Establishing a quantum communication network would provide advantages in areas such as security and information processing. Such a network would require the implementation of quantum teleportation between remote parties. However, for photonic "qudits" of dimension greater than two, this teleportation always fails due to the inability to carry out the required quantum Bell-state measurement. A quantum communication protocol called Superdense Teleportation (SDT) can allow the reconstruction of a state without the usual 2-photon Bell-state measurements, enabling the protocol to succeed deterministically even for high dimensional qudits. This technique restricts the class of states transferred to equimodular states, a type of superposition state where each term can differ from the others in phase but not in amplitude; this restricted space of transmitted states allows the transfer to occur deterministically. We report on our implementation of SDT using photon pairs that are entangled in both polarization and temporal mode. After encoding the phases of the desired equimodular state on the signal photon, we perform a complete tomography on the idler photon to verify that we properly prepared the chosen state. Beyond our tabletop demonstration, we are working towards an implementation between a space platform in low earth orbit and a ground telescope, to demonstrate the feasibility of space-based quantum communication. We will discuss the various challenges presented by moving the experiment out of the laboratory, and our proposed solutions to make Superdense Teleportation realizable in the space setting.
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.
We report the implementation of a novel entanglement-enabled quantum state communication protocol, known as
SuperDense Teleportation, using photons hyperentangled in polarization and orbital angular momentum. We used these
techniques to transmit unimodular ququart states between distant parties with an averaged fidelity of 86.2±3%; almost
twice the classical limit of 44%. We also propose a method to use SuperDense Teleportation to communicate quantum
states from a space platform, such as the International Space Station, to a terrestrial optical telescope. We evaluate
several configurations and investigate the challenges arising from the movement of the space station with respect to the