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We study the classical compilation of quantum circuits for the preparation of matrix product states (MPS), which are quantum states of low entanglement with an efficient classical description. Our algorithm represents a near-term…

Quantum Physics · Physics 2026-04-15 Refik Mansuroglu , Norbert Schuch

Quantum computing has the potential to transform simulations of quantum many-body problems at the heart of electronic structure theory. Efficient quantum algorithms to compute the eigenstates of fermionic Hamiltonians, such as quantum phase…

Quantum Physics · Physics 2026-05-29 Hugh G. A. Burton , Maria-Andreea Filip

In order to achieve fault-tolerant quantum computation, we need to repeat the following sequence of four steps: First, perform 1 or 2 qubit quantum gates (in parallel if possible). Second, do a syndrome measurement on a subset of the…

Quantum Physics · Physics 2024-12-11 Harry Buhrman , Marten Folkertsma , Bruno Loff , Niels M. P. Neumann

State preparation is a necessary component of many quantum algorithms. In this work, we combine a method for efficiently representing smooth differentiable probability distributions using matrix product states with recently discovered…

Quantum Physics · Physics 2024-02-19 Jason Iaconis , Sonika Johri , Elton Yechao Zhu

Quantum states that are symmetric under particle exchange play a crucial role in fields such as quantum metrology and quantum error correction. We use a variational circuit composed of global one-axis twisting and global rotations to…

We study two different methods to prepare excited states on a quantum computer, a key initial step to study dynamics within linear response theory. The first method uses unitary evolution for a short time $T=\mathcal{O}(\sqrt{1-F})$ to…

Quantum Physics · Physics 2021-01-12 Alessandro Roggero , Chenyi Gu , Alessandro Baroni , Thomas Papenbrock

We present a method that outputs a sequence of simple unitary operations to prepare a given quantum state that is a generalized coherent state. Our method takes as inputs the expectation values of some relevant observables on the state to…

Quantum Physics · Physics 2020-01-08 Rolando D. Somma

In the era of noisy intermediate scale quantum (NISQ) hardware, digital quantum computers are limited to shallow circuits on the order of a thousand layers due to system noise and qubit decoherence. Thus, every step of a simulation must be…

Quantum Physics · Physics 2026-02-26 Michael Hite

Efficient encoding of classical information plays a fundamental role in numerous practical quantum algorithms. However, the preparation of an arbitrary amplitude-encoded state has been proven to be time-consuming, and its deployment on…

Quantum Physics · Physics 2025-08-19 Chao Wang , Pengrui Zhou , Xi-Ning Zhuang , Ziwei Cui , Menghan Dou , Zhao-Yun Chen , Guo-Ping Guo

Simulating strongly correlated fermionic systems is notoriously hard on classical computers. An alternative approach, as proposed by Feynman, is to use a quantum computer. Here, we discuss quantum simulation of strongly correlated fermionic…

Quantum Physics · Physics 2018-05-02 Zhang Jiang , Kevin J. Sung , Kostyantyn Kechedzhi , Vadim N. Smelyanskiy , Sergio Boixo

Gaussian states hold a fundamental place in quantum mechanics, quantum information, and quantum computing. Many subfields, including quantum simulation of continuous-variable systems, quantum chemistry, and quantum machine learning, rely on…

Quantum Physics · Physics 2026-05-13 Yichen Xie , Nadav Ben-Ami

The most efficient known quantum circuits for preparing unitary coupled cluster states and applying Trotter steps of the arbitrary basis electronic structure Hamiltonian involve interleaved sequences of fermionic Gaussian circuits and Ising…

Quantum Physics · Physics 2021-09-13 Nicholas C. Rubin , Joonho Lee , Ryan Babbush

Ground state preparation is a central application of quantum algorithms for electronic structure. We introduce the classical reservoir approach, a low cost variational ansatz tailored to near-term hardware, requiring only nearest-neighbor…

Quantum Physics · Physics 2025-12-25 Zekun He , Dominika Zgid , A. F. Kemper , J. K. Freericks

We investigate the performance and accuracy of digital quantum algorithms for the study of static and dynamic properties of the fermionic Hubbard model at half-filling with next-nearest neighbour hopping terms. We provide quantum circuits…

Quantum state preparation is an important subroutine for quantum computing. We show that any $n$-qubit quantum state can be prepared with a $\Theta(n)$-depth circuit using only single- and two-qubit gates, although with a cost of an…

Quantum Physics · Physics 2023-04-25 Xiao-Ming Zhang , Tongyang Li , Xiao Yuan

Quantum circuit simulators running on classical computers offer a vital platform for designing, testing, and optimizing quantum algorithms, driving innovation despite limited access to real quantum hardware. However, their scalability is…

Quantum Physics · Physics 2025-10-29 Gleb Kalachev , Pavel Mosharev , Zuoheng Zou , Pavel Panteleev , Man-Hong Yung

Effective quantum computation relies upon making good use of the exponential information capacity of a quantum machine. A large barrier to designing quantum algorithms for execution on real quantum machines is that, in general, it is…

Quantum Physics · Physics 2020-05-12 Adam Holmes , A. Y. Matsuura

Measurement-based quantum computation, an alternative paradigm for quantum information processing, uses simple measurements on qubits prepared in cluster states, a class of multiparty entangled states with useful properties. Here we propose…

Quantum Physics · Physics 2019-05-01 Mikhail Mamaev , Rainer Blatt , Jun Ye , Ana Maria Rey

We propose a tomographic protocol for estimating any $ k $-body reduced density matrix ($ k $-RDM) of an $ n $-mode fermionic state, a ubiquitous step in near-term quantum algorithms for simulating many-body physics, chemistry, and…

Quantum Physics · Physics 2022-10-04 Andrew Zhao , Nicholas C. Rubin , Akimasa Miyake

We present and open source a quantum circuit simulator tailored to chemistry applications. More specifically, our simulator can compute the Born-rule probabilities of samples obtained from circuits containing passive fermionic linear…