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Quantum state discrimination depicts the general progress of extracting classical information from quantum systems. We show that quantum state discrimination can be realized in a device-independent scenario using tools of self-testing…

Quantum Physics · Physics 2024-01-25 Xinyu Qiu , Lin Chen

General conditions are derived for preventing the decoherence of a single two-state quantum system (qubit) in a thermal bath. The employed auxiliary systems required for this purpose are merely assumed to be weak for the general condition…

Quantum Physics · Physics 2009-11-07 Guihua Zeng , Christoph H. Keitel

A quantum algorithm for general combinatorial search that uses the underlying structure of the search space to increase the probability of finding a solution is presented. This algorithm shows how coherent quantum systems can be matched to…

Quantum Physics · Physics 2009-10-30 Tad Hogg

Observational entropy is interpreted as the uncertainty an observer making measurements associates with a system. So far, properties that make such an interpretation possible rely on the assumption of ideal projective measurements. We show…

Quantum Physics · Physics 2023-12-11 Dominik Šafránek , Juzar Thingna

We investigate quantum state discrimination with confidentiality. $N$ observers share a given quantum state belonging to a finite set of known states. The observers want to determine the state as accurately as possible and send a…

Quantum Physics · Physics 2015-06-30 Kenji Nakahira , Tsuyoshi Sasaki Usuda , Kentaro Kato

Quantum tomography is the main method used to assess the quality of quantum information processing devices, but its complexity presents a major obstacle for the characterization of even moderately large systems. The number of experimental…

Quantum Physics · Physics 2015-03-19 Marcus P. da Silva , Olivier Landon-Cardinal , David Poulin

We present a quantum algorithm that provides a general approach for obtaining the energy spectrum of a physical system without making a guess on its eigenstates. In this algorithm, a probe qubit is coupled to a quantum register $R$ which…

Quantum Physics · Physics 2014-07-14 Hefeng Wang

Quantum coherence is one of the most basic characteristics of quantum mechanics. Here we give some methods to detect and measure quantum coherence. Firstly, we propose a coherence criterion without full quantum state tomography based on…

Quantum Physics · Physics 2025-06-19 Yiding Wang , Tinggui Zhang

In a standard Quantum Sensing (QS) task one aims at estimating an unknown parameter $\theta$, encoded into an $n$-qubit probe state, via measurements of the system. The success of this task hinges on the ability to correlate changes in the…

Quantum process tomography, the standard procedure to characterize any quantum channel in nature, is affected by a circular argument: in order to characterize the channel, the tomographic preparation and measurement need in turn to be…

Quantum Physics · Physics 2016-06-13 Michele Dall'Arno , Sarah Brandsen , Francesco Buscemi

The primary consideration in developing new material platforms for quantum applications is to optimize coherence. Despite its importance, decoherence processes remains challenging to experimentally interrogate and quantify. In this…

Quantum Physics · Physics 2025-09-25 Albert Liu , Matthew W. Day , Steven T. Cundiff

Coherence is a fundamental resource in quantum information processing, which can be certified by a coherence witness. Due to the imperfection of measurement devices, a conventional coherence witness may lead to fallacious results. We show…

Quantum Physics · Physics 2019-08-30 You-Qi Nie , Hongyi Zhou , Jian-Yu Guan , Qiang Zhang , Xiongfeng Ma , Jun Zhang , Jian-Wei Pan

In this paper, we present schemes for a type of one-parameter bipartite quantum states to probe the quantum entanglement, the quantum discord, the classical correlation and the quantum state based on the cavity QED. It is shown that our…

Quantum Physics · Physics 2015-06-16 Zhen-ni Li , Jia-sen Jin , Chang-shui Yu

There are two complementary approaches to realizing quantum information so that it is protected from a given set of error operators. Both involve encoding information by means of subsystems. One is initialization-based error protection,…

Quantum Physics · Physics 2009-11-13 E. Knill

The ability of fully reconstructing quantum maps is a fundamental task of quantum information, in particular when coupling with the environment and experimental imperfections of devices are taken into account. In this context we carry out a…

Quantum Physics · Physics 2010-11-04 I. Bongioanni , L. Sansoni , F. Sciarrino , G. Vallone , P. Mataloni

A new method of approximation scheme with potential application to a general interacting quantum system is presented. The method is non-perturbative, self- consistent, systematically improvable and uniformly applicable for arbitrary…

Quantum Physics · Physics 2008-06-13 Nabaghan Santi

Quantum non-demolition measurements define a non-invasive protocol to extract information from a quantum system that we aim to monitor. They exploit an additional quantum system that is sequentially coupled to the system. Eventually, by…

Quantum Physics · Physics 2025-06-16 Paolo Solinas , Stefano Gherardini

The well-known algorithm for quantum phase estimation requires that the considered unitary is available as a conditional transformation depending on the quantum state of an ancilla register. We present an algorithm converting an unknown…

Quantum Physics · Physics 2007-05-23 Dominik Janzing

The notion of symmetry is shown to be at the heart of all error correction/avoidance strategies for preserving quantum coherence of an open quantum system S e.g., a quantum computer. The existence of a non-trivial group of symmetries of the…

Quantum Physics · Physics 2007-05-23 P. Zanardi

In this paper we introduce a novel noise model for quantum measurements motivated by an indirect measurement scheme with faulty preparation. Averaging over random dynamics governing the interaction between the quantum system and a probe, a…

Quantum Physics · Physics 2025-07-17 Faedi Loulidi , Ion Nechita , Clément Pellegrini