English
Related papers

Related papers: Coherence generation with Hamiltonians

200 papers

This paper considers a class of uncertain linear quantum systems subject to uncertain perturbations in the system Hamiltonian. We present a method to design a coherent robust H-infinity controller so that the closed loop system is robustly…

Systems and Control · Computer Science 2015-09-10 Chengdi Xiang , Ian R. Petersen , Daoyi Dong

Beam splitters are not-free operations with regard to quantum coherence. As a consequence, they can create coherence from both coherent and incoherent states. We investigate the increase in coherence produced by cascades of beam splitters.…

Quantum Physics · Physics 2024-06-18 Guillermo Díez , Laura Ares , Alfredo Luis

Recent results in quantum information theory characterize quantum coherence in the context of resource theories. Here we study the relation between quantum coherence and quantum discord, a kind of quantum correlation which appears even in…

Quantum Physics · Physics 2016-04-29 Jiajun Ma , Benjamin Yadin , Davide Girolami , Vlatko Vedral , Mile Gu

We investigate the inverse problem concerning the evolution of a qubit system, specifically we consider how one can establish the Hamiltonians that account for the evolution of a qubit along a prescribed path in the projected Hilbert space.…

Quantum Physics · Physics 2009-11-10 D. M. Tong , Jing-Ling Chen , L. C. Kwek , C. H. Lai , C. H. Oh

Measuring quantum states provides means to generate genuine random numbers. It has been shown that genuine randomness can be obtained even with an uncharacterized quantum source. In this work, we propose a framework that formalizes the idea…

Quantum Physics · Physics 2019-05-23 Jiajun Ma , Xiao Yuan , Aishwarya Hakande , Xiongfeng Ma

Simulating the unitary dynamics of a quantum system is a fundamental problem of quantum mechanics, in which quantum computers are believed to have significant advantage over their classical counterparts. One prominent such instance is the…

Quantum Physics · Physics 2024-09-04 John M. Martyn , Yuan Liu , Zachary E. Chin , Isaac L. Chuang

In this paper we develop a Hamiltonian approach to sufficient conditions in optimal control problems. We extend the known conditions for $C^2$ maximised Hamiltonians into two directions: on the one hand we explain the role of a super…

Optimization and Control · Mathematics 2015-07-15 Gianna Stefani , Pierluigi Zezza

Quantum coherence, encoded in the off-diagonal elements of a system's density matrix, is a key resource in quantum thermodynamics, fundamentally limiting the maximum extractable work known as ergotropy. While previous experiments have…

Quantum Physics · Physics 2025-12-04 Li Li , Silu Zhao , Yun-Hao Shi , Kai Xu , Heng Fan , Dongning Zheng , Zhongcheng Xiang

Coherence is the most fundamental quantum resource in quantum information processing. How fast a physical system gets coherence or decoherence is a critical ingredient. We present an attainable quantum speed limit based on the variation of…

Quantum Physics · Physics 2025-10-07 Zi-yi Mai , CHang-shui Yu

We derive upper bounds for Hilbert-Schmidt's quantum coherence of general states of a $d$-level quantum system, a qudit, in terms of its incoherent uncertainty, with the latter quantified using the linear and von Neumann's entropies of the…

Quantum Physics · Physics 2020-07-22 Marcos L. W. Basso , Diego S. S. Chrysosthemos , Jonas Maziero

Randomness generation through quantum-chaotic evolution underpins foundational questions in statistical mechanics and applications across quantum information science, including benchmarking, tomography, metrology, and demonstrations of…

Statistical Mechanics · Physics 2026-01-01 Souradeep Ghosh , Nicholas Hunter-Jones , Joaquin F. Rodriguez-Nieva

To guarantee the security of uniform random numbers generated by a quantum random number generator, we study secure extraction of uniform random numbers when the environment of a given quantum state is controlled by the third party, the…

Quantum Physics · Physics 2018-01-10 Masahito Hayashi , Huangjun Zhu

The optical phase of the driving field in the process of high harmonic generation and the coherence properties of the harmonics are fundamental concepts in attosecond physics. Here, we consider to drive the process by incoherent classical…

Quantum Physics · Physics 2024-09-16 Philipp Stammer

Quantum measurement not only can destroy coherence but also can create it. Here, we estimate the maximum amount of coherence, one can create under a complete non-selective measurement process. For our analysis, we consider projective as…

Quantum Physics · Physics 2022-03-14 Sanuja D. Mohanty , Gautam Sharma , Sk Sazim , Biswajit Pradhan , Arun K. Pati

We introduce a set of coherent states which are associated with quantum systems governed by a trilinear boson Hamiltonian. These states are produced by the action of a nonunitary displacement operator on a reference state and can be…

Quantum Physics · Physics 2009-10-30 C. Brif

Without wasting time and effort on philosophical justifications and implications, we write down the conditions for the Hamiltonian of a quantum system for rendering it mathematically equivalent to a deterministic system. These are the…

Quantum Physics · Physics 2020-06-09 Gerard t Hooft

The concept of bock-coherence, first introduced in [1] and developed in [2,3] encompasses the case where experimental capabilities are not so delicate to perform arbitrary refined measurements on individual atoms. We develop a framework…

Quantum Physics · Physics 2024-02-14 Azam Mani , Fatemeh Rezazadeh , Vahid Karimipour

In a wide range of quantum gravity theories, quasiclassical geometries, which are solutions to the Einstein field equations approximately, are described by "coherent states." Here we propose a Hamiltonian formalism for gravitational…

General Relativity and Quantum Cosmology · Physics 2025-12-01 Sijia Wang , Achintya Sajeendran , Dong-han Yeom , Robert B. Mann , Joshua Foo

A quantum optical model for the high-order harmonic generation is presented, in which both the exciting field and the high harmonic modes are quantized, while the target material appears via parameters only. As a consequence, the model is…

We introduce a procedure based on quantum expectation values of measurement observables to characterize quantum coherence. Our measure allows one to quantify coherence without having to perform tomography of the quantum state, and can be…