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We demonstrate that the performance of quantum error correction can be improved with noise-aware decoders that are calibrated to the likelihood of physical error configurations in a device. We show that noise-aware decoding increases the…

Quantum Physics · Physics 2025-04-02 Evan T. Hockings , Andrew C. Doherty , Robin Harper

High error rates and limited fidelity of quantum gates in near-term quantum devices are the central obstacles to successful execution of the Quantum Approximate Optimization Algorithm (QAOA). In this paper we introduce an…

Quantum Physics · Physics 2022-06-16 Ruslan Shaydulin , Alexey Galda

In quantum information processing, it is vital to protect the coherence of qubits in noisy environments. Dynamical decoupling (DD), which applies a sequence of flips on qubits and averages the qubit-environment coupling to zero, is a…

Quantum Physics · Physics 2011-01-12 Wen Yang , Zhen-Yu Wang , Ren-Bao Liu

Optimization is often cited as a promising application of quantum computers. However, the low degree of provable quantum speedups has led prior rigorous end-to-end resource analyses to conclude that a quantum computer is unlikely to surpass…

We investigate the possibility to achieve high-fidelity universal two-qubit gates by supplementing optimal tuning of individual qubits with dynamical decoupling (DD) of local 1/f noise. We consider simultaneous local pulse sequences applied…

Quantum Physics · Physics 2016-08-24 A. D'Arrigo , G. Falci , E. Paladino

This paper proposes an algorithm for synthesis of clock-follow-data designs that provides robustness against timing violations for RSFQ circuits while maintaining high performance and minimizing area costs. Since superconducting logic gates…

Emerging Technologies · Computer Science 2024-09-10 Robert S. Aviles , Phalgun G K , Peter A. Beerel

Variational quantum algorithms are believed to be promising for solving computationally hard problems and are often comprised of repeated layers of quantum gates. An example thereof is the quantum approximate optimization algorithm (QAOA),…

We study the possibility to stabilize unstable steady states and unstable periodic orbits in chaotic fractional-order dynamical systems by the time-delayed feedback method. By performing a linear stability analysis, we establish the…

General Physics · Physics 2011-07-07 Aleksandar Gjurchinovski , Trifce Sandev , Viktor Urumov

Minimizing phase and other errors in experimental quantum gates allows higher fidelity quantum processing. To quantify and correct for phase errors in particular, we have developed a new experimental metrology --- amplified phase error…

Quantum annealing (QA) and Quantum Alternating Operator Ansatz (QAOA) are both heuristic quantum algorithms intended for sampling optimal solutions of combinatorial optimization problems. In this article we implement a rigorous direct…

Quantum Physics · Physics 2023-08-31 Elijah Pelofske , Andreas Bärtschi , Stephan Eidenbenz

We present a systematic study of the phase-coherent dynamics of a superconducting three-Josephson-junction flux qubit. The qubit state is detected with the integrated-pulse method, which is a variant of the pulsed switching DC SQUID method.…

Superconductivity · Physics 2008-09-19 F. Deppe , M. Mariantoni , E. P. Menzel , S. Saito , K. Kakuyanagi , H. Tanaka , T. Meno , K. Semba , H. Takayanagi , R. Gross

Classical simulation of quantum circuits remains indispensable for algorithm development, hardware validation, and error analysis in the noisy intermediate-scale quantum (NISQ) era. However, state-vector simulation faces exponential memory…

We develop a quantum filter diagonalization method (QFD) that lies somewhere between the variational quantum eigensolver (VQE) and the phase estimation algorithm (PEA) in terms of required quantum circuit resources and conceptual…

Quantum Physics · Physics 2019-09-20 Robert M. Parrish , Peter L. McMahon

We introduce a novel hybrid quantum-classical variational optimization method for unconstrained binary combinatorial optimization problems on gate-model quantum computers, integrating a custom variational ansatz, staged feedback-based dual…

The Quantum Alternating Operator Ansatz (QAOA) represents a branch of quantum algorithms for solving combinatorial optimization problems. A specific variant, the Grover-Mixer Quantum Alternating Operator Ansatz (GM-QAOA), ensures uniform…

Quantum Physics · Physics 2024-05-27 Ningyi Xie , Jiahua Xu , Tiejin Chen , Xinwei Lee , Yoshiyuki Saito , Nobuyoshi Asai , Dongsheng Cai

This paper studies the linear quadratic regulation (LQR) problem of unknown discrete-time systems via dynamic output feedback learning control. In contrast to the state feedback, the optimality of the dynamic output feedback control for…

Systems and Control · Electrical Eng. & Systems 2025-05-29 Kedi Xie , Martin Guay , Shimin Wang , Fang Deng , Maobin Lu

Communication performance and channel estimation accuracy in MIMO systems are known to be limited by hardware impairments. Specifically, the presence of phase impairments, such as phase noise, makes real-time coherent transmission a…

Signal Processing · Electrical Eng. & Systems 2026-05-22 Carl Collmann , Ahmad Nimr , Gerhard Fettweis

Noisy Intermediate-Scale Quantum (NISQ) devices lack error correction, limiting scalability for quantum algorithms. In this context, digital-analog quantum computing (DAQC) offers a more resilient alternative quantum computing paradigm that…

Quantum Physics · Physics 2024-10-11 Paula García-Molina , Ana Martin , Mikel Garcia de Andoin , Mikel Sanz

A fault-tolerant quantum computer must decode and correct errors faster than they appear. The faster errors can be corrected, the more time the computer can do useful work. The Union-Find (UF) decoder is promising with an average time…

Quantum Physics · Physics 2023-05-16 Namitha Liyanage , Yue Wu , Alexander Deters , Lin Zhong

Systematic pulse-area errors limit the fidelity of quantum control across many qubit platforms. We introduce twinned dynamical decoupling (TDD), an analytic family of sequences $T2n$ in which a pulse sequence is paired with its…

Quantum Physics · Physics 2026-05-25 Nayden P. Nedev , Nikolay V. Vitanov