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The entangling power of a unitary operator quantifies its ability to generate entanglement from product states and provides a natural probe of quantum many-body dynamics. Entanglement extremization at points of enhanced symmetry has…

Quantum Physics · Physics 2026-05-21 Ian Low , Pallab Goswami

We describe the formalism for optimally estimating and controlling both the state of a spin ensemble and a scalar magnetic field with information obtained from a continuous quantum limited measurement of the spin precession due to the…

Quantum Physics · Physics 2007-05-23 John K. Stockton , JM Geremia , Andrew C. Doherty , H. Mabuchi

Quantum correlations are key information about the structures and dynamics of quantum many-body systems. There are many types of high-order quantum correlations with different time orderings, but only a few of them are accessible to the…

Quantum Physics · Physics 2022-06-14 Ze Wu , Ping Wang , Tianyun Wang , Yuchen Li , Ran Liu , Yuquan Chen , Xinhua Peng , Ren-Bao Liu , Jiangfeng Du

How can we analyze quantum correlations in large and noisy systems without quantum state tomography? An established method is to measure total angular momenta and employ the so-called spin-squeezing inequalities based on their expectations…

Quantum Physics · Physics 2024-08-23 Jan Lennart Bönsel , Satoya Imai , Ye-Chao Liu , Otfried Gühne

Interacting spins in quantum magnet can cooperate and exhibit exotic states like the quantum spin liquid. To explore the materialization of such intriguing states, the determination of effective spin Hamiltonian of the quantum magnet is…

Strongly Correlated Electrons · Physics 2021-09-01 Sizhuo Yu , Yuan Gao , Bin-Bin Chen , Wei Li

Precisely knowing an interaction Hamiltonian is crucial to realize quantum information tasks, especially to experimentally demonstrate a quantum computer and a quantum memory. We propose a scheme to experimentally evaluate the spin-spin…

Quantum Physics · Physics 2011-11-10 Yutaka Shikano , Shu Tanaka

In this paper we build on the ideas presented in previous works for perfectly transferring a quantum state between opposite ends of a spin chain using a fixed Hamiltonian. While all previous studies have concentrated on nearest-neighbor…

Quantum Physics · Physics 2007-05-23 Alastair Kay

Observing constituent particles with fractional quantum numbers in confined and deconfined states is an interesting and challenging problem in quantum many-body physics. Here we further explore a computational scheme [Y. Tang and A. W.…

Strongly Correlated Electrons · Physics 2016-01-05 Ying Tang , Anders W. Sandvik

A precise time-dependent control of a quantum system relies on an accurate account of the quantum interference among the system, the control and the environment. A diagrammatic technique has been recently developed to precisely calculate…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 Ching-Kit Chan , L. J. Sham

A scalable spin-based quantum processor requires a suitable semiconductor heterostructure and a gate design, with multiple alternatives being investigated. Characterizing such devices experimentally is a demanding task, with the full…

Mesoscale and Nanoscale Physics · Physics 2022-08-04 Sathish R. Kuppuswamy , Hugo Kerstens , Chun-Xiao Liu , Lin Wang , Anton Akhmerov

This paper deals with the problem of string stability in a chain of acceleration-controlled vehicles. It is known that string stability cannot be achieved, with any linear controller, when the vehicles' control inputs are based on relative…

Optimization and Control · Mathematics 2018-10-31 Arash Farnam , Alain Sarlette

This letter deals with the controllability issue of complex networks. An index is chosen to quantitatively measure the extent of controllability of given network. The effect of this index is analyzed based on empirical studies on various…

Systems and Control · Computer Science 2017-03-08 Ning Cai

A long-lived qubit is usually well-isolated from all other systems and the environments, and so is not easy to couple with measurement apparatus. It is sometimes difficult to implement reliable projective measurements on such a qubit. One…

Quantum Physics · Physics 2015-09-30 Suguru Endo , Yuichiro Matsuzaki , William J. Munro , Shiro Saito

We investigate the influences of quantum many-body effects, such as criticality and the existence of factorisation fields, in the thermodynamic cost of establishing a bonding link between two independent quantum spin chains. We provide a…

Statistical Mechanics · Physics 2015-10-28 Tony J. G. Apollaro , Gianluca Francica , Mauro Paternostro , Michele Campisi

Quantum state transfer in the presence of noise is one of the main challenges in building quantum computers. We compare the quantum state transfer properties for two classes of qubit chains under the influence of static randomness. In fully…

Quantum Physics · Physics 2012-01-24 Analia Zwick , Gonzalo A. Alvarez , Joachim Stolze , Omar Osenda

We derive exact formulas describing an indirect von Neumann measurement of a spin-1 system. The results hold for any interaction strength and for an arbitrary output variable $\Hat{O}$.

Quantum Physics · Physics 2015-09-08 Antonio Di Lorenzo

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

Entanglement is an essential property of quantum many-body systems. However, its local detection is challenging and was so far limited to spin degrees of freedom in ion chains. Here we measure entanglement between the spins of atoms located…

The mutual information has been successfully used as a measure of correlation strength between quantum systems, especially for bipartite systems. Here we examine the use of this measure for multipartite quantum systems. For system of qubits…

Quantum Physics · Physics 2016-10-04 Simon James Daniel Phoenix

In this article we describe the incoherent and coherent spin and charge dynamics of a single electron quantum dot. We use a stochastic master equation to model the state of the system, as inferred by an observer with access to only the…

Quantum Physics · Physics 2017-11-15 Eliska Greplova , Edward A. Laird , G. Andrew D. Briggs , Klaus Mølmer