Chip-to-chip Quantum Teleportation and Multi-photon Entanglement in silicon

Silicon is a compelling platform for classical optical telecommunications as well as quantum communications, both through optical fibers. In general, the silicon-based integrated quantum transceivers could provide possible low-cost and high-performance secure communication networks. A reliable transfer of single photon qubits from one silicon device to another has already been shown, and the distribution of entangled states has been verified through the violation of Bell inequalities. Here, researchers first distribute the full set of entangled Bell states between two devices, and then demonstrate key missing capabilities so far, i.e., the chip-to-chip teleportation.

Schematic of the chip-to-chip entanglement distribution and teleportation of single qubits using the path-polarisation conversion technique. a, Schematic of chip A that includes a switchable router on qubit 4. A pair of MZIs choose whether the qubit is encoded into dual-rail and output via two 1d SGCs, or converted to polarisation qubits and output via the 2d SGC. The former enables the implementation of arbitrary single-qubit measurement in chip A, while the latter enables the coherent distribution of qubit 4 from chip A to chip B. b, Schematic of Bob chip, which is able to reconvert polarisation-encoded qubits to path-encoded qubits, in order to perform reconstructive projective measurements on Bob. A pair of MZIs are used for the ease of calibrating the components in chip B. c, SEM images of the 2D SGC structure fabricated on chip A and chip B. It can coherently convert the two on-chip path-encoded {|0i,|1i} states to two orthogonal polarisation modes {|Hi,|Vi} in fiber, and vise verse.

Nature Physics – Chip-to-chip quantum teleportation and multi-photon entanglement in silicon

Exploiting semiconductor fabrication techniques, natural carriers of quantum information such as atoms, electrons, and photons can be embedded in scalable integrated devices. Integrated optics provides a versatile platform for large-scale quantum information processing and transceiving with photons. Scaling up the integrated devices for quantum applications requires high-performance single-photon generation and photonic qubit-qubit entangling operations. However, previous demonstrations report major challenges in producing multiple bright, pure and identical single-photons, and entangling multiple photonic qubits with high fidelity. Another notable challenge is to noiselessly interface multiphoton sources and multiqubit operators in a single device. Here we demonstrate on-chip genuine multipartite entanglement and quantum teleportation in silicon, by coherently controlling an integrated network of microresonator nonlinear single-photon sources and linear-optic multiqubit entangling circuits. The microresonators are engineered to locally enhance the nonlinearity, producing multiple frequency uncorrelated and indistinguishable single-photons, without requiring any spectral filtering. The multiqubit states are processed in a programmable linear circuit facilitating Bell-projection and fusion-operation in a measurement-based manner. We benchmark key functionalities, such as intra-/inter-chip teleportation of quantum states, and generation of four-photon Greenberger-HorneZeilinger entangled states. The production, control, and transceiving of states are all achieved in micrometer-scale silicon chips, fabricated by complementary metal-oxide-semiconductor processes. Our work lays the groundwork for scalable on-chip multiphoton technologies for quantum computing and communication.