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We give an algorithm for solving unique games (UG) instances whenever low-degree sum-of-squares proofs certify good bounds on the small-set-expansion of the underlying constraint graph via a hypercontractive inequality. Our algorithm is in…

Computational Complexity · Computer Science 2021-06-29 Mitali Bafna , Boaz Barak , Pravesh Kothari , Tselil Schramm , David Steurer

We report a cluster of results regarding the difficulty of finding approximate ground states to typical instances of the quantum satisfiability problem $k$-QSAT on large random graphs. As an approximation strategy, we optimize the solution…

Statistical Mechanics · Physics 2013-06-27 B. Hsu , C. R. Laumann , A. Laeuchli , R. Moessner , S. L. Sondhi

In a model of fault-tolerant quantum computation with quick and noiseless polyloglog-time auxiliary classical computation, we construct a fault tolerance protocol with constant-space and $\widetilde{O}(\log N)$-time overhead, where…

Quantum Physics · Physics 2025-08-15 Quynh T. Nguyen , Christopher A. Pattison

A new finite form of de Finetti's representation theorem is established using elementary information-theoretic tools. The distribution of the first $k$ random variables in an exchangeable vector of $n\geq k$ random variables is close to a…

Information Theory · Computer Science 2024-04-29 Mario Berta , Lampros Gavalakis , Ioannis Kontoyiannis

It is known that quantum correlations exhibited by a maximally entangled qubit pair can be simulated with the help of shared randomness, supplemented with additional resources, such as communication, post-selection or non-local boxes. For…

Quantum Physics · Physics 2009-11-11 Julien Degorre , Sophie Laplante , Jérémie Roland

In recent years, the use of information principles to understand quantum correlations has been very successful. Unfortunately, all principles considered so far have a bipartite formulation, but intrinsically multipartite principles, yet to…

Quantum Physics · Physics 2014-03-03 T. Fritz , A. B. Sainz , R. Augusiak , J. B. Brask , R. Chaves , A. Leverrier , A. Acín

Previously, Bennet and Feynman asked if Heisenberg's uncertainty principle puts a limitation on a quantum computer (Quantum Mechanical Computers, Richard P. Feynman, Foundations of Physics, Vol. 16, No. 6, p597-531, 1986). Feynman's answer…

Mathematical Physics · Physics 2007-05-23 Ken Loo

We propose a general method for studying properties of quantum channels acting on an n-partite system, whose action is invariant under permutations of the subsystems. Our main result is that, in order to prove that a certain property holds…

Quantum Physics · Physics 2009-11-13 Matthias Christandl , Robert Koenig , Renato Renner

Random local measurements have recently been proposed to construct entanglement witnesses and thereby detect the presence of bipartite entanglement. We experimentally demonstrate the efficacy of one such scheme on a two-qubit NMR quantum…

Quantum Physics · Physics 2016-12-13 Amandeep Singh , Arvind , Kavita Dorai

Estimation of local quantum fields is a crucial aspect of quantum metrology applications, and often also forms the test-bed to analyze the utility of quantum resources, like entanglement. However, so far, this has been analyzed using the…

Quantum Physics · Physics 2025-02-26 Aparajita Bhattacharyya , Ujjwal Sen

Quantum pseudotelepathy is a strong form of nonlocality. Different from the conventional non-local games where quantum strategies win statistically, e.g., the Clauser-Horne-Shimony-Holt game, quantum pseudotelepathy in principle allows…

Quantum metrology protocols are typically designed around the assumption that we have an abundance of measurement data, but recent practical applications are increasingly driving interest in cases with very limited data. In this regime the…

Quantum Physics · Physics 2019-04-18 Jesús Rubio , Jacob Dunningham

Uncertainty principle is an inherent nature of quantum system that undermines the precise measurement of incompatible observables and hence the applications of quantum theory. Entanglement, another unique feature of quantum physics, was…

Quantum Physics · Physics 2020-09-30 Jun-Li Li , Cong-Feng Qiao

Local search algorithms use the neighborhood relations among search states and often perform well for a variety of NP-hard combinatorial search problems. This paper shows how quantum computers can also use these neighborhood relations. An…

Quantum Physics · Physics 2007-05-23 Tad Hogg , Mehmet Yanik

Quantum networks are important for quantum communication, enabling tasks such as quantum teleportation, quantum key distribution, quantum sensing, and quantum error correction, often utilizing graph states, a specific class of multipartite…

Quantum Physics · Physics 2025-11-19 Aniruddha Sen , Kenneth Goodenough , Don Towsley

This paper considers the decidability of fully quantum nonlocal games with noisy maximally entangled states. Fully quantum nonlocal games are a generalization of nonlocal games, where both questions and answers are quantum and the referee…

Quantum Physics · Physics 2023-04-27 Minglong Qin , Penghui Yao

For two symmetric quantum states one may be interested in maximizing the overlap under local operations applied to one of them. The question arises whether the maximal overlap can be obtained by applying the same local operation to each…

Quantum Physics · Physics 2017-02-15 Antoine Neven , Pierre Mathonet , Otfried Gühne , Thierry Bastin

We study the estimation of the overlap between two unknown pure quantum states of a finite dimensional system, given $M$ and $N$ copies of each type. This is a fundamental primitive in quantum information processing that is commonly…

Entanglement does not correspond to any observable and its evaluation always corresponds to an estimation procedure where the amount of entanglement is inferred from the measurements of one or more proper observables. Here we address…

Quantum Physics · Physics 2009-11-13 Marco G. Genoni , Paolo Giorda , Matteo G. A. Paris

Proving the unconditional security of a quantum key distribution (QKD) scheme is a highly challenging task as one needs to determine the most efficient attack compatible with experimental data. This task is even more demanding for…

Quantum Physics · Physics 2010-03-15 Anthony Leverrier , Evgueni Karpov , Philippe Grangier , Nicolas J. Cerf