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The theory of quantum algorithms promises unprecedented benefits of harnessing the laws of quantum mechanics for solving certain computational problems. A persistent obstacle to using such algorithms for solving a wide range of real-world…

We prove new lower bounds on the growth of robust quantum circuit complexity -- the minimal number of gates $C_{\delta}(U)$ to approximate a unitary $U$ up to an error of $\delta$ in operator norm distance. More precisely we show two bounds…

Quantum Physics · Physics 2023-06-05 Jonas Haferkamp

From a geometric approach, we derive the minimum number of applications needed for an arbitrary Controlled-Unitary gate to construct a universal quantum circuit. A new analytic construction procedure is presented and shown to be either…

Quantum Physics · Physics 2009-11-10 Jun Zhang , Jiri Vala , Shankar Sastry , K. Birgitta Whaley

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…

Quantum computers are a revolutionary class of computational platforms with applications in combinatorial and global optimization, machine learning, and other domains involving computationally hard problems. While these machines typically…

Quantum Physics · Physics 2026-04-21 Aditya Sodhani , Keshab K. Parhi

Mutually unbiased bases (MUBs) play a crucial role in numerous applications within quantum information science, such as quantum state tomography, error correction, entanglement detection, and quantum cryptography. Utilizing \(2^n + 1\) MUB…

Quantum Physics · Physics 2024-07-22 Wang Yu , Wu Dongsheng

The quantum approximate optimization algorithm (QAOA) is a method of approximately solving combinatorial optimization problems. While QAOA is developed to solve a broad class of combinatorial optimization problems, it is not clear which…

Quantum Physics · Physics 2020-08-13 James Ostrowski , Rebekah Herrman , Travis S. Humble , George Siopsis

Qutrit (or ternary) structures arise naturally in many quantum systems, particularly in certain non-abelian anyon systems. We present efficient circuits for ternary reversible and quantum arithmetics. Our main result is the derivation of…

Quantum Physics · Physics 2016-06-13 Alex Bocharov , Shawn X. Cui , Martin Roetteler , Krysta M. Svore

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

The Quantum Approximate Optimization Algorithm (QAOA) requires considered optimization problems to be translated into a compatible format. A popular transformation step in this pipeline involves the quadratization of higher-order binary…

Quantum Physics · Physics 2025-11-26 Damian Rovara , Lukas Burgholzer , Robert Wille

While implementing a quantum algorithm it is crucial to reduce the quantum resources, in order to obtain the desired computational advantage. For most fault-tolerant quantum error-correcting codes the cost of implementing the non-Clifford…

Quantum Physics · Physics 2023-02-10 Vlad Gheorghiu , Michele Mosca , Priyanka Mukhopadhyay

Quantum state preparation (QSP) is a key component in many quantum algorithms. In particular, the problem of sparse QSP (SQSP) $\unicode{x2013}$ the task of preparing the states with only a small number of non-zero amplitudes…

Quantum Physics · Physics 2025-09-01 Yao-Cheng Lu , Han-Hsuan Lin

We investigate the problem of synthesizing T-depth optimal quantum circuits over the Clifford+T gate set. First we construct a special subset of T-depth 1 unitaries, such that it is possible to express the T-depth-optimal decomposition of…

Quantum Physics · Physics 2022-09-14 Vlad Gheorghiu , Michele Mosca , Priyanka Mukhopadhyay

Combinatorial optimization is a promising application for near-term quantum computers, however, identifying performant algorithms suited to noisy quantum hardware remains as an important goal to potentially realizing quantum computational…

Quantum Physics · Physics 2025-04-01 Titus D. Morris , Ananth Kaushik , Martin Roetteler , Phillip C. Lotshaw

Experimental design is a classical statistics problem and its aim is to estimate an unknown $m$-dimensional vector $\beta$ from linear measurements where a Gaussian noise is introduced in each measurement. For the combinatorial experimental…

Machine Learning · Statistics 2024-12-06 Mohit Singh , Weijun Xie

We study the scaling of the convergence of several statistical properties of a recently introduced random unitary circuit ensemble towards their limits given by the circular unitary ensemble (CUE). Our study includes the full distribution…

Quantum Physics · Physics 2010-06-23 Ludovic Arnaud , Daniel Braun

Although many of works have been done in multivalued quantum logic synthesis, the question whether multivalued quantum circuits are more efficient than the conventional binary quantum circuits is still open. In this article we devote to the…

Quantum Physics · Physics 2015-12-16 Yao-Min Di , Hai-Rui Wei

This study presents a roadmap towards utilizing a single arbitrary gate for universal quantum computing. Since two decades ago, it has been widely accepted that almost any single arbitrary gate with qubit number $>2$ is universal. Utilizing…

Quantum Physics · Physics 2024-10-01 Zhong-Yi Ni , Yu-Sheng Zhao , Jin-Guo Liu

This work presents an optimization-based scalable quantum neural network framework for approximating $n$-qubit unitaries through generic parametric representation of unitaries, which are obtained as product of exponential of basis elements…

Quantum Physics · Physics 2024-01-17 Rohit Sarma Sarkar , Bibhas Adhikari

We prove a new concentration result for non-catalytic decoupling by showing that, for suitably large $t$, applying a unitary chosen uniformly at random from an approximate $t$-design on a quantum system followed by a fixed quantum operation…

Quantum Physics · Physics 2023-11-15 Aditya Nema , Pranab Sen