless-powered optical communication system where a transmitter operates without batteries, instead harvesting energy from a radio-frequency source. The system employs a modulation technique called M-ary phase shift keying to transmit information through an optical channel affected by thermal noise. They developed a method to jointly optimise both the measurement process and the time allocated to energy harvesting, aiming to maximise the rate of effective communication within a given timeframe. Analytical solutions were derived for specific scenarios, simplifying analysis, while more complex cases were addressed using computational techniques.

The results demonstrate a unimodal relationship between the communication rate and the energy harvesting time, meaning there is a single peak performance point. Increasing the complexity of the modulation scheme reduces the maximum achievable communication rate, but requires a greater proportion of time dedicated to energy harvesting. The presence of thermal noise reduces the communication rate, although this effect is lessened with more complex modulation schemes. Interestingly, in very low-power conditions, a small amount of thermal noise can actually improve communication by increasing the separation between transmitted symbols.