Deterministic teleportation of a quantum gate between two logical qubits
Abstract
A quantum computer has the potential to efficiently solve problems that are intractable for classical computers. However, constructing a largescale quantum processor is challenging because of the errors and noise that are inherent in realworld quantum systems. One approach to addressing this challenge is to utilize modularity—a strategy used frequently in nature and engineering to build complex systems robustly. Such an approach manages complexity and uncertainty by assembling small, specialized components into a larger architecture. These considerations have motivated the development of a quantum modular architecture, in which separate quantum systems are connected into a quantum network via communication channels^{1,2}. In this architecture, an essential tool for universal quantum computation is the teleportation of an entangling quantum gate^{35}, but such teleportation has hitherto not been realized as a deterministic operation. Here we experimentally demonstrate the teleportation of a controlledNOT (CNOT) gate, which we make deterministic by using realtime adaptive control. In addition, we take a crucial step towards implementing robust, errorcorrectable modules by enacting the gate between two logical qubits, encoding quantum information redundantly in the states of superconducting cavities^{6}. By using such an errorcorrectable encoding, our teleported gate achieves a process fidelity of 79 per cent. Teleported gates have implications for faulttolerant quantum computation^{3}, and when realized within a network can have broad applications in quantum communication, metrology and simulations^{1,2,7}. Our results illustrate a compelling approach for implementing multiqubit operations on logical qubits and, if integrated with quantum errorcorrection protocols, indicate a promising path towards faulttolerant quantum computation using a modular architecture.
 Publication:

Nature
 Pub Date:
 September 2018
 DOI:
 10.1038/s415860180470y
 arXiv:
 arXiv:1801.05283
 Bibcode:
 2018Natur.561..368C
 Keywords:

 Quantum Physics
 EPrint:
 Main text: 7 pages, 4 figures