José Carlos Abadillo-Uriel

Website of an ice cream addict and physicist.

I am a Ramón y Cajal fellow working at ICMM-CSIC in the Theory of Quantum Materials and Solid State Quantum Technologies group on semiconductor-based quantum computation and hybrid quantum devices. Not too long ago I used to be a postdoctoral researcher at the CEA-Grenoble in the L-Sim group, where I worked from 2020 to 2023. Prior to this, I was also a postdoc at the University of Wisconsin-Madison in the Silicon Qubit Theory Group from 2018 to 2020.

My research focuses on quantum computation in condensed matter systems. In particular, I enjoy developing theory for the quantum phenomena that naturally arises in realistic devices, connecting directly with experimental results. I perform analytical and numerical calculations of such phenomena to optimize quantum operations.

news

Dec 30, 2024	Our work on the theory of proximitized super-holes is out!
Dec 17, 2024	Our work on the optimal operation of hole spin qubits is out!
Jul 3, 2024	Our work on a unifying framework for longitudinal and dispersive readout is on the arxiv
Apr 29, 2024	Interviews with the press about quantum computation
Mar 7, 2024	Comfuturo credentials ceremony
Mar 6, 2024	Publication of our work on non-symmetric Pauli spin blockade
Nov 14, 2023	Publication of our work on the first demonstration of hole spin-photon coupling in Si

Recent publications and preprints

Theory of superconducting proximity effect in hole-based hybrid semiconductor-superconductor devices

D Michel Pino, Rubén Seoane-Souto, Maria José Calderón, Ramón Aguado, and Jose Carlos Abadillo-Uriel

arXiv:2501.00088, 2025

Abs arXiv Bib URL

Hybrid superconductor-semiconductor systems have received a great deal of attention in the last few years because of their potential for quantum engineering, including novel qubits and topological devices. The proximity effect, the process by which the semiconductor inherits superconducting correlations, is an essential physical mechanism of such hybrids. Recent experiments have demonstrated the proximity effect in hole-based semiconductors, but, in contrast to electrons, the precise mechanism by which the hole bands acquire superconducting correlations remains an open question. In addition, hole spins exhibit a complex strong spin-orbit interaction, with largely anisotropic responses to electric and magnetic fields, further motivating the importance of understanding the interplay between such effects and the proximity effect. In this work, we analyze this physics with focus on germanium-based two-dimensional gases. Specifically, we develop an effective theory supported by full numerics, allowing us to extract various analytical expressions and predict different types of superconducting correlations including non-standard forms of singlet and triplet pairing mechanisms with non-trivial momentum dependence; as well as different Zeeman and Rashba spin-orbit contributions. This, together with their precise dependence on electric and magnetic fields, allows us to make specific experimental predictions, including the emergence of f-type superconductivity, Bogoliubov Fermi surfaces, and gapless regimes caused by large in-plane magnetic fields.
@article{pino2024theory, title = {Theory of superconducting proximity effect in hole-based hybrid semiconductor-superconductor devices}, author = {Pino, D Michel and Seoane-Souto, Rub{\'e}n and Calder{\'o}n, Maria Jos{\'e} and Aguado, Ram{\'o}n and Abadillo-Uriel, Jose Carlos}, journal = { arXiv:2501.00088}, year = {2025}, doi = {10.48550/arXiv.2501.00088}, }
Optimal operation of hole spin qubits

Marion Bassi, Esteban-Alonso Rodrıguez-Mena, Boris Brun, Simon Zihlmann, Thanh Nguyen, Victor Champain, and 5 more authors

arXiv:2412.13069, 2024

Abs arXiv Bib URL

Hole spins in silicon or germanium quantum dots have emerged as a compelling solid-state platform for scalable quantum processors. Besides relying on well-established manufacturing technologies, hole-spin qubits feature fast, electric-field-mediated control stemming from their intrinsically large spin-orbit coupling [1, 2]. This key feature is accompanied by an undesirable susceptibility to charge noise, which usually limits qubit coherence. Here, by varying the magnetic-field orientation, we experimentally establish the existence of “sweetlines” in the polar-azimuthal manifold where the qubit is insensitive to charge noise. In agreement with recent predictions [3], we find that the observed sweetlines host the points of maximal driving efficiency, where we achieve fast Rabi oscillations with quality factors as high as 1200. Furthermore, we demonstrate that moderate adjustments in gate voltages can significantly shift the sweetlines. This tunability allows multiple qubits to be simultaneously made insensitive to electrical noise, paving the way for scalable qubit architectures that fully leverage all-electrical spin control. The conclusions of this experimental study, performed on a silicon metal-oxide-semiconductor device, are expected to apply to other implementations of hole spin qubits.
@article{bassi2024optimal, title = {Optimal operation of hole spin qubits}, author = {Bassi, Marion and Rodr{\i}guez-Mena, Esteban-Alonso and Brun, Boris and Zihlmann, Simon and Nguyen, Thanh and Champain, Victor and Abadillo-Uriel, Jose Carlos and Bertrand, Benoit and Niebojewski, Heimanu and Maurand, Romain and others}, journal = { arXiv:2412.13069}, year = {2024}, doi = {10.48550/arXiv.2412.13069}, }
Unifying Floquet theory of longitudinal and dispersive readout

Alessandro Chessari, Esteban A Rodrı́guez-Mena, Jose Carlos Abadillo-Uriel, Victor Champain, Simon Zihlmann, Romain Maurand, and 2 more authors

arXiv:2407.03417, 2024

Abs arXiv Bib URL

We devise a Floquet theory of longitudinal and dispersive readout in circuit QED. By studying qubits coupled to cavity photons and driven at the resonance frequency of the cavity ωr, we establish a universal connection between the qubit AC Stark shift and the longitudinal and dispersive coupling to photons. We find that the longitudinal coupling g∥ is controlled by the slope of the AC Stark shift as function of the driving strength Aq, while the dispersive shift χ depends on its curvature. The two quantities become proportional to each other in the weak drive limit (Aq→0). Our approach unifies the adiabatic limit (ωr→0) – where g∥ is generated by the static spectrum curvature (or quantum capacitance) – with the diabatic one, where the static spectrum plays no role. We derive analytical results supported by exact numerical simulations. We apply them to superconducting and spin-hybrid cQED systems, showcasing the flexibility of faster-than-dispersive longitudinal readout.
@article{chessari2024unifying, title = {Unifying Floquet theory of longitudinal and dispersive readout}, author = {Chessari, Alessandro and Rodr{\'\i}guez-Mena, Esteban A and Abadillo-Uriel, Jose Carlos and Champain, Victor and Zihlmann, Simon and Maurand, Romain and Niquet, Yann-Michel and Filippone, Michele}, journal = { arXiv:2407.03417}, year = {2024}, doi = {10.48550/arXiv.2407.03417}, }
Non-symmetric Pauli spin blockade in a silicon double quantum dot

Theodor Lundberg, David J Ibberson, Jing Li, Louis Hutin, Jose C Abadillo-Uriel, Michele Filippone, and 5 more authors

npj Quantum Information, 2024

Abs arXiv Bib URL

Spin qubits in gate-defined silicon quantum dots are receiving increased attention thanks to their potential for large-scale quantum computing. Readout of such spin qubits is done most accurately and scalably via Pauli spin blockade (PSB), however various mechanisms may lift PSB and complicate readout. In this work, we present an experimental observation of a new, highly prevalent PSB-lifting mechanism in a silicon double quantum dot due to incoherent tunneling between different spin manifolds. Through dispersively-detected magnetospectroscopy of the double quantum dot in 16 charge configurations, we find the mechanism to be energy-level selective and non-reciprocal for neighbouring charge configurations. Additionally, using input-output theory we report a large coupling of different electron spin manifolds of 7.90 μeV, the largest reported to date, indicating an enhanced spin-orbit coupling which may enable all-electrical qubit control.
@article{lundberg2024non, title = {Non-symmetric Pauli spin blockade in a silicon double quantum dot}, author = {Lundberg, Theodor and Ibberson, David J and Li, Jing and Hutin, Louis and Abadillo-Uriel, Jose C and Filippone, Michele and Bertrand, Benoit and Nunnenkamp, Andreas and Lee, Chang-Min and Stelmashenko, Nadia and others}, journal = {npj Quantum Information}, volume = {10}, number = {1}, pages = {28}, year = {2024}, publisher = {Nature Publishing Group UK London}, url = {https://www.nature.com/articles/s41534-024-00820-1}, doi = {10.1038/s41534-024-00820-1}, }
Linear-in-momentum spin orbit interactions in planar Ge/GeSi heterostructures and spin qubits

Esteban A Rodriguez-Mena, Jose Carlos Abadillo-Uriel, Gaëtan Veste, Biel Martinez, Jing Li, Benoı̂t Sklénard, and 1 more author

Physical Review B, 2023

Abs arXiv Bib URL

We investigate the existence of linear-in-momentum spin-orbit interactions in the valence band of Ge/GeSi heterostructures using an atomistic tight-binding method. We show that symmetry breaking at the Ge/GeSi interfaces gives rise to a linear Dresselhaus-type interaction for heavy-holes. This interaction results from the heavy-hole/light-hole mixings induced by the interfaces and can be captured by a suitable correction to the minimal Luttinger-Kohn, four bands k⃗ ⋅p⃗ Hamiltonian. It is dependent on the steepness of the Ge/GeSi interfaces, and is suppressed if interdiffusion is strong enough. Besides the Dresselhaus interaction, the Ge/GeSi interfaces also make a contribution to the in-plane gyromagnetic g-factors of the holes. The tight-binding calculations also highlight the existence of a small linear Rashba interaction resulting from the couplings between the heavy-hole/light-hole manifold and the conduction band enabled by the low structural symmetry of Ge/GeSi heterostructures. These interactions can be leveraged to drive the hole spin. The linear Dresselhaus interaction may, in particular, dominate the physics of the devices for out-of-plane magnetic fields. When the magnetic field lies in-plane, it is, however, usually far less efficient than the g-tensor modulation mechanisms arising from the motion of the dot in non-separable, inhomogeneous electric fields and strains.
@article{rodriguez2023linear, title = {Linear-in-momentum spin orbit interactions in planar Ge/GeSi heterostructures and spin qubits}, author = {Rodriguez-Mena, Esteban A and Abadillo-Uriel, Jose Carlos and Veste, Ga{\"e}tan and Martinez, Biel and Li, Jing and Skl{\'e}nard, Beno{\^\i}t and Niquet, Yann-Michel}, journal = {Physical Review B}, volume = {108}, number = {20}, pages = {205416}, year = {2023}, publisher = {APS}, doi = {10.1103/PhysRevB.108.205416}, }
Hole spin driving by strain-induced spin-orbit interactions

Jose Carlos Abadillo-Uriel, Esteban A Rodrı́guez-Mena, Biel Martinez, and Yann-Michel Niquet

Physical Review Letters, 2023

Abs arXiv Bib URL

Hole spins in semiconductor quantum dots can be efficiently manipulated with radio-frequency electric fields owing to the strong spin-orbit interactions in the valence bands. Here we show that the motion of the dot in inhomogeneous strain fields gives rise to linear Rashba spin-orbit interactions (with spatially dependent spin-orbit lengths) and g-factor modulations that allow for fast Rabi oscillations. Such inhomogeneous strains may build up spontaneously due to process and cool down stress. We discuss spin qubits in Ge/GeSi heterostructures as an illustration. We highlight that Rabi frequencies can be enhanced by one order of magnitude by shear strain gradients as small as 3x10^-6 nm^-1 within the dots. This underlines that spin in solids can be very sensitive to strains and opens the way for strain engineering in hole spin devices for quantum information and spintronics.
@article{abadillo2022hole, title = {Hole spin driving by strain-induced spin-orbit interactions}, author = {Abadillo-Uriel, Jose Carlos and Rodr{\'\i}guez-Mena, Esteban A and Martinez, Biel and Niquet, Yann-Michel}, journal = {Physical Review Letters}, volume = {131}, number = {9}, pages = {097002}, year = {2023}, publisher = {APS}, doi = {10.1103/PhysRevLett.131.097002}, }
Strong coupling between a photon and a hole spin in silicon

Cécile X Yu, Simon Zihlmann, Jose C Abadillo-Uriel, Vincent P Michal, Nils Rambal, Heimanu Niebojewski, and 5 more authors

Nature Nanotechnology, Mar 2023

Abs arXiv Bib URL

Spins in semiconductor quantum dots constitute a promising platform for scalable quantum information processing. Coupling them strongly to the photonic modes of superconducting microwave resonators would enable fast non-demolition readout and long-range, on-chip connectivity, well beyond nearest-neighbor quantum interactions. Here we demonstrate strong coupling between a microwave photon in a superconducting resonator and a hole spin in a silicon-based double quantum dot issued from a foundry-compatible MOS fabrication process. By leveraging the strong spin-orbit interaction intrinsically present in the valence band of silicon, we achieve a spin-photon coupling rate as high as 330 MHz largely exceeding the combined spin-photon decoherence rate. This result, together with the recently demonstrated long coherence of hole spins in silicon, opens a new realistic pathway to the development of circuit quantum electrodynamics with spins in semiconductor quantum dots.
@article{yu2022strong, title = {Strong coupling between a photon and a hole spin in silicon}, author = {Yu, C{\'e}cile X and Zihlmann, Simon and Abadillo-Uriel, Jose C and Michal, Vincent P and Rambal, Nils and Niebojewski, Heimanu and Bedecarrats, Thomas and Vinet, Maud and Dumur, Etienne and Filippone, Michele and others}, journal = {Nature Nanotechnology}, pages = {1--6}, year = {2023}, month = mar, publisher = {Nature Publishing Group UK London}, url = {https://www.nature.com/articles/s41565-023-01332-3}, doi = {10.1038/s41565-023-01332-3}, }
Tunable hole spin-photon interaction based on g-matrix modulation

VP Michal, J C Abadillo-Uriel, S Zihlmann, R Maurand, Y-M Niquet, and M Filippone

Phys. Rev. B, Jan 2023

Abs arXiv Bib URL

We consider a spin circuit-QED device where a superconducting microwave resonator is capacitively coupled to a single hole confined in a semiconductor quantum dot. Thanks to the strong spin-orbit coupling intrinsic to valence-band states, the gyromagnetic g-matrix of the hole can be modulated electrically. This modulation couples the photons in the resonator to the hole spin. We show that the applied gate voltages and the magnetic-field orientation enable a versatile control of the spin-photon interaction, whose character can be switched from fully transverse to fully longitudinal. The longitudinal coupling is actually maximal when the transverse one vanishes and vice-versa. This "reciprocal sweetness" results from geometrical properties of the g-matrix and protects the spin against dephasing or relaxation. We estimate coupling rates reaching 10 MHz in realistic settings and discuss potential circuit-QED applications harnessing either the transverse or the longitudinal spin-photon interaction. Furthermore, we demonstrate that the g-matrix curvature can be used to achieve parametric longitudinal coupling with enhanced coherence.
@article{michal2022tunable, title = {Tunable hole spin-photon interaction based on g-matrix modulation}, author = {Michal, VP and Abadillo-Uriel, J C and Zihlmann, S and Maurand, R and Niquet, Y-M and Filippone, M}, journal = {Phys. Rev. B}, volume = {107}, issue = {4}, pages = {L041303}, numpages = {6}, year = {2023}, month = jan, publisher = {American Physical Society}, doi = {10.1103/PhysRevB.107.L041303}, url = {https://link.aps.org/doi/10.1103/PhysRevB.107.L041303}, }
Hole spin manipulation in inhomogeneous and nonseparable electric fields

Biel Martinez, Jose Carlos Abadillo-Uriel, Esteban A. Rodrı́guez-Mena, and Yann-Michel Niquet

Phys. Rev. B, Dec 2022

Abs arXiv Bib URL VIDEO

The usual models for electrical spin manipulation in semiconductor quantum dots assume that the confinement potential is separable in the three spatial dimensions and that the ac drive field is homogeneous. However, the electric field induced by the gates in quantum dot devices is not fully separable and displays significant inhomogeneities. Here we address the electrical manipulation of hole spins in semiconductor heterostructures subject to inhomogeneous vertical electric fields and/or in-plane ac electric fields. We consider Ge quantum dots electrically confined in a Ge/GeSi quantum well as an illustration. We show that the lack of separability between the vertical and in-plane motions gives rise to an additional spin-orbit coupling mechanism (beyond the usual linear and cubic in momentum Rashba terms) that modulates the principal axes of the hole gyromagnetic g matrix. This nonseparability mechanism can be of the same order of magnitude as Rashba-type interactions, and enables spin manipulation when the magnetic field is applied in the plane of the heterostructure even if the dot is symmetric (disk shaped). More generally, we show that Rabi oscillations in strongly patterned electric fields harness a variety of g-factor modulations. We discuss the implications for the design, modeling, and understanding of hole spin qubit devices.
@article{PhysRevB.106.235426, title = {Hole spin manipulation in inhomogeneous and nonseparable electric fields}, author = {Martinez, Biel and Abadillo-Uriel, Jose Carlos and Rodr\'{\i}guez-Mena, Esteban A. and Niquet, Yann-Michel}, journal = {Phys. Rev. B}, volume = {106}, issue = {23}, pages = {235426}, numpages = {12}, year = {2022}, month = dec, publisher = {American Physical Society}, doi = {10.1103/PhysRevB.106.235426}, url = {https://link.aps.org/doi/10.1103/PhysRevB.106.235426}, }
A single hole spin with enhanced coherence in natural silicon

N. Piot, B. Brun, V. Schmitt, S. Zihlmann, V. P. Michal, A. Apra, and 11 more authors

Nature Nanotechnology, Sep 2022

Abs arXiv Bib URL

Semiconductor spin qubits based on spin–orbit states are responsive to electric field excitations, allowing for practical, fast and potentially scalable qubit control. Spin electric susceptibility, however, renders these qubits generally vulnerable to electrical noise, which limits their coherence time. Here we report on a spin–orbit qubit consisting of a single hole electrostatically confined in a natural silicon metal-oxide-semiconductor device. By varying the magnetic field orientation, we reveal the existence of operation sweet spots where the impact of charge noise is minimized while preserving an efficient electric-dipole spin control. We correspondingly observe an extension of the Hahn-echo coherence time up to 88 μs, exceeding by an order of magnitude existing values reported for hole spin qubits, and approaching the state-of-the-art for electron spin qubits with synthetic spin–orbit coupling in isotopically purified silicon. Our finding enhances the prospects of silicon-based hole spin qubits for scalable quantum information processing.
@article{Piot2022, doi = {10.1038/s41565-022-01196-z}, url = {https://doi.org/10.1038/s41565-022-01196-z}, year = {2022}, month = sep, publisher = {Springer Science and Business Media {LLC}}, volume = {17}, number = {10}, pages = {1072--1077}, author = {Piot, N. and Brun, B. and Schmitt, V. and Zihlmann, S. and Michal, V. P. and Apra, A. and Abadillo-Uriel, J. C. and Jehl, X. and Bertrand, B. and Niebojewski, H. and Hutin, L. and Vinet, M. and Urdampilleta, M. and Meunier, T. and Niquet, Y.-M. and Maurand, R. and Franceschi, S. De}, title = {A single hole spin with enhanced coherence in natural silicon}, journal = {Nature Nanotechnology}, }