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Many quantum states arising in algorithms and physical systems occupy only a small, structured subset of the exponentially large Hilbert space, yet standard quantum state tomography fails to exploit this structure. We present an efficient…

Quantum Physics · Physics 2025-12-24 Chi-Kwong Li , Kevin Yipu Wu , Zherui Zhang

Quantum machine learning (QML) has become a promising area for real world applications of quantum computers, but near-term methods and their scalability are still important research topics. In this context, we analyze the trainability and…

Quantum Physics · Physics 2025-05-21 Léo Monbroussou , Eliott Z. Mamon , Jonas Landman , Alex B. Grilo , Romain Kukla , Elham Kashefi

We give an algorithm that converts any tensor network (TN) into a sequence of local unitaries whose composition block-encodes the network contraction, suitable for Quantum Eigenvalue / Singular Value Transformation (QET/QSVT). The…

Quantum Physics · Physics 2026-01-13 Sebastian Issel

We introduce a variational quantum solver for combinatorial optimizations over $m=\mathcal{O}(n^k)$ binary variables using only $n$ qubits, with tunable $k>1$. The number of parameters and circuit depth display mild linear and sublinear…

Quantum error correction is the art of protecting fragile quantum information through suitable encoding and active interventions. After encoding $k$ logical qubits into $n>k$ physical qubits using a stabilizer code, this amounts to…

Quantum Physics · Physics 2025-05-27 Eric J. Kuehnke , Kyano Levi , Joschka Roffe , Jens Eisert , Daniel Miller

Quantum data loading plays a central role in quantum algorithms and quantum information processing. Many quantum algorithms hinge on the ability to prepare arbitrary superposition states as a subroutine, with claims of exponential speedups…

Quantum Physics · Physics 2025-09-25 Chun-Tse Li , Hao-Chung Cheng

Quantum computers require precise control over parameters and careful engineering of the underlying physical system. In contrast, neural networks have evolved to tolerate imprecision and inhomogeneity. Here, using a reservoir computing…

Quantum Physics · Physics 2021-12-13 Sanjib Ghosh , Tanjung Krisnanda , Tomasz Paterek , Timothy C. H. Liew

Data representation is crucial for the success of machine learning models. In the context of quantum machine learning with near-term quantum computers, equally important considerations of how to efficiently input (encode) data and…

Quantum Physics · Physics 2020-10-07 Ryan LaRose , Brian Coyle

High-rate concatenated quantum codes offer a promising pathway toward fault-tolerant quantum computation, yet designing efficient decoders that fully exploit their error-correction capability remains a significant challenge. In this work,…

Quantum Physics · Physics 2026-01-15 Chao Zhang , Zipeng Wu , Jiahui Wu , Shilin Huang

We show that higher-dimensional versions of qubits, or qudits, can be encoded into spin systems and into harmonic oscillators, yielding important advantages for quantum computation. Whereas qubit-based quantum computation is adequate for…

Quantum Physics · Physics 2007-05-23 Stephen D. Bartlett , Hubert de Guise , Barry C. Sanders

Quantum signal processing combined with quantum eigenvalue transformation has recently emerged as a unifying framework for several quantum algorithms. In its standard form, it consists of two separate routines: block encoding, which encodes…

Quantum Physics · Physics 2024-10-25 Martina Nibbi , Christian B. Mendl

Quantum computing hardware is affected by quantum noise that undermine the quality of results of an executed quantum program. Amongst other quantum noises, coherent error that caused by parameter drifting and miscalibration, remains…

Hardware Architecture · Computer Science 2024-10-15 Xiangyu Ren , Junjie Wan , Zhiding Liang , Antonio Barbalace

We show how, given any set of generators of the stabilizer of a quantum code, an efficient gate array that computes the codewords can be constructed. For an n-qubit code whose stabilizer has d generators, the resulting gate array consists…

Quantum Physics · Physics 2009-10-30 Richard Cleve , Daniel Gottesman

We present a protocol for encoding $N$ real numbers stored in $N$ memory registers into the amplitudes of the quantum superposition that describes the state of $\log_2N$ qubits. This task is one of the main steps in quantum machine learning…

Quantum Physics · Physics 2022-02-07 Sahel Ashhab

Running quantum algorithms often involves implementing complex quantum circuits with such a large number of multi-qubit gates that the challenge of tackling practical applications appears daunting. To date, no experiments have successfully…

Subspace preserving quantum circuits are a class of quantum algorithms that, relying on some symmetries in the computation, can offer theoretical guarantees for their training. Those algorithms have gained extensive interest as they can…

Quantum Physics · Physics 2025-05-01 Léo Monbroussou , Jonas Landman , Letao Wang , Alex B. Grilo , Elham Kashefi

Fault-tolerant capacities quantify the ability of a quantum channel to reliably transmit information when every component of the encoding and decoding procedure is noisy. Earlier work analyzed achievable communication rates under such noise…

Quantum Physics · Physics 2026-02-11 Paula Belzig , Hayata Yamasaki

This work introduces the Schmidt quantum compressor, an innovative approach to quantum data compression that leverages the principles of Schmidt decomposition to encode quantum information efficiently. In contrast to traditional variational…

Quantum Physics · Physics 2025-08-06 Israel F. Araujo , Hyeondo Oh , Nayeli A. Rodríguez-Briones , Daniel K. Park

Quantum arithmetic computation requires a substantial number of scratch qubits to stay reversible. These operations necessitate qubit and gate resources equivalent to those needed for the larger of the input or output registers due to state…

Quantum Physics · Physics 2025-07-21 Omid Faizy , Norbert Wehn , Paul Lukowicz , Maximilian Kiefer-Emmanouilidis

A quantum compiler is a software program for decomposing ("compiling") an arbitrary unitary matrix into a sequence of elementary operations (SEO). The author of this paper is also the author of a quantum compiler called Qubiter. Qubiter…

Quantum Physics · Physics 2007-05-23 Robert R. Tucci