Asymmetry and decoherence in a double-layer persistent-current qubit

Abstract

Superconducting circuits fabricated using the widely used shadow evaporation technique can contain unintended junctions which change their quantum dynamics. We discuss a superconducting flux qubit design that exploits the symmetries of a circuit to protect the qubit from unwanted coupling to the noisy environment, in which the unintended junctions can spoil the quantum coherence. We present a theoretical model based on a recently developed circuit theory for superconducting qubits and calculate relaxation and decoherence times that can be compared with existing experiments. Furthermore, the coupling of the qubit to a circuit resonance (plasmon mode) is explained in terms of the asymmetry of the circuit. Finally, possibilities for prolonging the relaxation and decoherence times of the studied superconducting qubit are proposed on the basis of the obtained results.

v.2: published version; 8 pages, 12 figures; added comparison with experiment, improved discussion of T_phi

References in corpus (7)

• Quantum state engineering with Josephson-junction devices
• Coherent Quantum Dynamics of a Superconducting Flux Qubit
• A Superconducting Persistent Current Qubit
• Coherent dynamics of a flux qubit coupled to a harmonic oscillator
• Decoherence in Josephson Qubits from Junction Resonances
• Multi-level quantum description of decoherence in superconducting qubits
• Dephasing of solid-state qubits at optimal points

Cited by in corpus (19)

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• Dephasing of a superconducting qubit induced by photon noise
• Decoherence in Solid State Qubits
• Two-photon quantum Rabi model with superconducting circuits
• Parametric coupling for superconducting qubits
• Transformed Dissipation in Superconducting Quantum Circuits
• Efficient evaluation of decoherence rates in complex Josephson circuits
• Superconducting Quantum Circuits, Qubits and Computing
• Full control of qubit rotations in a voltage-biased superconducting flux qubit
• Reduced visibility of quantum oscillations in the spin-boson model
• Tunable Flux Qubit manipulated by fast pulses: operating requirements, dissipation and decoherence
• Preparing ground states of the XXZ model using the quantum annealing with inductively coupled superconducting flux qubits
• Theory of solid state quantum information processing
• Dissipative dynamics of a qubit coupled to a nonlinear oscillator
• Symmetry operators of the asymmetric two-photon quantum Rabi model
• Optimal effective current operator for flux qubit accounting for inductive effects