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In this work, we consider the fundamental task of quantum state certification: given copies of an unknown quantum state $\rho$, test whether it matches some target state $\sigma$ or is $\epsilon$-far from it. For certifying $d$-dimensional…

Quantum Physics · Physics 2026-04-10 Chirag Wadhwa , Sitan Chen

We examine two quantum operations, the Permutation Test and the Circle Test, which test the identity of n quantum states. These operations naturally extend the well-studied Swap Test on two quantum states. We first show the optimality of…

Quantum Physics · Physics 2009-11-13 Masaru Kada , Harumichi Nishimura , Tomoyuki Yamakami

In this paper, we show that $\Theta(\mathrm{poly}(n)\cdot\frac{4^n}{\epsilon^2})$ is the sample complexity of testing whether two $n$-qubit quantum states $\rho$ and $\sigma$ are identical or $\epsilon$-far in trace distance using…

Quantum Physics · Physics 2020-09-25 Nengkun Yu

Given a multiparticle quantum state, one may ask whether it can be represented as a thermal state of some Hamiltonian with k-particle interactions only. The distance from the exponential family defined by these thermal states can be…

Quantum Physics · Physics 2013-03-08 Sönke Niekamp , Tobias Galla , Matthias Kleinmann , Otfried Gühne

Bell sampling is a simple yet powerful tool based on measuring two copies of a quantum state in the Bell basis, and has found applications in a plethora of problems related to stabiliser states and measures of magic. However, it was not…

Quantum Physics · Physics 2025-11-13 Jonathan Allcock , Joao F. Doriguello , Gábor Ivanyos , Miklos Santha

We show that measuring any two quantum states by a random POVM, under a suitable definition of randomness, gives probability distributions having total variation distance at least a universal constant times the Frobenius distance between…

Quantum Physics · Physics 2007-05-23 Pranab Sen

We introduce a new method to estimate unknown pure $d$-dimensional quantum states using the probability distributions associated with only three measurement bases. Measurement results of $2d$ projectors are employed to generate a set of…

Quantum Physics · Physics 2020-06-08 L. Zambrano , L. Pereira , D. Martínez , G. Cañas , G. Lima , A. Delgado

We study efficient quantum certification algorithms for quantum state set and unitary quantum channel. We present an algorithm that uses $O(\varepsilon^{-4}\ln |\mathcal{P}|)$ copies of an unknown state to distinguish whether the unknown…

Quantum Physics · Physics 2021-03-05 Wei Xie

We consider the problem of determining the mixed quantum state of a large but finite number of identically prepared quantum systems from data obtained in a sequence of ideal (von Neumann) measurements, each performed on an individual copy…

Quantum Physics · Physics 2009-11-10 Franz Embacher , Heide Narnhofer

We derive an exact uncertainty relation for arbitrary quantum states of finite-dimensional Hilbert spaces. For any given $k$-partition of a $d$-dimensional multipartite system, we introduce the total uncertainty as the sum of the…

Quantum Physics · Physics 2026-03-19 G. Tartaglione , G. Zanfardino , F. Illuminati

Given $n$ copies of an unknown quantum state $\rho\in\mathbb{C}^{d\times d}$, quantum state certification is the task of determining whether $\rho=\rho_0$ or $\|\rho-\rho_0\|_1>\varepsilon$, where $\rho_0$ is a known reference state. We…

Quantum Physics · Physics 2024-01-19 Yuhan Liu , Jayadev Acharya

We present a simple algorithm that estimates the cardinality $n$ of a set $V$ when allowed to sample elements of $V$ uniformly and independently at random. Our algorithm with probability $(1-\delta)$ returns a $(1\pm\epsilon)-$approximation…

Discrete Mathematics · Computer Science 2018-04-13 Marco Bressan , Enoch Peserico , Luca Pretto

Pauli Measurements are the most important measurements in both theoretical and experimental aspects of quantum information science. In this paper, we explore the power of Pauli measurements in the state tomography related problems. Firstly,…

Quantum Physics · Physics 2020-09-15 Nengkun Yu

The identification of an unknown quantum gate is a significant issue in quantum technology. In this paper, we propose a quantum gate identification method within the framework of quantum process tomography. In this method, a series of pure…

Quantum Physics · Physics 2019-05-15 Yuanlong Wang , Qi Yin , Daoyi Dong , Bo Qi , Ian R. Petersen , Zhibo Hou , Hidehiro Yonezawa , Guo-Yong Xiang

In this work we present novel differentially private identity (goodness-of-fit) testers for natural and widely studied classes of multivariate product distributions: Gaussians in $\mathbb{R}^d$ with known covariance and product…

Data Structures and Algorithms · Computer Science 2022-03-07 Clément L. Canonne , Gautam Kamath , Audra McMillan , Jonathan Ullman , Lydia Zakynthinou

In the past decades, quantum entanglement has been recognized to be the basic resource in quantum information theory. A fundamental need is then the understanding its qualification and its quantification: Is the quantum state entangled, and…

Quantum Physics · Physics 2013-02-20 Szilárd Szalay

We investigate generalized measurements, based on positive-operator-valued measures, and von Neumann measurements for the unambiguous discrimination of two mixed quantum states that occur with given prior probabilities. In particular, we…

Quantum Physics · Physics 2009-11-11 Ulrike Herzog , Janos A. Bergou

This work investigates which sets of quantum states give rise to the highest achievable success probability in minimum-error state discrimination if multiple copies of the unknown state are given. Specifically, we consider uniformly…

A promising use of quantum computers is to prepare quantum states that model complex domains, such as correlated electron wavefunctions or the underlying distribution of a complex dataset. Such states need to be verified in view of…

Quantum Physics · Physics 2020-12-16 Ryan S. Bennink

Shadow tomography for quantum states provides a sample efficient approach for predicting the properties of quantum systems when the properties are restricted to expectation values of $2$-outcome POVMs. However, these shadow tomography…

Quantum Physics · Physics 2022-09-08 Weiyuan Gong , Scott Aaronson