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We introduce two methods for speeding up adiabatic quantum computations by increasing the energy between the ground and first excited states. Our methods are even more general. They can be used to shift a Hamiltonian's density of states…

Quantum Physics · Physics 2015-10-27 Richard Tanburn , Oliver Lunt , Nikesh S. Dattani

Solving optimisation problems encoded in the ground state of classical-spin systems is a focus area for quantum computing devices, providing upper bounds to the unknown solution. To certify these bounds, they are compared to those obtained…

Quantum Physics · Physics 2020-11-04 Flavio Baccari , Christian Gogolin , Peter Wittek , Antonio Acín

Drawing inspiration from the Lyapunov control technique for quantum systems, feedback-based quantum algorithms have been proposed for calculating the ground states of Hamiltonians. In this work, we consider extending these algorithms to…

Quantum Physics · Physics 2024-07-23 Salahuddin Abdul Rahman , Özkan Karabacak , Rafal Wisniewski

In this work, we compare the performance of the Quantum Approximate Optimization Algorithm (QAOA) with state-of-the-art classical solvers such as Gurobi and MQLib to solve the combinatorial optimization problem MaxCut on 3-regular graphs.…

Quantum Physics · Physics 2024-05-01 Danylo Lykov , Jonathan Wurtz , Cody Poole , Mark Saffman , Tom Noel , Yuri Alexeev

In this paper, we aim to expand the understanding of the relationship between the composition of the Hamiltonian in the Quantum Approximate Optimization Algorithm (QAOA) and the corresponding cost landscape characteristics. QAOA is a…

Quantum Physics · Physics 2024-05-21 Michał Stęchły , Lanruo Gao , Boniface Yogendran , Enrico Fontana , Manuel Rudolph

We present an efficient quantum algorithm for preparing a pure state on a quantum computer, where the quantum state corresponds to that of a molecular system with a given number $m$ of electrons occupying a given number $n$ of spin…

Quantum Physics · Physics 2009-05-01 Hefeng Wang , S. Ashhab , Franco Nori

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

A promising approach to solving hard binary optimisation problems is quantum adiabatic annealing (QA) in a transverse magnetic field. An instantaneous ground state --- initially a symmetric superposition of all possible assignments of $N$…

Quantum Physics · Physics 2016-05-18 Sergey Knysh

Models of interacting many-body quantum systems that may realize new exotic phases of matter, notably quantum spin liquids, are challenging to study using even state-of-the-art classical methods such as tensor network simulations. Quantum…

Quantum Physics · Physics 2025-04-16 Aaron Szasz , Ed Younis , Wibe Albert de Jong

The quantum alternating operator ansatz (QAOA) is a prominent example of variational quantum algorithms. We propose a generalized QAOA called CD-QAOA, which is inspired by the counterdiabatic driving procedure, designed for quantum…

Quantum Physics · Physics 2021-10-05 Jiahao Yao , Lin Lin , Marin Bukov

The Quantum Approximate Optimisation Algorithm (QAOA) is a widely studied quantum-classical iterative heuristic for combinatorial optimisation. While QAOA targets problems in complexity class NP, the classical optimisation procedure…

Quantum Physics · Physics 2025-11-12 Tom Krüger , Wolfgang Mauerer

This paper presents an enhancement to Grover's search algorithm for instances where the number of items (or the size of the search problem) $N$ is not a power of 2. By employing an efficient algorithm for the preparation of uniform quantum…

Quantum Physics · Physics 2025-06-06 Alok Shukla , Prakash Vedula

The recently proposed QAOA-GPT framework demonstrated that generative pre-trained transformers can learn mappings between problem graphs and optimized quantum circuits for the Quantum Approximate Optimization Algorithm (QAOA). In this work,…

Quantum Physics · Physics 2025-11-11 Leanto Sunny , Abhinav Rijal , George Siopsis

The Rodeo Algorithm is a quantum computing method for computing the energy spectrum of a Hamiltonian and preparing its energy eigenstates. We discuss how to improve the performance of the rodeo algorithm for each of these two applications.…

Quantum Physics · Physics 2026-02-06 Matthew Patkowski , Onat Ayyildiz , Katherine Hunt , Nathan Jansen , Dean Lee

Solving the Anderson impurity model typically involves a two-step process, where one first calculates the ground state of the Hamiltonian, and then computes its dynamical properties to obtain the Green's function. Here we propose a hybrid…

We study the fair sampling properties of hybrid quantum-classical Markov chain Monte Carlo (MCMC) algorithms for combinatorial optimization problems with degenerate ground states. While quantum optimization heuristics such as quantum…

Quantum Physics · Physics 2025-12-17 Yuichiro Nakano , Keisuke Fujii

We present calculations of the ground and excited state energies of spin defects in solids carried out on a quantum computer, using a hybrid classical/quantum protocol. We focus on the negatively charged nitrogen vacancy center in diamond…

Quantum Physics · Physics 2025-07-01 Benchen Huang , Marco Govoni , Giulia Galli

Loading classical data into quantum computers represents an essential stage in many relevant quantum algorithms, especially in the field of quantum machine learning. Therefore, the inefficiency of this loading process means a major…

Quantum Physics · Physics 2023-09-25 Gabriel Marin-Sanchez , Javier Gonzalez-Conde , Mikel Sanz

Quantum computation using continuous-time evolution under a natural hardware Hamiltonian is a promising near- and mid-term direction toward powerful quantum computing hardware. We investigate the performance of continuous-time quantum walks…

Quantum Physics · Physics 2019-12-24 Adam Callison , Nicholas Chancellor , Florian Mintert , Viv Kendon

We exploit Grover operator of database search algorithm for weight decision algorithm. In this research, weight decision problem is to find an exact weight w from given two weights as w1 and w2 where w1+w2=1 and 0<w1<w2<1. Firstly, if a…