Long-distance connecting of Logical-qubits with different encoding schemes

A scalable fault-tolerant quantum-computer hardware with current noisy intermediate-scale quantum (NISQ) devices requires the juxtaposition of different types of quantum systems. In this sense, long-distance entanglement of stationary error-corrected logical qubits requires a photonic bus facilitating inter/intra-connection among the cores of quantum processors, the units of quantum memories [1], and the worldwide quantum internet. Laser-excited Rydberg atoms are an ideal example where the long-range interactions allow simultaneous operations on multiple qubits [2-9], with bonus opportunities in quantum optics [7-15]. In this presentation, I propose a photonic interface for 4 and 6-qubit encoding of surface-code logical-qubits in an atomic-lattice platform [16]. Accommodating the lattice inside a cavity, the gate emits photonic-qubits that are entangled by the logical-qubits. The entangling mechanism is provided by the Fermi scattering of a Rydberg electron from the plaquette atoms trapped in a qubit-dependent lattice [17]. Therefore, different arrangements of logical-qubits derive the central atom over distinguished eigenstates, featuring photon emission at the early or late times distinguished by quantum interference. Finally, entanglement swapping of two emitted photons would make the far separated plaquettes entangled in the logical basis.



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