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We study the low-temperature transport properties of the systems of parallel quantum dots described by the N-impurity Anderson model. We calculate the quasiparticle scattering phase shifts, spectral functions and correlations as a function…

Mesoscale and Nanoscale Physics · Physics 2009-03-05 Rok Zitko , Janez Bonca

The technology of Quantum Computing (QC) is continuously evolving, as researchers explore new technologies and the public gains access to quantum computers with an increasing number of qubits. In addition, the research community and…

We study the ballistic magnetotransport in a double quantum point contact (QPC) device consisting of a quasi-one-dimensional quantum wire with an embedded island-like impurity - etched nano-hole as in a recently published experiment [J. C.…

Mesoscale and Nanoscale Physics · Physics 2011-05-05 Rubén C. Villarreal , Francisco Mireles , Ernesto E. Marinero , Bruce A. Gurney

The central challenge of quantum computing is implementing high-fidelity quantum gates at scale. However, many existing approaches to qubit control suffer from a scale-performance trade-off, impeding progress towards the creation of useful…

As quantum circuits become more integrated and complex, additional error sources that were previously insignificant start to emerge. Consequently, the fidelity of quantum gates benchmarked under pristine conditions falls short of predicting…

Applications for noisy intermediate-scale quantum computing devices rely on the efficient entanglement of many qubits to reach a potential quantum advantage. Although entanglement is typically generated using two-qubit gates, direct control…

Quantum Physics · Physics 2023-04-18 Niklas J. Glaser , Federico Roy , Stefan Filipp

In transport experiments the quantum nature of matter becomes directly evident when changes in conductance occur only in discrete steps, with a size determined solely by Planck's constant h. The observations of quantized steps in the…

A behavior of a two qubit system coupled by the electric capacitance has been studied quantum mechanically. We found that the interaction is essentially the same as the one for the dipole-dipole interaction; i.e., qubit-qubit coupling of…

Quantum Physics · Physics 2016-09-08 T. Murakami , M. Iinuma , T. Takahashi , Y. Kadoya , M. Yamanishi

We present a fabrication process for fully superconducting interconnects compatible with superconducting qubit technology. These interconnects allow for the 3D integration of quantum circuits without introducing lossy amorphous dielectrics.…

We investigate integer and fractional quantum Hall states in quantum point contacts (QPCs) of different geometries, defined in AlGaAs/GaAs heterostructures employing different doping and screening techniques. We find that, even in the…

Mesoscale and Nanoscale Physics · Physics 2014-03-11 S. Baer , C. Rössler , E. C. de Wiljes , P. -L. Ardelt , T. Ihn , K. Ensslin , C. Reichl , W. Wegscheider

We report on charge sensing measurements of a GaAs semiconductor quantum dot device using a radio frequency quantum point contact (rf-QPC). The rf-QPC is fully characterized at 4 K and milli-Kelvin temperatures and found to have a bandwidth…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 M. C. Cassidy , A. S. Dzurak , R. G. Clark , K. D. Petersson , I. Farrer , D. A. Ritchie , C. G. Smith

We report on the effects of a global top gate on low-frequency noise in Schottky gate-defined quantum point contacts (QPCs) and quantum dots (QDs) in a modulation-doped Si/SiGe heterostructure. For a relatively large top gate voltage, the…

Mesoscale and Nanoscale Physics · Physics 2013-04-02 K. Takeda , T. Obata , Y. Fukuoka , W. M. Akhtar , J. Kamioka , T. Kodera , S. Oda , S. Tarucha

Nanopores made with low dimensional semiconducting materials, such as carbon nanotubes and graphene slit pores, are used in supercapacitors. In theories and simulations of their operation, it is often assumed that such pores screen ion-ion…

Materials Science · Physics 2017-01-24 Alpha A. Lee , Dominic Vella , Alain Goriely

We have measured the shot noise in a quantum point contact (QPC) fabricated by using InGaAs/InGaAsP heterostructure, whose conductance can be electrically tuned by the gate voltages. The reduced shot noise is observed when the QPC…

Mesoscale and Nanoscale Physics · Physics 2015-06-05 Yoshitaka Nishihara , Shuji Nakamura , Kensuke Kobayashi , Teruo Ono , Makoto Kohda , Junsaku Nitta

A Quantum Point Contact (QPC) causes a one-dimensional constriction on the spatial potential landscape of a two-dimensional electron system. By tuning the voltage applied on a QPC at low temperatures the resulting regular step-like electron…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 E. Schubert , J. Heyder , F. Bauer , W. Stumpf , W. Wegscheider , J. v. Delft , S. Ludwig , A. Högele

Gate-defined quantum dots (QDs) have appealing attributes as a quantum computing platform. However, near-term devices possess a range of possible imperfections that need to be accounted for during the tuning and operation of QD devices. One…

Mesoscale and Nanoscale Physics · Physics 2023-05-26 Joshua Ziegler , Florian Luthi , Mick Ramsey , Felix Borjans , Guoji Zheng , Justyna P. Zwolak

We propose a superconducting circuit architecture suitable for digital-analog quantum computing (DAQC) based on an enhanced NISQ family of nearest-neighbor interactions. DAQC makes a smart use of digital steps (single qubit rotations) and…

Quantum Physics · Physics 2022-05-17 J. Yu , J. C. Retamal , M. Sanz , E. Solano , F. Albarrán-Arriagada

The superconducting ground state in many two-dimensional materials can be created or destroyed through quantum phase transitions (QPTs) controlled by non-thermal parameters such as carrier density or magnetic field. While various mechanisms…

Superconductivity · Physics 2025-06-04 Andrey Rogachev , Samuel Feldman , Kevin Davenport

We demonstrate a robust quantum control framework that enables high-fidelity gate operations in semiconductor spin qubit systems with always-on couplings. Always-on interactions between qubits pose a fundamental challenge for quantum…

Quantum Physics · Physics 2025-03-18 Yong-Ju Hai , Shihang Zhang , Haoyu Guan , Peihao Huang , Yu He , Xiu-Hao Deng

High-fidelity gate operations are essential to the realization of a fault-tolerant quantum computer. In addition, the physical resources required to implement gates must scale efficiently with system size. A longstanding goal of the…