A 0.1–5 GHz Cryogenic SiGe MMIC LNA

In this letter, the design and measurement of the first SiGe integrated-circuit LNA specifically designed for operation at cryogenic temperatures is presented. At room temperature, the circuit provides greater than 25.8 dB of gain with an average noise temperature (T_e) of 76 K (NF = 1 dB) and S11 of -9 dB for frequencies in the 0.1-5 GHz band. At 15 K, the amplifier has greater than 29.6 dB of gain with an average Te of 4.3 K and S11 of -14.6 dB for frequencies in the 0.1-5 GHz range. To the authors' knowledge, this is the lowest noise ever reported for a silicon integrated circuit operating in the low microwave range and the first matched wideband cryogenic integrated circuit LNA that covers frequencies as low as 0.1 GHz

SILICON-GERMANIUM HETEROJUNCTION BIPOLAR TRANSISTORS FOR LARGE-SCALE LOW-POWER CRYOGENIC SENSING SYSTEMS

Cryogenic low noise amplifiers (LNAs) are one of the key components in many emerging applications such as radio astronomy or quantum computing in which a weak incoming signal needs to be read out. There have been extensive studies on the feasibility of leveraging silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) to implement cryogenic LNAs in the past. The deployment of such LNAs in the future large-scale systems in radio astronomy or quantum computing is contingent upon the possibility of developing LNAs with reduced DC power dissipation to enable the cooling of a large number of array elements inside a cryogenic cooler. In this dissertation, we focus on the cryogenic operation of SiGe HBTs at reduced supply voltages for the implementation of ultra low- power LNAs and their applications for scalable receiver systems. In addition, the limitations of the SiGe HBT cryogenic models for the operation at high current densities are investigated for the implementation of modern high speed SiGe HBT circuits

An Overview of Solid-State Integrated Circuit Amplifiers in the Submillimeter-Wave and THz Regime

We present an overview of solid-state integrated circuit amplifiers approaching terahertz frequencies based on the latest device technologies which have emerged in the past several years. Highlights include the best reported data from heterojunction bipolar transistor (HBT) circuits, high electron mobility transistor (HEMT) circuits, and metamorphic HEMT (mHEMT) amplifier circuits. We discuss packaging techniques for the various technologies in waveguide modules and describe the best reported noise figures measured in these technologies. A consequence of THz transistors, namely ultra-low-noise at cryogenic temperatures, will be explored and results presented. We also present a short review of power amplifier technologies for the THz regime. Finally, we discuss emerging materials for THz amplifiers into the next decade

Detection chain and electronic readout of the QUBIC instrument

The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10⁻¹⁶ W/√Hz

Detection chain and electronic readout of the QUBIC instrument

The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10⁻¹⁶ W/√Hz

Low-Power HEMT LNAs for Quantum Computing

The rapid development of quantum computing technology predicts much more qubits to handle in the detection, readout, and amplification of qubits than in today\u27s system. Due to the limited cooling capability of the dilution refrigerator, the current low-noise amplifiers (LNAs) are in need of ten to hundred times reduced dc power consumption yet with lowest noise temperature at qubit readout frequencies, typcially 4-12 GHz. Cryogenic indium phosphide (InP) high electron mobility transistor (HEMT) LNAs, are the standard qubit amplifier at 4 K in today\u27s superconducting quantum system. However, the power consumption of current InP HEMT LNAs is still too high for future quantum system up-scaling.A small-signal noise model of a 100-nm gate-length InP HEMTs has been characterized and extracted at 4 K ambient under low-power bias down to 1 μW. The extracted low-power small-signal noise models revealed fast degradation points of drain voltage bias for RF and noise performance.The design goals of the cryogenic LNA were tailored for a superconducting qubit readout application based on the extracted low-power small-signal noise model of the InP HEMT for optimum noise and power consumption trade-off. A cryogenic InP HEMT hybrid LNA operating in the 4-6 GHz frequency range at 200 μW with an average noise temperature of 2.0 K has been designed, fabricated, and successfully demonstrated, validating the extracted model and design methodology.An epitaxially-optimized InP HEMT was modeled with the low-power methodology. The comparison of the small-signal noise model parameters to the standard InP HEMT showed improved transconductance, matching, and noise at the same bias power. The demonstrated three-stage cryogenic 4-6 GHz LNA equipped with an optimized HEMT as the first stage achieved 2.0 K average noise temperature at 100 μW dc power dissipation, representing a new state-of-the-art. This licentiate thesis has presented experimental evidence that there is large potential in reducing dc power in the cryogenic InP HEMT LNA for qubit readout which can be important for the planned up-scaling in future quantum computing

The SpinBus Architecture: Scaling Spin Qubits with Electron Shuttling

Quantum processor architectures must enable scaling to large qubit numbers while providing two-dimensional qubit connectivity and exquisite operation fidelities. For microwave-controlled semiconductor spin qubits, dense arrays have made considerable progress, but are still limited in size by wiring fan-out and exhibit significant crosstalk between qubits. To overcome these limitations, we introduce the SpinBus architecture, which uses electron shuttling to connect qubits and features low operating frequencies and enhanced qubit coherence. Device simulations for all relevant operations in the Si/SiGe platform validate the feasibility with established semiconductor patterning technology and operation fidelities exceeding 99.9 %. Control using room temperature instruments can plausibly support at least 144 qubits, but much larger numbers are conceivable with cryogenic control circuits. Building on the theoretical feasibility of high-fidelity spin-coherent electron shuttling as key enabling factor, the SpinBus architecture may be the basis for a spin-based quantum processor that meets the scalability requirements for practical quantum computing.Comment: 15 pages, 9 figure

A LEKID-based CMB instrument design for large-scale observations in Greenland

We present the results of a feasibility study, which examined deployment of a ground-based millimeter-wave polarimeter, tailored for observing the cosmic microwave background (CMB), to Isi Station in Greenland. The instrument for this study is based on lumped-element kinetic inductance detectors (LEKIDs) and an F/2.4 catoptric, crossed-Dragone telescope with a 500 mm aperture. The telescope is mounted inside the receiver and cooled to $<\,4$ K by a closed-cycle $^4$He refrigerator to reduce background loading on the detectors. Linearly polarized signals from the sky are modulated with a metal-mesh half-wave plate that is rotated at the aperture stop of the telescope with a hollow-shaft motor based on a superconducting magnetic bearing. The modular detector array design includes at least 2300 LEKIDs, and it can be configured for spectral bands centered on 150~GHz or greater. Our study considered configurations for observing in spectral bands centered on 150, 210 and 267~GHz. The entire polarimeter is mounted on a commercial precision rotary air bearing, which allows fast azimuth scan speeds with negligible vibration and mechanical wear over time. A slip ring provides power to the instrument, enabling circular scans (360 degrees of continuous rotation). This mount, when combined with sky rotation and the latitude of the observation site, produces a hypotrochoid scan pattern, which yields excellent cross-linking and enables 34\% of the sky to be observed using a range of constant elevation scans. This scan pattern and sky coverage combined with the beam size (15~arcmin at 150~GHz) makes the instrument sensitive to $5 < \ell < 1000$ in the angular power spectra