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Entanglement distribution over long distances is essential for many quantum communication schemes like quantum teleportation, some variants of quantum key distribution, or implementations of a quantum internet. Distributing entanglement…
We proposed a scheme of continuous-variable quantum key distribution, in which the bright Einstein-Podolsky-Rosen entangled optical beams are utilized. The source of the entangled beams is placed inside the receiving station, where half of…
Quantum networks will provide multi-node entanglement over long distances to enable secure communication on a global scale. Traditional quantum communication protocols consume pair-wise entanglement, which is sub-optimal for distributed…
The BB84 and B92 protocols based on polarization coding are usually used in free-space quantum key distribution. Polarization tracking technique is one of the key techniques in the satellite quantum key distribution. Because the photon…
The probabilistic nature of single-photon sources and photon-photon interactions encourages encoding as much quantum information as possible in every photon for the purpose of photonic quantum information processing. Here, by encoding…
We propose a novel scheme to implement the BB84 quantum key distribution (QKD) protocol in optical fibers based on a quantum frequency-translation (QFT) process. Unlike conventional QKD systems, which rely on photon polarization/phase to…
A photon with a modulated wavefront can produce a quantum communication channel in a larger Hilbert space. For example, higher dimensional quantum key distribution (HD-QKD) can encode information in the transverse linear momentum (LM) or…
We present our approach for sharing photons and assessing resultant four-photon visibility between two distant parties using concatenated entanglement swapping. In addition we determine the corresponding key generation rate and the quantum…
We present two robust quantum key distribution protocols against two kinds of collective noise, following some ideas in quantum dense coding. Three-qubit entangled states are used as quantum information carriers, two of which forming the…
We report on a complete free-space field implementation of a modified Ekert91 protocol for quantum key distribution using entangled photon pairs. For each photon pair we perform a random choice between key generation and a Bell inequality.…
We investigate the advantages of high-dimensional encoding for a quantum key distribution protocol. In particular, we address a BBM92-like protocol where the dimension of the systems can be larger than two and more than two mutually…
We report on the experimental demonstration of a source of hybrid entanglement pairs between two different degrees of freedom, a 1550 nm time-bin qubit and an 810 nm polarization qubit. The polarization qubit at 810 nm is transformed by an…
We present three quantum key distribution protocols using entangled state. In the first two protocols, all Einstein-Podolsky-Rosen pairs are used to distribute a secret key except those chosen for eavesdropping check, because the…
Many quantum key distribution analyses examine the link security in a subset of the full Hilbert space that is available to describe the system. In reality, information about the photon state can be embedded in correlations between the…
Despite its widespread use in fiber optics, encoding quantum information in photonic time-bin states is usually considered impractical for free-space quantum communication as turbulence-induced spatial distortion impedes the analysis of…
A new scheme of quantum key distribution (QKD) using frequency and time coding is proposed, in which the security is based on the frequency-time uncertainty relation. In this scheme, the binary information sequence is encoded randomly on…
A new protocol for quantum key distribution based on entanglement swapping is presented. In this protocol, both certain key and random key can be generated without any loss of security. It is this property differs our protocol from the…
An energy-time entanglement-based dispersive optics quantum key distribution (DO-QKD) is demonstrated experimentally over optical fibers of 20 km. In the experiment, the telecom band energy-time entangled photon pairs are generated through…
Standard quantum key distribution (QKD) protocols typically assume that the distant parties share a common reference frame. In practice, however, establishing and maintaining a good alignment between distant observers is rarely a trivial…
The ability to distribute secret keys between two parties with information-theoretic security, that is, regardless of the capacities of a malevolent eavesdropper, is one of the most celebrated results in the field of quantum information…