No abstract

Quantum network scales the advantages of quantum communication protocols to more than two detached users, which offers great potential to realize the quantum internet. Here, a fully connected continuous‐variable (CV) quantum teleportation network architecture is presented, in which a squeezed state of light distributes each pair of entangled sideband modes to each communication link that bridges any pair of users. The quantum teleportation scheme is similar to standard two‐party ones for each communication link, without sacrificing communication capability and reliability. The demonstration based on CV‐entangled sideband modes opens an innovative possibility to implement many tasks of deterministic quantum information processing.

Quantum teleportation is a key primitive across a number of quantum information tasks and represents a fundamental ingredient for many quantum technologies. Channel capacity, other than the fidelity, becomes another focus of quantum communication. Here, we present a 5-channel multiplexing continuous-variable quantum teleportation protocol in the optical frequency comb system, exploiting five-order entangled sideband modes. Because of the resonant electro-optical modulation (EOM) that is specifically designed, the fidelities of five channels are greater than 0.78, which are superior to the no-cloning limit of 2 / 3 . This work provides a feasible scheme for implementing efficient quantum information processing.

Quantum entanglement is an important pillar of quantum information processing. In addition to the entanglement degree, the bandwidth of entangled states becomes another focus of quantum communication. Here, by virtue of a broadband frequency-dependent beam splitter, we experimentally demonstrate six pairs of independent entangled sideband modes with maximum entanglement degree of 8.1 dB. Utilizing a time delay compensation scheme, the bandwidth of independent entangled sideband modes is expanded to dozens of megahertz. This work provides a valuable resource to implement efficient quantum information processing.

Reversed nonlinear dynamics is predicted to be capable of enhancing the quantum sensing in unprecedented ways. Here, we report the experimental demonstration of a loss-tolerant (external loss) and quantum-enhanced interferometer. Two cascaded optical parametric amplifiers are used to judiciously construct an interferometry with two orthogonal squeezing operation. As a consequence, a weak displacement introduced by a test cavity can be amplified for measurement, and the measured signal-to-noise ratio is better than that of both conventional photon shot-noise limited and squeezed-light assisted interferometers. We further confirm its superior loss-tolerant performance by varying the external losses and comparing with both conventional photon shot-noise limited and squeezed-light assisted configurations, illustrating the potential application in gravitational wave detection.