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Quantum computing leverages quantum mechanics to achieve computational advantages over classical hardware, but the use of third-party quantum compilers in the Noisy Intermediate-Scale Quantum (NISQ) era introduces risks of intellectual…

Quantum Physics · Physics 2025-05-21 Amal Raj , Vivek Balachandran

We solve a well known and long-standing open problem in database theory, proving that Conjunctive Query Finite Determinacy Problem is undecidable. The technique we use builds on the top of our Red Spider method which we developed in our…

Databases · Computer Science 2015-12-08 Tomasz Gogacz , Jerzy Marcinkowski

We show that the value of a general two-prover quantum game cannot be computed by a semi-definite program ofvpolynomial size (unless P=NP), a method that has been successful in more restricted quantum games. More precisely, we show that…

Quantum Physics · Physics 2007-05-23 Julia Kempe , Thomas Vidick

We report the first end-to-end hardware-validated demonstration of a reversible Quantum Memory Matrix QMM imprint retrieval cycle. Using IBM Quantum back ends, we realize five imprint retrieval experiments that scale from a minimal…

General Physics · Physics 2025-06-12 Florian Neukart , Eike Marx , Valerii Vinokur

The most general examples of quantum learning advantages involve data labeled by cryptographic or intrinsically quantum functions, where classical learners are limited by the infeasibility of evaluating the labeling functions using…

Quantum Physics · Physics 2026-02-19 Riccardo Molteni , Simon C. Marshall , Vedran Dunjko

We identify and study a particular class of distinguishability problems for quantum observables (POVMs), in which observables with permuted effects are involved, which we call as the labeling problem. Consequently, we identify the binary…

Quantum Physics · Physics 2024-07-09 Nidhin Sudarsanan Ragini , Mário Ziman

The Learning with Errors (LWE) problem underlies modern lattice-based cryptography and is assumed to be quantum hard. Recent results show that estimating entanglement entropy is as hard as LWE, creating tension with quantum gravity and…

Quantum Physics · Physics 2025-10-20 Yunfei Wang , Xin Jin , Junyu Liu

A critical milestone on the path to useful quantum computers is quantum supremacy - a demonstration of a quantum computation that is prohibitively hard for classical computers. A leading near-term candidate, put forth by the Google/UCSB…

Quantum Physics · Physics 2020-11-13 Adam Bouland , Bill Fefferman , Chinmay Nirkhe , Umesh Vazirani

We show that given a satisfiable instance of the 2-to-1 Label Cover problem, it is NP-hard to find a $(23/24 + \eps)$-satisfying assignment.

Computational Complexity · Computer Science 2012-04-26 Per Austrin , Ryan O'Donnell , John Wright

In the presence of spin-orbit coupling, quantum models for semiconductor materials are generally not exactly solvable. As a result, understanding of the strong spin-orbit coupling effects in these systems remains poor. Here we develop an…

Mesoscale and Nanoscale Physics · Physics 2015-09-14 Rui Li , Lian-Ao Wu , Xuedong Hu , J. Q. You

Despite remarkable achievements in its practical tractability, the notorious class of NP-complete problems has been escaping all attempts to find a worst-case polynomial time-bound solution algorithms for any of them. The vast majority of…

Computational Complexity · Computer Science 2017-05-05 Stefan Rass

In recent years, achieving verifiable quantum advantage on a NISQ device has emerged as an important open problem in quantum information. The sampling-based quantum advantages are not known to have efficient verification methods. This paper…

Quantum Physics · Physics 2025-10-29 Nai-Hui Chia , Honghao Fu , Fang Song , Penghui Yao

In complexity theory, gap-preserving reductions play a crucial role in studying hardness of approximation and in analyzing the relative complexity of multiprover interactive proof systems. In the quantum setting, multiprover interactive…

Quantum Physics · Physics 2025-09-01 Laura Mančinska , Pieter Spaas , Taro Spirig , Matthijs Vernooij

Randomized Kaczmarz (RK) is a simple and fast solver for consistent overdetermined systems, but it is known to be fragile under noise. We study overdetermined $m\times n$ linear systems with a sparse set of corrupted equations, $ {\bf…

Numerical Analysis · Mathematics 2026-02-16 Sofiia Shvaiko , Longxiu Huang , Elizaveta Rebrova

The oracle identification problem (OIP) is, given a set $S$ of $M$ Boolean oracles out of $2^{N}$ ones, to determine which oracle in $S$ is the current black-box oracle. We can exploit the information that candidates of the current oracle…

We identify a formal connection between physical problems related to the detection of separable (unentangled) quantum states and complexity classes in theoretical computer science. In particular, we show that to nearly every quantum…

Quantum Physics · Physics 2015-03-27 Gus Gutoski , Patrick Hayden , Kevin Milner , Mark M. Wilde

In continuous-variable quantum key distribution, information reconciliation is required to extract a shared secret key from correlated random variables obtained through the quantum channel. Reverse reconciliation (RR) is generally…

Information Theory · Computer Science 2026-05-13 Marco Origlia , Emanuele Parente , Marco Secondini

We investigate the first-order theory of closed subspaces of complex Hilbert spaces in the signature $(\lor,\perp,0,1)$, where `$\perp$' is the orthogonality relation. Our main result is that already its quasi-identities are undecidable:…

Quantum Physics · Physics 2021-06-22 Tobias Fritz

We present a protocol that transforms any quantum multi-prover interactive proof into a nonlocal game in which questions consist of logarithmic number of bits and answers of constant number of bits. As a corollary, this proves that the…

Quantum Physics · Physics 2016-10-12 Zhengfeng Ji

The field of quantum computation currently lacks a formal proof of experimental feasibility. Qubits are fragile and sophisticated quantum error correction is required to achieve reliable quantum computation. The surface code is a promising…

Quantum Physics · Physics 2012-12-04 Austin G. Fowler