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We propose the generalized controlled X (GCX) gate as the two-qudit elementary gate, and based on Cartan decomposition, we also give the one-qudit elementary gates. Then we discuss the physical implementation of these elementary gates and…

Quantum Physics · Physics 2015-06-12 Yao-Min Di , Hai-Rui Wei

Gate-based quantum computers typically encode and process information in two-dimensional units called qubits. Using $d$-dimensional qudits instead may offer intrinsic advantages, including more efficient circuit synthesis, problem-tailored…

We demonstrate a hardware-agnostic protocol for realizing fast, high-fidelity gates through dynamical decoupling (DD) pulse sequences applied to a central qubit coupled to target qubits. The target qubits are controlled by leveraging their…

Quantum Physics · Physics 2026-05-06 Lucas Tsunaki , Michael Dotan , Kseniia Volkova , Boris Naydenov

We exploit hyperfine interactions in a single Mn-ion confined in a quantum dot (QD) to create a qudit, i.e. a multi-level quantum-bit system, with well defined, addressable and robust set of spin states for the realization of universal…

Mesoscale and Nanoscale Physics · Physics 2019-09-18 Fabrizio Moro , Alistair J. Fielding , Lyudmila Turyanska , Amalia Patanè

We present a novel continuous dynamical decoupling scheme for the construction of a robust qubit in a three-level system. By means of a clock transition adjustment, we first show how robustness to environmental noise is achieved, while…

Quantum computers must be able to function in the presence of decoherence. The simplest strategy for decoherence reduction is dynamical decoupling (DD), which requires no encoding overhead and works by converting quantum gates into…

Quantum Physics · Physics 2018-12-05 Bibek Pokharel , Namit Anand , Benjamin Fortman , Daniel Lidar

The inevitable dissipative interaction of an entangled quantum system with its environment causes degradation in quantum correlations present in the system. This can lead to a finite-time disappearance of entanglement, which is known as…

Quantum Physics · Physics 2022-07-22 Ashutosh Singh , Urbasi Sinha

The conditional displacement (CD) gate between an oscillator and a discrete-variable auxiliary qubit plays a key role in quantum information processing tasks, such as enabling universal control of the oscillator and longitudinal readout of…

Quantum Physics · Physics 2025-06-03 Guo Zheng , Simon Lieu , Emma L. Rosenfeld , Kyungjoo Noh , Connor T. Hann

We study the dissipative dynamics of a qubit that is afflicted by classical random telegraph noise and it is subject to dynamical decoupling. We derive exact formulas for the qubit dynamics at arbitrary working points in the limit of…

Mesoscale and Nanoscale Physics · Physics 2015-06-25 Joakim Bergli , Lara Faoro

We present a comprehensive and self-contained framework for the efficient classical simulation of Clifford circuits acting on $d$-dimensional qudits, including realistic Pauli/Weyl noise via stochastic simulation. Our approach uses the…

Quantum Physics · Physics 2026-03-26 Nina Brandl , Mykyta Cherniak , Johannes Kofler , Richard Kueng

A central task towards building a practical quantum computer is to protect individual qubits from decoherence while retaining the ability to perform high-fidelity entangling gates involving arbitrary two qubits. Here we propose and…

Superconducting circuit quantum electrodynamical (cQED) platforms present a persistent modeling challenge: the intrinsic nonlinearity of the Josephson potential couples to a dissipative electromagnetic environment in ways that resist both…

Quantum Physics · Physics 2026-05-14 M. Gabriela Boada G. , Nicolas Dirnegger , Andrea Delgado , Prineha Narang

We generalize an efficient decomposition method for diagonal operators by Welch et al. to qudit systems. The phase-context aware method focusses on cascaded entanglers whose decomposition into multi-controlled INC-gates can be optimized by…

Quantum Physics · Physics 2016-06-01 Kerstin Beer , Friederike Anna Dziemba

Couplings between qubits, while essential for generating multi-qubit entanglement, can induce crosstalk errors that significantly degrade single-qubit gate fidelity. In this paper, we present a novel non-perturbative analytical framework…

Quantum Physics · Physics 2025-03-18 Junkai Zeng , Lin Chen , Xiu-Hao Deng

Realistic quantum computing is subjected to noise. A most important frontier in research of quantum computing is to implement noise-resilient quantum control over qubits. Dynamical decoupling can protect coherence of qubits. Here we…

Quantum Physics · Physics 2013-10-16 Gang-Qin Liu , Hoi Chun Po , Jiangfeng Du , Ren-Bao Liu , Xin-Yu Pan

Fault-tolerant quantum computation requires low physical-qubit gate errors. Many approaches exist to reduce gate errors, including both hardware- and control-optimization strategies. Dynamically corrected gates are designed to cancel…

Quantum Physics · Physics 2024-12-13 Habitamu Y. Walelign , Xinxin Cai , Bikun Li , Edwin Barnes , John M. Nichol

Overcoming the influence of noise and imperfections in quantum devices is one of the main challenges for viable quantum applications. In this article, we present different protocols, which we denote as "superposed quantum error mitigation",…

Prior work has shown that there exists a relation problem which can be solved with certainty by a constant-depth quantum circuit composed of geometrically local gates in two dimensions, but cannot be solved with high probability by any…

Quantum Physics · Physics 2020-07-14 Sergey Bravyi , David Gosset , Robert Koenig , Marco Tomamichel

Quantum computing with qudits, quantum systems with $d > 2$ levels, offers a powerful extension beyond qubits, expanding the computational possibilities of quantum systems, allowing the simplification of the implementation of several…

Quantum Physics · Physics 2024-10-10 Francesco Pudda , Mario Chizzini , Luca Crippa

We investigate the amount of noise required to turn a universal quantum gate set into one that can be efficiently modelled classically. This question is useful for providing upper bounds on fault tolerant thresholds, and for understanding…

Quantum Physics · Physics 2007-05-23 S. Virmani , Susana F. Huelga , Martin B. Plenio