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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

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

A recently developed theory for eliminating decoherence and design constraints in quantum computers, ``encoded recoupling and decoupling'', is shown to be fully compatible with a promising proposal for an architecture enabling scalable…

Quantum Physics · Physics 2016-09-08 D. A. Lidar , L. -A Wu

Recent years have seen rapid development in the subject of quantum coding theory, with breakthroughs on many exciting classes of codes, including quantum LDPC codes, quantum locally testable codes, and quantum codes with interesting…

Quantum Physics · Physics 2026-03-06 Adam Wills , Ting-Chun Lin , Rachel Yun Zhang , Min-Hsiu Hsieh

One limitation of the variational quantum eigensolver algorithm is the large number of measurement steps required to estimate different terms in the Hamiltonian of interest. Unitary partitioning reduces this overhead by transforming the…

Quantum Physics · Physics 2021-09-01 Alexis Ralli , Peter Love , Andrew Tranter , Peter Coveney

Recent advancements in quantum annealing hardware and numerous studies in this area suggests that quantum annealers have the potential to be effective in solving unconstrained binary quadratic programming problems. Naturally, one may desire…

Quantum Physics · Physics 2019-03-01 Sahar Karimi , Pooya Ronagh

Number-conserved subspace encoding reduces resources needed for quantum simulations, but scalable complexity trade-off bounds for $M$ modes and $N$ particles with $\mathcal{O}(N\log M)$ qubits have remained unknown. We study…

Quantum Physics · Physics 2025-09-23 M. H. Cheng , Yu-Cheng Chen , Qian Wang , V. Bartsch , M. S. Kim , Alice Hu , Min-Hsiu Hsieh

In Quantum Machine Learning (QML) and Quantum Finance, amplitude encoding is often motivated by its logarithmic storage capacity arXiv:1307.0411. This paradigm typically relies on the mapping $\psi = \sqrt{P}$, treating the quantum state as…

Quantum Physics · Physics 2026-02-26 Sebastian Zając , Jacob L. Cybulski , Bartosz Dziewit , Tomasz Kulpa

When creating a quantum system whose natural dynamics provide useful computational operations, designers have two key tools at their disposal: the (constrained) choice of both the Hamiltonian and the the initial state of the system (an…

Quantum Physics · Physics 2024-04-10 Alastair Kay

We introduce a cavity-enhanced optical architecture for collective quantum processing in which logical qubits are encoded in the polarization subspace of recirculating intracavity modes. The physical carrier and computational degree of…

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…

Quantum process tomography is an experimental technique to fully characterize an unknown quantum process. Standard quantum process tomography suffers from exponentially scaling of the number of measurements with the increasing system size.…

Quantum Physics · Physics 2022-08-02 Shichuan Xue , Yong Liu , Yang Wang , Pingyu Zhu , Chu Guo , Junjie Wu

We discuss encodings of fermionic many-body systems by qubits in the presence of symmetries. Such encodings eliminate redundant degrees of freedom in a way that preserves a simple structure of the system Hamiltonian enabling quantum…

Quantum Physics · Physics 2017-01-31 Sergey Bravyi , Jay M. Gambetta , Antonio Mezzacapo , Kristan Temme

The natural Hilbert Space of quantum particles can implement maximum-likelihood (ML) decoding of classical information. The 'Quantum Product Algorithm' (QPA) is computed on a Factor Graph, where function nodes are unitary matrix operations…

Quantum Physics · Physics 2007-05-23 Matthew G. Parker

Quantum machine learning (QML) is a discipline that seeks to transfer the advantages of quantum computing to data-driven tasks. However, many studies rely on toy datasets or heavy feature reduction, raising concerns about their scalability.…

Quantum Physics · Physics 2025-04-16 Federico Tiblias , Anna Schroeder , Yue Zhang , Mariami Gachechiladze , Iryna Gurevych

We present EHands, a quantum-native protocol for implementing multivariable polynomial transformations on quantum processors. The protocol introduces four fundamental, reversible operators: multiplication, addition, negation, and parity…

Current and near-term quantum hardware is constrained by limited qubit counts, circuit depth, and the high cost of repeated measurements. We address these challenges for solid state Hamiltonians by introducing a logarithmic-qubit encoding…

Quantum Physics · Physics 2026-05-13 Martin Plesch , Martin Friák , Ijaz Ahamed Mohammad

We develop and analyze a fault-tolerant quantum algorithm for computing $n$-th order response properties necessary for analysis of non-linear spectroscopies of molecular and condensed phase systems. We use a semi-classical description in…

Quantum Physics · Physics 2024-04-23 Tyler Kharazi , Torin F. Stetina , Liwen Ko , Guang Hao Low , K. Birgitta Whaley

Classical data encoding is usually treated as a black-box in the oracle-based quantum algorithms. On the other hand, their constructions are crucial for practical algorithm implementations. Here, we open the black-boxes of data encoding and…

Quantum Physics · Physics 2024-04-30 Xiao-Ming Zhang , Xiao Yuan

Quantum signal processing (QSP) provides a representation of scalar polynomials of degree $d$ as products of matrices in $\mathrm{SU}(2)$, parameterized by $(d+1)$ real numbers known as phase factors. QSP is the mathematical foundation of…

Quantum Physics · Physics 2025-10-02 Lin Lin