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Quantum computers are on the brink of surpassing the capabilities of even the most powerful classical computers. This naturally raises the question of how one can trust the results of a quantum computer when they cannot be compared to…

When comparing quantum states to each other, it is possible to obtain an unambiguous answer, indicating that the states are definitely different, already after a single measurement. In this paper we investigate comparison of coherent…

Quantum Physics · Physics 2007-05-23 Erika Andersson , Marcos Curty , Igor Jex

Partial tomography, which focuses on reconstructing reduced density matrices (RDMs), has emerged as a promising approach for characterizing complex quantum systems, particularly when full state tomography is impractical. Recently,…

Quantum Physics · Physics 2024-10-18 Chao Wei , Tao Xin

Among supervised learning models, Support Vector Machine stands out as one of the most robust and efficient models for classifying data clusters. At the core of this method, a kernel function is employed to calculate the distance between…

Quantum Physics · Physics 2024-02-29 Alessio Baldazzi , Nicolò Leone , Matteo Sanna , Stefano Azzini , Lorenzo Pavesi

Since, in general, non-orthogonal states cannot be cloned, any eavesdropping attempt in a Quantum Communication scheme using non-orthogonal states as carriers of information introduces some errors in the transmission, leading to the…

Via a multidimensional complementarity relation we derive a novel operational entanglement measure for any discrete quantum system, i.e. for any multidimensional and multipartite system. This new measure admits a separation into different…

Quantum Physics · Physics 2009-11-13 Beatrix C. Hiesmayr , Marcus Huber

Quantum incompatibility, referred as the phenomenon that some quantum measurements cannot be performed simultaneously, is necessary for various quantum information processing tasks, such as nonlocality and steering. When these applications…

Quantum Physics · Physics 2024-11-19 Xiaolin Zhang , Rui Qu , Zehong Chang , Yunlong Wang , Zhenyu Guo , Min An , Hong Gao , Fuli Li , Pei Zhang

W states are a valuable resource for various quantum information tasks, and several protocols to generate them have been proposed and implemented. We introduce a quantum repeater protocol to efficiently distribute three-qubit W states over…

Quantum Physics · Physics 2023-11-09 Jorge Miguel-Ramiro , Ferran Riera-Sàbat , Wolfgang Dür

We employ a genuine multipartite entanglement measure, the generalized geometric measure, for investigating the quantum phase transition in an infinite quantum spin-1/2 chain with two-spin as well as three-spin interactions. We show that in…

Quantum Physics · Physics 2012-09-10 Manabendra N. Bera , R. Prabhu , Aditi Sen De , Ujjwal Sen

The transfer of an unknown quantum state, from a sender to a receiver, is one of the main requirements to perform quantum information processing tasks. In this respect, the state transfer of a single qubit by means of spin chains has been…

Quantum Physics · Physics 2015-10-09 T. J. G. Apollaro , S. Lorenzo , A. Sindona , S. Paganelli , G. L. Giorgi , F. Plastina

Predicting the optimum SWAP depth of a quantum circuit is useful because it informs the compiler about the amount of necessary optimization. Fast prediction methods will prove essential to the compilation of practical quantum circuits. In…

Quantum Physics · Physics 2021-06-29 Evan E. Dobbs , Robert Basmadjian , Alexandru Paler , Joseph S. Friedman

An open question in quantum optics is how to manipulate and control complex quantum states in an experimentally feasible way. Here we present concepts for transformations of high-dimensional multi-photonic quantum systems. The proposals…

Quantum Physics · Physics 2020-07-30 Xiaoqin Gao , Manuel Erhard , Anton Zeilinger , Mario Krenn

In order to achieve fault-tolerant quantum computation, we need to repeat the following sequence of four steps: First, perform 1 or 2 qubit quantum gates (in parallel if possible). Second, do a syndrome measurement on a subset of the…

Quantum Physics · Physics 2024-12-11 Harry Buhrman , Marten Folkertsma , Bruno Loff , Niels M. P. Neumann

I present a general scheme through which the evidence of a superposition involving distinct classical-like states of a macroscopic system can be probed. The scheme relies on a qubit being coupled to a macroscopic harmonic oscillator in such…

Quantum Physics · Physics 2007-05-23 Sougato Bose

We consider an exact state swap, defined as the swap between two quantum states |A> and |B> in the Hilbert space of a quantum system. We show that, given an arbitrary Hamiltonian dynamics, there is a straightforward approach to calculating…

Quantum Physics · Physics 2013-05-30 Ben-Qiong Liu , Lian-Ao Wu , Bin Shao , Jian Zou

We consider a unitary transformation which maps any given state of an $n$-qubit quantum register into another one. This transformation has applications in the initialization of a quantum computer, and also in some quantum algorithms.…

Quantum Physics · Physics 2007-05-23 Mikko Mottonen , Juha J. Vartiainen , Ville Bergholm , Martti M. Salomaa

Quantum computing will change the way we tackle certain problems. It promises to dramatically speed-up many chemical, financial, and machine-learning applications. However, to capitalize on those promises, complex design flows composed of…

Quantum Physics · Physics 2020-10-28 Lukas Burgholzer , Robert Wille

Distributing quantum states reliably among distant locations is a key challenge in the field of quantum networks. One-way quantum networks address this by using one-way communication and quantum error correction. Here, we analyze quantum…

Quantum Physics · Physics 2024-11-04 Álvaro G. Iñesta , Hyeongrak Choi , Dirk Englund , Stephanie Wehner

Quantum computing employs controllable interactions to perform sequences of logical gates and entire algorithms on quantum registers. This paradigm has been widely explored, e.g., for simulating dynamics of manybody systems by decomposing…

Quantum Physics · Physics 2025-05-21 S. Alipour , A. T. Rezakhani , Alireza Tavanfar , K. Mölmer , T. Ala-Nissila

We generalize the entanglement swapping scheme originally proposed for two pairs of qubits to an arbitrary number $q$ of systems composed from an arbitrary number $m_j$ of qudits. Each of the system is supposed to be prepared in a maximally…

Quantum Physics · Physics 2009-11-07 Jan Bouda , Vladimir Buzek