Efficient ion-photon qubit SWAP gate in realistic ion cavity-QED systems without strong coupling

Abstract

Deterministic ion-photon qubit exchange -a highly desirable building block for quantum information networks -is often assumed to require strong coupling, namely having the single-photon Rabi frequency be the fastest rate in the system. Yet the two native photon-atom gates demonstrated to date (C-phase and SWAP) require only Purcell enhancement that corresponds to high single-atom cooperativities, not strong coupling. This implies that small mode volume cavities -which are challenging to incorporate with ions due to the difficulty of trapping them close to dielectric surfacesare not mandatory. Instead, larger cavities that are more compatible with the trap apparatus are enough, as long as their numerical aperture is high enough to maintain a small mode area at the ion's position. Here we outline the details of a scheme for a deterministic ion-photon SWAP gate based on realistic cavity-QED systems with 171 Yb + , 40 Ca + and 138 Ba + ions. We define the optimal coupling and detuning parameters and simulate the resulting fidelities and efficiencies of the gate, demonstrating that highly efficient photon-ion two-qubit gates indeed do not require strong coupling and are practically attainable with current experimental capabilities.I.

Analysis of multipartite entanglement distribution using a central quantum-network node

“…by driving them with laser pulses. Trapped ions have properties that would make them suitable to implement a factory node, such as long coherence times [83][84][85], high-fidelity state preparation and readout [86][87][88], and a good optical interface [7,[89][90][91][92][93][94] that has allowed for the generation of entanglement with remote nodes [64,65,95].…”

Analysis of Multipartite Entanglement Distribution using a Central Quantum-Network Node

“…The energy levels of the ions can be used to define qubits, and these qubits can be manipulated by driving them with laser pulses. Trapped ions have properties that would make them suitable to implement a factory node, such as long coherence times [80][81][82], high-fidelity state preparation and readout [83][84][85], and a good optical interface [7,[86][87][88][89][90][91] that has allows for the generation of entanglement with remote nodes [61,62,92].…”

Quantum state transfer between a frequency-encoded photonic qubit and a quantum dot spin in a nanophotonic waveguide

“…SPRINT was first considered by Pinotsi and Imamoglu [22] as an ideal absorber of a single photon. Subsequent theoretical works [20,[23][24][25][26][27][28] established that it acts as a photon-atom swap gate and accordingly serves as a quantum memory, which includes a heralding mechanism that validates the arrival of the input photon. It was experimentally demonstrated with a single atom implementing a single-photon router [29], extraction of a single photon from an optical pulse [30], and a photon-atom qubit swap gate [21].…”