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Fastness and robustness are both critical in the implementation of high-fidelity gates for quantum computation, but in practice, a trade-off has to be made between them. In this paper, we investigate the underlying robust time-optimal…

Quantum Physics · Physics 2023-09-12 Xi Cao , Jiangyu Cui , Man Hong Yung , Re-Bing Wu

Electron spins in semiconductors are promising qubits because their long coherence times enable nearly 10^9 coherent quantum gate operations. However, developing a scalable high-fidelity two-qubit gate remains challenging. Here, we…

Mesoscale and Nanoscale Physics · Physics 2016-08-16 John M. Nichol , Lucas A. Orona , Shannon P. Harvey , Saeed Fallahi , Geoffrey C. Gardner , Michael J. Manfra , Amir Yacoby

The three-spin-$1/2$ decoherence-free subsystem defines a logical qubit protected from collective noise and supports exchange-only universal gates. Such logical qubits are well-suited for implementation with electrically-defined quantum…

Quantum Physics · Physics 2019-04-26 James. R. van Meter , Emanuel Knill

Robust gate sequences are widely used to reduce the sensitivity of gate operations to experimental imperfections. Typically, the optimization minimizes the average gate error, however, recent work in quantum error correction has…

Quantum Physics · Physics 2023-10-31 Sven Jandura , Jeff D Thompson , Guido Pupillo

A new method for simulation of a binary homogeneous Markov process using a quantum computer was proposed. This new method allows using the distinguished properties of the quantum mechanical systems -- superposition, entanglement and…

Quantum Physics · Physics 2021-03-12 Petar Nikolov

We investigate the potential of bio-inspired evolutionary algorithms for designing quantum circuits with specific goals, focusing on two particular tasks. The first one is motivated by the ideas of Artificial Life that are used to reproduce…

Quantum Physics · Physics 2025-10-02 Shailendra Bhandari , Stefano Nichele , Sergiy Denysov , Pedro G. Lind

Combinatorial optimization is a promising application for near-term quantum computers, however, identifying performant algorithms suited to noisy quantum hardware remains as an important goal to potentially realizing quantum computational…

Quantum Physics · Physics 2025-04-01 Titus D. Morris , Ananth Kaushik , Martin Roetteler , Phillip C. Lotshaw

Single-qubit operations on singlet-triplet qubits in GaAs double quantum dots have not yet reached the fidelities required for fault-tolerant quantum information processing. Considering experimentally important constraints and using…

Quantum Physics · Physics 2021-01-25 Pascal Cerfontaine , Tim Botzem , David P. DiVincenzo , Hendrik Bluhm

Building a quantum computer is a daunting challenge since it requires good control but also good isolation from the environment to minimize decoherence. It is therefore important to realize quantum gates efficiently, using as few operations…

Quantum Physics · Physics 2019-10-28 T. Bækkegaard , L. B. Kristensen , N. J. S. Loft , C. K. Andersen , D. Petrosyan , N. T. Zinner

Quantum Hamiltonian Computing is a recent approach that uses quantum systems, in particular a single molecule, to perform computational tasks. Within this approach, we present explicit methods to construct logic gates using two different…

Quantum Physics · Physics 2019-06-18 Omid Faizy Namarvar , Olivier Giraud , Bertrand Georgeot , Christian Joachim

We discuss the implementation of frequency selective rotations using sequences of hard pulses and delays. These rotations are suitable for implementing single qubit gates in Nuclear Magnetic Resonance (NMR) quantum computers, but can also…

Quantum Physics · Physics 2007-05-23 Mark D. Bowdrey , Jonathan A. Jones

Engineering the Hamiltonian of a quantum system is fundamental to the design of quantum systems. Automating Hamiltonian design through gradient-based optimization can dramatically accelerate this process. However, computing the gradients of…

One of the largest obstacles to building a quantum computer is gate error, where the physical evolution of the state of a qubit or group of qubits during a gate operation does not match the intended unitary transformation. Gate error stems…

Quantum Physics · Physics 2018-02-07 Eliot Kapit

Variational hybrid quantum-classical optimization represents one of the most promising avenue to show the advantage of nowadays noisy intermediate-scale quantum computers in solving hard problems, such as finding the minimum-energy state of…

Quantum Physics · Physics 2020-11-18 Laura Gentini , Alessandro Cuccoli , Stefano Pirandola , Paola Verrucchi , Leonardo Banchi

We consider quantum computer architectures where interactions are mediated between hot qubits that are not in their mechanical ground state. Such situations occur, e.g., when not cooling ideally, or when moving ions or atoms around. We…

Quantum Physics · Physics 2024-07-26 Ferran Riera-Sàbat , Pavel Sekatski , Wolfgang Dür

We provide an analytic way to implement any arbitrary two-qubit unitary operation, given an entangling two-qubit gate together with local gates. This is shown to provide explicit construction of a universal quantum circuit that exactly…

Quantum Physics · Physics 2009-11-07 Jun Zhang , Jiri Vala , Shankar Sastry , K. Birgitta Whaley

Quantum Variational Circuits (QVCs) are often claimed as one of the most potent uses of both near term and long term quantum hardware. The standard approaches to optimizing these circuits rely on a classical system to compute the new…

Quantum Physics · Physics 2022-02-11 Owen Lockwood

Variational Quantum algorithms, especially Quantum Approximate Optimization and Variational Quantum Eigensolver (VQE) have established their potential to provide computational advantage in the realm of combinatorial optimization. However,…

Quantum Physics · Physics 2023-07-11 Dheeraj Peddireddy , Utkarsh Priyam , Vaneet Aggarwal

Quantum language models have shown competitive performance on sequential tasks, yet whether trained quantum circuits exploit genuinely quantum resources -- or merely embed classical computation in quantum hardware -- remains unknown. Prior…

Quantum Physics · Physics 2026-03-30 Nathan Roll

Optimization problems in disciplines such as machine learning are commonly solved with iterative methods. Gradient descent algorithms find local minima by moving along the direction of steepest descent while Newton's method takes into…

Quantum Physics · Physics 2018-08-20 Patrick Rebentrost , Maria Schuld , Leonard Wossnig , Francesco Petruccione , Seth Lloyd