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Maximally entangled bipartite unitary operators or gates find various applications from quantum information to being building blocks of minimal models of many-body quantum chaos, and have been referred to as "dual unitaries". Dual unitary…

Quantum Physics · Physics 2020-08-19 Suhail Ahmad Rather , S. Aravinda , Arul Lakshminarayan

Whether noisy quantum devices without error correction can provide quantum advantage over classical computers is a critical issue of current quantum computation. In this work, the random quantum circuits, which are used as the paradigm…

Quantum Physics · Physics 2022-12-07 Meng Zhang , Chao Wang , Shaojun Dong , Hao Zhang , Yongjian Han , Lixin He

Quantum coherence is an essential ingredient in quantum information processing and plays a central role in emergent fields such as nanoscale thermodynamics and quantum biology. However, our understanding and quantitative characterization of…

It is well known that many operations in quantum information processing depend largely on a special kind of quantum correlation, that is, entanglement. However, there are also quantum tasks that display the quantum advantage without…

Quantum Physics · Physics 2015-05-14 Jin-Shi Xu , Xiao-Ye Xu , Chuan-Feng Li , Cheng-Jie Zhang , Xu-Bo Zou , Guang-Can Guo

A bipartite state which is secretly chosen from a finite set of known entangled pure states cannot be immediately useful in standard quantum information processing tasks. To effectively make use of the entanglement contained in this unknown…

Quantum Physics · Physics 2015-05-14 Yangjia Li , Runyao Duan , Mingsheng Ying

Quantum discord is significant in analyzing quantum nonclassicality beyond the paradigm of entanglement. Presently we have explored the effectiveness of global unitary operations in manifesting quantum discord from a general two qubit zero…

Quantum Physics · Physics 2021-03-17 Kaushiki Mukherjee , Biswajit Paul , Sumana Karmakar

We consider the entanglement entropy in critical one-dimensional quantum systems with open boundary conditions. We show that the second R\'enyi entropy of an interval away from the boundary can be computed exactly, provided the same…

Mathematical Physics · Physics 2022-05-18 Benoit Estienne , Yacine Ikhlef , Andrei Rotaru

The most important ability of a quantum channel is to preserve the quantum properties of transmitted quantum states. We experimentally demonstrate a continuous-variable system for efficient benchmarking of quantum channels. We probe the…

Reversible work extraction from identical quantum systems via collective operations was shown to be possible even without producing entanglement among the sub-parts. Here, we show that implementing such global operations necessarily imply…

Quantum Physics · Physics 2015-03-31 Gian Luca Giorgi , Steve Campbell

The accurate identification of faulty hardware is a fundamental requirement for reliable quantum information processing. We address this problem in a quantum setting, where a series of $n$ devices is intended to apply the same unitary…

Quantum Physics · Physics 2026-05-07 Santiago Llorens , Arnau Diebra , Michal Sedlák , Ramon Muñoz-Tapia

One of the characteristic features of quantum mechanics is that every measurement that extracts information about a general quantum system necessarily causes an unavoidable disturbance to the state of this system. A plethora of different…

Quantum discord is a more general measure of quantum correlations than entanglement and has been proposed as a resource in certain quantum information processing tasks. The computation of discord is mostly confined to two-qubit systems for…

Quantum Physics · Physics 2015-06-05 Indrani Bose , Amit Kumar Pal

Quantum mechanical properties like entanglement, discord and coherence act as fundamental resources in various quantum information processing tasks. Consequently, generating more resources from a few, typically termed as broadcasting is a…

Quantum Physics · Physics 2019-10-23 Rounak Mundra , Dhrumil Patel , Indranil Chakrabarty , Nirman Ganguly , Sourav Chatterjee

The problem of distinguishing between a random function and a random permutation on a domain of size $N$ is important in theoretical cryptography, where the security of many primitives depend on the problem's hardness. We study the quantum…

Computational Complexity · Computer Science 2013-12-23 Henry Yuen

In this work, we prove a lower bound on the difference between the first and second singular values of quantum channels induced by random isometries, that is tight in the scaling of the number of Kraus operators. This allows us to give an…

Quantum Physics · Physics 2018-11-22 Carlos E. González-Guillén , Marius Junge , Ion Nechita

Quantification of quantum entanglement plays a crucial role in the study of quantum information tasks. We present analytical lower bounds for both concurrence and 2-concurrence based on the correlation matrices of bipartite quantum states.…

Quantum Physics · Physics 2025-03-21 Zhi-Bo Chen , Shao-Ming Fei

In this work, we establish the first separation between computation with bounded and unbounded space, for problems with short outputs (i.e., working memory can be exponentially larger than output size), both in the classical and the quantum…

Computational Complexity · Computer Science 2026-04-07 Zihan Hao , Zikuan Huang , Qipeng Liu

We study the number of measurements required for quantum process tomography under prior information, such as a promise that the unknown channel is unitary. We introduce the notion of an interactive observable and we show that any unitary…

Quantum Physics · Physics 2014-03-31 Gus Gutoski , Nathaniel Johnston

The phenomenon of quantum entanglement is fundamental to the implementation of quantum computation, and requires at least two qubits for its demonstration. However, both Deutsch algorithm and Grover's search algorithm for two bits do not…

Quantum Physics · Physics 2007-05-23 Arvind , N. Mukunda

There have been many instances where the maximally entangled state as a probe acts better than the product and the non-maximally entangled states in the task of distinguishing quantum channels. We provide a proof that for single-shot…

Quantum Physics · Physics 2025-12-16 Satyaki Manna , Anandamay Das Bhowmik , Debashis Saha