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In this paper we develop a classical algorithm of complexity $O(K \, 2^n)$ to simulate parametrized quantum circuits (PQCs) of $n$ qubits, where $K$ is the total number of one-qubit and two-qubit control gates. The algorithm is developed by…

Quantum Physics · Physics 2024-02-01 Bibhas Adhikari , Aryan Jha

We present a polynomial-time classical algorithm for estimating expectation values of arbitrary observables on typical quantum circuits under any incoherent local noise, including non-unital or dephasing. Although previous research…

Quantum Physics · Physics 2026-04-23 Armando Angrisani , Antonio A. Mele , Manuel S. Rudolph , M. Cerezo , Zoë Holmes

Quantum computing promises transformative impacts in simulating Hamiltonian dynamics, essential for studying physical systems inaccessible by classical computing. However, existing compilation techniques for Hamiltonian simulation, in…

Pauli-based computation (PBC) is driven by a sequence of adaptively chosen, non-destructive measurements of Pauli observables. Any quantum circuit written in terms of the Clifford+$T$ gate set and having $t$ $T$ gates can be compiled into a…

Quantum Physics · Physics 2023-10-04 Filipa C. R. Peres , Ernesto F. Galvão

In this paper, we design quantum circuits for the exponential of scaled $n$-qubit Pauli strings using single-qubit rotation gates, Hadamard gate, and CNOT gates. A key result we derive is that any two Pauli-string operators composed of…

Quantum Physics · Physics 2024-11-05 Rohit Sarma Sarkar , Sabyasachi Chakraborty , Bibhas Adhikari

One of the most promising applications of quantum computers is solving partial differential equations (PDEs). By using the Schrodingerisation technique - which converts non-conservative PDEs into Schrodinger equations - the problem can be…

Quantum Physics · Physics 2025-08-01 Nikita Guseynov , Xiajie Huang , Nana Liu

We present an efficient quantum algorithm for simulating the dynamics of Markovian open quantum systems. The performance of our algorithm is similar to the previous state-of-the-art quantum algorithm, i.e., it scales linearly in evolution…

Quantum Physics · Physics 2023-07-11 Xiantao Li , Chunhao Wang

The Pauli matrices are 2-by-2 matrices that are very useful in quantum computing. They can be used as elementary gates in quantum circuits but also to decompose any matrix of $\mathbb{C}^{2^n \times 2^n}$ as a linear combination of tensor…

Quantum Physics · Physics 2024-03-19 Océane Koska , Marc Baboulin , Arnaud Gazda

Many methods solve Poisson equations by using grid techniques which discretize the problem in each dimension. Most of these algorithms are subject to the curse of dimensionality, so that they need exponential runtime. In the paper "Quantum…

Emerging Technologies · Computer Science 2020-06-17 Michael Holzmann , Harald Koestler

We construct quantum circuits which exactly encode the spectra of correlated electron models up to errors from rotation synthesis. By invoking these circuits as oracles within the recently introduced "qubitization" framework, one can use…

We propose an effective and flexible scheme for reverse engineering of a Hamiltonian by designing the evolution operators to eliminate the terms of Hamiltonian which are hard to be realized in practice. Different from transitionless quantum…

Quantum Physics · Physics 2016-08-15 Yi-Hao Kang , Ye-Hong Chen , Qi-Cheng Wu , Bi-Hua Huang , Yan Xia , Jie Song

We present an efficient quantum circuit for block encoding pairing Hamiltonian often studied in nuclear physics. Our block encoding scheme does not require mapping the creation and annihilation operators to the Pauli operators and…

Nuclear Theory · Physics 2024-02-22 Diyi Liu , Weijie Du , Lin Lin , James P. Vary , Chao Yang

We present a classical algorithm based on Pauli propagation for estimating expectation values of arbitrary observables on random unstructured quantum circuits across all circuit architectures and depths, including those with all-to-all…

Many promising quantum applications depend on the efficient quantum simulation of an exponentially large sparse Hamiltonian, a task known as sparse Hamiltonian simulation, which is fundamentally important in quantum computation. Although…

Quantum Physics · Physics 2025-09-16 Jiaqi Leng , Joseph Li , Yuxiang Peng , Xiaodi Wu

Quantum chemistry provides a target for quantum simulation of considerable scientific interest and industrial importance. The majority of algorithms to date have been based on a second-quantized representation of the electronic structure…

Quantum Physics · Physics 2013-12-17 Borzu Toloui , Peter J. Love

Computer-aided engineering techniques are indispensable in modern engineering developments. In particular, partial differential equations are commonly used to simulate the dynamics of physical phenomena, but very large systems are often…

Quantum Physics · Physics 2022-04-26 Yuki Sato , Ruho Kondo , Satoshi Koide , Hideki Takamatsu , Nobuyuki Imoto

Unitary evolution under a time dependent Hamiltonian is a key component of simulation on quantum hardware. Synthesizing the corresponding quantum circuit is typically done by breaking the evolution into small time steps, also known as…

Hamiltonian simulation, i.e., simulating the real time evolution of a target quantum system, is a natural application of quantum computing. Trotter-Suzuki splitting methods can generate corresponding quantum circuits; however, a faithful…

Quantum Physics · Physics 2024-03-21 Ayse Kotil , Rahul Banerjee , Qunsheng Huang , Christian B. Mendl

We study the problem of simulating the time evolution of a lattice Hamiltonian, where the qubits are laid out on a lattice and the Hamiltonian only includes geometrically local interactions (i.e., a qubit may only interact with qubits in…

Quantum Physics · Physics 2021-08-24 Jeongwan Haah , Matthew B. Hastings , Robin Kothari , Guang Hao Low

We introduce a simple algorithm that efficiently computes tensor products of Pauli matrices. This is done by tailoring the calculations to this specific case, which allows to avoid unnecessary calculations. The strength of this strategy is…

Quantum Physics · Physics 2023-12-20 Sebastián V. Romero , Juan Santos-Suárez