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The rapid evolution of quantum devices fuels concerted efforts to experimentally establish quantum advantage over classical computing. Many demonstrations of quantum advantage, however, rely on computational assumptions and face…

Low depth measurement-based quantum computation with qudits ($d$-level systems) is investigated and a precise relationship between this powerful model and qudit quantum circuits is derived in terms of computational depth and size…

Quantum Physics · Physics 2015-10-23 Timothy J. Proctor

Quantum versus classical separation plays a central role in understanding the advantages of quantum computation. In this paper, we present the first exponential separation between quantum and bounded-error randomized communication…

Quantum Physics · Physics 2025-06-23 Guangxu Yang , Jiapeng Zhang

Implicit methods are attractive for hybrid quantum-classical CFD solvers as the flow equations are combined into a single coupled matrix that is solved on the quantum device, leaving only the CFD discretisation and matrix assembly on the…

Quantum Physics · Physics 2022-09-19 Leigh Lapworth

Current implementations of quantum logic gates can be highly faulty and introduce errors. In order to correct these errors, it is necessary to first identify the faulty gates. We demonstrate a procedure to diagnose where gate faults occur…

Quantum Physics · Physics 2021-01-20 Margarite L. LaBorde , Allee C. Rogers , Jonathan P. Dowling

Simon in his FOCS'94 paper was the first to show an exponential gap between classical and quantum computation. The problem he dealt with is now part of a well-studied class of problems, the hidden subgroup problems. We study Simon's problem…

Quantum Physics · Physics 2007-05-23 Pascal Koiran , Vincent Nesme , Natacha Portier

Random quantum circuits are commonly viewed as hard to simulate classically. In some regimes this has been formally conjectured, and there had been no evidence against the more general possibility that for circuits with uniformly random…

Comparator circuits are a natural circuit model for studying bounded fan-out computation whose power sits between nondeterministic branching programs and general circuits. Despite having been studied for nearly three decades, the first…

Computational Complexity · Computer Science 2021-12-01 Bruno P. Cavalar , Zhenjian Lu

In breakthrough work, Bravyi, Gosset, and K\"{o}nig (BGK) [Science, 2018] unconditionally proved that constant depth quantum circuits are more powerful than their classical counterparts. Their result is equivalent to saying that a…

Quantum Physics · Physics 2022-12-23 Daochen Wang

Recently, a class of spin chains known as ``free fermions in disguise'' (FFD) has been discovered, which possess hidden free-fermion spectra even though they are not solvable via the standard Jordan-Wigner transformation. In this work, we…

Statistical Mechanics · Physics 2026-03-24 Kohei Fukai , Hironobu Yoshida , Hosho Katsura

Recent discoveries in asymptotically good quantum codes have intensified research on their application in quantum computation and fault-tolerant operations. This study focuses on the addressability problem within CSS codes: what circuits…

Quantum Physics · Physics 2025-02-26 Jérôme Guyot , Samuel Jaques

Recently, perfect matching in bounded planar cutwidth bipartite graphs (\BGGM) was shown to be in ACC$^0$ by Hansen et al.. They also conjectured that the problem is in AC$^0$. In this paper, we disprove their conjecture by showing that the…

Computational Complexity · Computer Science 2018-01-04 Aayush Ojha , Raghunath Tewari

Alternating current optimal power flow (AC-OPF) is one of the fundamental problems in power systems operation. AC-OPF is traditionally cast as a constrained optimization problem that seeks optimal generation set points whilst fulfilling a…

Machine Learning · Computer Science 2020-12-18 Henning Lange , Bingqing Chen , Mario Berges , Soummya Kar

The standard circuit model for quantum computation presumes the ability to directly perform gates between arbitrary pairs of qubits, which is unlikely to be practical for large-scale experiments. Power-law interactions with strength…

We demonstrate that valid inequalities, or lifted nonlinear cuts (LNC), can be projected to tighten the Second Order Cone (SOC), Convex DistFlow (CDF), and Network Flow (NF) relaxations of the AC Optimal Power Flow (AC-OPF) problem. We…

Optimization and Control · Mathematics 2024-09-27 Sergio I. Bugosen , Robert B. Parker , Carleton Coffrin

Proving super-polynomial size lower bounds for $\textsf{TC}^0$, the class of constant-depth, polynomial-size circuits of Majority gates, is a notorious open problem in complexity theory. A major frontier is to prove that $\textsf{NEXP}$…

Computational Complexity · Computer Science 2018-05-29 Lijie Chen

We provide an $\Omega(log(n))$ lower bound for the depth of any quantum circuit generating the unique groundstate of Kitaev's spherical code. No circuit-depth lower bound was known before on this code in the general case where the gates can…

Quantum Physics · Physics 2018-10-10 Dorit Aharonov , Yonathan Touati

Metric facility location is a well-studied problem for which linear programming methods have been used with great success in deriving approximation algorithms. The capacity-constrained generalizations, such as capacitated facility location…

Data Structures and Algorithms · Computer Science 2014-06-17 Stavros G. Kolliopoulos , Yannis Moysoglou

In this paper we treat a cavity QED quantum computation. Namely, we consider a model of quantum computation based on n atoms of laser-cooled and trapped linearly in a cavity and realize it as the n atoms Tavis-Cummings Hamiltonian…

Quantum Physics · Physics 2007-07-02 Kazuyuki Fujii , Kyoko Higashida , Ryosuke Kato , Yukako Wada

Recent breakthroughs have opened the possibility to intermediate-scale quantum computing with tens to hundreds of qubits, and shown the potential for solving classical challenging problems, such as in chemistry and condensed matter physics.…

Quantum Physics · Physics 2025-10-30 Zhong-Xia Shang , Ming-Cheng Chen , Xiao Yuan , Chao-Yang Lu , Jian-Wei Pan