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Related papers: On estimating the quantum $\ell_{\alpha}$ distance

200 papers

Large-scale eigenvalue problems pose a significant challenge to classical computers. While there are efficient quantum algorithms for unitary or Hermitian matrices, eigenvalue problems for non-normal matrices remain open in quantum…

Quantum Physics · Physics 2026-03-25 Honghong Lin , Yun Shang

Estimation of Shannon and R\'enyi entropies of unknown discrete distributions is a fundamental problem in statistical property testing and an active research topic in both theoretical computer science and information theory. Tight bounds on…

Quantum Physics · Physics 2023-07-19 Tongyang Li , Xiaodi Wu

Fidelity is a fundamental measure for the closeness of two quantum states, which is important both from a theoretical and a practical point of view. Yet, in general, it is difficult to give good estimates of fidelity, especially when one…

Quantum Physics · Physics 2022-03-31 András Gilyén , Alexander Poremba

Quantum computers can produce a quantum encoding of the solution of a system of differential equations exponentially faster than a classical algorithm can produce an explicit description. However, while high-precision quantum algorithms for…

Quantum Physics · Physics 2021-11-10 Andrew M. Childs , Jin-Peng Liu , Aaron Ostrander

We derive an inequality relating the entropy difference between two quantum states to their trace norm distance, sharpening a well-known inequality due to M. Fannes. In our inequality, equality can be attained for every prescribed value of…

Quantum Physics · Physics 2009-11-13 Koenraad M. R. Audenaert

A family of quantum measures like the Shannon distinguishability is presented. These measures are defined over the two classes of POVM measurements and related to separate parts in the expression for mutual information. Changes of Ky Fan's…

Quantum Physics · Physics 2011-03-02 Alexey E. Rastegin

We analyze the restrictions on the distinguishability of quantum states imposed by special relativity. An explicit expression relating the error probability for distinguishing between two orthogonal single-photon states with the time $T$…

Quantum Physics · Physics 2009-11-07 S. N. Molotkov , S. S. Nazin

We describe the first strongly subquadratic time algorithm with subexponential approximation ratio for approximately computing the Fr\'echet distance between two polygonal chains. Specifically, let $P$ and $Q$ be two polygonal chains with…

Computational Geometry · Computer Science 2021-03-30 Connor Colombe , Kyle Fox

We revisit the problem of Pauli shadow tomography: given copies of an unknown $n$-qubit quantum state $\rho$, estimate $\text{tr}(P\rho)$ for some set of Pauli operators $P$ to within additive error $\epsilon$. This has been a popular…

Quantum Physics · Physics 2024-11-18 Sitan Chen , Weiyuan Gong , Qi Ye

We focus on determining the separability of an unknown bipartite quantum state $\rho$ by invoking a sufficiently large subset of all possible entanglement witnesses given the expected value of each element of a set of mutually orthogonal…

Quantum Physics · Physics 2009-11-13 Lawrence M. Ioannou , Benjamin C. Travaglione

This paper is concerned with the phase estimation algorithm in quantum computing algorithms, especially the scenarios where (1) the input vector is not an eigenvector; (2) the unitary operator is not exactly implemented; (3) random…

Quantum Physics · Physics 2022-08-10 Xiantao Li

In the problem of quantum state discrimination, one has to determine by measurements the state of a quantum system, based on the a priori side information that the true state is one of two given and completely known states, rho or sigma. In…

Quantum Physics · Physics 2012-12-11 Koenraad M. R. Audenaert , Milan Mosonyi , Frank Verstraete

We define the quantum Wasserstein distance such that the optimization of the coupling is carried out over bipartite separable states rather than bipartite quantum states in general, and examine its properties. Surprisingly, we find that the…

Quantum Physics · Physics 2023-10-17 Géza Tóth , József Pitrik

Standard approaches to quantum statistical inference rely on measurements that induce a collapse of the wave function, effectively consuming the quantum state to extract information. In this work, we investigate the fundamental limits of…

Quantum Physics · Physics 2026-02-20 Cristina Butucea , Jan Johannes , Henning Stein

We propose a generalization of the Wasserstein distance of order 1 to the quantum states of $n$ qudits. The proposal recovers the Hamming distance for the vectors of the canonical basis, and more generally the classical Wasserstein distance…

Quantum Physics · Physics 2022-01-14 Giacomo De Palma , Milad Marvian , Dario Trevisan , Seth Lloyd

We give a pair of algorithms that efficiently learn a quantum state prepared by Clifford gates and $O(\log n)$ non-Clifford gates. Specifically, for an $n$-qubit state $|\psi\rangle$ prepared with at most $t$ non-Clifford gates, our…

Quantum Physics · Physics 2025-11-07 Sabee Grewal , Vishnu Iyer , William Kretschmer , Daniel Liang

A discrete time quantum walker is considered in one dimension, where at each step, the translation can be more than one unit length chosen randomly. In the simplest case, the probability that the distance travelled is $\ell$ is taken as…

Quantum Physics · Physics 2018-10-17 Parongama Sen

Finding the closest separable state to a given target state is a notoriously difficult task, even more difficult than deciding whether a state is entangled or separable. To tackle this task, we parametrize separable states with a neural…

Quantum Physics · Physics 2022-07-08 Antoine Girardin , Nicolas Brunner , Tamás Kriváchy

Given a positive integer k, it is natural to ask for a formula for the distance between a given density matrix (i.e., mixed quantum state) and the set of density matrices of rank at most k. This problem has already been solved when…

Quantum Physics · Physics 2026-01-26 Nathaniel Johnston , Chi-Kwong Li

In quantum estimation theory and quantum tomography, the quantum state obtained by sampling converges to the `true' unknown density matrix under topologies that are different from the natural notion of distance in the space of quantum…

Quantum Physics · Physics 2009-11-13 Paolo Albini , Alessandro Toigo , Veronica Umanità