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Many theoretical problems in quantum technology can be formulated and addressed as constrained optimization problems. The most common quantum mechanical constraints such as, e.g., orthogonality of isometric and unitary matrices, CPTP…

Quantum Physics · Physics 2021-11-18 I. A. Luchnikov , A. Ryzhov , S. N. Filippov , H. Ouerdane

We give a construction of Quantum Low-Density Parity Check (QLDPC) codes with near-optimal rate-distance tradeoff and efficient list decoding up to the Johnson bound in polynomial time. Previous constructions of list decodable good distance…

Information Theory · Computer Science 2024-11-08 Thiago Bergamaschi , Fernando Granha Jeronimo , Tushant Mittal , Shashank Srivastava , Madhur Tulsiani

Two-dimensional topological translationally-invariant (TTI) quantum codes, such as the toric code (TC) and bivariate bicycle (BB) codes, are promising candidates for fault-tolerant quantum computation. For such codes to be practically…

Quantum key distribution (QKD offers a long-term solution to establish information-theoretically secure keys between two distant users. In practice, with a careful characterization of quantum sources and the decoy-state method,…

Quantum error correction has recently been shown to benefit greatly from specific physical encodings of the code qubits. In particular, several researchers have considered the individual code qubits being encoded with the continuous…

The Quantum Approximate Optimization Algorithm (QAOA) is a general purpose quantum algorithm designed for combinatorial optimization. We analyze its expected performance and prove concentration properties at any constant level (number of…

Quantum Physics · Physics 2023-07-19 Joao Basso , David Gamarnik , Song Mei , Leo Zhou

The quantum approximate optimization algorithm (QAOA) is one of the most promising candidates for achieving quantum advantage through quantum-enhanced combinatorial optimization. A near-optimal solution to the combinatorial optimization…

Quantum Physics · Physics 2023-07-12 Alexey Galda , Eesh Gupta , Jose Falla , Xiaoyuan Liu , Danylo Lykov , Yuri Alexeev , Ilya Safro

In this work, we prove the strongest known lower bounds for QAC$^0$, allowing polynomially many gates and ancillae. Our main results show that: (1) Depth-3 QAC$^0$ circuits cannot compute PARITY, and require $\Omega(\exp(\sqrt{n}))$ gates…

Quantum Physics · Physics 2026-01-21 Malvika Raj Joshi , Avishay Tal , Francisca Vasconcelos , John Wright

The quantum approximate optimization algorithm (QAOA) is a promising method of solving combinatorial optimization problems using quantum computing. QAOA on the MaxCut problem has been studied extensively on specific families of graphs,…

The Quantum Approximate Optimization Algorithm (QAOA) has been proposed as a method to obtain approximate solutions for combinatorial optimization tasks. In this work, we study the underlying algebraic properties of three QAOA ans\"atze for…

Quantum Physics · Physics 2025-11-27 Sujay Kazi , Martín Larocca , Marco Farinati , Patrick J. Coles , M. Cerezo , Robert Zeier

The $2 \rightarrow q$ norm of a matrix $X \in \mathbb{R}^{n \times d}$ is defined as $\lVert X \rVert_{2 \rightarrow q} = \sup_{\lVert v \rVert_2 = 1} \lVert Xv \rVert_q$. We give polynomial-time multiplicative approximation algorithms for…

Data Structures and Algorithms · Computer Science 2026-05-29 Samuel B. Hopkins , Stefan Tiegel

While the proper orthogonal decomposition (POD) is optimal under certain norms it's also expensive to compute. For large matrix sizes, it is well known that the QR decomposition provides a tractable alternative. Under the assumption that it…

Distributed, Parallel, and Cluster Computing · Computer Science 2018-12-18 Harbir Antil , Dangxing Chen , Scott E. Field

The Quantum Approximate Optimization Algorithm (QAOA) is a general-purpose algorithm for combinatorial optimization problems whose performance can only improve with the number of layers $p$. While QAOA holds promise as an algorithm that can…

Quantum Physics · Physics 2022-07-08 Edward Farhi , Jeffrey Goldstone , Sam Gutmann , Leo Zhou

The Quantum approximate optimization algorithm (QAOA) is one of the most promising candidates for achieving quantum advantage through quantum-enhanced combinatorial optimization. In a typical QAOA setup, a set of quantum circuit parameters…

Quantum Physics · Physics 2021-06-15 Alexey Galda , Xiaoyuan Liu , Danylo Lykov , Yuri Alexeev , Ilya Safro

Quantum algorithms must be scaled up to tackle real-world applications. Doing so requires overcoming the noise present on today's hardware. The quantum approximate optimization algorithm (QAOA) is a promising candidate for scaling up, due…

Quantum Physics · Physics 2026-02-23 Zichang He , David Amaro , Ruslan Shaydulin , Marco Pistoia

The progress in building quantum computers to execute quantum algorithms has recently been remarkable. Grover's search algorithm in a binary quantum system provides considerable speed-up over classical paradigm. Further, Grover's algorithm…

Quantum Physics · Physics 2022-08-24 Amit Saha , Ritajit Majumdar , Debasri Saha , Amlan Chakrabarti , Susmita Sur-Kolay

Topological quantum error-correcting codes are a promising candidate for building fault-tolerant quantum computers. Decoding topological codes optimally, however, is known to be a computationally hard problem. Various decoders have been…

Quantum Physics · Physics 2020-04-01 Milap Sheth , Sara Zafar Jafarzadeh , Vlad Gheorghiu

A canonical feature of the constraint satisfaction problems in NP is approximation hardness, where in the worst case, finding sufficient-quality approximate solutions is exponentially hard for all known methods. Fundamentally, the lack of…

Quantum-classical interfaces (QCIs) for fault-tolerant quantum computing must manage simultaneous, real-time decoding across thousands to millions of logical qubits. Scaling these architectures necessitates sharing expensive decoding…

A directed odd cycle transversal of a directed graph (digraph) $D$ is a vertex set $S$ that intersects every odd directed cycle of $D$. In the Directed Odd Cycle Transversal (DOCT) problem, the input consists of a digraph $D$ and an integer…

Data Structures and Algorithms · Computer Science 2017-04-17 Daniel Lokshtanov , M. S. Ramanujan , Saket Saurabh , Meirav Zehavi