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Open AccessArticle

Implementation of Traveling Odd Schrödinger Cat States in Circuit-QED

School of Computational Sciences, Korea Institute for Advanced Study, Seoul 02455, Korea
Author to whom correspondence should be addressed.
Photonics 2016, 3(4), 57;
Received: 4 October 2016 / Revised: 24 October 2016 / Accepted: 27 October 2016 / Published: 31 October 2016
(This article belongs to the Special Issue Quantum Photonics Circuits)
PDF [2826 KB, uploaded 31 October 2016]


We propose a realistic scheme of generating a traveling odd Schrödinger cat state and a generalized entangled coherent state in circuit quantum electrodynamics (circuit-QED). A squeezed vacuum state is used as the initial resource of nonclassical states, which can be created through a Josephson traveling-wave parametric amplifier, and travels through a transmission line. Because a single-photon subtraction from the squeezed vacuum gives an odd Schrödinger cat state with very high fidelity, we consider a specific circuit-QED setup consisting of the Josephson amplifier creating the traveling resource in a line, a beam-splitter coupling two transmission lines, and a single photon detector located at the end of the other line. When a single microwave photon is detected by measuring the excited state of a superconducting qubit in the detector, a heralded cat state is generated with high fidelity in the opposite line. For example, we show that the high fidelity of the outcome with the ideal cat state can be achieved with appropriate squeezing parameters theoretically. As its extended setup, we suggest that generalized entangled coherent states can be also built probabilistically and that they are useful for microwave quantum information processing for error-correctable qudits in circuit-QED. View Full-Text
Keywords: Schrödinger cat states; single-photon subtraction; circuit quantum electrodynamics Schrödinger cat states; single-photon subtraction; circuit quantum electrodynamics

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Joo, J.; Lee, S.-Y.; Kim, J. Implementation of Traveling Odd Schrödinger Cat States in Circuit-QED. Photonics 2016, 3, 57.

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