Periodic Reporting for period 4 - LONGSPIN (Long-range coupling of hole spins on a silicon chip)
Reporting period: 2022-09-01 to 2023-12-31
With the miniaturization of electronic devices, the semiconductor industry has to deal with complex technical barriers and is forced to introduce novel and innovative concepts. LONGSPIN is exactly in line with this new paradigm as it diverts CMOS technology to explore a new path for quantum information processing with spin quantum bits (qubits). Concretely the project developed ultra-fast and ultra-coherent spin-orbit qubits based on silicon CMOS nanowire transistors. While spins are excellent qubits, their long-range coupling remains a challenge to tackle towards complex quantum computing architectures. LONGSPIN started to take up this challenge with the vision to use microwave photons as quantum mediators between spin-orbit qubits. To the end, LONGSPIN used a unique approach leveraging a standard silicon-on-insulator CMOS process for the implementation of the qubits co-integrated with microwave resonators made from disordered superconductor. With these new chips combining two worlds of the solid-states physics i.e. semiconductor quantum dot device and microwave quantum electrodynamics, LONGSPIN realized and studied the quantum coupling between CMOS spin qubits and microwave photons.
At the end of this five yearlong research project, a CMOS quantum toolkit with optimized designs and materials for fast and coherent qubits is available with a profound understanding of the physical limitations to coherence and qubit gate fidelity of hole spin in silicon. Moreover, LONGSPIN results open the path towards spin circuit electrodynamics coupling silicon hole spin qubits to microwave photons promising new capabilities for quantum information processing ranging from spin qubit readout to long distance spin-spin entanglement.
At the end of this five yearlong research project, a CMOS quantum toolkit with optimized designs and materials for fast and coherent qubits is available with a profound understanding of the physical limitations to coherence and qubit gate fidelity of hole spin in silicon. Moreover, LONGSPIN results open the path towards spin circuit electrodynamics coupling silicon hole spin qubits to microwave photons promising new capabilities for quantum information processing ranging from spin qubit readout to long distance spin-spin entanglement.
The LONGSPIN team has equipped a dilution refrigerator to perform both state-of-the art spin qubits measurement as well as microwave resonator measurement in the single photon regime under static magnetic field.
Measurements on hole spin-orbit qubit in silicon have allowed LONGPSIN to explore the physical mechanism behind the electrically driven spin resonance (Crippa et al. Physical Review Letters 2018). With the understanding of this driving mechanism it should be possible to engineer devices to get faster and more coherent spin-orbit qubits.
LONGSPIN also managed to readout a silicon hole spin-orbit qubit by low frequency dispersive gate reflectometry (Crippa et al. Nature Communications 2019). This readout proof-of-concept realized on an isolated double quantum dot should pave the way towards qubit readout in dense array of quantum dots. In line with this work, LONGSPIN demonstrated the microwave spectroscopy of a silicon hole double quantum dot (Ezzouch et al. Physical Review Applied 2021)
LONGSPIN has also started to co-integrate high impedance superconducting microwave resonator and CMOS silicon qubit devices. The resonators are made from Nobium Nitride thin films patterned as coplanar microwave cavities. Impedance as high as 4.5kOhms with internal quality factor above 20.000 under a static magnetic field of 1T has been demonstrated and published (Yu et al. Applied Physics Letters 2021).
Following the 2018 results of Crippa et. al. PRL 2018, LONGSPIN members participated to the discovery of coherence sweetspot for a hole spin in a silicon quantum dot (Piot et al. Nature Nanotechnology 2022). LONGSPIN has published a theoretical work on the coupling of hole spin to microwave photons (Michal et al. Physical Review B 2023). Summer 2023, the experimental efforts of LONGSPIN made it up to the cover of Nature Nanotechnology for a published work (Yu et al. Nature Nanotechnology 2023) in which the LONGSPIN team demosntrates the strong coupling between a hole spin qubit and a microwave photons.
During the five years of the project, LONGSPIN members participated to 35 conferences to disseminate the LONGSPIN results worldwide.
Measurements on hole spin-orbit qubit in silicon have allowed LONGPSIN to explore the physical mechanism behind the electrically driven spin resonance (Crippa et al. Physical Review Letters 2018). With the understanding of this driving mechanism it should be possible to engineer devices to get faster and more coherent spin-orbit qubits.
LONGSPIN also managed to readout a silicon hole spin-orbit qubit by low frequency dispersive gate reflectometry (Crippa et al. Nature Communications 2019). This readout proof-of-concept realized on an isolated double quantum dot should pave the way towards qubit readout in dense array of quantum dots. In line with this work, LONGSPIN demonstrated the microwave spectroscopy of a silicon hole double quantum dot (Ezzouch et al. Physical Review Applied 2021)
LONGSPIN has also started to co-integrate high impedance superconducting microwave resonator and CMOS silicon qubit devices. The resonators are made from Nobium Nitride thin films patterned as coplanar microwave cavities. Impedance as high as 4.5kOhms with internal quality factor above 20.000 under a static magnetic field of 1T has been demonstrated and published (Yu et al. Applied Physics Letters 2021).
Following the 2018 results of Crippa et. al. PRL 2018, LONGSPIN members participated to the discovery of coherence sweetspot for a hole spin in a silicon quantum dot (Piot et al. Nature Nanotechnology 2022). LONGSPIN has published a theoretical work on the coupling of hole spin to microwave photons (Michal et al. Physical Review B 2023). Summer 2023, the experimental efforts of LONGSPIN made it up to the cover of Nature Nanotechnology for a published work (Yu et al. Nature Nanotechnology 2023) in which the LONGSPIN team demosntrates the strong coupling between a hole spin qubit and a microwave photons.
During the five years of the project, LONGSPIN members participated to 35 conferences to disseminate the LONGSPIN results worldwide.
The co-integration of CMOS spin-orbit qubit and microwave cavities goes beyond technological state of the art. The demonstration of coherence sweetspots for a hole spin is beyond state of the art as well as the demonstration of the strong coupling between a hole spin in a double quantum dot and a microwave photon.