Pierre Hamonic, Martin Nurizzo, Jayshankar Nath, Matthieu C. Dartiailh, Victor El-Homsy, Mathis Fragnol, Biel Martinez, Pierre-Louis Julliard, Bruna Cardoso Paz, Mathilde Ouvrier-Buffet, Jean-Baptiste Filippini, Benoit Bertrand, Heimanu Niebojewski, Christopher Bäuerle, Maud Vinet, Franck Balestro, Tristan Meunier, Matias Urdampilleta Semiconductor quantum dot arrays are a promising platform to perform spin-based error-corrected quantum computation with large numbers of qubits. However, due to the diverging number of possible charge configurations combined with the limited sensitivity of large-footprint charge sensors, achieving single-spin occupancy in each dot in a growing quantum dot array is exceedingly complex. Therefore, to scale-up a spin-based architecture we must change how individual charges are readout and controlled. Here, we demonstrate single-spin occupancy of each dot in a foundry-fabricated array by combining two methods. 1/ Loading a finite number of electrons into the quantum dot array; simplifying electrostatic tuning by isolating the array from the reservoirs. 2/ Deploying multiplex gate-based reflectometry to dispersively probe charge tunneling and spin states without charge sensors or reservoirs. Our isolated arrays probed by embedded multiplex readout can be readily electrostatically tuned. They are thus a viable, scalable approach for spin-based quantum architectures.
We report local time-resolved thermometry in a silicon nanowire quantum dot device designed to host a linear array of spin qubits. Using two alternative measurement schemes based on rf reflectometry, we are able to probe either local electron or phonon temperatures with $\mu$s-scale time resolution and a noise equivalent temperature of $3$ $\rm mK/\sqrt{\rm Hz}$. Following the application of short microwave pulses, causing local periodic heating, time-dependent thermometry can track the dynamics of thermal excitation and relaxation, revealing clearly different characteristic time scales. This work opens important prospects to investigate the out-of-equilibrium thermal properties of semiconductor quantum electronic devices operating at very low temperature. In particular, it may provide a powerful handle to understand heating effects recently observed in semiconductor spin-qubit systems.
Victor Elhomsy, Luca Planat, David J. Niegemann, Bruna Cardoso-Paz, Ali Badreldin, Bernhard Klemt, Vivien Thiney, Renan Lethiecq, Eric Eyraud, Matthieu C. Dartiailh, Benoit Bertrand, Heimanu Niebojewski, Christopher Bäuerle, Maud Vinet, Tristan Meunier, Nicolas Roch, Matias Urdampilleta Spins in semiconductor quantum dots hold great promise as building blocks of quantum processors. Trapping them in SiMOS transistor-like devices eases future industrial scale fabrication. Among the potentially scalable readout solutions, gate-based dispersive radiofrequency reflectometry only requires the already existing transistor gates to readout a quantum dot state, relieving the need for additional elements. In this effort towards scalability, traveling-wave superconducting parametric amplifiers significantly enhance the readout signal-to-noise ratio (SNR) by reducing the noise below typical cryogenic low-noise amplifiers, while offering a broad amplification band, essential to multiplex the readout of multiple resonators. In this work, we demonstrate a 3GHz gate-based reflectometry readout of electron charge states trapped in quantum dots formed in SiMOS multi-gate devices, with SNR enhanced thanks to a Josephson traveling-wave parametric amplifier (JTWPA). The broad, tunable 2GHz amplification bandwidth combined with more than 10dB ON/OFF SNR improvement of the JTWPA enables frequency and time division multiplexed readout of interdot transitions, and noise performance near the quantum limit. In addition, owing to a design without superconducting loops and with a metallic ground plane, the JTWPA is flux insensitive and shows stable performances up to a magnetic field of 1.2T at the quantum dot device, compatible with standard SiMOS spin qubit experiments.
T. Bédécarrats, B. Cardoso Paz, B. Martinez Diaz, H. Niebojewski, B. Bertrand1, N. Rambal, C. Comboroure, A. Sarrazin, F. Boulard, E. Guyez, J.-M. Hartmann, Y. Morand, A. Magalhaes-Lucas, E. Nowak, E. Catapano, M. Cassé, M. Urdampilleta, Y.-M. Niquet, F. Gaillard, S. De Franceschi, et al (2) Operating Si quantum dot (QD) arrays requires homogeneous and ultra-dense structures with aggressive gate pitch. Such a density is necessary to separately control the QDs chemical potential (i.e. charge occupation of each QD) from the exchange interaction (i.e. tunnel barriers between each QD). We present here a novel Si quantum device integration that halves the effective gate pitch and provides full controllability in 1D FDSOI QD arrays. The major advantages of this architecture are explored through numerical simulations. Functionality of the fabricated structure is validated via 300K statistical electrical characterization, while tunnel-coupling control is demonstrated at cryogenic temperature.
Bernhard Klemt, Victor El-Homsy, Martin Nurizzo, Pierre Hamonic, Biel Martinez, Bruna Cardoso Paz, Cameron spence, Matthieu Dartiailh, Baptiste Jadot, Emmanuel Chanrion, Vivien Thiney, Renan Lethiecq, Benoit Bertrand, Heimanu Niebojewski, Christopher Bäuerle, Maud Vinet, Yann-Michel Niquet, Tristan Meunier, Matias Urdampilleta For semiconductor spin qubits, complementary-metal-oxide-semiconductor (CMOS) technology is the ideal candidate for reliable and scalable fabrication. Making the direct leap from academic fabrication to qubits fabricated fully by industrial CMOS standards is difficult without intermediate solutions. With a flexible back-end-of-line (BEOL) new functionalities such as micromagnets or superconducting circuits can be added in a post-CMOS process to study the physics of these devices or achieve proof of concepts. Once the process is established it can be incorporated in the foundry-compatible process flow. Here, we study a single electron spin qubit in a CMOS device with a micromagnet integrated in the flexible BEOL. We exploit the synthetic spin orbit coupling (SOC) to control the qubit via electric field and we investigate the spin-valley physics in the presence of SOC where we show an enhancement of the Rabi frequency at the spin-valley hotspot. Finally, we probe the high frequency noise in the system using dynamical decoupling pulse sequences and demonstrate that charge noise dominates the qubit decoherence in this range.
David J. Niegemann, Victor El-Homsy, Baptiste Jadot, Martin Nurizzo, Bruna Cardoso-Paz, Emmanuel Chanrion, Matthieu Dartiailh, Bernhard Klemt, Vivien Thiney, Christopher Bäuerle, Pierre-André Mortemousque, Benoit Bertrand, Heimanu Niebojewski, Maud Vinet, Franck Balestro, Tristan Meunier, Matias Urdampilleta We demonstrate singlet-triplet readout and parity readout allowing to distinguish T0 and the polarized triplet states. We achieve high fidelity spin readout with an average fidelity above $99.9\%$ for a readout time of $20~\mu$s and $99\%$ for $4~\mu$s at a temperature of $0.5~K$. We initialize a singlet state in a single dot with a fidelity higher than $99\%$ and separate the two electrons while keeping the same spin state with $a \approx 95.6\%$ fidelity.
Cécile X. Yu, Simon Zihlmann, José C. Abadillo-Uriel, Vincent P. Michal, Nils Rambal, Heimanu Niebojewski, Thomas Bedecarrats, Maud Vinet, Etienne Dumur, Michele Filippone, Benoit Bertrand, Silvano De Franceschi, Yann-Michel Niquet, Romain Maurand 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.
N. Piot, B. Brun, V. Schmitt, S. Zihlmann, V. P. Michal, A. Apra, J. C. Abadillo-Uriel, X. Jehl, B. Bertrand, H. Niebojewski, L. Hutin, M. Vinet, M. Urdampilleta, T. Meunier, Y.-M. Niquet, R. Maurand, S. De Franceschi Semiconductor spin qubits based on spin-orbit states are responsive to electric field excitation 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 $\mu$s, exceeding by an order of magnitude the best reported values for hole-spin qubits, and approaching the state-of-the-art for electron spin qubits with synthetic spin-orbit coupling in isotopically-purified silicon. This finding largely enhances the prospects of silicon-based hole spin qubits for scalable quantum information processing.
Cameron Spence, Bruna Cardoso Paz, Bernhard Klemt, Emmanuel Chanrion, David J. Niegemann, Baptiste Jadot, Vivien Thiney, Benoit Bertrand, Heimanu Niebojewski, Pierre-André Mortemousque, Xavier Jehl, Romain Maurand, Silvano De Franceschi, Maud Vinet, Franck Balestro, Christopher B?äuerle, Yann-Michel Niquet, Tristan Meunier, Matias Urdampilleta One of the main advantages of silicon spin qubits over other solid-state qubits is their inherent scalability and compatibility with the 300 mm CMOS fabrication technology that is already widely used in the semiconductor industry, whilst maintaining high readout and gate fidelities. We demonstrate detection of a single electron spin using energy-selective readout in a CMOS-fabricated nanowire device with an integrated charge detector. We measure a valley splitting of 0.3 meV and 0.16 meV in two similar devices. The anisotropy of the spin-valley mixing is measured and shown to follow the dependence expected from the symmetry of the local confinement, indicating low disorder in the region of the quantum dot. Finally the charge noise in the spin-valley coupling regime is investigated and found to induce fluctuations in the qubit energy in the range of $0.6GHz/\sqrt{Hz}$.
Braneshop, and
the US National Science Foundation.
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