Inbetriebnahme, Optimierung und Verifikation eines Antennenmessplatzes für 5,8 GHz Antennen

Die Bachelorarbeit gliedert sich in vier Kapitel. In der Einleitung wird zum einen dasProjekt beschrieben in dem die Arbeit angesiedelt ist. Außerdem wird das Thema aus denauftretenden Problemstellungen abgeleitet. Im weiteren Verlauf werden zunächst die für denAufbau entscheidenden Theoriegrundlagen erläutert und darauf aufbauend der Messaufbauund die Durchführung aufgezeigt. Der Diskussion der ersten Ergebnisse im anschließendenKapitel folgt die Aufführung der darauf basierenden, durchgeführten Optimierungen. Nachder Erörterung der Verifikation des Aufbaus mit einem bekannten Objekt werden endgültigeErgebnisse beispielhaft präsentier

Physical Integration of Cryogenic Control Electronics Togetherwith a Spin Qubit Sample at mK Temperatures

A universal quantum computer requires the control and read out of millions of physical quantum bits (qubits). Due to wiring limitation in current state-of-the-art dilution refrigerators scaling up to millions of qubits with room-temperature electronics is challenging. Integrated Circuits (ICs) operating next to the qubits will help solving this scalability problem but require novel approaches for cryogenic circuits. This talk will focus on the physical design layer of the integration of a custom-designed 65nm CMOS low-power digital to analog converter(DAC) for qubit bias together with a spin qubit sample. In total, eight DAC channels are integrated at the mixing chamber stage of a dilution refrigerator and are operated at milli-kelvin temperatures. Additionally, engineering aspects regarding the sample space setup, cryostat wiring, and the tight density are pointed out

Qubit control using a CMOS DAC at mK temperatures

Scaling up a quantum processor to tackle real-world problems requires qubit numbers in the millions. Scaleable semiconductor-based architectures have been proposed, many of them relying on integrated control instead of room-temperature electronics. However, it has not yet been shown that this can be achieved. For developing a high-density, low-cost wiring solution, it is highly advantageous for the electronics to be placed at the same temperature as the qubit chip. Therefore, tight integration of the qubit chip with ultra low power CMOS electronics presents a promising route. We demonstrate DC biasing qubit electrodes using a custom-designed 65nm CMOS capacitive DAC operating below 100mK [1]. Our chip features a complete proof of principle solution including interface, DAC memory and logic, the capacitive DAC, and sample-and-hold structures to provide voltages for multiple qubit gates. The bias DAC is combined with the qubit using a silicon interposer chip, enabling flexible routing and tight integration. Voltage stability, noise performance, and temperature are benchmarked using the qubit chip. Our results validate the potential of very low power qubit biasing using highly integrated circuits.[1] P. Vliex et al., IEEE Solid-State Circuits Letters, vol. 3, pp. 218-221, 202

Qubit Bias using a CMOS DAC at mK Temperatures

Scaling up a quantum processor to tackle real-world problems requires qubit numbers in the millions. Scalable semiconductor-based architectures have been proposed, many of them relying on integrated control instead of room-temperature electronics. However, it has not yet been shown that this can be achieved. For developing a high-density, low-cost wiring solution, it is highly advantageous for the electronics to be placed at the same temperature as the qubit chip. Therefore, tight integration of the qubit chip with ultra low power complementary metal–oxide–semiconductor (CMOS) electronics presents a promising route. We demonstrate DC biasing qubit electrodes using a custom-designed 65nm CMOS capacitive digital-to-analog converter (DAC) operating on the mixing chamber of a dilution refrigerator below 45 mK. Our chip features a complete proof of principle solution including interface, DAC memory and logic, the capacitive DAC, and sample-and-hold structures to provide voltages for multiple qubit gates. The bias-DAC (CryoDAC) is combined with the qubit using a silicon interposer chip, enabling flexible routing and tight integration. Voltage stability, noise performance, and temperature are benchmarked using the qubit chip. Our results indicate that qubit bias at cryogenic temperatures with a power consumption of 4 nW/ch is feasible with this approach. They validate the potential of very low power qubit biasing using highly integrated circuits whose connectivity requirements do not increase with the number of qubits

Cryogenic CMOS for Local Qubit Control and Readout – A Path to Scaling

The majority of the scientific research community for quantum computing agrees that an estimated number of around 106 qubits are required to build a universal quantum computer [1]. This number leads to foreseeable connectivity bottlenecks to feed all the required biasing, control and read-out signals into and out of the cryostat. A proposed solution is local cryogenic classical electronics, bringing control and read-out closer to the quantum bits themselves.For this task, the ZEA-2 – Electronic Systems institute – develops classical electronic systems using modern CMOS technologies, due to their low area footprint, ultra-low power consumption and natural synergy with semiconductor qubits. This poster highlights the ongoing development and measurement results at ZEA-2 for integrated cryogenic circuits and co-integrating them directly with qubits. This includes experimental results of a qubit bias voltage digital-to-analog converter (Bias-DAC) in a bulk 65 nm CMOS technology [2], placed at the milli-Kelvin stage alongside the qubit [3,4]. Results of cryogenic supply regulation circuits in an advanced 22nm FDSOI CMOS process are shown as well [5]. Furthermore, a brief introduction into CMOS and possible options for an optimized cryogenic specific CMOS technology is given to enhance future IC designs in power efficiency and outlook to qubit readout. This method of integration paves a way for QC scalability.[1] Vandersypen, L.M.K., Bluhm, H., Clarke, J.S. et al. Interfacing spin qubits in quantum dots and donors—hot, dense, and coherent. npj Quantum Inf 3, 34 (2017). https://doi.org/10.1038/s41534-017-0038-y[2] P. Vliex et al., "Bias Voltage DAC Operating at Cryogenic Temperatures for Solid-State Qubit Applications," in IEEE Solid-State Circuits Letters, vol. 3, pp. 218-221, 2020, doi: 10.1109/LSSC.2020.3011576.[3] R. Otten, L. Schreckenberg, P. Vliex et al., "Qubit Bias using a CMOS DAC at mK Temperatures," 2022 29th IEEE International Conference on Electronics, Circuits and Systems (ICECS), Glasgow, United Kingdom, 2022, pp. 1-4, doi: 10.1109/ICECS202256217.2022.9971043. [4] L. Schreckenberg, R. Otten, P. Vliex et al., "SiGe Qubit Biasing with a Cryogenic CMOS DAC at mK Temperature„ To be published in 2023 49th IEEE European Conference on Solid-State Circuits (ESSCIRC)[5] A. R. Cabrera-Galicia, A. Ashok, P. Vliex et al., "Towards the Development of Cryogenic Integrated Power Management Units," 2022 IEEE 15th Workshop on Low Temperature Electronics (WOLTE), Matera, Italy, 2022, pp. 1-4, doi: 10.1109/WOLTE55422.2022.9882781

Social assessment of conservation initiatives: a review of rapid methodologies

Book reviewing different options for assessing the social impacts of conservation initiative

SiGe Qubit Biasing with a Cryogenic CMOS DAC at mK Temperature

For running advanced algorithms on a universal quantum computer, millions of qubits are required. To make use of quantum effects, state-of-the-art solid-state qubit devices have to be cooled to mK temperatures, which limits the systems’ scalability with room temperature (RT) electronics. We present the direct co-integration of a scalable, fully integrated, eight channel Bias-DAC designed in a 65-nm bulk CMOS technology and a Si/SiGe spin qubit device at the mixing chamber (MC) of a dilution refrigerator operating below 45 mK MC temperature. As a full proof of principle, the bias of a single electron transistor used as a sensing dot, as well as a single and double quantum dot bias of the qubit device is reported. The slow drift of the DAC S&H output circuit of 0.96 μV/s leads to a calculated prospective power consumption of 64.5 pW/ch for DC qubit bias voltages generated at low temperatur