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Scaling up quantum computing hardware is hindered by the narrow operating margins of current quantum components. Here, we introduce a composite qubit and gate scheme that achieves wide margins by use of transistor-like nonlinearities to…

Quantum Physics · Physics 2022-02-23 Ryan J. Epstein

Performing qubit gate operations as quickly as possible can be important to minimize the effects of decoherence. For resonant gates, this requires applying a strong ac drive. However, strong driving can present control challenges by causing…

Mesoscale and Nanoscale Physics · Physics 2017-07-07 Yuan-Chi Yang , S. N. Coppersmith , Mark Friesen

Recently, several groups have demonstrated two-qubit gate fidelities in semiconductor spin qubit systems above 99%. Achieving this regime of fault-tolerant compatible high fidelities is nontrivial and requires exquisite stability and…

A simulation methodology for ultra-scaled InAs quantum well field effect transistors (QWFETs) is presented and used to provide design guidelines and a path to improve device performance. A multiscale modeling approach is adopted, where…

Mesoscale and Nanoscale Physics · Physics 2011-10-28 Neerav Kharche , Gerhard Klimeck , Dae-Hyun Kim , Jesús. A. del Alamo , Mathieu Luisier

The implementation of a quantum computer requires a qubit-specific measurement capability to read-out the final state of a quantum system. The model of spin dependent tunneling followed by charge readout has been highly successful in…

Mesoscale and Nanoscale Physics · Physics 2015-04-07 M. F. Gonzalez-Zalba , A. J. Ferguson , S. Barraud , A. C. Betz

In order to enable semiconductor-based quantum computing with many qubits, issues like residual interqubit coupling and constraints from scalable control hardware need to be tackled to retain the high gate fidelities demonstrated in current…

Quantum Physics · Physics 2021-01-25 Pascal Cerfontaine , René Otten , M. A. Wolfe , Patrick Bethke , Hendrik Bluhm

We analyze a scheme for quantum computation where quantum gates can be continuously changed from standard dynamic gates to purely geometric ones. These gates are enacted by controlling a set of parameters that are subject to unwanted…

Quantum Physics · Physics 2009-11-10 Shi-Liang Zhu , Paolo Zanardi

Noisy Intermediate-Scale Quantum (NISQ) machines are not fault-tolerant, operate few qubits (currently, less than hundred), but are capable of executing interesting computations. Above the quantum supremacy threshold (approx. 60 qubits),…

Quantum Physics · Physics 2019-01-31 Alexandru Paler

As systems for quantum computing keep growing in size and number of qubits, challenges in scaling the control capabilities are becoming increasingly relevant. Efficient schemes to simultaneously mediate coherent interactions between…

The increasing number of control lines connecting quantum processors to external electronics constitutes a major bottleneck in the realization of large-scale quantum computers. Frequency-division multiplexing is expected to enable control…

Quantum Physics · Physics 2026-03-12 Haruki Mitarai , Yukihiro Tadokoro , Hiroya Tanaka

A major challenge in the field of quantum computing is the construction of scalable qubit coupling architectures. Here, we demonstrate a novel tuneable coupling circuit that allows superconducting qubits to be coupled over long distances.…

The scaling barriers currently faced by both quantum networking and quantum computing technologies ultimately amount to the same core challenge of distributing high-quality entanglement at scale. In this Perspective, a novel quantum…

Quantum Physics · Physics 2023-11-09 Stephanie Simmons

Transpilation, particularly noise-aware optimization, is widely regarded as essential for maximizing the performance of quantum circuits on superconducting quantum computers. The common wisdom is that each circuit should be transpiled using…

Quantum Physics · Physics 2025-10-03 Yuqian Huo , Jinbiao Wei , Christopher Kverne , Mayur Akewar , Janki Bhimani , Tirthak Patel

Electron shuttling is emerging as a key enabler of scalable silicon spin-qubit quantum computing, but fidelities are limited by atomistic disorder. We introduce a multiscale simulation framework combining time-dependent finite-element…

Modular quantum computing provides a scalable approach to overcome the limitations of monolithic quantum architectures by interconnecting multiple Quantum Processing Units (QPUs) through a quantum network. In this work, we explore and…

Quantum Physics · Physics 2025-04-30 Shahrooz Pouryousef , Reza Nejabati , Don Towsley , Ramana Kompella , Eneet Kaur

Dynamic control via optimized, piecewise-constant pulses is a common paradigm for open-loop control to implement quantum gates. While numerous methods exist for the synthesis of such controls, there are many open questions regarding the…

Quantum Physics · Physics 2024-06-25 S. P. O'Neil , C. A. Weidner , E. A. Jonckheere , F. C. Langbein , S. G. Schirmer

Microwave cavities coupled to superconducting qubits have been demonstrated to be a promising platform for quantum information processing. A major challenge in this setup is to realize universal control over the cavity. A promising approach…

Quantum Physics · Physics 2020-04-30 Thomas Fösel , Stefan Krastanov , Florian Marquardt , Liang Jiang

An average gate fidelity is a standard performance metric to quantify deviation between an ideal unitary gate transformation and its realistic experimental implementation. The average is taken with respect to states uniformly distributed…

Quantum Physics · Physics 2020-11-13 Filip Wudarski , Jeffrey Marshall , Andre Petukhov , Eleanor Rieffel

Designing efficient quantum circuits is a central bottleneck to exploring the potential of quantum computing, particularly for noisy intermediate-scale quantum (NISQ) devices, where circuit efficiency and resilience to errors are paramount.…

Quantum Physics · Physics 2025-10-31 Jun Dai , Michael Rizvi-Martel , Guillaume Rabusseau

We characterize the pre-softmax attention matrix $\mathbf{QK^\top}$ in transformers as an associative memory matrix encoding pairwise associations between input features. By decomposing this matrix into its symmetric and skew-symmetric…

Machine Learning · Computer Science 2026-05-28 Hyunmin Cho , Woo Kyoung Han , Kyong Hwan Jin