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The variational quantum eigensolver has been proposed as a low-depth quantum circuit that can be employed to examine strongly correlated systems on today's noisy intermediate-scale quantum computers. We examine details associated with the…

Quantum Physics · Physics 2020-08-26 Luogen Xu , Joseph T. Lee , J. K. Freericks

In classical computational chemistry, the coupled-cluster ansatz is one of the most commonly used $ab~initio$ methods, which is critically limited by its non-unitary nature. The unitary modification as an ideal solution to the problem is,…

Quantum Physics · Physics 2017-03-01 Yangchao Shen , Xiang Zhang , Shuaining Zhang , Jing-Ning Zhang , Man-Hong Yung , Kihwan Kim

Quantum computers have emerged as a promising platform to simulate the strong electron correlation that is crucial to catalysis and photochemistry. However, owing to the choice of a trial wave function employed in the popular hybrid…

Chemical Physics · Physics 2023-07-17 Fabijan Pavošević , Ivano Tavernelli , Angel Rubio

We present a quantum linear response (qLR) approach within an active-space framework for computing indirect nuclear spin-spin coupling constants, a key ingredient in NMR spectra predictions. The method employs the unitary coupled cluster…

One of the fundamental conditions for one-way quantum computation (1WQC) is the ability to make sequential measurements on isolated qubits that comprise the highly entangled resource for 1WQC, the cluster state. This has been a significant…

Quantum Physics · Physics 2009-11-13 Timothy P. Friesen , David L. Feder

This paper proposes a hybrid quantum-classical algorithm to solve a fundamental power system problem called unit commitment (UC). The UC problem is decomposed into a quadratic subproblem, a quadratic unconstrained binary optimization (QUBO)…

Quantum Physics · Physics 2022-04-19 Reza Mahroo , Amin Kargarian

We present a new method for state preparation using the Unitary Vibrational Coupled-Cluster (UVCC) technique. Our approach utilizes redundancies in the Hilbert space in the direct mapping of vibrational modes into qubits. By eliminating…

Quantum Physics · Physics 2024-12-06 Michal Szczepanik , Emil Zak

We describe a compilation strategy for Variational Quantum Eigensolver (VQE) algorithms which use the Unitary Coupled Cluster (UCC) ansatz, designed to reduce circuit depth and gate count. This is achieved by partitioning Pauli exponential…

Quantum Physics · Physics 2020-08-28 Alexander Cowtan , Will Simmons , Ross Duncan

The one-way quantum computer (QCc) is a universal scheme of quantum computation consisting only of one-qubit measurements on a particular entangled multi-qubit state, the cluster state. The computational model underlying the QCc is…

Quantum Physics · Physics 2007-05-23 R. Raussendorf , H. J. Briegel

The Trotterized Unitary Coupled Cluster Single and Double (UCCSD) ansatz has recently attracted interest due to its use in Variation Quantum Eigensolver (VQE) molecular simulations on quantum computers. However, when the size of molecules…

Chemical Physics · Physics 2023-05-29 Mohammad Haidar , Marko J. Rančić , Yvon Maday , Jean-Philip Piquemal

Planning energy production is a challenging task due to its cost-sensitivity, fast-moving energy markets, uncertainties in demand, and technical constraints of power plants. Thus, more complex models of this so-called \emph{unit commitment…

Quantum Physics · Physics 2024-03-07 Pascal Halffmann , Patrick Holzer , Kai Plociennik , Michael Trebing

Circuit depth reduction is of critical importance for quantum chemistry simulations on current and near term quantum computers. This issue is tackled by introducing a chemically aware strategy for the Unitary Coupled Cluster ansatz. The…

We propose a non-iterative, post hoc correction to the unitary coupled cluster theory with single, double, and triple excitations (UCCSDT) ansatz, which considers the leading-order effects of neglected quadruple excitations. We present two…

Chemical Physics · Physics 2025-08-14 Zachary W. Windom , Luke Bertels , Daniel Claudino , Rodney J. Bartlett

Quantum chemistry simulations that accurately predict the properties of materials are among the most highly anticipated applications of quantum computing. It is widely believed that simulations running on quantum computers will allow for…

We present a four-component relativistic unitary coupled cluster method for molecules. We have used commutator-based non-perturbative approximation using the ''Bernoulli expansion'' to derive an approximation to the relativistic unitary…

Chemical Physics · Physics 2024-03-06 Kamal Majee , Tamoghna Mukhopadhyay , Malaya K. Nayak , Achintya Kumar Dutta

The exact evaluation of the molecular ground state in quantum chemistry requires an exponentially increasing computational cost. Quantum computation is a promising way to overcome the exponential problem using polynomial-time quantum…

Quantum Physics · Physics 2023-05-30 Changsu Cao , Jiaqi Hu , Wengang Zhang , Xusheng Xu , Dechin Chen , Fan Yu , Jun Li , Hanshi Hu , Dingshun Lv , Man-Hong Yung

Clustering is one of the most crucial problems in unsupervised learning, and the well-known $k$-means clustering algorithm has been shown to be implementable on a quantum computer with a significant speedup. However, many clustering…

Quantum Physics · Physics 2023-01-03 Qingyu Li , Yuhan Huang , Shan Jin , Xiaokai Hou , Xiaoting Wang

One of the commonly used chemical-inspired approaches in variational quantum computing is the unitary coupled-cluster (UCC) ansatze. Despite being a systematic way of approaching the exact limit, the number of parameters in the standard UCC…

Quantum Physics · Physics 2023-06-06 Shashank G Mehendale , Bo Peng , Niranjan Govind , Yuri Alexeev

Quantum computing (QC) has gained popularity due to its unique capabilities that are quite different from that of classical computers in terms of speed and methods of operations. This paper proposes hybrid models and methods that…

Quantum Physics · Physics 2019-11-12 Akshay Ajagekar , Travis Humble , Fengqi You

Ab initio wavefunction methods provide accurate molecular simulations but their computational scaling restricts applications to small systems. We develop a workflow combining quantum embedding to decompose a molecule into fragments with a…