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In this work, a scalable algorithm for the approximate quantum state preparation problem is proposed, facing a challenge of fundamental importance in many topic areas of quantum computing. The algorithm uses a variational quantum circuit…

Quantum Physics · Physics 2025-03-19 Giacomo Belli , Marco Mordacci , Michele Amoretti

While the preparation of a general quantum state is challenging, realistic problem instances, such as those encountered in quantum chemistry and quantum machine learning-typically exhibit hierarchical amplitude structures, consisting of a…

Quantum Physics · Physics 2026-01-15 Yue Wang , Xiao-Ming Zhang , Xiao Yuan , Qi Zhao

We present an n-bit Toffoli gate quantum circuit based on the realization proposed by Barenco, where some of the Toffoli gates in their construction are replaced with Peres gates. This results in a significant cost reduction. Our main…

Quantum Physics · Physics 2011-08-01 Dmitri Maslov , Gerhard W. Dueck

We present two scalable and entanglement-free methods for estimating the collective state of an n-qubit quantum computer. The first method consists of a fixed set of five quantum circuits-regardless of the number of qubits-that avoid the…

The Quantum State Preparation problem aims to prepare an $n$-qubit quantum state $|\psi_v\rangle =\sum_{k=0}^{2^n-1}v_k|k\rangle$ from the initial state $|0\rangle^{\otimes n}$, for a given unit vector $v=(v_0,v_1,v_2,\ldots,v_{2^n-1})^T\in…

Quantum Physics · Physics 2023-02-23 Xiaoming Sun , Guojing Tian , Shuai Yang , Pei Yuan , Shengyu Zhang

While quantum computing holds great potential in combinatorial optimization, electronic structure calculation, and number theory, the current era of quantum computing is limited by noisy hardware. Many quantum compilation approaches can…

Quantum Physics · Physics 2024-08-13 Max Aksel Bowman , Pranav Gokhale , Jeffrey Larson , Ji Liu , Martin Suchara

Quantum state purification is the functionality that, given multiple copies of an unknown state, outputs a state with increased purity. This will be an essential building block for near- and middle-term quantum ecosystems before the…

Quantum Physics · Physics 2024-06-14 Bo Yang , Elham Kashefi , Dominik Leichtle , Harold Ollivier

Initializing classical data in a quantum device is an essential step in many quantum algorithms. As a consequence of measurement and noisy operations, some algorithms need to reinitialize the prepared state several times during its…

Quantum Physics · Physics 2022-06-27 Tiago M. L. de Veras , Leon D. da Silva , Adenilton J. da Silva

We study the approximate state preparation problem on noisy intermediate-scale quantum (NISQ) computers by applying a genetic algorithm to generate quantum circuits for state preparation. The algorithm can account for the specific…

Quantum Physics · Physics 2023-05-10 Tom Rindell , Berat Yenilen , Niklas Halonen , Arttu Pönni , Ilkka Tittonen , Matti Raasakka

Black-box quantum state preparation is an important subroutine in many quantum algorithms. The standard approach requires the quantum computer to do arithmetic, which is a key contributor to the complexity. Here we present a new algorithm…

Quantum Physics · Physics 2019-02-01 Yuval R. Sanders , Guang Hao Low , Artur Scherer , Dominic W. Berry

We study the problems of state preparation, ground state preparation and quantum state preparation. We propose an analytic approach to a stochastic quantum algorithm which prepares the ground state for $n$-qubit Hamiltonian that is…

Quantum Physics · Physics 2025-12-02 Taehee Ko , Sungbin Lim

Quantum circuits can be reduced through optimization to better fit the constraints of quantum hardware. One such method, initial-state dependent optimization (ISDO), reduces gate count by leveraging knowledge of the input quantum states.…

The preparation of tensor network states is a fundamental prerequisite for a wide range of quantum simulation tasks. While many unitary protocols for preparing these states have been investigated, dissipative state preparation provides a…

Quantum Physics · Physics 2026-05-26 Drishti Baruah , Georgios Styliaris , J. Ignacio Cirac , Rahul Trivedi

In this work, we investigate the trade-off between the circuit depth and the number of ancillary qubits for preparing sparse quantum states. We prove that any $n$-qubit $d$-spare quantum state (i.e., it has only $d$ non-zero amplitudes) can…

Quantum Physics · Physics 2025-06-23 Jingquan Luo , Guanzhong Li , Lvzhou Li

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 image computing has emerged as a groundbreaking field, revolutionizing how we store and process data at speeds incomparable to classical methods. Nevertheless, as image sizes expand, so does the complexity of qubit connections,…

Quantum Physics · Physics 2025-02-26 Ershadul Haque , Manoranjan Paul

In quantum computation every unitary operation can be decomposed into quantum circuits-a series of single-qubit rotations and a single type entangling two-qubit gates, such as controlled-NOT (CNOT) gates. Two measures are important when…

Quantum Physics · Physics 2011-03-07 Martin Plesch , Časlav Brukner

We study the question of when investing additional quantum resources in preparing a ground state will improve the aggregate runtime associated with estimating its energy. We analyze Lin and Tong's near-optimal state preparation algorithm…

Quantum Physics · Physics 2023-04-26 Shivesh Pathak , Antonio Russo , Stefan Seritan , Andrew Baczewski

Modeling low energy eigenstates of fermionic systems can provide insight into chemical reactions and material properties and is one of the most anticipated applications of quantum computing. We present three techniques for reducing the cost…

Efficient state preparation is a challenging and important problem in quantum computing. In this work, we present a recursive state preparation algorithm that combines logarithmic-depth Dicke state circuits with Hamming weight encoders for…

Quantum Physics · Physics 2025-11-17 Sunil Vittal , Anthony Wilkie , Nika Rastegari , Mostafa Atallah , Rebekah Herrman