Related papers: Cryogenic microwave loss in epitaxial Al/GaAs/Al t…
We report on the analysis of electroabsorption in thin GaAs/Al$_{0.3}$Ga$_{0.7}$As nanophotonic waveguides with an embedded $p$-$i$-$n$ junction. By measuring the transmission through waveguides of different lengths, we derive the…
We investigate the impact of two-level systems (TLSs) on superconductivity, treating them as soft modes localised in real space. We show that these defects can either enhance or suppress the superconducting critical temperature, depending…
Modular architectures are a promising route toward scalable superconducting quantum processors, but finite fabrication yield and the lack of high quality temporary interconnects impose fundamental limitations on system size. Here, we…
Trapped magnetic vortices in niobium introduce microwave losses that degrade the performance of superconducting resonators. While such losses have been extensively studied above 1~K, we report here their direct quantification in the…
Two-level systems (TLSs) are tunneling states commonly found in amorphous materials that electrically couple to qubits, resonators, and vibrational modes in materials, leading to energy loss in those systems. Recent studies suggest that…
We report results of microwave surface impedance measurements of LiFeAs single crystals. The in-plane penetration depth depends on temperature exponentially at low temperatures, which strongly suggests that this material has the nodeless…
The cross-plane thermal conductivity of a type II InAs/GaSb superlattice (T2SL) is measured from 13 K to 300 K using the 3{\omega} method. Thermal conductivity is reduced by up to 2 orders of magnitude relative to the GaSb bulk substrate.…
Superconducting high kinetic inductance elements constitute a valuable resource for quantum circuit design and millimeter-wave detection. Granular aluminum (GrAl) in the superconducting regime is a particularly interesting material since it…
We present microwave-frequency NbTiN resonators on silicon, systematically achieving internal quality factors above 1 M in the quantum regime. We use two techniques to reduce losses associated with two-level systems: an additional substrate…
Solid-state devices used for quantum computation and quantum sensing applications are adversely affected by loss and noise caused by spurious, charged two-level systems (TLS) and stray paramagnetic spins. These two sources of noise are…
Epitaxial growth of III-V semiconductors on Si is a promising route for silicon photonics. Threading dislocations and the residual thermal stress generated during growth are expected to affect the thermal conductivity of the III-V…
The coherence of state-of-the-art superconducting qubit devices is predominantly limited by two-level-system defects, found primarily at amorphous interface layers. Reducing microwave loss from these interfaces by proper surface treatments…
Superconducting transmon qubits are commonly made with thin-film Nb wiring, but recent studies have shown increased performance with Ta wiring. In this work, we compare the resonator-induced single photon, millikelvin dielectric loss for…
We model s- and d-wave ceramic superconductors with a three-dimensional lattice of randomly distributed Josephson junctions with finite self-inductance. The field and temperature dependences of the microwave absoption are obtained by…
We report dynamical shear-modulus measurements for five glass-forming liquids (pentaphenyl trimethyl trisiloxane, diethyl phthalate, dibutyl phthalate, 1,2-propanediol, and m-touluidine). The shear-mechanical spectra are obtained by the…
Nanomechanical resonators have demonstrated great potential for use as versatile tools in a number of emerging quantum technologies. For such applications, the performance of these systems is restricted by the decoherence of their fragile…
The loss tangent of medium, low and very low loss dielectric substrates (including the Rogers RT Duroid 5880 and 6010.2, LaAlO3, (La, Sr)(Al, Ta)O3, MgO and Quartz) was measured at varying temperatures with two TE01{\delta} dielectric…
Strongly disordered superconductors (SDSCs) are widely used in qubits, microwave resonators, photon detectors, and other superconducting quantum devices. In SDSC-based devices, coherence times are limited by low-temperature microwave…
Transmon qubits are a cornerstone of modern superconducting quantum computing platforms. Temporal fluctuations of energy relaxation in these qubits are widely attributed to microscopic two-level systems (TLSs) in device dielectrics and…
We have investigated the nonlinear surface impedance and two-tone intermodulation distortion of nine epitaxial YBa2Cu3O7-d films on MgO substrates, using stripline resonators, at frequencies f=2.3-11.2GHz and temperatures T=1.7K-Tc. The…