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This paper presents novel methods for optimizing multi-controlled quantum gates, which naturally arise in high-level quantum programming. Our primary approach involves rewriting $U(2)$ gates as $SU(2)$ gates, utilizing one auxiliary qubit…

Quantum Physics · Physics 2025-03-12 Evandro C. R. Rosa , Eduardo I. Duzzioni , Rafael de Santiago

Superconducting fluxonium qubits provide a promising alternative to transmons on the path toward large-scale superconductor-based quantum computing due to their better coherence and larger anharmonicity. A major challenge for multi-qubit…

We analyze the cross-resonance effect for fluxonium circuits and investigate a two-qubit gate scheme based on selective darkening of a transition. In this approach, two microwave pulses at the frequency of the target qubit are applied…

Quantum Physics · Physics 2022-09-27 Konstantin N. Nesterov , Chen Wang , Vladimir E. Manucharyan , Maxim G. Vavilov

We employ quantum optimal control theory to realize quantum gates for two protected superconducting circuits: the heavy-fluxonium qubit and the 0-$\pi$ qubit. Utilizing automatic differentiation facilitates the simultaneous inclusion of…

While real quantum devices have been increasingly used to conduct research focused on achieving quantum advantage or quantum utility in recent years, executing deep quantum circuits or performing quantum machine learning with large-scale…

Quantum Physics · Physics 2026-04-06 Yoshiaki Kawase

Spins associated to solid-state colour centers are a promising platform for investigating quantum computation and quantum networks. Recent experiments have demonstrated multi-qubit quantum processors, optical interconnects, and basic…

Simulating the properties of many-body fermionic systems is an outstanding computational challenge relevant to material science, quantum chemistry, and particle physics. Although qubit-based quantum computers can potentially tackle this…

We present QEst, a procedure to systematically generate approximations for quantum circuits to reduce their CNOT gate count. Our approach employs circuit partitioning for scalability with procedures to 1) reduce circuit length using…

Quantum Physics · Physics 2021-08-31 Tirthak Patel , Ed Younis , Costin Iancu , Wibe de Jong , Devesh Tiwari

The quantum approximate optimization algorithm (QAOA) is a promising quantum-classical hybrid technique to solve combinatorial optimization problems in near-term gate-based noisy quantum devices. In QAOA, the objective is a function of the…

Quantum Physics · Physics 2019-07-24 Mahabubul Alam , Abdullah Ash-Saki , Swaroop Ghosh

Near term quantum computers with a high quantity (around 50) and quality (around 0.995 fidelity for two-qubit gates) of qubits will approximately sample from certain probability distributions beyond the capabilities of known classical…

Quantum Physics · Physics 2018-01-23 Sergio Boixo , Sergei V. Isakov , Vadim N. Smelyanskiy , Hartmut Neven

Quantum computing promises significant speed-up for certain types of computational problems. However, robust implementations of semiconducting qubits must overcome the effects of charge noise that currently limit coherence during gate…

Quantum Physics · Physics 2017-07-12 Mark Friesen , Joydip Ghosh , M. A. Eriksson , S. N. Coppersmith

We derive a set of composite pulse sequences that generates CNOT gates and correct all systematic errors within the logical subspace to arbitrary order. These sequences are applicable for any two-qubit interaction Hamiltonian, and make no…

Quantum Physics · Physics 2017-04-19 Fernando A. Calderon-Vargas , J. P. Kestner

Implementing high-fidelity controlled two-qubit gates in dipole-dipole interacting systems, such as rare-earth-ion crystals, in hindered by spectral inhomogeneity and weak coupling. Existing method often rely on detuned pulses, making them…

Quantum Physics · Physics 2026-04-09 Licheng Lin , Jize Han , Peng Zhu , Ziyu Wang , Ying Yan , Jie Lu , Zhiguo Huang

The superconducting fluxonium circuit is an RF-SQUID-type flux qubit that uses a large inductance built from an array of Josephson junctions or a high kinetic inductance material. This inductance suppresses charge sensitivity exponentially…

Quantum Physics · Physics 2022-04-01 I. N. Moskalenko , I. S. Besedin , I. A. Simakov , A. V. Ustinov

In this work we propose a novel numerical approach to decompose general quantum programs in terms of single- and two-qubit quantum gates with a $CNOT$ gate count very close to the current theoretical lower bounds. In particular, it turns…

Quantum Physics · Physics 2022-05-18 Péter Rakyta , Zoltán Zimborás

We present two efficient methods for implementing the Fredkin gate with atoms separately trapped in an array of three high-$Q$ coupled cavities. The first proposal is based on the resonant dynamics, which leads to a fast resonant…

Quantum Physics · Physics 2015-06-17 Xiao-Qiang Shao , Tai-Yu Zheng , Xun-Li Feng , C. H. Oh , Shou Zhang

In this paper, we propose a novel method using Deep Neural Networks (DNNs) to optimise the parameters of pulse waveforms used for manipulating qubit states, resulting in high fidelity implementation of qubit gates. High fidelity quantum…

Quantum Physics · Physics 2024-08-06 Zachary Fillingham , Hossein Nevisi , Shirin Dora

This paper investigates quantum error correction schemes for fully-correlated noise channels on an $n$-qubit system, where error operators take the form $W^{\otimes n}$, with $W$ being an arbitrary $2\times 2$ unitary operator. In previous…

Quantum Physics · Physics 2023-03-30 Chi-Kwong Li , Yuqiao Li , Diane Christine Pelejo , Sage Stanish

Recently an algorithm has been constructed that shows the binary icosahedral group $\2I$ together with a $T$-like gate forms the most efficient single-qubit universal gate set. To carry out the algorithm fault tolerantly requires a code…

Quantum Physics · Physics 2024-02-05 Eric Kubischta , Ian Teixeira

High-fidelity two-qubit entangling gates play an important role in many quantum information processing tasks and are a necessary building block for constructing a universal quantum computer. Such high-fidelity gates have been demonstrated…

Quantum Physics · Physics 2018-11-07 Yotam Shapira , Ravid Shaniv , Tom Manovitz , Nitzan Akerman , Roee Ozeri