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Shor's factoring algorithm illustrates the potential power of quantum computation. Here we present and numerically investigate a proposal for a compiled version of such an algorithm based on a quantum-wire network exploiting the…

Quantum Physics · Physics 2011-01-14 Fabrizio Buscemi

We demonstrate the simple and deep equivalence between quantum coherence and nonclassicality and the definite way in which they determine metrological resolution. Moreover, we define a coherence observable consistent with a classical…

Quantum Physics · Physics 2021-09-10 Laura Ares , Alfredo Luis

We propose a new measure of relative incompatibility for a quantum system with respect to two non-commuting observables, and call it quantumness of relative incompatibility. In case of a classical state, order of observation is…

Quantum Physics · Physics 2019-09-30 Manish Kumar Shukla , Rounak Mundra , Arun K Pati , Indranil Chakrabarty , Junde Wu

This is a review paper concerned with the global consistency of the quantum dynamics of non-commutative systems. Our point of departure is the theory of constrained systems, since it provides a unified description of the classical and…

High Energy Physics - Theory · Physics 2015-05-13 F. S. Bemfica , H. O. Girotti

Quantum tomography is a fundamental technique for characterizing, benchmarking, and verifying quantum states and devices. It plays a crucial role in advancing quantum technologies and deepening our understanding of quantum mechanics.…

The intermediate quantum states of multiple qubits, generated during the operation of Shor's factoring algorithm are analyzed. Their entanglement is evaluated using the Groverian measure. It is found that the entanglement is generated…

Quantum Physics · Physics 2009-11-11 Yishai Shimoni , Daniel Shapira , Ofer Biham

Quantum metrology is a rapidly developing branch of quantum technologies. While various theories have been established on quantum metrology for Markovian processes, i.e., quantum channel estimation, quantum metrology for non-Markovian…

Quantum Physics · Physics 2021-08-04 Anian Altherr , Yuxiang Yang

It has recently been argued that the inability to measure the absolute phase of an electromagnetic field prohibits the representation of a laser's output as a quantum optical coherent state. This argument has generally been considered…

Quantum Physics · Physics 2009-11-10 Kae Nemoto , Samuel L. Braunstein

The concept of entanglement fraction is generalized to define coherence fraction of a quantum state. Precisely, it quantifies the proximity of a quantum state to maximally coherent state and it can be used as a measure of coherence.…

Quantum Physics · Physics 2019-06-21 Sumana Karmakar , Ajoy Sen , Indrani Chattopadhyay , Amit Bhar , Debasis Sarkar

Quantum coherence can be used to infer the presence of a detector without triggering it. Here we point out that, according to quantum mechanics, such interaction-free measurements cannot be perfect, i.e., in a single-shot experiment one has…

Quantum phase estimation (QPE) is one of the core algorithms for quantum computing. It has been extensively studied and applied in a variety of quantum applications such as the Shor's factoring algorithm, quantum sampling algorithms and the…

We theoretically and experimentally investigate conditional enhancement of overall coherence of quantum states by probabilistic quantum operations that apply to the input state a quantum filter diagonal in the basis of incoherent states. We…

Quantum Physics · Physics 2021-08-03 Robert Stárek , Michal Mičuda , Michal Kolář , Radim Filip , Jaromír Fiurášek

In this work, we study the dynamics of quantum coherence (total coherence, global coherence and local coherence) evolving under a local PT-symmetric Hamiltonian in maximally entangled bipartite and tripartite states. Our results indicate…

Quantum Physics · Physics 2024-11-07 Akanksha Gautam , Kavita Dorai , Arvind

In measurement-based quantum computing an algorithm is performed by measurements on highly-entangled resource states. To date, several implementations were demonstrated, all of them assuming perfect noise-free environments. Here we consider…

Coherent ensembles of $N$ qubits present an advantage in quantum phase estimation over separable mixtures, but coherence decay due to classical phase diffusion reduces overall precision. In some contexts, the strength of diffusion may be…

Quantum Physics · Physics 2013-07-02 Sergey I. Knysh , Gabriel A. Durkin

The notion of a macroscopic quantum state must be pinned down in order to assess how well experiments probe the large-scale limits of quantum mechanics. However, the issue of quantifying so-called quantum macroscopicity is fraught with…

Quantum Physics · Physics 2025-03-12 Benjamin Yadin , Matteo Fadel

Quantum memories are an important building block for quantum information processing. Ideally, these memories preserve the quantum properties of the input. We present general criteria for measures to evaluate the quality of quantum memories.…

Quantum Physics · Physics 2019-06-19 Timo Simnacher , Nikolai Wyderka , Cornelia Spee , Xiao-Dong Yu , Otfried Gühne

Detecting multipartite quantum coherence usually requires quantum state reconstruction, which is quite inefficient for large-scale quantum systems. Along this line of research, several efficient procedures have been proposed to detect…

Quantum Physics · Physics 2021-12-01 Qi-Ming Ding , Xiao-Xu Fang , He Lu

The problem of estimating a generic phase-shift experienced by a quantum state is addressed for a generally degenerate phase shift operator. The optimal positive operator-valued measure is derived along with the optimal input state. Two…

Quantum Physics · Physics 2009-10-31 G. M. D'Ariano , C. Macchiavello , M. F. Sacchi

Quantum entanglement and coherence are crucial resources in quantum information theory. In some scenarios, however, it is not necessary to directly estimate entanglement or coherence measures to quantify the capabilities of a state in…

Quantum Physics · Physics 2025-11-11 Si-Qi Zhou , Jin-Min Liang , Jiayin Peng , Zhihua Chen , Shao-Ming Fei , Zhihao Ma