Increasing energy relaxation time of superconducting qubits with nonmagnetic infrared filter and shield

One of the primary origins of the energy relaxation in superconducting qubits is the quasiparticle loss. The quasiparticles can be excited remarkably by infrared radiation. In order to minimize the density of quasiparticle and increase the qubit relaxation time, we design and fabricate the infrared filter and shield for superconducting qubits. In comparison with previous filters and shields, a nonmagnetic dielectric is used as the infrared absorbing material, greatly suppressing the background magnetic fluctuations. The filters can be made to impedance-match with other microwave devices. Using the as-fabricated infrared filter and shield, we increased the relaxation time of a transmon qubit from 519 ns to 1125 ns.

Sodium tungsten bronze(Na_(x)WO_(3))-doped near-infrared-shielding bulk glasses for energy-saving applications

Tungsten bronze coatings and films have attracted global attention for their applications in near-infrared(NIR)-shielding windows.However,they are unstable in strong ultraviolet,humid heat,alkaline and/or oxidizing environments and are difficult to be coated on glass surfaces with complex shape.Here,we address these limitations by doping sodium tungsten bronze(Na_(x)WO_(3))into bulk glasses using a simple glass melting method.X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,TEM and SEM-EDS characterization confirmed the presence of sodium tungsten bronze(Na_(x)WO_(3))functional units inside the 34SiO_(2)-38B_(2)O_(3)-28NaF glass matrix.Because the functional units are well protected by the glass matrix,the fabricated glasses are stable under hot,humid,oxidizing conditions,as well as under ambient conditions,with no change after 360 days.The NIR-shielding performance of these glasses can be adjusted to as high as 100%by varying WO_(x)concentration(2-8 mol%)and quenching temperature(1000-1400℃).With a content of 6 mol%WO_(x)and a quenching temperature of 1000℃,the bulk glass shows 63%transmission of visible light and only 11%transmission of NIR light at 1100 nm.Thermal insulation experiments show that the NIR-shielding performance of the glasses are far superior to commercial soda lime window glass or indium-doped tin oxide(ITO)glass,and comparable to cesium tungsten bronze coated glass.The novel bulk glasses have higher stability,simpler processing,and can be easily made into complex shapes,making them excellent alternative materials for energy-saving glasses.

Recent research progress on mixed valence state tungsten based materials

Synthesis and characterization of tungsten based mixed valence state nanoparticles and their novel applications are reviewed.The mixed valence state tungsten based homogeneous nanomaterials such as bronze structure M_(x)WO_(3)(M=Na^(+),K^(+),Rb^(+),Cs^(+),NH_(4)^(+),etc.)and tungsten sub-oxide W_(18)O_(49) possess excellent infrared(IR)light shielding property,implying their great potential applications on heat ray shielding and indoor energy saving effect in summer season.Also,some novel properties such as electric conductivity,bio thermal therapy function and electrochromic properties of mixed valence state tungsten based materials are introduced.The design of components,formation of composites and structure control of thin films are expected to realize the property enhancement and candidates for practice application as window materials.The multifunc-tionality of the mixed valence state based composites also implies great potential on novel applications of various building materials.