Article
Physics, Multidisciplinary
Chuyao Tong, Annika Kurzmann, Rebekka Garreis, Wei Wister Huang, Samuel Jele, Marius Eich, Lev Ginzburg, Christopher Mittag, Kenji Watanabe, Takashi Taniguchi, Klaus Ensslin, Thomas Ihn
Summary: The study reports experiments on coupled bilayer graphene double quantum dots, where the spin and valley states are precisely controlled, enabling the observation of two-electron combined blockade physics. The switching of selection rules is demonstrated by switching between different ground states with gate and magnetic-field tuning, showing either valley blockade or spin blockade depending on the ground state configuration.
PHYSICAL REVIEW LETTERS
(2022)
Article
Quantum Science & Technology
Jonas Schuff, Dominic T. Lennon, Simon Geyer, David L. Craig, Federico Fedele, Florian Vigneau, Leon C. Camenzind, Andreas V. Kuhlmann, Andrew D. Briggs, Dominik M. Zumbuhl, Dino Sejdinovic, Natalia Ares
Summary: This study presents a machine learning algorithm capable of automatically identifying Pauli spin blockade (PSB) and utilizing it for spin qubit initialization and readout, even at elevated temperatures. The scarcity of PSB data is overcome by training the algorithm with simulated data and using cross-device validation. The algorithm is demonstrated on a silicon field-effect transistor device, achieving an accuracy of 96% on different test devices and showing robustness to device variability. It is expected to be applicable across all types of quantum dot devices, serving as an essential step towards fully automatic qubit tuning.
Article
Materials Science, Multidisciplinary
Philipp M. Mutter, Guido Burkard
Summary: The Pauli spin blockade in double quantum dots has evolved into a key technique for precise measurements of nanoscale system parameters. This work demonstrates that systems with site-dependent g tensors and spin-polarized leads can fully characterize the g tensors in the dots through magnetotransport experiments alone. Additionally, special polarization configurations can enhance the magnetotransport signal and induce a giant tunnel magnetoresistance effect, making the proposed technique robust against system noise. Incorporating the effects of spin-orbit interaction, the leakage current contains information about the g tensors and the degree of spin polarization in the leads.
Article
Nanoscience & Nanotechnology
Joseph Hillier, Keiji Ono, Kouta Ibukuro, Fayong Liu, Zuo Li, Muhammad Husain Khaled, Harvey Nicholas Rutt, Isao Tomita, Yoshishige Tsuchiya, Koji Ishibashi, Shinichi Saito
Summary: By utilizing disorder based quantum dots with strong orbital quantization, we achieved single hole transport and spin detection in standard p-type silicon transistors, highlighting important attributes for hole spin state control. The demonstrated strong spin-orbit interaction at the interface supports electric-field mediated control and provides motivation for investigating interactions useful for quantum information processing using scalable platforms like industry standard silicon technology.
Article
Materials Science, Multidisciplinary
Ankan Mukherjee, Bhaskaran Muralidharan
Summary: Recent experiments on current blockades in 2D material quantum-dot platforms have provided new opportunities for spin and valley-qubit processing. In this study, we propose a model to simulate the Pauli blockades in a double quantum dot structure, taking into account the interplay of Coulomb interactions, inter-dot tunneling, Zeeman splittings, and intrinsic spin-orbit coupling. We show that the conducting and blocking states responsible for the blockades cannot be explained solely by spin or valley pseudo-spins, but are a result of the coupled effect of all degrees of freedom. We also numerically predict the occurrence of Pauli blockades and verify our model with experimental data, suggesting its potential application in machine learning algorithms.
Article
Materials Science, Multidisciplinary
Meng Zeng, Dong-Hui Xu, Zi-Ming Wang, Lun-Hui Hu
Summary: This study investigates the effects of spin-symmetry pairing and atomic spin-orbit coupling on superconductivity in a two-band superconductor with two nearly degenerate orbitals. It discovered that the spin-orbit coupling can lead to the realization of topological chiral or helical Majorana edge states without external magnetic fields or Zeeman fields, and a spin-polarized superconducting state when time-reversal symmetry is spontaneously broken.
Article
Nanoscience & Nanotechnology
M. Milivojevic
Summary: The study explores the possibility of determining the Rashba spin-orbit coupling strength in InSb nanowire quantum dots by measuring the magnetic susceptibility of the two-electron system in a double quantum dot. It is found that the magnetic susceptibility reaches a maximal value when the spin-orbit and magnetic field are parallel/antiparallel, which can be used to extract the value of the Rashba parameter.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2021)
Article
Materials Science, Multidisciplinary
Arnau Sala, Jeroen Danon
Summary: In this study, the detailed line shape of EDSR-induced resonances in the leakage current in the regime of spin blockade is theoretically investigated, connecting different line shapes to the different underlying physical mechanisms that can enable the EDSR. Both numerical and analytical investigations are carried out, producing simple analytic expressions that provide insight into the physics at play. The results offer a means to extract more information about the detailed system parameters of quantum dots hosting spin qubits from an EDSR experiment than just their level structure based on the location of the resonances.
Article
Materials Science, Multidisciplinary
M. Kondo, S. Miyota, W. Izumida, S. Amaha, T. Hatano
Summary: The study investigates the impact of thermal energy on the current flow and electron spin states in double quantum dots. At low temperatures, quadruplet Pauli spin blockade is affected by thermal energy, leading to the coexistence of Coulomb and Pauli spin blockades, while the standard triplet Pauli spin blockade leads to a monotonic smearing of current as temperature increases.
Article
Optics
Xiao-Feng Shi
Summary: This study focuses on hyperentanglement in individual neutral atoms, demonstrating the controlled-Z operation in electronic and nuclear qubits through the Rydberg blockade effect. This offers opportunities for research in quantum science and technology based on neutral atoms.
Article
Quantum Science & Technology
Amanda E. Seedhouse, Tuomo Tanttu, Ross C. C. Leon, Ruichen Zhao, Kuan Yen Tan, Bas Hensen, Fay E. Hudson, Kohei M. Itoh, Jun Yoneda, Chih Hwan Yang, Andrea Morello, Arne Laucht, Susan N. Coppersmith, Andre Saraiva, Andrew S. Dzurak
Summary: The study discusses the importance of measuring qubits for quantum computation and error correction, introducing different types of blockade readout methods. Through experiments and theoretical models, the study explores the crossover point between parity and singlet-triplet readout, as well as the underlying physics mechanisms.
Article
Physics, Applied
Yun-Pil Shim
Summary: The article investigates the Pauli spin blockade in a triple quantum dot molecule in a semiconductor and demonstrates the potential of selectively allowing certain spin states to add an additional electron. This has significant importance in maintaining the performance of qubits in quantum dot systems.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Maria Spethmann, Xian-Peng Zhang, Jelena Klinovaja, Daniel Loss
Summary: Superconducting spin qubits, coupled to each other via a superconductor, demonstrate fast controlled phase-flip gates. The effective interaction between these qubits can be adjusted by the superconducting phase difference, the tunnel barrier strength, or the spin-orbit interaction parameters.
Article
Chemistry, Multidisciplinary
T. S. Shamirzaev, A. V. Shumilin, D. S. Smirnov, D. Kudlacik, S. V. Nekrasov, Yu G. Kusrayev, D. R. Yakovlev, M. Bayer
Summary: This study investigated exciton recombination and spin dynamics in (In,Al)As/AlAs quantum dots with indirect band gap and type-I band alignment. The anisotropic exchange interaction in these quantum dots was found to be negligible, enabling the formation of spin-polarized bright excitons under quasi-resonant, circularly polarized excitation. The recombination and spin dynamics of excitons were controlled by the hyperfine interaction between the electron and nuclear spins. A kinetic model was developed to quantitatively describe the experimental data, taking into account the population dynamics of the bright and dark exciton states as well as the spin dynamics.
Article
Multidisciplinary Sciences
J. Yoneda, W. Huang, M. Feng, C. H. Yang, K. W. Chan, T. Tanttu, W. Gilbert, R. C. C. Leon, F. E. Hudson, K. M. Itoh, A. Morello, S. D. Bartlett, A. Laucht, A. Saraiva, A. S. Dzurak
Summary: The article demonstrates high-fidelity coherent transport of an electron spin qubit between quantum dots in isotopically-enriched silicon, with a reported polarization transfer fidelity of 99.97% and an average coherent transfer fidelity of 99.4%. The results suggest that this method can reduce the cost of fault-tolerant quantum processors and provide key elements for high-fidelity, on-chip quantum information distribution.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Applied
Tsuyoshi Hatano, Toshihiro Kubo, Shinichi Amaha, Yasuhiro Tokura, Seigo Tarucha
Summary: The study investigates the electron transport properties of parallel-coupled double quantum dot devices under magnetic fields, observing different behaviors such as electron tunneling at low magnetic fields and the coexistence of parallel- and series-coupled DQDs under high magnetic fields. The observations are attributed to changes in tunnel couplings induced by the magnetic fields.
APPLIED PHYSICS EXPRESS
(2021)
Article
Physics, Applied
Noriyuki Lee, Ryuta Tsuchiya, Yusuke Kanno, Toshiyuki Mine, Yoshitaka Sasago, Go Shinkai, Raisei Mizokuchi, Jun Yoneda, Tetsuo Kodera, Chihiro Yoshimura, Shinichi Saito, Digh Hisamoto, Hiroyuki Mizuno
Summary: We developed a hybrid chip consisting of a 16 x 8 quantum dot array and a CMOS circuit (Q-CMOS). By optimizing the transistor design of Q-CMOS made from fully depleted (FD)-SOI, we were able to selectively control each of the 16 x 8 quantum dots and observed their characteristic variations for the first time. Through this study, we discovered the importance of suppressing variability in order to realize a large-scale quantum computer. We also found that the characteristics of the quantum dots change depending on the applied gate voltages.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Multidisciplinary
Shunsuke Kamimura, Hideaki Hakoshima, Yuichiro Matsuzaki, Kyo Yoshida, Yasuhiro Tokura
Summary: This study presents a quantum-enhanced heat engine with entanglement, utilizing superabsorption to enhance energy absorption by entangled qubits. Compared to conventional engines, this quantum heat engine provides power with a quantum scaling advantage of P = Theta(N-2), elucidating the quantum properties allowing for enhanced performance.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Hiroto Kasai, Yuki Takeuchi, Hideaki Hakoshima, Yuichiro Matsuzaki, Yasuhiro Tokura
Summary: This research introduces an anonymous quantum sensor that can hide the information of positions having non-zero magnetic fields after measurement, ensuring security and privacy. The effectiveness and feasibility of the quantum sensor are demonstrated by evaluating its sensitivity.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2022)
Article
Physics, Multidisciplinary
Kazuyuki Kuroyama, Sadashige Matsuo, Jo Muramoto, Shunsuke Yabunaka, Sascha R. Valentin, Arne Ludwig, Andreas D. Wieck, Yasuhiro Tokura, Seigo Tarucha
Summary: We report experimental observations of charge-spin cooperative dynamics of two-electron states in a GaAs double quantum dot located in a nonequilibrium phonon environment. The spin-flip rate of a single electron is significantly enhanced when the phonon energy exceeds the lowest excitation energy in the quantum dot. In addition, the spatial gradient of phonon density between the dots leads to a higher probability of parallel spin states than antiparallel ones.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Junliang Wang, Shunsuke Ota, Hermann Edlbauer, Baptiste Jadot, Pierre-Andre Mortemousque, Aymeric Richard, Yuma Okazaki, Shuji Nakamura, Arne Ludwig, Andreas D. Wieck, Matias Urdampilleta, Tristan Meunier, Tetsuo Kodera, Nobu-Hisa Kaneko, Shintaro Takada, Christopher Bauerle
Summary: This study addresses the challenge of large spatial extent of surface acoustic waves (SAW) by demonstrating single-shot chirp synthesis of a strongly compressed acoustic pulse. It successfully transports a single electron between distant quantum dots with high efficiency and competes with regular transduction approaches. Furthermore, the research finds that chirp synthesis can generate arbitrary acoustic waveforms tailored to various (opto)nanomechanical applications.
Article
Physics, Applied
Takeru Utsugi, Noriyuki Lee, Ryuta Tsuchiya, Toshiyuki Mine, Raisei Mizokuchi, Jun Yoneda, Tetsuo Kodera, Shinichi Saito, Digh Hisamoto, Hiroyuki Mizuno
Summary: Loading single electrons into an array of quantum dots is essential for developing scalable silicon-based quantum computers, but the variability of quantum dot characteristics presents significant challenges. In this study, we used a single-electron pump to load single electrons into a quantum dot array, achieving 100 MHz operation with 99% accuracy at 4 K. By controlling the timing of subsequent gates, we minimized jitter in electron transfer to less than 10 ns, suitable for typical silicon qubit operating speeds around 1 MHz.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Multidisciplinary
Yudai Ueki, Shunsuke Kamimura, Yuichiro Matsuzaki, Kyo Yoshida, Yasuhiro Tokura
Summary: This article presents a quantum battery system that utilizes collective and entanglement effects to achieve ultra-fast charging.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2022)
Article
Physics, Applied
Masato Machida, Raisei Mizokuchi, Jun Yoneda, Takashi Tomura, Tetsuo Kodera
Summary: RF reflectometry is a promising technique for spin qubit readout, which can be used in large-scale integrated qubit systems by combining with multiplexing techniques and gate-based readout. However, one challenge in such systems is the degradation of the accuracy of RF readout due to crosstalk among dense RF readout lines. In this study, we propose a mixed-mode RF reflectometry to reduce the effect of crosstalk and verify its effectiveness through electromagnetic field simulations. The simulation results show the possibility of suppressing the influence of crosstalk by using mixed modes.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Multidisciplinary
Toshiaki Hayashi, Yasuhiro Tokura, Katsuhiko Nishiguchi
Summary: Variable-range hopping transport is studied from a new perspective, focusing on the statistical properties of voltage potential at different sites. By calculating the deviations in the voltage potentials using rate equations, it is found that there are two temperature regimes: nearest-neighbor hopping at high temperatures and variable-range hopping at low temperatures. The temperature dependence of the correlation length confirms the development of long-range order in the variable-range hopping regime.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2023)
Article
Nanoscience & Nanotechnology
J. Kamioka, R. Matsuda, R. Mizokuchi, J. Yoneda, T. Kodera
Summary: This paper reports on the extraction and design of the equivalent circuit model parameters of a silicon quantum dot at a low temperature, as well as the impedance matching circuits for improving the performance of a charge sensor. The I-V characteristics and S-parameters of the quantum dot device were measured and modeled using an RC parallel circuit. Three impedance matching circuits for RF reflectometry of a quantum dot were considered and analyzed for sensitivity and bandwidth. The results and analysis provided useful insights for selecting the optimal matching circuit and parameters for a given equivalent circuit and working frequency, facilitating fast semiconductor qubit readout in various quantum dot platforms.
Article
Physics, Multidisciplinary
Shunsuke Kamimura, Kyo Yoshida, Yasuhiro Tokura, Yuichiro Matsuzaki
Summary: In this study, new boundaries on the heat current in a quantum system coupled with an environment are derived and specific examples and restrictions are provided. These results are important for evaluating the performance of quantum-enhanced thermodynamic devices.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Tsuyoshi Yamamoto, Yasuhiro Tokura, Takeo Kato
Summary: We study the backaction of quantum measurements on heat transport through a two-level system. The nonselective measurement leads to dephasing effect on the two-level system. We formulate the heat current under the selective measurement with a stochastic master equation and show that the cross-correlation between the measurement outcomes and the heat current contains information on the backaction. We expect that our findings can be verified using a platform of superconducting circuits.
Article
Materials Science, Multidisciplinary
M. Kondo, S. Miyota, W. Izumida, S. Amaha, T. Hatano
Summary: The study investigates the impact of thermal energy on the current flow and electron spin states in double quantum dots. At low temperatures, quadruplet Pauli spin blockade is affected by thermal energy, leading to the coexistence of Coulomb and Pauli spin blockades, while the standard triplet Pauli spin blockade leads to a monotonic smearing of current as temperature increases.
