Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Quantum Information Processing

Quantum state control, entanglement, and readout of the Josephson persistent-current qubit

Kouichi Semba, J. Johansson, Kosuke Kakuyanagi, H. Nakano, Shiro Saito, Hirotaka Tanaka, Hideaki Takayanagi

Published Feb 18, 2009• 5 citations
Publisher
DOI
10.1007/s11128-009-0098-9

Related papers

Engineering decoherence in Josephson persistent-current qubits

Caspar H. van der Wal, Frank K. Wilhelm, C. J. P. M. Harmans +1 more

arXiv:cond-mat/0211664•The European Physical Journal B•Jan 1, 2003•105 citations

Scalable quantum computing using persistent current qubits with Josephson junctions

Mun Dae Kim, Dongkwan Shin, Jongbae Hong

Physica E Low-dimensional Systems and Nanostructures•Feb 28, 2003•2 citations

Josephson Persistent-Current Qubit

Johan E. Mooij, Terry P. Orlando, Leonid S Levitov +3 more

A qubit was designed that can be fabricated with conventional electron beam lithography and is suited for integration into a large quantum computer. The qubit consists of a micrometer-sized loop with three or four Josephson junctions; the two qubit states have persistent currents of opposite direction. Quantum superpositions of these states are obtained by pulsed microwave modulation of the enclosed magnetic flux by currents in control lines. A superconducting flux transporter allows for controlled transfer between qubits of the flux that is generated by the persistent currents, leading to entanglement of qubit information.

Science•Aug 13, 1999•1,373 citations

Manipulation and Readout of a Josephson Qubit

D. Vion, A. Aassime, Audrey Cottet +5 more

Springer eBooks•Jan 1, 2004•0 citations

Josephson Persistent-Current Qubit

Johan E. Mooij, Terry P. Orlando, Leonid S Levitov +3 more

A qubit was designed that can be fabricated with conventional electron beam lithography and is suited for integration into a large quantum computer. The qubit consists of a micrometer-sized loop with three or four Josephson junctions; the two qubit states have persistent currents of opposite direction. Quantum superpositions of these states are obtained by pulsed microwave modulation of the enclosed magnetic flux by currents in control lines. A superconducting flux transporter allows for controlled transfer between qubits of the flux that is generated by the persistent currents, leading to entanglement of qubit information.

Physical Review B•Jan 1, 1999•12 citations

Experimental analysis of the measurement strength dependence of superconducting qubit readout using a Josephson bifurcation readout method

Kosuke Kakuyanagi, S Kagei, R. Koibuchi +4 more

We succeeded in controlling the measurement strength of a macroscopic quantum system, namely a persistent current quantum bit (qubit), by using a transmission line type Josephson bifurcation amplifier (JBA: an ac-driven superconducting quantum interferometer device) as a probe. By employing a special pulse sequence, we found that the weighted average of the Ramsey fringe visibility ( α -value) can be used as an indicator of quantum state projection. The sudden change in the α -value magnitude at around the threshold suggests that an entangled state of the qubit–JBA composite system settles in one of the two possible classically correlated qubit–JBA states caused by strong decoherence. This is an important result in terms of understanding the mechanisms of quantum state measurement.

New Journal of Physics•Apr 17, 2013•9 citations
A qubit was designed that can be fabricated with conventional electron beam lithography and is suited for integration into a large quantum computer. The qubit consists of a micrometer-sized loop with three or four Josephson junctions; the two qubit states have persistent currents of opposite direction. Quantum superpositions of these states are obtained by pulsed microwave modulation of the enclosed magnetic flux by currents in control lines. A superconducting flux transporter allows for controlled transfer between qubits of the flux that is generated by the persistent currents, leading to entanglement of qubit information.
A qubit was designed that can be fabricated with conventional electron beam lithography and is suited for integration into a large quantum computer. The qubit consists of a micrometer-sized loop with three or four Josephson junctions; the two qubit states have persistent currents of opposite direction. Quantum superpositions of these states are obtained by pulsed microwave modulation of the enclosed magnetic flux by currents in control lines. A superconducting flux transporter allows for controlled transfer between qubits of the flux that is generated by the persistent currents, leading to entanglement of qubit information.
We succeeded in controlling the measurement strength of a macroscopic quantum system, namely a persistent current quantum bit (qubit), by using a transmission line type Josephson bifurcation amplifier (JBA: an ac-driven superconducting quantum interferometer device) as a probe. By employing a special pulse sequence, we found that the weighted average of the Ramsey fringe visibility ( α -value) can be used as an indicator of quantum state projection. The sudden change in the α -value magnitude at around the threshold suggests that an entangled state of the qubit–JBA composite system settles in one of the two possible classically correlated qubit–JBA states caused by strong decoherence. This is an important result in terms of understanding the mechanisms of quantum state measurement.