Article
Materials Science, Multidisciplinary
V. N. Mantsevich, D. S. Smirnov
Summary: The weak spin-orbit coupling in nonmagnetic semiconductor nanostructures limits the current-induced spin accumulation. However, the Kondo effect provides a possibility to parametrically increase spin polarization. By considering the many-body correlations between a quantum dot and a quantum wire, the current-induced spin accumulation can be enhanced by almost two orders of magnitude at low temperatures, due to the Kondo peak formation and the spin instability caused by strong Coulomb interaction. This effect could be useful for electrically manipulating localized electron spins in quantum dots for quantum applications.
Article
Chemistry, Multidisciplinary
Saptarshi Mandal, Prolay Das
Summary: By combining carbon dots with DNA, the migration of charge in DNA was controlled through light irradiation, leading to a breakthrough in visible-light-induced charge transfer that could potentially be applied in optobioelectronics.
Article
Physics, Multidisciplinary
Ali Moulhim, Brijesh Tripathi, Manoj Kumar
Summary: Through non-equilibrium Green function formalism, we analyzed the electron transport characteristics of nanoelectronic devices by coupling a quantum dot to metallic electrodes, and discussed the relationship between current and quantum dot size, level width, and temperature using analytical approximations. Furthermore, we also studied the dependence of current on applied voltage to understand the behavior of dual-channel nano-devices.
Article
Chemistry, Multidisciplinary
Levente Mathe, Zoltan Kovacs-Krausz, Ioan Botiz, Ioan Grosu, Khadija El Anouz, Abderrahim El Allati, Liviu P. P. Zarbo
Summary: We theoretically analyze the phonon-assisted tunneling transport in a quantum dot connected to a Majorana bound state in a topological superconducting nanowire. We investigate the behavior of the current through the dot under different experimentally relevant parameters and the influence of electron-phonon coupling. The presence of electron-phonon coupling affects the current behavior similarly to the renormalized gate voltage. At large bias voltages, the current presents a dip or a plateau, depending on the size of the dot-Majorana coupling. Our results reveal the complex physics of quantum dot devices used to study Majorana bound states.
Article
Physics, Condensed Matter
Natalya A. Zimbovskaya
Summary: The present study focuses on the theoretical analysis of thermoelectric transport and heat transfer in a junction consisting of a T-shaped double quantum dot coupled to nonmagnetic electrodes and supplemented with a third dot in a parallel configuration. The results show that the combination of Coulomb interactions and quantum interference in the T-shaped portion of the system significantly affects both charge and heat transfer.
PHYSICA B-CONDENSED MATTER
(2022)
Article
Materials Science, Multidisciplinary
Peng-Chao Wang, Yi-Hui Wang, Chong Chen, Jun Zhang, Wei Li, Nan Nan, Jia-Ning Wang, Jun-Tao Yang, Amel Laref, Yong-Chen Xiong
Summary: This study investigates the electronic transport and quantum phase transition of a tetrahedrally shaped colloidal quadruple quantum dot structure. The results reveal a two-stage Kondo effect when the interdot hopping is absent, and the appearance of a new two-stage Kondo effect when the hopping is present. Charging the central dot triggers a transition from antiferromagnetic to ferromagnetic correlation among the side dots.
Article
Chemistry, Multidisciplinary
Emma L. Minarelli, Jonas B. Rigo, Andrew K. Mitchell
Summary: This article investigates a graphene-based two-channel charge-Kondo device and uncovers a rich phase diagram. It finds that the strong coupling pseudogap Kondo phase persists in the channel-asymmetric case. Furthermore, despite the vanishing density of states in the graphene leads, a finite linear conductance is observed at the frustrated critical point.
Article
Nanoscience & Nanotechnology
G. A. Lara, J. P. Ramos-Andrade, D. Zambrano, P. A. Orellana
Summary: In this article, the quantum transport through a single-level quantum dot in the Kondo regime coupled to topological superconductors with Majorana zero modes is investigated. The results show that the presence of Majorana zero modes modifies the Kondo resonance, leading to spin-resolved behavior of the measurable current and differential conductance. This study provides insights into the interplay between the Kondo effect and Majorana zero modes.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2023)
Article
Physics, Condensed Matter
Ali Moulhim, Brijesh Tripathi, Abul Kalam, Manoj Kumar
Summary: The electron transport through a single electron transistor consisting of a quantum dot coupled to two metallic electrodes was studied using the non-equilibrium Green function technique. An analytical approximation of the Meir-Wingreen formula was presented under different conditions to investigate the current-voltage characteristics of the quantum dot.
SUPERLATTICES AND MICROSTRUCTURES
(2021)
Article
Materials Science, Multidisciplinary
D. Krychowski, S. Lipinski
Summary: The study discusses spin polarized transport through a quantum dot coupled to ferromagnetic electrodes with noncollinear magnetizations using nonequilibrium Green functions in the finite-U slave boson mean field approximation. The difference in magnetization orientations of the electrodes opens off diagonal spin-orbital transmission and leads to spin-flip currents. The study also explores the impact of spin-orbit coupling, magnetization orientation, and gate voltage on tunneling magnetoresistance (TMR).
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Utso Bhattacharya, Tobias Grass, Adrian Bachtold, Maciej Lewenstein, Fabio Pistolesi
Summary: This study explores the transition from a Mott insulating state to a polaronic state in a system of four quantum dots coupled to the flexural degrees of freedom of a suspended carbon nanotube. The findings suggest potential for using nano-electromechanical systems to simulate strongly correlated systems with electron-phonon interactions.
Article
Physics, Multidisciplinary
Yanqiang Guo, Jianfei Zhang, Xiaomin Guo, Stephan Reitzenstein, Liantuan Xiao
Summary: The emission characteristics of quantum-dot micropillar lasers (QDMLs) lie at the intersection of nanophotonics and nonlinear dynamics, providing an ideal platform for studying the optical interface between classical and quantum systems. In this research, a noise-induced bimodal QDML with orthogonal dual-mode outputs is modeled, and the nonlinear dynamics, stochastic mode jumping, and quantum statistics are investigated. The results show that noise-induced effects lead to the emergence of two intensity bifurcation points for the strong and weak modes, and the maximum output power of the strong mode increases with the noise intensity. The anti-correlation of the two modes reaches its maximum at the second intensity bifurcation point. The dual-mode stochastic jumping frequency and effective bandwidth can exceed 100 GHz and 30 GHz under the noise-induced effect. Photon bunching (g((2))(0) > 1) of both modes is observed over a wide range of noise intensities and injection currents. The photon number distribution of the strong or weak mode becomes a mixture of Bose-Einstein and Poisson distributions, with the proportion of the Poisson distribution increasing in the high injection current region for the strong mode and decreasing for the weak mode.
NEW JOURNAL OF PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Somnath Koley, Jiabin Cui, Yossef. E. Panfil, Yonatan Ossia, Adar Levi, Einav Scharf, Lior Verbitsky, Uri Banin
Summary: The charge redistribution upon optical excitation of various necked homodimer colloidal quantum dot molecules (CQDMs) is investigated using single-particle emission spectroscopy. By tuning the hybridization of the electron wavefunctions at a fixed center-to-center distance through controlling the neck girth, we reveal two coupling limits: weak-coupling regime and strong-coupling regime. The emitted photons from CQDMs in the weak-coupling regime show high bunching while the antibunching is regained at the strong-coupling regime.
Editorial Material
Chemistry, Physical
Naomi S. Ginsberg, William A. Tisdale
Summary: Early time transient absorption microscopy in quantum dot solids reveals different temporal regimes of exciton transport within hundreds of femtoseconds after photoexcitation.
Article
Materials Science, Multidisciplinary
Fatemeh Mohammadi, Amirhossein Saedpanah, Abolhassan Vaezi, Mehdi Kargarian
Summary: In this work, we study a superconducting Kondo lattice model to explore the interplay between electron correlations and conduction electrons. We obtain the phase diagram of the model and identify a topological order phase and a Kondo compensated phase. Numerical calculations show that the topological order is a stable phase.
Article
Physics, Multidisciplinary
B. Friess, I. A. Dmitriev, V Umansky, L. Pfeiffer, K. West, K. von Klitzing, J. H. Smet
PHYSICAL REVIEW LETTERS
(2020)
Article
Physics, Multidisciplinary
S. I. Dorozhkin, A. A. Kapustin, V. Umansky, J. H. Smet
Article
Quantum Science & Technology
Wonjin Jang, Jehyun Kim, Min-Kyun Cho, Hwanchul Chung, Sanghyeok Park, Jaeun Eom, Vladimir Umansky, Yunchul Chung, Dohun Kim
NPJ QUANTUM INFORMATION
(2020)
Article
Chemistry, Multidisciplinary
Wonjin Jang, Min-Kyun Cho, Hyeongyu Jang, Jehyun Kim, Jaemin Park, Gyeonghun Kim, Byoungwoo Kang, Hwanchul Jung, Vladimir Umansky, Dohun Kim
Summary: This study presents a high-fidelity readout method for a semiconductor hybrid qubit in GaAs double quantum dots, achieving quantum state mapping with voltage-controlled adiabatic transitions and energy-selective tunneling-based spin-to-charge conversion with a visibility of approximately 92.6%. The research also demonstrates coherent oscillations of a hybrid qubit in GaAs and explores the potential applications of this method in other materials.
Article
Multidisciplinary Sciences
Bivas Dutta, Wenmin Yang, Ron Melcer, Hemanta Kumar Kundu, Moty Heiblum, Vladimir Umansky, Yuval Oreg, Ady Stern, David Mross
Summary: Quantum Hall states have unique quantum phases characterized by gapless edge modes. The most studied nonabelian state is the spin-polarized filling factor 5/2, which can have different topological orders. By interfacing this state with another, we were able to identify its topological order as the particle-hole Pfaffian (PH-Pf) order.
Article
Physics, Applied
D. Yavorskiy, M. Szola, T. Tarkowski, J. Wrobel, P. Nowicki, V Umansky, W. Knap, J. Lusakowski
Summary: The study focuses on processing high-electron-mobility GaAs/Al0.36Ga0.64As heterostructures using electron-beam lithography and successfully achieving stimulated terahertz emission at low temperatures. The emitted photon energy is found to be smaller compared to previously reported emissions in the same category.
PHYSICAL REVIEW APPLIED
(2021)
Article
Physics, Multidisciplinary
Jehyun Kim, Jonginn Yun, Wonjin Jang, Hyeongyu Jang, Jaemin Park, Younguk Song, Min-Kyun Cho, Sangwoo Sim, Hanseo Sohn, Hwanchul Jung, Vladimir Umansky, Dohun Kim
Summary: In this study, we report energy-selective tunneling readout-based Hamiltonian parameter estimation of a two-electron spin qubit in a GaAs quantum dot array. By optimizing the readout fidelity, we achieved an average single-shot measurement time of 16 μs, along with adaptive initialization and efficient qubit frequency estimation based on realtime Bayesian inference. We observed a 40-fold increase in coherence time for qubit operation in a frequency heralded mode, without resorting to dynamic nuclear polarization. Additionally, we demonstrated active frequency feedback with quantum oscillation visibility, single-shot measurement fidelity, and gate fidelity of 97.7%, 99%, and 99.6%, respectively, showcasing the improvements in the overall capabilities of GaAs-based spin qubits. Pushing the sensitivity of energy-selective tunneling-based spin to charge conversion to the limit, this technique is useful for advanced quantum control protocols such as error mitigation schemes, where fast qubit parameter calibration with a high signal-to-noise ratio is crucial.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
Subhradeep Misra, Michael Stern, Vladimir Umansky, Israel Bar-Joseph
Summary: This study demonstrates the characteristics and dynamics of Bose-Einstein condensation of dark excitons in GaAs coupled quantum wells at low temperatures. The results show that the condensate extends spatially beyond the optical excitation region and its density is determined by spin-flipping collisions among the excitons. The interaction between bright excitons and the condensate leads to its depletion.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Physics, Multidisciplinary
Sourav Biswas, Rajarshi Bhattacharyya, Hemanta Kumar Kundu, Ankur Das, Moty Heiblum, Vladimir Umansky, Moshe Goldstein, Yuval Gefen
Summary: The fractional charge of quasiparticles is a fundamental feature of quantum Hall effect states. At sufficiently low temperatures, the Fano factor is found to be equal to the bulk filling factor, and this noise pattern is also observed on intermediate conductance plateaux.
Article
Multidisciplinary Sciences
Bivas Dutta, Vladimir Umansky, Mitali Banerjee, Moty Heiblum
Summary: This study gapped out the integer modes by interfacing the nu = 5/2 state with integer states nu = 2 and nu = 3, and measured the thermal conductance of the isolated-interface channel. The measured half-quantized thermal conductance confirms the non-abelian nature of the nu = 5/2 state and its particle-hole Pfaffian topological order.
Article
Physics, Multidisciplinary
Ron Aharon Melcer, Sofia Konyzheva, Moty Heiblum, Vladimir Umansky
Summary: Thermal conductance measurements are crucial in condensed-matter physics for understanding topological order in two-dimensional topological insulators. A new local power measurement technique is presented to reveal the topological thermal Hall conductance, going beyond traditional two-terminal conductance measurements. This technique also proves useful in studying power carried by current fluctuations of partitioned edge modes with out-of-equilibrium distributions.
Article
Physics, Multidisciplinary
Hemanta Kumar Kundu, Sourav Biswas, Nissim Ofek, Vladimir Umansky, Moty Heiblum
Summary: In this article, the authors demonstrate the interference and braiding of anyons in a Mach-Zehnder interferometer, proving that this device is a powerful tool for probing the quantum statistics of anyonic fractional quantum Hall states.
Article
Quantum Science & Technology
Jonginn Yun, Jaemin Park, Hyeongyu Jang, Jehyun Kim, Wonjin Jang, Younguk Song, Min-Kyun Cho, Hanseo Sohn, Hwanchul Jung, Vladimir Umansky, Dohun Kim
Summary: We demonstrate the simultaneous operation and measurement of two-electron spin qubits, decoupled from nuclear noise, in a GaAs quadruple quantum dot array. Coherent Rabi oscillations of both qubits are achieved by tuning their drive frequency using real-time Hamiltonian estimators. Strong two-qubit capacitive interaction and state-conditional frequency shift are observed, consistent with theoretical predictions. The high coherence to conditional phase-flip time ratio suggests the potential for generating high-fidelity and fast quantum entanglement using a simple capacitive interaction.
NPJ QUANTUM INFORMATION
(2023)
Article
Physics, Multidisciplinary
S. Dorozhkin, A. A. Kapustin, V Umansky, J. H. Smet
Summary: The dependence of amplitudes of Shubnikov-de Haas oscillations on the magnetic field in GaAs/AlGaAs heterostructure samples irradiated with microwave radiation in the range of 130-170 GHz has been studied. Two features of radiation-induced suppression of amplitudes have been identified, with resonances appearing at the second harmonic and a more complex dependence of the second resonance on radiation frequency. Resonance absorption at the second harmonic may explain the anomalous peak in magnetoresistance observed recently.
Article
Physics, Multidisciplinary
Dongsung T. Park, Uhjin Kim, Dongkun Kim, Hwanchul Jung, Juho Choi, Cheolhee Han, Yunchul Chung, H-S Sim, V Umansky, Hyoungsoon Choi, Hyung Kook Choi
Summary: Research on mesoscopic quantum dots shows a significant energy relaxation phenomenon of hot electrons emitted, deviating from Fermi gas predictions. Simulation experiments indicated a capacitive interaction transferring energy from hot electrons to quantum dots, suggesting the presence of an overlooked relaxation mechanism intrinsic to QD emissions.
PHYSICAL REVIEW RESEARCH
(2021)