arXiv subjects

Aldo Tarascio

Publications and source records attributed to Aldo Tarascio.

4 recordsLinked to original sources

arXiv2026

High-Q cryogenic surface acoustic wave resonators in the GHz range

Surface acoustic wave (SAW) resonators provide a compact platform for confining microwave-frequency phonons and are widely used in radio-frequency technologies, but their operation at gigahertz frequencies and cryogenic temperatures remains challenging. In this regime, conventional design rules do not directly apply, and achieving high-quality acoustic confinement requires careful consideration about geometry and loss mechanisms. Here, we present a systematic experimental study of SAW resonators on gallium arsenide, a platform of particular interest for hybrid quantum devices but comparatively unexplored for high-Q SAW cavities. By varying key design parameters such as cavity length, wavelength, and crystal orientation, we study resonator performance and achieve quality factors up to 28000 in the gigahertz range. In addition, we introduce mesa steps within the acoustic cavity, mimicking realistic device architectures and providing insight into scattering processes and additional dissipation channels. Our results establish practical design guidelines for GaAs-based SAW resonators and support their development as a scalable platform for quantum acoustics and phonon-mediated hybrid systems.

cond-mat.mes-hall↗

arXiv2026

A scalable non-superconducting tunnel junction technology

Tunnel junctions are one of the key elements of chip-scale microsystems serving various technologies from classical microelectronics to quantum information. Aluminium and its oxide (AlOx) have dominated cryogenic tunnel junction technology for decades due to the high quality of AlOx barriers and Al superconducting properties below 1.2 K. However, many applications require non-superconducting junctions, either standalone or in combination with superconducting technology, motivating efforts to suppress Al superconductivity through magnetic fields, doping, or proximity effects -- approaches that so far suffered from integration compatibility and scalability issues. Here, we present a CMOS-compatible normal-metal tunnel junction technology based on TiW alloy and AlOx barriers. We demonstrate wafer-scale fabrication of TiW/Al-AlOx/TiW junctions and validate their performance in Coulomb blockade thermometers operating down to 20 mK, confirming robust normal-state behavior. This TiW-based architecture offers a scalable solution for non-superconducting tunnel junctions across a broad temperature range, enabling integration into advanced cryogenic, quantum and nanoelectronic chip-level systems.

cond-mat.mes-hall↗

arXiv2026

Compact self-matched gyrators using edge magnetoplasmons

Edge magnetoplasmons provide a natural platform for chiral electrodynamics, where broken time-reversal symmetry enforces unidirectional propagation. When probed at microwave frequencies, they offer a route to compact non-reciprocal devices. So far, implementations have suffered from large losses or required complicated matching networks. Here we show that the circulating modes coupled to capacitive gates give rise to a gyrator response, characterized by directional {\pi} phase difference between forward and reverse transmission. By engineering a three-terminal capacitive geometry, we realize a self-impedance matched gyrator in which the gyration points coincide with transmission maxima, enabling nearly lossless gyration without external matching networks. Our devices are implemented on a GaAs 2D gas, operate from 0.2 to 2 GHz, tuned by magnetic field, with sub-millimeter footprints and insertion loss as low as 2 dB. This is a factor of 100 smaller and less lossy than commercial and plasmon units, respectively. A dissipative model, in agreement with experiment, provides the fundamental physics and delivers the key materials parameters, leading the way to even less lossy devices approaching ideal operation by materials improvement. The self-impedance matched concept is broadly applicable to a variety of devices, thus providing a foundation for a new generation of high-quality microwave plasmon technology.

cond-mat.mes-hall↗

arXiv2025

High-Efficiency Tunable Microwave Photon Detector Based on a Semiconductor Double Quantum Dot Coupled to a Superconducting High-Impedance Cavity

High-efficiency single-photon detection in the microwave domain is a key enabling technology for quantum sensing, communication, and information processing. However, the extremely low energy of microwave photons (~{\mu}eV) presents a fundamental challenge, preventing direct photon-to-charge conversion as achieved in optical systems using semiconductors. Semiconductor quantum dot (QD) charge qubits offer a compelling solution due to their highly tunable energy levels in the microwave regime, enabling coherent coupling with single photons. In this work, we demonstrate microwave photon detection with an efficiency approaching 70% in the single-photon regime. We use a hybrid system comprising a double quantum dot (DQD) charge qubit electrostatically defined in a GaAs/AlGaAs heterostructure, coupled to a high-impedance Josephson junction (JJ) array cavity. We systematically optimize the hybrid device architecture to maximize the conversion efficiency, leveraging the strong charge-photon coupling and the tunable DQD tunnel coupling rates. Incoming cavity photons coherently excite the DQD qubit, which in turn generates a measurable electrical current, realizing deterministic photon-to-charge conversion. Moreover, by exploiting the independent tunability of both the DQD transition energy and the cavity resonance frequency, we characterize the system efficiency over a range of 3-5.2 GHz. Our results establish semiconductor-based cavity-QED architectures as a scalable and versatile platform for efficient microwave photon detection, opening new avenues for quantum microwave optics and hybrid quantum information technologies.

quant-ph↗