Article
Materials Science, Multidisciplinary
M. Vladimirova, S. Cronenberger, A. Colombier, D. Scalbert, V. M. Litvyak, K. V. Kavokin, A. Lemaitre
Summary: The heat capacity of the nuclear-spin system in GaAs-based microstructures is found to be higher than expected, and it is suggested that the quadrupole interaction induced by residual strain could be the additional reservoir for heat storage. Experimental results confirm this hypothesis and provide further understanding of the relation between mechanical strain and electric field gradients in GaAs.
Article
Physics, Multidisciplinary
Xinxin Cai, Elliot J. Connors, Lisa F. Edge, John M. Nichol
Summary: Electron spins in silicon quantum dots are excellent qubits due to their long coherence times, high gate fidelities, and compatibility with advanced semiconductor manufacturing techniques. In this study, we demonstrate that spin-valley coupling in Si enables coherent control of single and multi-electron spin states without oscillating electromagnetic fields. Our results establish spin-valley coupling as a promising mechanism for coherent control of qubits based on electron spins in semiconductor quantum dots.
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
Chemistry, Multidisciplinary
Bin Leong Ong, Muhammad Avicenna Naradipa, Angga Dito Fauzi, Muhammad Aziz Majidi, Caozheng Diao, Satoshi Kurumi, Pranab Kumar Das, Chi Xiao, Ping Yang, Mark B. H. Breese, Sheau Wei Ong, Khay Ming Tan, Eng Soon Tok, Andrivo Rusydi
Summary: A new concept of spin correlated-plasmon has been proposed and demonstrated in highly oriented single-crystalline gold quantum-dots at room temperature, with tunable properties from infrared to visible light, as well as high sensitivity for surface-enhanced Raman spectroscopy applications.
Article
Materials Science, Multidisciplinary
Mohsen Yarmohammadi, Katrin Bolsmann, Yvonne Ribbeheger, Timo Graesser, Goetz S. Uhrig
Summary: The central spin model is highly applicable to describe small quantum systems in contact with a bath of spins. A large bath of quantum spins can be represented by quantum harmonic oscillators, but the resulting model is still challenging to solve. This study examines the effectiveness of a semi-classical truncated Wigner approximation compared to other approximate and exact methods, finding that it works well for short times but deviates for long times. The applicability of semi-classical approaches depends strongly on the variables used to formulate the model.
Article
Physics, Applied
Yao-Chun Chang, Ian Huang, Chiung-Yu Chen, Min-Jui Lin, Shih-Yuan Chen, Jiun-Yun Li
Summary: This study proposes an ESR meanderline design for large-scale Si QDs, which can effectively enhance magnetic fields with low electric fields according to simulations, enabling high-fidelity and low-noise control over electron spins in a 50-qubit system. On-wafer microwave measurements show low loss (-7 dB) for a 3-qubit device at a frequency range of 10 to 50 GHz.
APPLIED PHYSICS LETTERS
(2021)
Article
Quantum Science & Technology
Stefano Bosco, Bence Hetenyi, Daniel Loss
Summary: Hole Si fin field-effect transistors (FinFETs) are shown to be highly compatible with modern CMOS technology and have operational sweet spots where charge noise is completely removed. The presence of these sweet spots is a result of the interplay between material anisotropy and the shape of the FinFET cross section. Designs that maximize qubit performance and potentially pave the way towards a scalable spin-based quantum computer are identified.
Article
Materials Science, Multidisciplinary
Patrick Del Vecchio, Oussama Moutanabbir
Summary: The selective confinement of light holes (LHs) is achieved in a low-dimensional system of Ge quantum wells, allowing for the design of an ultrafast gate-defined spin qubit under electric dipole spin resonance. The qubit size-dependent g factor and dipole moment are determined, and the parameters affecting their modulation are discussed. The dipole moment of the LH qubit is found to be orders of magnitude higher than that of the heavy-hole qubit due to significant spin splitting caused by unique cubic and linear Rashba spin-orbit interactions. The proposed all-group IV, direct band-gap LH qubit offers an effective platform for long-range entanglement distribution and quantum networks.
Article
Materials Science, Multidisciplinary
L. Banszerus, K. Hecker, E. Icking, S. Trellenkamp, F. Lentz, D. Neumaier, K. Watanabe, T. Taniguchi, C. Volk, C. Stampfer
Summary: The study focuses on transport through a high-frequency gate-controlled single-electron bilayer graphene quantum dot. By utilizing transient current spectroscopy of single-electron spin states, the researchers extracted a lower bound of the spin relaxation time of 0.5 μs, which is an important step towards investigating spin coherence times in graphene-based quantum dots and implementing spin qubits.
Article
Chemistry, Physical
Chang Woo Kim, In Ho Kim, Young Soo Kang
Summary: A facile strategy for fabricating exchange-coupled nanomagnets with a large energy product was suggested in this study, successfully obtaining a SmCo5/Co nanocomposite magnet through a three-step approach, demonstrating the importance of dimension and arrangement of hard and soft phases for effective magnetic spin exchange interaction.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2021)
Article
Quantum Science & Technology
Michael Berger, Jamal Berakdar
Summary: Quantum states of systems with classical chaotic dynamics can be scarred, and this study demonstrates how the scarred state can be imaged to a region that does not support scarring. This phantom scar has a significant impact on the spin-dependent system dynamics, as shown by explicit calculations for fidelity and correlation functions. Numerical simulations and analysis for the spin-dependent electron dynamics in semiconductor-based double quantum dots provide insights into the coherent phenomenon of scarring and its localization properties in a narrow spectral window.
ADVANCED QUANTUM TECHNOLOGIES
(2023)
Article
Optics
Zhu-yao Jin, Jia-shun Yan, Jun Jing
Summary: In this article, we propose a protocol for nuclear spin polarization in a spin-star configuration, achieved through measurements. By optimizing a sequence of measurements with unequal time spacing, hundreds or even thousands of randomly aligned nuclear spins can be almost fully polarized. Compared to conventional methods, this protocol is not sensitive to magnetic field intensity and is robust against extra counterrotating interaction in the near-resonant situation.
Article
Physics, Multidisciplinary
Long-Hin Tang, David M. Long, Anatoli Polkovnikov, Anushya Chandran, Pieter W. Claeys
Summary: Central spin models provide an idealized description of interactions between a central degree of freedom and a mesoscopic environment of surrounding spins. In this article, we demonstrate the integrability of a family of models with a spin-1 at the center and XX interactions of arbitrary strength with surrounding spins. By using the Bethe ansatz, we derive a comprehensive set of conserved quantities and obtain the exact eigenstates. We also explore the dynamics of these states and their implications in quench dynamics.
Article
Materials Science, Multidisciplinary
Guo Xuan Chan, J. P. Kestner, Xin Wang
Summary: Theoretically, a range of nearly sweet spots appears in the coupled singlet-triplet qubit system when a strong enough external magnetic field is applied. Ramping to and from the judiciously chosen nearly sweet spot using sequences based on the shortcut to adiabaticity offers maximal gate fidelities under charge noise and phonon-induced decoherence, facilitating realization of high-fidelity two-qubit gates in singlet-triplet qubit systems.
Article
Optics
Yuqing Huang, Ville Polojarvi, Satoshi Hiura, Pontus Hojer, Arto Aho, Riku Isoaho, Teemu Hakkarainen, Mircea Guina, Shino Sato, Junichi Takayama, Akihiro Murayama, Irina A. Buyanova, Weimin M. Chen
Summary: An electron spin polarization of over 90% has been achieved at room temperature in a non-magnetic nanostructure, utilizing remote spin filtering of InAs quantum-dot electrons through an adjacent GaNAs spin filter. This paves the way for implementing opto-spintronic functionalities in common semiconductor nanostructures.
Article
Physics, Multidisciplinary
Jon Lasa-Alonso, Martin Molezuelas-Ferreras, J. J. Miguel Varga, Aitzol Garcia-Etxarri, Geza Giedke, Gabriel Molina-Terriza
NEW JOURNAL OF PHYSICS
(2020)
Article
Quantum Science & Technology
M. K. Schmidt, R. Esteban, G. Giedke, J. Aizpurua, A. Gonzalez-Tudela
Summary: This paper analyzes the frequency-resolved photon correlations emitted from an optomechanical system, revealing a rich landscape of frequency-resolved correlations and discussing how time-delayed correlations can reveal information about system dynamics. The study also investigates the dependence of correlations on relevant parameters, triggering new experiments to probe nonlinear phenomena in optomechanics and providing insights into dynamics of generic nonlinear systems.
QUANTUM SCIENCE AND TECHNOLOGY
(2021)
Article
Physics, Condensed Matter
M. Blanco de Paz, M. A. J. Herrera, P. Arroyo Huidobro, H. Alaeian, M. G. Vergniory, B. Bradlyn, G. Giedke, A. Garcia-Etxarri, D. Bercioux
Summary: This article studies the topological properties of various two-dimensional photonic crystal structures through the combined study of topological quantum chemistry, Wilson loop spectra, and electromagnetic energy density.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Physics, Applied
Jan Hellemann, Filipp Muller, Madeleine Msall, Paulo Santos, Stefan Ludwig
Summary: We present a method for accurately determining the amplitude of surface acoustic waves by comparing force-curve measurements with the equation of motion of a driven cantilever. We demonstrate the effectiveness of our method in measuring a standing surface acoustic wave on a GaAs crystal.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Multidisciplinary
Sofia Sanz, Nick Papior, Geza Giedke, Daniel Sanchez-Portal, Mads Brandbyge, Thomas Frederiksen
Summary: This study investigated structures composed of narrow zigzag graphene nanoribbons (GNRs) and found that the beam-splitting effect can survive under Coulomb repulsion and a spin-dependent scattering potential can emerge. The researchers also discovered that this is a general feature with edge-polarized nanoribbons, and near-perfect polarization can be achieved by joining several junctions in series.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Applied
Miguel Bello, Monica Benito, Martin J. A. Schuetz, Gloria Platero, Geza Giedke
Summary: We propose a protocol for generating entanglement between two ensembles of nuclear spins surrounding two distant quantum dots. The protocol involves injecting polarized electrons, interacting sequentially with the nuclear ensembles of each quantum dot, and transferring each electron coherently from one quantum dot to the other.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Condensed Matter
Sofia Sanz, Nick Papior, Geza Giedke, Daniel Sanchez-Portal, Mads Brandbyge, Thomas Frederiksen
Summary: We theoretically study electron interference in a Mach-Zehnder-like geometry formed by four parallel pairs of zigzag graphene nanoribbons. By adjusting the interribbon separation, each intersection can function as an electron beam splitter or mirror, allowing for tuneable circuitry with interfering pathways. We evaluate the electron transport properties of these eight-terminal devices and identify pairs of terminals subject to self-interference. The proposed devices have potential applications as magnetic field sensors, detectors of phase shifts induced by local scatterers, and for the study of quantum entanglement.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Physics, Applied
M. Hanke, N. Ashurbekov, E. Zatterin, M. E. Msall, J. Hellemann, P. V. Santos, T. U. Schulli, S. Ludwig
Summary: Using scanning x-ray diffraction microscopy, we have directly mapped the complete strain field generated near the GaAs surface by a standing surface acoustic wave with a wavelength of 500 nm corresponding to frequencies near 6 GHz. Our measurements show that the lattice distortions perpendicular to the surface are phase shifted compared to those in the propagation direction. This breakthrough provides a full characterization of a radio-frequency surface acoustic wave beyond plain imaging.
PHYSICAL REVIEW APPLIED
(2023)
Article
Materials Science, Multidisciplinary
Ricardo Ortiz, Geza Giedke, Thomas Frederiksen
Summary: In this study, we investigate the main magnetic interactions in Oligo(indenoindenes) (OInIn), which are pi-conjugated ladder carbon polymers with alternating hexagons and pentagons containing one unpaired electron in each pentagon. We classify the six possible isomers into two classes, with each class consisting of three isomers. We find that one class can be described as frustrated S = 1/2 Heisenberg chains with antiferromagnetic interactions between second-neighbor sites, while the other class exhibits antiferromagnetic order. Using various theoretical approaches, we further demonstrate that the ground state of one isomer is a valence-bond solid of ferromagnetic dimers (S = 1), which is topologically similar to the Affleck-Kennedy-Lieb-Tasaki (AKLT) model known for fractional S = 1/2 states at the edges.
Article
Materials Science, Multidisciplinary
Sanghita Sengupta, Thomas Frederiksen, Geza Giedke
Summary: In this study, we investigated the hyperfine interaction (HFI) in several planar sp2 carbon nanostructures exhibiting pi magnetism using density-functional theory. Our results revealed the anisotropic nature of HFI, with both isotropic Fermi contact and anisotropic dipolar terms contributing significantly. The magnitude of HFI in these structures was found to exceed 100 MHz, making experimental detection possible through techniques like electron spin resonance-scanning tunneling microscopy. We also developed empirical models based on pi-spin polarizations at carbon sites, allowing for the determination of hyperfine tensors in large systems where existing methodologies are not feasible. Additionally, we discussed the implications of HFI on electron spin decoherence and coherent nuclear dynamics.
Article
Optics
H. Alaeian, G. Giedke, I Carusotto, R. Loew, T. Pfau
Summary: This article theoretically investigates the first- and second-order quantum dissipative phase transitions of a three-mode cavity with a Hubbard interaction. By employing the Wigner function formalism, the study shows that quantum fluctuations notably limit the coherence time of the Goldstone mode. The theoretical predictions suggest that interacting multimode photonic systems are versatile test beds for investigating the crossovers between mean-field picture and quantum phase transitions.
Article
Materials Science, Multidisciplinary
Sofia Sanz, Pedro Brandimarte, Geza Giedke, Daniel Sanchez-Portal, Thomas Frederiksen
Article
Quantum Science & Technology
Maria Blanco de Paz, Chiara Devescovi, Geza Giedke, Juan Jose Saenz, Maia G. Vergniory, Barry Bradlyn, Dario Bercioux, Aitzol Garcia-Etxarri
ADVANCED QUANTUM TECHNOLOGIES
(2020)
Article
Optics
Tiago Debarba, Fernando Iemini, Geza Giedke, Nicolai Friis
Article
Materials Science, Multidisciplinary
J. Knoerzer, M. J. A. Schuetz, G. Giedke, D. S. Wild, K. De Greve, R. Schmidt, M. D. Lukin, J. Cirac
