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Date and time: 7 April 2022 15:00 (CEST). Abstract: For decades, silicon and germanium have played an essential role in semiconductor-based information technology. They are also excellent host materials for new devices in quantum computation and spintronics, due to the natural abundance (> 90%) of non-magnetic nuclei and the consequent reduction of the decoherence due to hyperfine interaction. Si and Ge devices benefit from established industrial fabrication techniques, allowing for scalability and for the achievement of homogeneous building blocks for the qubits and control electronics of a quantum computer. CMOS qubits have been implemented by modifying transistors currently fabricated in foundry processes. Within the project IQubits, our group deals with the theoretical characterization of one- and two-hole Si and Ge quantum dots, for their use as qubits. We combine the multi-band “k dot p” description of confined single-hole states with the full-configuration-interaction treatment of interactions, and with semi-analytical methods. In this talk, I will present our results on single and double quantum dots, including the effects of interband Coulomb interactions, signals of Wigner crystallization, and the mapping of double-dot states on a four-band Hubbard model. The latter allows us to describe in a transparent way the two-hole low-energy states, which display a high degree of mixing of angular-momentum eigenstates, even with different permutational symmetries, in contrast with the common case of single-band systems. We also discuss how, in the regime of weak entanglement between band and orbital degrees of freedom, it is possible to reduce the four-band Hubbard model to an effective pseudospin-1/2 model. For further information visit Events.

Joint research paper from Aarhus University and University of Toronto titled "Cryogenic Compact Low-Power 60GHz Amplifier for Spin Qubit Control in Monolithic Silicon Quantum Processors", has been accepted for presentation at the IEEE IMS 2022.

Joint research paper from Aarhus University and University of Toronto titled "Cryogenic Compact mm-Wave Broadband SPST Switch in 22nm FDSOI CMOS for Monolithic Quantum Processors", has been accepted for presentation at the IEEE IMS 2022.

Professor Voinigescu (University of Toronto) has been interviewed by Physics Today on the topic of CMOS electronics for quantum computing.

Professor Voinigescu (University of Toronto) has been interviewed by Physics World on the topic of cryogenic CMOS controllers for quantum computer.

CNR and UofT research on - Toward Hole-Spin Qubits in Si p-MOSFETs within a Planar CMOS Foundry Technology, appeared in Physical Review Applied.

We have a new Doctor! Congratulations to Michele Spasaro (Aarhus University) who has defended successfully the PhD research on low-power mm-wave low-noise amplifiers carried out at the Wireless Transceivers research laboratory at Aarhus University under supervision of Professor Domenico Zito (AU). The PhD research has contributed to the IQubits research on Silicon spin qubit control and readout circuits in 22nm FDSOI CMOS. This research was supported by Poul Due Jensen foundation, Keysight Technologies and European Commission through the project IQubits.

CNR, AMat, and UofT research - Toward hole-spin qubits in Si p-MOSFETs within a planar CMOS foundry technology, has been accepted for publication in Physical Review Applied.

Abstract: Super and semiconductors represent the two most relevant categories of conductors for quantum technology. When employed in nanodevices properly engineered, these materials can be used to implement the quantum counterpart of bits, called qubits. So far, among the two classes of materials mentioned above, the leading role in the quest for a platform for quantum computation has been taken by the superconducting qubits, mainly in the architectures of flux qubits and transmon qubits. However, semiconductor spin qubits are gaining interest due to the compatibility with industrial fabrication techniques and long coherence times. Lately, a 4-qubit processor based on single holes spins in a 4-quantum dot structure on planar Ge has demonstrated universal quantum logic [arXiv:2109.07837 (2021)]; on top, rumors report that experiments with 16 qubits on a 4x4 qubit array are on the way. The 53 qubits by Google [Nature 574, 505 (2019)] or the 66 qubits recently fabbed in China [arXiv 2106.14734 (2021)] are not within reach yet, but they don’t look impossible to catch in few years.

Professor Voinigescu (University of Toronto) will give an invited presentation at the workshop titled "Closing the Temperature Gap between Spin-qubits and their Control Electronics" at the IEEE Quantum Week 2021.

CNR will host the online seminar titled ”Hole spin qubits in Si and Ge quantum dots: Ultrafast gates and noise resilient qubits”, Dr. Stefano Bosco, University of Basel.

Dr. Fillipo Troiani was interviewed live by the association ”Dalla Piramide al Cerchio”. The interview addressed quantum physics and quantum computers, and reported the research carried out in IQubits. The interview (in Italian) was streamed live on 22 Jun 2021 and it is now available online.

University of Toronto research paper titled "A DC to 220 GHz High-Isolation SPST Switch in 22nm FDSOI CMOS", has been accepted from presentation at the IEEE IMS 2021.

Check out the European Quantum Week 2020 organized by European Quantum Flagship, in collaboration with the European Commission, for the latest results obtained by the Quantum Flagship projects.

Joint article by Google AI Quantum and other research partners reported about - Quantum supremacy using a programmable superconducting processor, appeared in Nature.

CNR research on - Manipulation of spin cluster qubits by electric field induced modulation of exchange coupling, g-factor, and axial anisotropy, appeared in Physical Review B.

A successful kick-off meeting of IQubits was held at the Department of Engineering, Aarhus University. The meeting gathered together 17 participants from the six partner institutions, who went through in-depth technical discussions and details of the research plan. The meeting included also social events, which allowed the participants to experience Aarhus University and the city of Aarhus.

University of Toronto and IMT's research on - Cryogenic characterization of 22nm FDSOI CMOS technology for quantum computing ICs, appeared in IEEE Electron Device Letters.