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Quantum chemistry is envisioned as an early and disruptive application for quantum computers. Yet, closer scrutiny of the proposed algorithms shows that there are considerable difficulties along the way. Here, we propose two criteria for…

Quantum Physics · Physics 2026-04-09 Thibaud Louvet , Thomas Ayral , Xavier Waintal

Access to quantum computing is steadily increasing each year as the speed advantage of quantum computers solidifies with the growing number of usable qubits. However, the inherent noise encountered when running these systems can lead to…

Quantum Physics · Physics 2024-09-24 Jon Gardeazabal-Gutierrez , Erik B. Terres-Escudero , Pablo García Bringas

Constructing high-fidelity control fields that are robust to control, system, and/or surrounding environment uncertainties is a crucial objective for quantum information processing. Using the two-state Landau-Zener model for illustrative…

Quantum Physics · Physics 2012-05-23 Matthew D. Grace , Jason Dominy , Wayne M. Witzel , Malcolm S. Carroll

A method is presented in which the ground-state subspace is projected out of a Hamiltonian representation. As a result of this projection, an effective Hamiltonian is constructed where its ground-state coincides with an excited-state of the…

Quantum Physics · Physics 2023-08-14 P. Jouzdani , S. Bringuier , M. Kostuk

We study the impact of static disorder on a globally-controlled superconducting quantum computing architecture based on a quasi-two-dimensional ladder geometry [R. Menta et al., Phys. Rev. Research 7, L012065 (2025)]. Specifically, we…

Achieving fast and high-fidelity qubit operations is crucial for unlocking the potential of quantum computers. In particular, reaching low gate errors in two-qubit gates has been a long-standing challenge in the field of superconducting…

We present a continuous-time, neural-network-based approach to optimal control in quantum systems, with a focus on pulse engineering for quantum gates. Leveraging the framework of neural ordinary differential equations, we construct control…

As a hybrid quantum-classical algorithm, the variational quantum eigensolver is widely applied in quantum chemistry simulations, especially in computing the electronic structure of complex molecular systems. However, on existing noisy…

Quantum Physics · Physics 2025-01-28 Wanqi Sun , Jungang Xu , Chenghua Duan

Quantum computers can be used to address molecular structure, materials science and condensed matter physics problems, which currently stretch the limits of existing high-performance computing resources. Finding exact numerical solutions to…

Quantum computers have the potential to outperform classical computers in a range of computational tasks, such as prime factorisation and unstructured searching. However, real-world quantum computers are subject to noise. Quantifying noise…

Quantum Physics · Physics 2023-03-01 Conrad Strydom , Mark Tame

We experimentally demonstrate the coherent oscillations of a tunable superconducting flux qubit by manipulating its energy potential with a nanosecond-long pulse of magnetic flux. The occupation probabilities of two persistent current…

We develop schemes for designing pulses that implement fast and precise entangling quantum gates in superconducting qubit systems despite the presence of nearby harmful transitions. Our approach is based on purposely involving the nearest…

Mesoscale and Nanoscale Physics · Physics 2015-04-13 Sophia E. Economou , Edwin Barnes

This work studies pulse based variational quantum algorithms (VQAs), which are designed to determine the ground state of a quantum mechanical system by combining classical and quantum hardware. In contrast to more standard gate based…

Quantum Physics · Physics 2023-02-01 Robert de Keijzer , Oliver Tse , Servaas Kokkelmans

A new method of preparing the pseudo-pure state of a spin system for quantum computation in liquid nuclear magnetic resonance (NMR) was put forward and demonstrated experimentally. Applying appropriately connected line-selective pulses…

Quantum Physics · Physics 2019-08-17 Xinhua Peng , Xiwen Zhu , Ximing Fang , Mang Feng , Keli Gao , Xiaodong Yang , Maili Liu

Quantum computer emulators model the behavior and error rates of specific quantum processors. Without accurate noise models in these emulators, it is challenging for users to optimize and debug executable quantum programs prior to running…

Quantum Physics · Physics 2026-05-20 Matthew Ho , Jun Yong Khoo , Adrian M. Mak , Stefano Carrazza

Quantum computing requires the optimization of control pulses to achieve high-fidelity quantum gates. We propose a machine learning-based protocol to address the challenges of evaluating gradients and modeling complex system dynamics. By…

Quantum Physics · Physics 2026-01-27 Paul Surrey , Julian D. Teske , Tobias Hangleiter , Hendrik Bluhm , Pascal Cerfontaine

Control electronics for superconducting quantum processors have strict requirements for accurate command of the sensitive quantum states of their qubits. Hinging on the purity of ultra-phase-stable oscillators to upconvert very-low-noise…

Quantum annealers are an alternative approach to quantum computing which make use of the adiabatic theorem to efficiently find the ground state of a physically realizable Hamiltonian. Such devices are currently commercially available and…

Quantum Physics · Physics 2021-02-24 Justin Copenhaver , Adam Wasserman , Birgit Wehefritz-Kaufmann

We propose a general-purpose quantum algorithm for preparing ground states of quantum Hamiltonians from a given trial state. The algorithm is based on techniques recently developed in the context of solving the quantum linear systems…

Quantum Physics · Physics 2018-02-05 Yimin Ge , Jordi Tura , J. Ignacio Cirac

We address the issue of improving the quality of the joint remote preparation of an arbitrary two-qubit in case four qubits of the quantum channel which consists of a GHZ state and a GHZ-like one are subjected to noises. Two controlling…

Quantum Physics · Physics 2017-03-21 Thanh Dat Le , Van Hop Nguyen