Meissner transmon qubit - architecture and characterization

Abstract

We present a new type of transmon split-junction qubit which can be tuned by Meissner screening currents in the adjacent superconducting film electrodes. The best detected relaxation time ($T_1$) was of the order of 50 $\mu$s and the dephasing time ($T_2$) about 40 $\mu$s. The achieved period of oscillation with magnetic field was much smaller than in usual SQUID-based transmon qubits, thus a strong effective field amplification has been realized. This Meissner qubit allows an efficient coupling to superconducting vortices. We present a quantitative analysis of the radiation-free energy relaxation in qubits coupled to Abrikosov vortices. The observation of coherent quantum oscillations provides strong evidence that vortices can exist in coherent quantum superpositions of different position states. According to our suggested model, the wave function collapse is defined by Caldeira-Leggett dissipation associated with viscous motion of the vortex cores.

13 pages and 9 figures; added references in the introduction section

References in corpus (10)

• Charge insensitive qubit design derived from the Cooper pair box
• Superconducting Circuits and Quantum Information
• Superconducting qubit in waveguide cavity with coherence time approaching 0.1ms
• Suppressing Charge Noise Decoherence in Superconducting Charge Qubits
• High-Fidelity Readout in Circuit Quantum Electrodynamics Using the Jaynes-Cummings Nonlinearity
• Measurement and Control of Quasiparticle Dynamics in a Superconducting Qubit
• Microwave response of vortices in superconducting thin films of Re and Al
• Photon Shot Noise Dephasing in the Strong-Dispersive Limit of Circuit QED
• Trapping a single vortex and reducing quasiparticles in a superconducting resonator
• Ultra low noise YBCO nanoSQUIDs implementing nanowires

Cited by in corpus (6)

• A graphene transmon operating at 1 T
• Using materials for quasiparticle engineering
• Magnetic-field resilience of 3D transmons with thin-film Al/AlO${}_x$/Al Josephson junctions approaching 1 T
• Method to extracting the penetration field in superconductors from DC magnetization data
• Nonequilibrium Quasiparticles in Superconducting Circuits: Energy Relaxation, Charge and Flux Noise
• Cooper pair ring model