TY - JOUR

T1 - Implementation of traveling odd schrödinger cat states in circuit-QED

AU - Joo, Jaewoo

AU - Lee, Su Yong

AU - Kim, Jaewan

N1 - Funding Information:
Acknowledgments: This work was supported by the KIST Institutional Program (Project No. 2E26680-16-P025). We thank S. Kono, E. Ginossar, Y. Nakamura, and H. Paik for useful discussions.
AC note - Due to technical issue on publisher website cannot download OA PDF.

PY - 2016/10/31

Y1 - 2016/10/31

N2 - 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.

AB - 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.

KW - Circuit quantum electrodynamics

KW - Schrödinger cat states

KW - Single-photon subtraction

UR - http://www.scopus.com/inward/record.url?scp=85031007948&partnerID=8YFLogxK

U2 - 10.3390/photonics3040057

DO - 10.3390/photonics3040057

M3 - Article

AN - SCOPUS:85031007948

VL - 3

JO - Photonics

JF - Photonics

IS - 4

M1 - 57

ER -