Double-Well Potentials in Current Qubits

Abstract

The effective potentials of the rf-SQUID and three-Josephson junction loop with a penetrating external magnetic flux are studied. Using the periodic boundary condition for the phase evolution of the wave function of Cooper pairs, we obtain new periodic potentials with cusp barriers in contrast with the usual smooth double-well potential. The tunneling through the cusp barrier becomes dominant for a parameter regime where the self inductance of the superconducting loop and the Josephson coupling energy are large. Calculating the tunneling frequency we see that the cusp potential may offer a more efficient qubit.

6 pages, 6 figures, version to appear in Phys. Rev. B

References in corpus (5)

• Quantum state engineering with Josephson-junction devices
• Manipulating the Quantum State of an Electrical Circuit
• A Superconducting Persistent Current Qubit
• Persistent current in superconducting nanorings
• Simple Phase Bias for Superconducting Circuits

Cited by in corpus (12)

• Superconducting Qubits Coupled to Nanoelectromechanical Resonators: An Architecture for Solid-State Quantum Information Processing
• Fast entanglement of two charge-phase qubits through nonadiabatic coupling to a large junction
• Macroscopic Greenberger-Horne-Zeilinger and W States in Flux Qubits
• Coupling of Josephson current qubits using a connecting loop
• Controllable Coupling in Phase-Coupled Flux Qubits
• Entanglement and Bell States in Superconducting Flux Qubits
• Scalable quantum computing model in the circuit-QED lattice with circulator function
• Ultrastrong coupling in a scalable design for circuit QED with superconducting flux qubits
• Macroscopic Many-Qubit Interactions in Superconducting Flux Qubits
• Quantum thermodynamics of Gross-Pitaevskii qubits
• Current-phase relation of the SNS junction in a superconducting loop
• Current biased gradiometric flux qubit in a circuit-QED architecture