Superconducting pi qubit with three Josephson junctions

Abstract

We propose a new qubit consisting of a superconducting ring with two ordinary zero junctions and one ferromagnetic pi junction. In the system, two degenerate stable states appear in the phase space without an external magnetic field because of a competition between the zero and pi states. Quantum tunneling between the two degenerate states leads to a formation of bonding and antibonding states (coherent states) which are used as a bit. For manipulating the states of the qubit, only small external magnetic field around zero is required. This feature leads to a large-scale integration and a construction of the qubit with a smaller size which is robust to the decoherence by external noises.

3 pages, 3 figures

References in corpus (7)

• Coherent Quantum Dynamics of a Superconducting Flux Qubit
• Coherent dynamics of a flux qubit coupled to a harmonic oscillator
• Spectroscopy on two coupled flux qubits
• Superconducting pi qubit with a ferromagnetic Josephson junction
• Evidence for entangled states of two coupled flux qubits
• Spontaneous supercurrent induced by ferromagnetic pi-junctions
• Josephson effect in double-barrier superconductor-ferromagnet junctions

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• Visualizing supercurrents in ferromagnetic Josephson junctions with various arrangements of 0 and πsegments
• Josephson Coupling and Fiske Dynamics in Ferromagnetic Tunnel Junctions
• The effect of normal metal layers in ferromagnetic Josephson junctions
• Superconducting flux qubit with ferromagnetic Josephson $\pi$-junction operating at zero magnetic field
• Ferromagnetic 0-pi Josephson junctions
• Controllable pi junction with magnetic nanostructures
• Theory of fractional vortex escape in a 0-kappa long Josephson junction
• Quantum tunneling of a single semifluxon in a 0-pi Josephson junction
• Andreev spin-noise detector
• Superconductor-ferromagnet junction phase qubit
• Width of the $0-\pi$ phase transition in diffusive magnetic Josephson junctions
• Half-integer Shapiro-steps in superconducting qubit with a $\pi$-Josephson junction
• Sign reversal of ac Josephson current in a ferromagnetic Josephson junction