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Quantum state and process tomography are typically analyzed under the assumption that devices emit independent and identically distributed (i.i.d.) states or channels. In realistic experiments, however, noise, drift, feedback, or…

Quantum Physics · Physics 2026-02-26 Leonardo Zambrano

The unique features of entanglement and non-locality in quantum systems, where there are pairs of bipartite states perfectly distinguishable by general entangled measurements yet indistinguishable by local operations and classical…

Quantum Physics · Physics 2024-11-19 Chenghong Zhu , Chengkai Zhu , Zhiping Liu , Xin Wang

In this work, we study the problem of testing properties of the spectrum of a mixed quantum state. Here one is given $n$ copies of a mixed state $\rho\in\mathbb{C}^{d\times d}$ and the goal is to distinguish whether $\rho$'s spectrum…

Quantum Physics · Physics 2015-01-22 Ryan O'Donnell , John Wright

Non-locality without entanglement is a rather counter-intuitive phenomenon in which information may be encoded entirely in product (unentangled) states of composite quantum systems in such a way that local measurement of the subsystems is…

Quantum Physics · Physics 2017-03-08 Sarah Croke , Stephen M Barnett

Recently, a technique known as quantum symmetry test has gained increasing attention for detecting bipartite entanglement in pure quantum states. In this work we show that, beyond qualitative detection, a family of well-defined measures of…

Quantum Physics · Physics 2025-11-12 Xiaoyu Liu , Jordi Tura , Albert Rico

The so-called state-carving protocol generates high-fidelity entangled states at an atom-cavity interface without requiring high cavity cooperativity. However, this protocol is limited to 50\% efficiency, which restricts its applicability.…

Quantum state tomography is a technique in quantum information science used to reconstruct the density matrix of an unknown quantum state, providing complete information about the quantum state. It is of significant importance in fields…

Quantum Physics · Physics 2025-07-23 Wenlong Zhao , Da Zhang , Huili Zhang , Haifeng Yu , Zhang-qi Yin

Quantum information science has profoundly changed the ways we understand, store, and process information. A major challenge in this field is to look for an efficient means for classifying quantum state. For instance, one may want to…

Quantum Physics · Physics 2017-05-03 Yue-Chi Ma , Man-Hong Yung

We propose new optimality criterion for the estimation of state-dependent cloning. We call this measure the relative error because the one compares the errors in the copies with contiguous size taking into account the similarity of states…

Quantum Physics · Physics 2007-05-23 A. E. Rastegin

We describe algorithms to obtain an approximate classical description of a $d$-dimensional quantum state when given access to a unitary (and its inverse) that prepares it. For pure states we characterize the query complexity for…

Quantum Physics · Physics 2022-07-19 Joran van Apeldoorn , Arjan Cornelissen , András Gilyén , Giacomo Nannicini

The ability to extract general laws from a few known examples depends on the complexity of the problem and on the amount of training data. In the quantum setting, the learner's generalization performance is further challenged by the…

Quantum Physics · Physics 2024-11-12 Leonardo Banchi , Jason Pereira , Marco Zamboni

We study the process of quantum telecloning of $d$-dimensional pure quantum states using partially entangled pure states as quantum channel. This process efficiently mixes optimal universal symmetric cloning with quantum teleportation. It…

Quantum Physics · Physics 2017-12-05 Gabriel Araneda , Nataly Cisternas , Aldo Delgado

We study quantum hypothesis testing between orthogonal states under restricted local measurements in the many-copy scenario. For testing arbitrary multipartite entangled pure state against its orthogonal complement state via the local…

Quantum Physics · Physics 2024-09-25 Hao-Chung Cheng , Andreas Winter , Nengkun Yu

Distinguishing physical processes is one of the fundamental problems in quantum physics. Although distinguishability of quantum preparations and quantum channels have been studied considerably, distinguishability of quantum measurements…

Quantum Physics · Physics 2021-04-13 Chandan Datta , Tanmoy Biswas , Debashis Saha , Remigiusz Augusiak

Estimating the trace of quantum state powers, $\text{Tr}(\rho^k)$, for $k$ identical quantum states is a fundamental task with numerous applications in quantum information processing, including nonlinear function estimation of quantum…

Quantum Physics · Physics 2025-09-03 Myeongjin Shin , Junseo Lee , Seungwoo Lee , Kabgyun Jeong

We introduce an experimental procedure for the detection of quantum entanglement of an unknown quantum state with as few measurements as possible. The method requires neither a priori knowledge of the state nor a shared reference frame…

The goal of entanglement distillation is to turn a large number of weakly entangled states into a smaller number of highly entangled ones. Practical entanglement distillation schemes offer a tradeoff between the fidelity to the target…

Entanglement is at the heart of quantum theory and is responsible for various quantum-enabling technologies. In practice, during its preparation, storage, and distribution to the intended recipients, this valuable quantum resource may…

Quantum Physics · Physics 2025-05-08 Xiao-Xu Fang , Gelo Noel M. Tabia , Kai-Siang Chen , Yeong-Cherng Liang , He Lu

Quantum technologies lead to a variety of applications that outperform their classical counterparts. In order to build a quantum device it must be verified that it operates below some error threshold. Recently, because of technological…

The classical shadows protocol is an efficient strategy for estimating properties of an unknown state $\rho$ using a small number of state copies and measurements. In its original form, it involves twirling the state with unitaries from…

Quantum Physics · Physics 2024-01-23 Pierre-Gabriel Rozon , Ning Bao , Kartiek Agarwal