Deterministic quantum state transfer and remote entanglement using microwave photons

Abstract

Sharing information coherently between nodes of a quantum network is fundamental to distributed quantum information processing. In this scheme, the computation is divided into subroutines and performed on several smaller quantum registers that are connected by classical and quantum channels . A direct quantum channel, which connects nodes deterministically rather than probabilistically, achieves larger entanglement rates between nodes and is advantageous for distributed fault-tolerant quantum computation . Here we implement deterministic state-transfer and entanglement protocols between two superconducting qubits fabricated on separate chips. Superconducting circuits constitute a universal quantum node that is capable of sending, receiving, storing and processing quantum information. Our implementation is based on an all-microwave cavity-assisted Raman process , which entangles or transfers the qubit state of a transmon-type artificial atom with a time-symmetric itinerant single photon. We transfer qubit states by absorbing these itinerant photons at the receiving node, with a probability of 98.1 ± 0.1 per cent, achieving a transfer-process fidelity of 80.02 ± 0.07 per cent for a protocol duration of only 180 nanoseconds. We also prepare remote entanglement on demand with a fidelity as high as 78.9 ± 0.1 per cent at a rate of 50 kilohertz. Our results are in excellent agreement with numerical simulations based on a master-equation description of the system. This deterministic protocol has the potential to be used for quantum computing distributed across different nodes of a cryogenic network.

A quantum engineer's guide to superconducting qubits

“…183. Another important step towards large-scale quantum processor architecture is that of remote entanglement, enabling quantum information to be distributed across different nodes of a quantum processing network 428,429 .…”

Deterministic Shaping and Reshaping of Single-Photon Temporal Wave Functions

“…We also identified efficiency limitations from destructive interference of emission pathways as well as decoherence issues from spontaneous emission and optical pumping. It is worth noting that the drawn results apply formally to any CQED system, and that most of the observed effects are relevant for other physical platforms [39].…”

“…We also identified efficiency limitations from destructive interference of emission pathways as well as decoherence issues from spontaneous emission and optical pumping. It is worth noting that the drawn results apply formally to any CQED system, and that most of the observed effects are relevant for other physical platforms [39].Second, we used this understanding to demonstrate an unprecedented level of control of the temporal shape of a single photon in absorption and emission, and thus transformation. These are crucial capabilities in many quantum information protocols involving single-photon states.…”

Tripartite Entanglement: Foundations and Applications

“…Currently, this topic has been studied considering the preparation of multipartite entangled states. It is an interesting task since the production of entanglement remotely can help in using this resource to establish quantum communication between distant multi-users and establish quantum distributed computation [167]. In [168], it was presented a scheme for remote preparation of a four-qubit GHZ state through two non-maximally entangled threequbit GHZ states.…”