vitae

2019

1. Phys. Rev. B

   Topological signatures in quantum transport in anomalous Floquet-Anderson insulators

   Esteban A. Rodríguez-Mena;  Luis E. F. Foa Torres

   Physical Review B Nov 2019

   Abstract arXiv Bib URL

   Topological states require the presence of extended bulk states, as usually found in the picture of energy bands and topological states bridging the bulk gaps. But in driven systems this can be circumvented, and one can get topological states coexisting with fully localized bulk states, as in the case of the anomalous Floquet-Anderson insulator. Here, we show the fingerprints of this peculiar topological phase in the transport properties and their dependence on the disorder strength, geometrical configuration (two-terminal and multiterminal setups), and details of the driving protocol.

   @article{rodriguez-mena_topological_2019,
     abbr = {Phys. Rev. B},
     title = {Topological signatures in quantum transport in anomalous {Floquet}-{Anderson} insulators},
     volume = {100},
     url = {https://link.aps.org/doi/10.1103/PhysRevB.100.195429},
     html = {https://link.aps.org/doi/10.1103/PhysRevB.100.195429},
     doi = {10.1103/PhysRevB.100.195429},
     optnumber = {19},
     urldate = {2021-10-03},
     journal = {Physical Review B},
     author = {Rodríguez-Mena, Esteban A. and Foa Torres, Luis E. F.},
     month = nov,
     year = {2019},
     pages = {195429},
     arxiv = {1909.05957},
     bibtex_show = {true}
   }

2021

1. Nano Lett.

   Spin-Polarized Tunable Photocurrents

   Matías Berdakin*;  Esteban A. Rodríguez-Mena*;  Luis E. F Foa Torres;  *Contributed equally.

   Nano Letters Apr 2021

   Abstract arXiv Bib URL

   Harnessing the unique features of topological materials for the development of a new generation of topological based devices is a challenge of paramount importance. Using Floquet scattering theory combined with atomistic models we study the interplay among laser illumination, spin, and topology in a two-dimensional material with spin–orbit coupling. Starting from a topological phase, we show how laser illumination can selectively disrupt the topological edge states depending on their spin. This is manifested by the generation of pure spin photocurrents and spin-polarized charge photocurrents under linearly and circularly polarized laser illumination, respectively. Our results open a path for the generation and control of spin-polarized photocurrents.

   @article{berdakin_spin-polarized_2021,
     abbr = {Nano Lett.},
     title = {Spin-{Polarized} {Tunable} {Photocurrents}},
     volume = {21},
     issn = {1530-6984},
     url = {https://doi.org/10.1021/acs.nanolett.1c00420},
     html = {https://doi.org/10.1021/acs.nanolett.1c00420},
     doi = {10.1021/acs.nanolett.1c00420},
     number = {7},
     urldate = {2021-10-04},
     journal = {Nano Letters},
     author = {Berdakin${*}$, Matías and Rodríguez-Mena${*}$, Esteban A. and Foa Torres, Luis E. F and equally., ${*}$Contributed},
     month = apr,
     year = {2021},
     pages = {3177},
     arxiv = {2010.11883},
     bibtex_show = {true}
   }

2022

1. Phys. Rev. B

   Hole spin manipulation in inhomogeneous and nonseparable electric fields

   Biel Martinez*;  José Carlos Abadillo-Uriel*;  Esteban A. Rodríguez-Mena*;  Yann-Michel Niquet;  *Contributed equally.

   Phys. Rev. B Dec 2022

   Abstract arXiv URL

   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 of the hole 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 non-separability 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 when 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.

2023

1. Phys. Rev. Lett.

   Hole spin driving by strain-induced spin-orbit interactions

   José Carlos Abadillo-Uriel;  Esteban A. Rodríguez-Mena;  Biel Martinez;  Yann-Michel Niquet

   Phys. Rev. Lett. Sep 2023

   Abstract 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 \gt-factor modulations that allow for fast Rabi oscillations. Such inhomogeneous strains build up spontaneously in \YMNthe devices 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 3\times 10^-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{strains_2022,
     abbr = {Phys. Rev. Lett.},
     title = {Hole spin driving by strain-induced spin-orbit interactions},
     url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.097002},
     html = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.097002},
     journal = {Phys. Rev. Lett.},
     doi = {https://doi.org/10.1103/PhysRevLett.131.097002},
     author = {Abadillo-Uriel, José Carlos and Rodríguez-Mena, Esteban A. and Martinez, Biel and Niquet, Yann-Michel},
     publisher = {American Physical Society},
     year = {2023},
     month = sep,
     volume = {131},
     issue = {9},
     pages = {097002},
     arxiv = {2212.03691},
     bibtex_show = {true}
   }

2. Phys. Rev. B

   Linear-in-momentum spin orbit interactions in planar Ge/GeSi heterostructures and spin qubits

   Esteban A. Rodríguez-Mena;  José Carlos Abadillo-Uriel;  Gaëtan Veste;  Biel Martinez;  Jing Li;  Benoît Sklénard;  Yann-Michel Niquet

   Phys. Rev. B Nov 2023

   Abstract 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 kp 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{linearinmomentum_2023,
     abbr = {Phys. Rev. B},
     title = {Linear-in-momentum spin orbit interactions in planar Ge/GeSi heterostructures and spin qubits},
     url = {https://link.aps.org/doi/10.1103/PhysRevB.108.205416},
     html = {https://link.aps.org/doi/10.1103/PhysRevB.108.205416},
     journal = {Phys. Rev. B},
     doi = {10.1103/PhysRevB.108.205416},
     author = {Rodríguez-Mena, Esteban A. and Abadillo-Uriel, José Carlos and Veste, Gaëtan and Martinez, Biel and Li, Jing and Sklénard, Benoît and Niquet, Yann-Michel},
     keywords = {Mesoscale and Nanoscale Physics (cond-mat.mes-hall), FOS: Physical sciences, FOS: Physical sciences},
     publisher = {American Physical Society},
     year = {2023},
     month = nov,
     arxiv = {2307.10007},
     bibtex_show = {true}
   }

2024

1. Phys. Rev. B

   Geometry of the dephasing sweet spots of spin-orbit qubits

   Lorenzo Mauro*;  Esteban A. Rodríguez-Mena*;  Marion Bassi;  Vivien Schmitt;  Yann-Michel Niquet;  *Contributed equally.

   Phys. Rev. B Apr 2024

   Abstract arXiv Bib URL

   The dephasing time of spin-orbit qubits is limited by the coupling with electrical and charge noise. However, there may exist "dephasing sweet spots" where the qubit decouples (to first order) from the noise so that the dephasing time reaches a maximum. Here we discuss the nature of the dephasing sweet spots of a spin-orbit qubit electrically coupled to some fluctuator. We characterize the Zeeman energy E_\mathrmZ of this qubit by the tensor G such that E_\mathrmZ=\mu_B\sqrt\vecB^\mathrmTG\vecB (with \mu_B the Bohr magneton and \vecB the magnetic field), and its response to the fluctuator by the derivative G^\prime of G with respect to the fluctuating field. The geometrical nature of the sweet spots on the unit sphere describing the magnetic field orientation depends on the sign of the eigenvalues of G^\prime. We show that sweet spots usually draw lines on this sphere. We then discuss how to characterize the electrical susceptibility of a spin-orbit qubit with test modulations on the gates. We apply these considerations to a Ge/GeSi spin qubit heterostructure, and discuss the prospects for the engineering of sweet spots.

   @article{mauro2024geometry,
     abbr = {Phys. Rev. B},
     title = {Geometry of the dephasing sweet spots of spin-orbit qubits},
     url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.155406},
     html = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.155406},
     journal = {Phys. Rev. B},
     doi = {https://doi.org/10.1103/PhysRevB.109.155406},
     author = {Mauro${*}$, Lorenzo and Rodríguez-Mena${*}$, Esteban A. and Bassi, Marion and Schmitt, Vivien and Niquet, Yann-Michel and equally., *Contributed},
     publisher = {American Physical Society},
     year = {2024},
     volume = {109},
     issue = {15},
     month = apr,
     arxiv = {2312.09840},
     bibtex_show = {true}
   }

2. arXiv

   Optimal operation of hole spin qubits

   Marion Bassi;  Esteban-Alonso Rodríguez-Mena;  Boris Brun;  Simon Zihlmann;  Thanh Nguyen;  Victor Champain;  José Carlos Abadillo-Uriel;  Benoit Bertrand;  Heimanu Niebojewski;  Romain Maurand;  Yann-Michel Niquet;  Xavier Jehl;  Silvano De Franceschi;  Vivien Schmitt

   arXiv Dec 2024

   Abstract 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,
     abbr = {arXiv},
     title = {Optimal operation of hole spin qubits},
     url = {https://arxiv.org/abs/2412.13069},
     html = {https://arxiv.org/abs/2412.13069},
     journal = {arXiv},
     doi = {https://doi.org/10.48550/arXiv.2412.13069},
     author = {Bassi, Marion and Rodríguez-Mena, Esteban-Alonso and Brun, Boris and Zihlmann, Simon and Nguyen, Thanh and Champain, Victor and Abadillo-Uriel, José Carlos and Bertrand, Benoit and Niebojewski, Heimanu and Maurand, Romain and Niquet, Yann-Michel and Jehl, Xavier and Franceschi, Silvano De and Schmitt, Vivien},
     keywords = {Mesoscale and Nanoscale Physics (cond-mat.mes-hall), FOS: Physical sciences, FOS: Physical sciences},
     publisher = {arXiv},
     year = {2024},
     month = dec,
     arxiv = {2412.13069},
     bibtex_show = {true}
   }

3. arXiv

   A two-dimensional 10-qubit array in germanium with robust and localised qubit control

   Valentin John;  Cécile X. Yu;  Barnaby Straaten;  Esteban A. Rodríguez-Mena;  Mauricio Rodríguez;  Stefan Oosterhout;  Lucas E. A. Stehouwer;  Giordano Scappucci;  Stefano Bosco;  Maximilian Rimbach-Russ;  Yann-Michel Niquet;  Francesco Borsoi;  Menno Veldhorst

   arXiv Dec 2024

   Abstract arXiv Bib URL

   Quantum computers require the systematic operation of qubits with high fidelity. For holes in germanium, the spin-orbit interaction allows for \textitin situ electric fast and high-fidelity qubit gates. However, the interaction also causes a large qubit variability due to strong g-tensor anisotropy and dependence on the environment. Here, we leverage advances in material growth, device fabrication, and qubit control to realise a two-dimensional 10-spin qubit array, with qubits coupled up to four neighbours that can be controlled with high fidelity. By exploring the large parameter space of gate voltages and quantum dot occupancies, we demonstrate that plunger gate driving in the three-hole occupation enhances electric-dipole spin resonance (EDSR), creating a highly localised qubit drive. Our findings, confirmed with analytical and numerical models, highlight the crucial role of intradot Coulomb interaction and magnetic field direction. Furthermore, the ability to engineer qubits for robust control is a key asset for further scaling.

   @article{john2024_10qubit,
     abbr = {arXiv},
     title = {A two-dimensional 10-qubit array in germanium with robust and localised qubit control},
     url = {https://arxiv.org/abs/2412.16044},
     html = {https://arxiv.org/abs/2412.16044},
     journal = {arXiv},
     doi = {https://doi.org/10.48550/arXiv.2412.16044},
     author = {John, Valentin and Yu, Cécile X. and van Straaten, Barnaby and Rodríguez-Mena, Esteban A. and Rodríguez, Mauricio and Oosterhout, Stefan and Stehouwer, Lucas E. A. and Scappucci, Giordano and Bosco, Stefano and Rimbach-Russ, Maximilian and Niquet, Yann-Michel and Borsoi, Francesco and Veldhorst, Menno},
     keywords = {Mesoscale and Nanoscale Physics (cond-mat.mes-hall), FOS: Physical sciences, FOS: Physical sciences},
     publisher = {arXiv},
     year = {2024},
     month = dec,
     arxiv = {2412.16044},
     bibtex_show = {true}
   }