Deterministic quantum teleportation with feed-forward in a solid state system

Superconducting circuits combined with real-time feed-forward electronics are used to teleport a quantum state between two macroscopic solid-state systems. Efficient teleportation on demand Quantum teleportation is one of the most important elementary protocols in quantum information processing. Previous studies have achieved quantum teleportation, but usually randomly and at low rates. Two groups reporting in this issue of Nature have used contrasting methods to achieve the same aim —more efficient quantum teleportation. Takeda et al . describe the experimental realization of fully deterministic, unconditional quantum teleportation of photonic qubits — an optimum choice for information carrying — with overall transfer fidelities exceeding the classical limit of teleportation. The technique may facilitate the development of large-scale optical quantum networks. Steffen et al . report quantum teleportation in a solid-state system, achieving deterministic quantum teleportation in a chip-based superconducting circuit architecture. They teleport quantum states between two macroscopic systems separated by 6 mm at a rate of 10,000 per second, exceeding other reported implementations. Transmission loss in superconducting waveguides is low, so this system should be scalable to significantly larger distances, a step towards quantum communication at microwave frequencies. Engineered macroscopic quantum systems based on superconducting electronic circuits are attractive for experimentally exploring diverse questions in quantum information science 1 , 2 , 3 . At the current state of the art, quantum bits (qubits) are fabricated, initialized, controlled, read out and coupled to each other in simple circuits. This enables the realization of basic logic gates 4 , the creation of complex entangled states 5 , 6 and the demonstration of algorithms 7 or error correction 8 . Using different variants of low-noise parametric amplifiers 9 , dispersive quantum non-demolition single-shot readout of single-qubit states with high fidelity has enabled continuous 10 and discrete 11 feedback control of single qubits. Here we realize full deterministic quantum teleportation with feed-forward in a chip-based superconducting circuit architecture 12 , 13 , 14 . We use a set of two parametric amplifiers for both joint two-qubit and individual qubit single-shot readout, combined with flexible real-time digital electronics. Our device uses a crossed quantum bus technology that allows us to cr