We use photons simultaneously entangled in polarization and temporal mode to implement hyperdense coding, a quantum-enhanced communication protocol that can transmit up to 2.81 bits of classical information for every 2-qubit photon received.
We present a method, known as hyperdense coding, which uses photons hyperentangled in polarization and temporal mode to transmit up to 2.81 bits/photon of classical information over a two-qubit quantum channel. Furthermore, the hyperentangled photons used in this approach are much less susceptible to the influences of turbulence than spatial qubits, allowing for turbulence-resistant communication. We compare this technique to previously implemented hyperentanglement-enhanced superdense coding implementations which have a maximum theoretical channel capacity of 2 bits/photon.
Superdense coding proved that entanglement-assisted quantum communications can improve the data transmission rates compared to classical systems. It allows sending 2 classical bits between the parties in exchange of 1 quantum bit and a pre-shared entangled Bell pair. This paper introduces a new protocol which is intended for distributed communication. Using a pre-shared entangled Bell pair and 1 classical bit 2,5 classical bits can be transmitted in average. This means not only valuable increase in capacity but the two-way distributed operation opens new fields of investigation.
Quantum networks provide a versatile infrastructure for communication, computing, and sensing with quantum information. Novel sources and detectors for transmitting and receiving quantum states are critical elements in the development and eventual deployment of robust quantum networks. Alongside performance, the compatibility of quantum network devices with modern networking infrastructure is an important requirement for deployment. We present results on the integration of quantum communication using superdense coding transmitted over optical fiber links into network environments. Our approach takes advantage of a novel complete Bell-state measurement setup that relies on hyper-entanglement in the temporal and polarization degrees of freedom for a two-photon state emitted from a quantum light source. Using linear optics and common single-photon detectors, we record a single-qubit channel capacity of 1.665±0.018. We then demonstrate a full experimental implementation of hybrid, quantum-classical communication protocol for image transfer applications. Our devices integrate with existing fiber optical network and software-defined transmitters and receivers as part of a modular design to provide an extensible quantum communication system that can adapt to future quantum technology goals.