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Quantum state preparation is a critical task in quantum computing, particularly in fields such as quantum machine learning, Hamiltonian simulation, and quantum algorithm design. The depth of preparation circuit for the most general state…

Quantum Physics · Physics 2025-08-21 Yu Li , Guojing Tian , Xiaoyu He , Xiaoming Sun

We perform optimal-control-theory calculations to determine the minimum number of two-qubit CNOT gates needed to perform quantum state preparation and unitary operator synthesis for few-qubit systems. By considering all possible gate…

Quantum Physics · Physics 2022-08-24 Sahel Ashhab , Naoki Yamamoto , Fumiki Yoshihara , Kouichi Semba

Fault-tolerant quantum error correction provides a strategy to protect information processed by a quantum computer against noise which would otherwise corrupt the data. A fault-tolerant universal quantum computer must implement a universal…

We present a deterministic framework for preparing an arbitrary three-qubit pure state. To leverage entanglement structure in the state-preparation task, we classify three-qubit pure states into five types with respect to a $1|2$…

Quantum Physics · Physics 2026-03-03 Yonghae Lee , Taewan Kim

Robust quantum computation requires encoding delicate quantum information into degrees of freedom that are hard for the environment to change. Quantum encodings have been demonstrated in many physical systems by observing and correcting…

Quantum Physics · Physics 2017-11-08 Maika Takita , Andrew W. Cross , A. D. Córcoles , Jerry M. Chow , Jay M. Gambetta

The exact number of CNOT and single qubit gates needed to implement a Quantum Algorithm in a given architecture is one of the central problems of Quantum Computation. In this work we study the importance of concise realizations of Partially…

Quantum Physics · Physics 2020-07-21 Chandra Sekhar Mukherjee , Subhamoy Maitra , Vineet Gaurav , Dibyendu Roy

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

Quantum state preparation is a crucial process within numerous quantum algorithms, and the need for efficient initialization of quantum registers is ever increasing as demand for useful quantum computing grows. The problem arises as the…

Quantum Physics · Physics 2024-09-11 Andrew Wright , Marco Lewis , Paolo Zuliani , Sadegh Soudjani

We propose a scheme for fault-tolerant long-range entanglement generation at the ends of a rectangular array of qubits of length $R$ and a square cross section of size $d\times d$ with $d=O(\log R)$. Up to an efficiently computable Pauli…

Quantum Physics · Physics 2022-09-21 Shin Ho Choe , Robert Koenig

Quantum state preparation is a fundamental primitive in quantum algorithms for encoding classical data into quantum amplitudes. We compare the cost of preparing general $n$-qubit states with real amplitudes using two common paradigms:…

Quantum Physics · Physics 2026-05-20 Diyi Liu , Hanyu Wang , Shuchen Zhu , Jason Cong , Wibe A. de Jong , Di Fang , Zhen Huang , Costin Iancu , Chao Yang

Many-body ground state preparation is an important subroutine used in the simulation of physical systems. In this paper, we introduce a flexible and efficient framework for obtaining a state preparation circuit for a large class of…

Quantum Physics · Physics 2024-11-05 Hyun-Soo Kim , Isaac H. Kim , Daniel Ranard

Quantum computing promises to solve problems previously deemed infeasible. However, high error rates necessitate quantum error correction for practical applications. Seminal experiments with zoned neutral atom architectures have shown…

Quantum Physics · Physics 2025-06-03 Yannick Stade , Ludwig Schmid , Lukas Burgholzer , Robert Wille

Fermionic ansatz state preparation is a critical subroutine in many quantum algorithms such as Variational Quantum Eigensolver for quantum chemistry and condensed matter applications. The shallowest circuit depth needed to prepare Slater…

Quantum Physics · Physics 2023-08-22 Chong Hian Chee , Daniel Leykam , Adrian M. Mak , Dimitris G. Angelakis

High-rate and large-distance quantum codes are expected to make fault-tolerant quantum computing more efficient, but most of them lack efficient fault-tolerant encoded-state preparation methods. We propose such a fault-tolerant encoder for…

Quantum Physics · Physics 2025-09-22 Naoyuki Kanomata , Hayato Goto

We describe a qubit encoded in continuous quantum variables of an rf superconducting quantum interference device. Since the number of accessible states in the system is infinite, we may protect its two-dimensional subspace from small errors…

Mesoscale and Nanoscale Physics · Physics 2007-08-02 Mateusz Cholascinski , Yuriy Makhlin , Gerd Schön

We propose a variational approach for preparing entangled quantum states on quantum computers. The methodology involves training a unitary operation to match with a target unitary using the Fubini-Study distance as a cost function. We…

Quantum Physics · Physics 2023-07-03 Vu Tuan Hai , Nguyen Tan Viet , Le Bin Ho

The preparation of quantum states using short quantum circuits is one of the most promising near-term applications of small quantum computers, especially if the circuit is short enough and the fidelity of gates high enough that it can be…

Quantum Physics · Physics 2015-10-07 D. Wecker , M. B. Hastings , M. Troyer

A common requirement of quantum simulations and algorithms is the preparation of complex states through sequences of 2-qubit gates. For a generic quantum state, the number of gates grows exponentially with the number of qubits, becoming…

Quantum Physics · Physics 2024-07-08 Matan Ben Dov , David Shnaiderov , Adi Makmal , Emanuele G. Dalla Torre

Quantum error correction protects fragile quantum information by encoding it into a larger quantum system. These extra degrees of freedom enable the detection and correction of errors, but also increase the operational complexity of the…

Dynamic quantum circuits (DQCs) incorporate mid-circuit measurements and gates conditioned on these measurement outcomes. DQCs can prepare certain long-range entangled states in constant depth, making them a promising route to preparing…

Quantum Physics · Physics 2024-10-14 Faisal Alam , Bryan K. Clark