Losses in superconducting planar resonators are presently assumed to predominantly arise from surfaceoxide dissipation, due to experimental losses varying with choice of materials. We model and simulate the magnitude of the loss from interface surfaces in the resonator, and investigate the dependence on power, resonator geometry, and dimensions. Surprisingly, the dominant surface loss is found to arise from the metalsubstrate and substrate-air interfaces. This result will be useful in guiding device optimization, even with conventional materials.

Abstract. In the summer of 2010, atmosphere-ice-ocean interaction was studied aboard the icebreaker R/V Xuelong during the Chinese National Arctic Research Expedition (CHINARE), in the sea ice zone of the Pacific Arctic sector between 150 • W and 180 • W up to 88.5 • N. The expedition lasted from 21 July to 28 August and comprised of ice observations and measurements along the cruise track, 8 short-term stations and one 12-day drift station. Ship-based observations of ice thickness and concentration are compared with ice thickness measured by an electromagnetic induction device (EM31) mounted off the ship's side and ice concentrations obtained from AMSR-E. It is found that the modal thickness from ship-based visual observations matches well with the modal thickness from the mounted EM31. A grid of 8 profiles of ice thickness measurements (four repeats) was conducted at the 12-day drift station in the central Arctic (∼ 86 • 50 N-87 • 20 N) and an average melt rate of 2 cm day −1 , primarily bottom melt, was found. As compared with the 2005 data from the Healy/Oden Trans-Arctic Expedition (HOTRAX) for the same sector but ∼ 20 days later (9 August to 10 September), the summer 2010 was first-year ice dominant (vs. the multi-year ice dominant in 2005), 70 % or less in mean ice concentration (vs. 90 % in 2005), and 94-114 cm in mean ice thickness (vs. 150 cm in 2005). Those changes suggest the continuation of ice thinning, less concentration, and younger ice for the summer sea ice in the sector since 2007 when a record minimum sea ice extent was observed. Overall, the measurements provide a valuable dataset of sea ice morphological properties over the Arctic Pacific Sector in summer 2010 and can be used as a benchmark for measurements of future changes.

Freestanding nanocrystalline ␤-Ga 2 O 3 particles with an average grain size of 14 nm prepared by chemical method was investigated by angle-dispersive synchrotron x-ray diffraction in diamond-anvil cell up to 64.9 GPa at ambient temperature. The evolution of x-ray diffraction patterns indicated that nanocrystalline monoclinic ␤-Ga 2 O 3 underwent a phase transition to rhombohedral ␣-Ga 2 O 3 . It was found that ␤-to ␣-Ga 2 O 3 transition began at about 13.6-16.4 GPa, and extended up to 39.2 GPa. At the highest pressure used, only ␣-Ga 2 O 3 was present, which remained after pressure release. A Birch-Murnaghan fit to the P-V data yielded a zero-pressure bulk modulus at fixed B 0 Ј=4: B 0 = 228͑9͒ GPa and B 0 = 333͑19͒ GPa for ␤-Ga 2 O 3 and ␣-Ga 2 O 3 phases, respectively. We compared our results with bulk ␤-Ga 2 O 3 , and concluded that the phase-transition pressure and bulk modulus of nanocrystalline ␤-Ga 2 O 3 are higher than those of bulk counterpart.

No abstract

No abstract

Superconducting qubits provide a competitive platform for quantum simulation of complex dynamics that lies at the heart of quantum many-body systems, because of the flexibility and scalability afforded by the nature of microfabrication. However, in a multiqubit device, the physical form of couplings between qubits is either an electric (capacitor) or magnetic field (inductor), and the associated quadratic field energy determines that only two-body interaction in the Hamiltonian can be directly realized. Here we propose and experimentally synthesize the three-body spin-chirality interaction in a superconducting circuit based on Floquet engineering. By periodically modulating the resonant frequencies of the qubits connected with each other via capacitors, we can dynamically turn on and off qubit-qubit couplings, and further create chiral flows of the excitations in the three-qubit circular loop. Our result is a step toward engineering dynamical and many-body interactions in multiqubit superconducting devices, which potentially expands the degree of freedom in quantum simulation tasks.

No abstract

No abstract