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We study the stochastic dynamics of a two-level quantum system interacting with a stochastic magnetic field, and a single frequency electromagnetic field, with and without making the rotating wave approximation (RWA). The transformation to…

Quantum Physics · Physics 2014-12-23 Y. B. Band

Quantum trajectory techniques have been used in the theory of open systems as a starting point for numerical computations and to describe the monitoring of a quantum system in continuous time. Here we extend this technique and use it to…

Quantum Physics · Physics 2026-05-05 Alberto Barchielli

Models based on non-Hermitian Hamiltonians can exhibit a range of surprising and potentially useful phenomena. Physical realizations typically involve couplings to sources of incoherent gain and loss; this is problematic in quantum…

Quantum Physics · Physics 2019-07-03 Yu-Xin Wang , A. A. Clerk

We investigate simultaneous estimation of multi-parameter quantum estimation with time-dependent Hamiltonians. We analytically obtain the maximal quantum Fisher information matrix for two-parameter in time-dependent three-level systems. The…

Quantum Physics · Physics 2021-09-06 Dong Xie , Chunling Xu

Identifying unknown Hamiltonians from their quantum dynamics is a pivotal challenge in quantum technologies. In this paper, we introduce Hamiltonian recognition, a framework that bridges quantum hypothesis testing and quantum metrology,…

Quantum Physics · Physics 2026-02-26 Chengkai Zhu , Shuyu He , Yu-Ao Chen , Lei Zhang , Xin Wang

Control of multi-level quantum systems is sensitive to implementation errors in the control field and uncertainties associated with system Hamiltonian parameters. A small variation in the control field spectrum or the system Hamiltonian can…

Quantum Physics · Physics 2015-06-23 Andy Koswara , Raj Chakrabarti

Emerging quantum hardware provides new possibilities for quantum simulation. While much of the research has focused on simulating closed quantum systems, the real-world quantum systems are mostly open. Therefore, it is essential to develop…

Quantum Physics · Physics 2024-02-14 Huo Chen , Niladri Gomes , Siyuan Niu , Wibe Albert de Jong

We show that nonlinear problems including nonlinear partial differential equations can be efficiently solved by variational quantum computing. We achieve this by utilizing multiple copies of variational quantum states to treat…

Quantum Physics · Physics 2020-01-15 Michael Lubasch , Jaewoo Joo , Pierre Moinier , Martin Kiffner , Dieter Jaksch

We consider finite-dimensional Markovian open quantum systems, and characterize the extent to which time-independent Hamiltonian control may allow to stabilize a target quantum state or subspace and optimize the resulting convergence speed.…

Quantum Physics · Physics 2015-03-17 Francesco Ticozzi , Riccardo Lucchese , Paola Cappellaro , Lorenza Viola

We provide a general framework for the identification of open quantum systems. By looking at the input-output behavior, we try to identify the system inside a black box in which some Markovian time-evolution takes place. Due to the…

Quantum Physics · Physics 2014-03-19 Daniel Burgarth , Kazuya Yuasa

We show that the dynamics of a closed quantum system obeys the Hamilton variation principle. Even though quantum particles lack well-defined trajectories, their evolution in the Husimi representation can be treated as a flow of…

Quantum Physics · Physics 2022-03-02 Dmitry V. Zhdanov , Denys I. Bondar

We develop an approach based on stochastic quantum trajectories for an incoherently pumped system of interacting bosons relaxing their energy in a thermal reservoir. Our approach enables the study of the versatile coherence properties of…

Quantum Gases · Physics 2015-09-17 H. Flayac , I. G. Savenko , M. Möttönen , T. Ala-Nissila

We present a quantum algorithm based on repeated measurement to solve initial-value problems for nonlinear ordinary differential equations (ODEs), which may be generated from partial differential equations in plasma physics. We map a…

Quantum Physics · Physics 2025-04-30 Joseph Andress , Alexander Engel , Yuan Shi , Scott Parker

With the fast development of quantum technology, the sizes of both digital and analog quantum systems increase drastically. In order to have better control and understanding of the quantum hardware, an important task is to characterize the…

Quantum Physics · Physics 2023-07-05 Wenjun Yu , Jinzhao Sun , Zeyao Han , Xiao Yuan

Hamiltonian diagonalization is at the heart of understanding physical properties and practical applications of quantum systems. It is highly desired to design quantum algorithms that can speedup Hamiltonian diagonalization, especially those…

Quantum Physics · Physics 2021-07-23 Jinfeng Zeng , Chenfeng Cao , Chao Zhang , Pengxiang Xu , Bei Zeng

Non-autonomous dynamical systems appear in a very wide range of interesting applications, both in classical and quantum dynamics, where in the latter case it corresponds to having a time-dependent Hamiltonian. However, the quantum…

Quantum Physics · Physics 2025-04-22 Yu Cao , Shi Jin , Nana Liu

We review our results on a mathematical dynamical theory for observables for open many-body quantum nonlinear bosonic systems for a very general class of Hamiltonians. We show that non-quadratic (nonlinear) terms in a Hamiltonian provide a…

Quantum Physics · Physics 2008-01-29 Gennady P. Berman , Fausto Borgonovi , Diego A. R. Dalvit

Quantum control in large dimensional Hilbert spaces is essential for realizing the power of quantum information processing. For closed quantum systems the relevant input/output maps are unitary transformations, and the fundamental challenge…

Quantum Physics · Physics 2014-10-17 B. E. Anderson , H. Sosa-Martinez , C. A. Riofrío , I. H. Deutsch , P. S. Jessen

The interaction between a quantum system and its environment limits our ability to control it and perform quantum operations on it. We present an efficient method to find optimal controls for quantum systems coupled to non-Markovian…

We present an efficient quantum algorithm for simulating the dynamics of Markovian open quantum systems. The performance of our algorithm is similar to the previous state-of-the-art quantum algorithm, i.e., it scales linearly in evolution…

Quantum Physics · Physics 2023-07-11 Xiantao Li , Chunhao Wang