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We characterize the set of generalized quantum measurements that can be decomposed into a continuous measurement process using a stream of probe qubits and a tunable interaction Hamilto- nian. Each probe in the stream interacts weakly with…

Quantum Physics · Physics 2015-12-16 Jan Florjanczyk , Todd A. Brun

The study of phase transitions in dissipative quantum systems based on the Liouvillian is often hindered by the difficulty of constructing a time-local master equation when the system-environment coupling is strong. To address this issue,…

Quantum Physics · Physics 2024-04-09 H. T. Cui , Y. A. Yan , M. Qin , X. X. Yi

Information scrambling, which is the spread of local information through a system's many-body degrees of freedom, is an intrinsic feature of many-body dynamics. In quantum systems, the out-of-time-ordered correlator (OTOC) quantifies…

Quantum Physics · Physics 2022-03-09 Bhuvanesh Sundar , Andreas Elben , Lata Kh Joshi , Torsten V. Zache

Mapping the system evolution of a two-state system allows the determination of the effective system Hamiltonian directly. We show how this can be achieved even if the system is decohering appreciably over the observation time. A method to…

Quantum entanglement is an essential resource for quantum science and technology. However, entanglement detection and quantification, via typical entanglement measures such as linear entanglement entropy or negativity, can be a very…

Quantum Physics · Physics 2025-06-17 Diego Fallas Padilla , Mingjian Zhu , Han Pu

We study non-interacting fermionic systems dissipatively driven at their boundaries, focusing in particular on the case of a non-number-conserving Hamiltonian, which for example describes an $XY$ spin chain. We show that despite the lack of…

Quantum Physics · Physics 2018-11-28 Chu Guo , Dario Poletti

In view of making progress towards establishing a holographic duality for theories defined on a discrete tiling of the hyperbolic plane, we consider a recently proposed boundary spin chain Hamiltonian with aperiodic couplings that are…

High Energy Physics - Theory · Physics 2023-11-29 Pablo Basteiro , Rathindra Nath Das , Giuseppe Di Giulio , Johanna Erdmenger

We present a protocol that sets maximum stationary entanglement between remote spins through scattering of mobile mediators without initialization, post-selection or feedback of the mediators' state. No time-resolved tuning is needed and,…

Quantum Physics · Physics 2015-05-14 Francesco Ciccarello , Mauro Paternostro , G. Massimo Palma , M. Zarcone

We study the entanglement Hamiltonian for free-fermion chains with a particular form of inhomogeneity. The hopping amplitudes and chemical potentials are chosen such that the single-particle eigenstates are related to discrete orthogonal…

Statistical Mechanics · Physics 2025-11-04 Pierre-Antoine Bernard , Riccarda Bonsignori , Viktor Eisler , Gilles Parez , Luc Vinet

Efficiently characterising quantum systems, verifying operations of quantum devices and validating underpinning physical models, are central challenges for the development of quantum technologies and for our continued understanding of…

We discuss how the observation of population localization effects in periodically driven systems can be used to quantify the presence of quantum coherence in interacting qubit arrays. Essential for our proposal is the fact that these…

Quantum Physics · Physics 2015-06-11 J. Almeida , P. C. de Groot , S. F. Huelga , A. M. Liguori , M. B. Plenio

We describe an algorithm that computes the ground state energy and correlation functions for 2-local Hamiltonians in which interactions between qubits are weak compared to single-qubit terms. The running time of the algorithm is polynomial…

Quantum Physics · Physics 2009-11-13 Sergey Bravyi , David DiVincenzo , Daniel Loss

We use an n-spin system with permutation symmetric zz-interaction for simulating arbitrary pair-interaction Hamiltonians. The calculation of the required time overhead is mathematically equivalent to a separability problem of n-qubit…

Quantum Physics · Physics 2007-05-23 P. Wocjan , D. Janzing , Th. Beth

We study the reduced dynamics of open quantum spin chains of arbitrary length $N$ with nearest neighbour $XX$ interactions, immersed within an external constant magnetic field along the $z$ direction, whose end spins are weakly coupled to…

Quantum Physics · Physics 2021-09-22 Fabio Benatti , Roberto Floreanini , Laleh Memarzadeh

We analyze a model for spin squeezing based on the so-called counter-twisting Hamiltonian, including the effects of dissipation and finite system size. We discuss the conditions under which the Heisenberg limit, i.e. phase sensitivity…

Quantum Physics · Physics 2009-11-07 A. André , M. D. Lukin

We investigate the problem of determining the Hamiltonian of a locally interacting open-quantum system. To do so, we construct model estimators based on inverting a set of stationary, or dynamical, Heisenberg-Langevin equations of motion…

Quantum Physics · Physics 2020-08-19 Eugene F. Dumitrescu , Pavel Lougovski

Certifying quantum entanglement is a critical step towards realizing quantum-coherent applications of surface spin systems. In this work, we show that entanglement can be unambiguously shown in a scanning tunneling microscope (STM) with…

Mesoscale and Nanoscale Physics · Physics 2024-01-29 Rik Broekhoven , Curie Lee , Soo-hyon Phark , Sander Otte , Christoph Wolf

We study the general quantum Hamiltonian that can be realized with two species of mutually interacting degenerate ultracold atoms in a ring-shaped trap, with the options of rotation and an azimuthal lattice. We examine the spectrum and the…

Quantum Gases · Physics 2023-11-28 Tomáš Opatrný , Kunal K. Das

Characterizing quantum systems by learning their underlying Hamiltonians is a central task in quantum information science. While recent algorithmic advances have achieved near-optimal efficiency in this task, they critically rely on…

Quantum Physics · Physics 2026-05-01 Myeongjin Shin , Junseo Lee , Changhun Oh

Identifying the Hamiltonian of a quantum system from experimental data is considered. General limits on the identifiability of model parameters with limited experimental resources are investigated, and a specific Bayesian estimation…

Quantum Physics · Physics 2019-10-15 S. G. Schirmer , F. C. Langbein