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With the help of a given distance matrix of size $n$, we construct an infinite family of distances $d_p$ (where $p \geq 2$) on the complex projective space $\mathbb{P}(\mathbb{C}^n)$ modelling the space of pure states of an $n$-level…

Mathematical Physics · Physics 2025-12-04 Tomasz Miller , Rafał Bistroń

We show that the manifold of quantum states is endowed with a rich and nontrivial geometric structure. We derive the Fubini-Study metric of the projective Hilbert space of a multi-qubit quantum system, endowing it with a Riemannian metric…

Quantum Physics · Physics 2024-04-19 Arthur Vesperini , Ghofrane Bel-Hadj-Aissa , Lorenzo Capra , Roberto Franzosi

We report on experimental measurement of the Hilbert-Schmidt distance between two two-qubit states by many-particle interference. We demonstrate that our three-step method for measuring distances in Hilbert space is far less complex than…

Quantum Physics · Physics 2021-12-28 Vojtěch Trávníček , Karol Bartkiewicz , Antonín Černoch , Karel Lemr

Measurement incompatibility stipulates the existence of quantum measurements that cannot be carried out simultaneously on single systems. We show that the set of input-output probabilities obtained from d-dimensional classical systems…

Quantum Physics · Physics 2023-06-13 Debashis Saha , Debarshi Das , Arun Kumar Das , Bihalan Bhattacharya , A. S. Majumdar

The tight, in a sense, lower estimates of diamond-norm distance from a given quantum channel to the sets of degradable, antidegradable and entanglement-breaking channels are obtained via the tight continuity bounds for quantum mutual…

Quantum Physics · Physics 2019-10-18 M. E. Shirokov , A. V. Bulinski

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

A new quantum correlation in terms of the average distance between the reduced state and the $i$-th output reduced states under local von Neumann measurements is proposed. It is shown that only the product states do not contain this quantum…

Quantum Physics · Physics 2015-05-12 Yu Guo , Xiulan Li , Bo Li , Heng Fan

Estimating the difference between quantum data is crucial in quantum computing. However, as typical characterizations of quantum data similarity, the trace distance and quantum fidelity are believed to be exponentially-hard to evaluate in…

Quantum Physics · Physics 2021-12-28 Ranyiliu Chen , Zhixin Song , Xuanqiang Zhao , Xin Wang

We investigate and compare three distinguished geometric measures of bipartite quantum correlations that have been recently introduced in the literature: the geometric discord, the measurement-induced geometric discord, and the discord of…

Quantum Physics · Physics 2016-05-26 Wojciech Roga , Dominique Spehner , Fabrizio Illuminati

Combining gravity with quantum theory is still work in progress. On the one hand, classical gravity, is the geometry of space-time determined by the energy-momentum tensor of matter and the resulting nonlinear equations; on the other hand,…

Quantum Physics · Physics 2024-01-26 P. Gusin , D. Burys , A. Radosz

Fault-tolerant quantum computation requires non-destructive quantum measurements with classical feed-forward. Many experimental groups are actively working towards implementing such capabilities and so they need to be accurately evaluated.…

Quantum Physics · Physics 2023-06-14 Darian McLaren , Matthew A. Graydon , Joel J. Wallman

Quantum correlations may be measured by means of the distance of the state to the subclass of states $\Omega$ having well defined classical properties. In particular, a geometric measure of asymmetric discord [Dakic et al., Phys. Rev. Lett.…

Quantum Physics · Physics 2012-12-06 Adam Miranowicz , Pawel Horodecki , Ravindra W. Chhajlany , Jan Tuziemski , Jan Sperling

Positive semi-definite kernels are used to induce pseudo-metrics, or ``distances'', between measures. We write these as an expected quadratic variation of, or expected inner product between, a random field and the difference of measures.…

Probability · Mathematics 2025-05-30 Ian Langmore

Quantum coherence is the most fundamental feature of quantum mechanics. The usual understanding of it depends on the choice of the basis, that is, the coherence of the same quantum state is different within different reference framework. To…

Quantum Physics · Physics 2017-04-17 Chang-shui Yu , Yi-ren Yang , Bao-qing Guo

The quantum relative entropy is a fundamental quantity in quantum information science, characterizing the distinguishability between two quantum states. However, this quantity is not additive in general for correlated quantum states,…

Quantum Physics · Physics 2025-06-05 Kun Fang , Hamza Fawzi , Omar Fawzi

Measurement uncertainty relations are lower bounds on the errors of any approximate joint measurement of two or more quantum observables. The aim of this paper is to provide methods to compute optimal bounds of this type. The basic method…

Quantum Physics · Physics 2016-06-08 René Schwonnek , David Reeb , Reinhard F. Werner

The (standard) average mixing matrix of a continuous-time quantum walk is computed by taking the expected value of the mixing matrices of the walk under the uniform sampling distribution on the real line. In this paper we consider…

Quantum Physics · Physics 2023-09-01 Pedro Baptista , Gabriel Coutinho , Vitor Marques

Quantum trajectories are dynamical equations for quantum states conditioned on the results of a time-continuous measurement, such as a continuous-in-time current $\vec y_t$. Recently there has been renewed interest in dynamical maps for…

Quantum Physics · Physics 2026-02-12 Nattaphong Wonglakhon , Areeya Chantasri , Howard M. Wiseman

Achieving error rates that meet or exceed the fault-tolerance threshold is a central goal for quantum computing experiments, and measuring these error rates using randomized benchmarking is now routine. However, direct comparison between…

Quantum Physics · Physics 2016-10-26 Richard Kueng , David M. Long , Andrew C. Doherty , Steven T. Flammia

We propose protocols for determining the distances in Hilbert space between pure and mixed quantum states prepared on a quantum computer. In the case of pure quantum states, the protocol is based on measuring the square of modulus of scalar…

Quantum Physics · Physics 2021-08-27 A. R. Kuzmak