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We present a control-theoretic analysis of the system consisting of a two-level atom coupled with a quantum harmonic oscillator. We show that by applying external fields with just two resonant frequencies, any desired unitary operator can…

Quantum Physics · Physics 2009-11-13 Haidong Yuan , Seth Lloyd

Controlling ensembles of weakly coupled spins typically requires computationally expensive multispin optimisations. We present a compact framework that enables control of weakly coupled spin systems (of any spin), but using RF pulses…

Quantum Physics · Physics 2026-02-12 Suzanne Lim , Bowen Guo , Abi Turner , Charles Buchanan , Andrew Baldwin , Jonathan A. Jones

The feedback stabilization problem for ensembles of coupled spin 1/2 systems is discussed from a control theoretic perspective. The noninvasive nature of the bulk measurement allows for a fully unitary and deterministic closed loop. The…

Quantum Physics · Physics 2018-08-30 Claudio Altafini

In this article, we give a complete characterization of all the unitary transformations that can be synthesized in a given time for a system of coupled spin-1/2 in presence of general time varying coupling tensor. Our treatment is quite…

Quantum Physics · Physics 2010-04-26 Haidong Yuan , Navin Khaneja

Controlling the directionality of surface plasmon polaritons (SPPs) has been widely studied, while the direction of SPPs was always switched by orthogonal polarizations in the reported methods. Here, we present a scheme to control the…

Optics · Physics 2018-07-30 Hailong Zhou , Jinran Qie , Jianji Dong , Xinliang Zhang

A new way of getting controlled spin dependent transport through a two-terminal bridge setup is explored. The system comprises a magnetic quantum ring which is directly coupled to a magnetic quantum wire and subjected to an in-plane…

Mesoscale and Nanoscale Physics · Physics 2015-07-09 Santanu K. Maiti

We investigate the time-optimal solution of the selective control of two uncoupled spin 1/2 particles. Using the Pontryagin Maximum Principle, we derive the global time-optimal pulses for two spins with different offsets. We show that the…

Quantum Physics · Physics 2018-11-14 L. Van Damme , Q. Ansel , S. J. Glaser , D. Sugny

We report an interaction that controls spin squeezing in a collection of spin 1/2 particles. We describe how spin squeezing can be generated and maintained in time. Our scheme can be applied to control the spin squeezing in a Bose…

Quantum Physics · Physics 2009-11-06 C. K. Law , H. T. Ng , P. T. Leung

We propose a realization of an antisymmetric spin-split band structure through magnetic phase transitions without spin-orbit coupling. It enables us to utilize for a variety of magnetic-order-driven cross-correlated and nonreciprocal…

Strongly Correlated Electrons · Physics 2020-07-01 Satoru Hayami , Yuki Yanagi , Hiroaki Kusunose

Squeezed states of spin systems are an important entangled resource for quantum technologies, particularly quantum metrology and sensing. Here we consider the generation of spin squeezed states by interacting the spins with a dissipative…

Quantum Physics · Physics 2016-05-19 Shane Dooley , Emi Yukawa , Yuichiro Matsuzaki , George C. Knee , William J. Munro , Kae Nemoto

Considering the problem of the control of a two-state quantum system by an external field, we establish a general and versatile method that allows the derivation of smooth pulses, suitable for ultrafast applications, that feature the…

Quantum Physics · Physics 2015-06-15 D. Daems , A. Ruschhaupt , D. Sugny , S. Guerin

We analyze the simultaneous time-optimal control of two-spin systems. The two non coupled spins which differ in the value of their chemical offsets are controlled by the same magnetic fields. Using an appropriate rotating frame, we restrict…

Quantum Physics · Physics 2015-05-19 E. Assemat , M. Lapert , Y. Zhang , M. Braun , S. J. Glaser , D. Sugny

We propose a setup which allows to couple the electron spin degree of freedom to the mechanical motions of a nanomechanical system not involving any of the ferromagnetic components. The proposed method employs the strain induced spin-orbit…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 A. G. Mal'shukov , C. S. Tang , C. S. Chu , K. A. Chao

We present a general procedure to implement a NOT gate by composite pulses robust against both offset uncertainties and control field variations. We define different degrees of robustness in this two-parameter space, namely along one, two…

Quantum Physics · Physics 2020-02-19 G. Dridi , M. Mejatty , S. J. Glaser , D. Sugny

Recently it has been shown that ac-driven double quantum dots can act as spin pumps and spin filters. By calculating the current through the system for each spin polarization, by means of the time evolution of the reduced density matrix in…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Rafael Sánchez , Ernesto Cota , Ramón Aguado , Gloria Platero

Focusing on the efficient probe and manipulation of single-particle spin states, we investigate the coupled spin and orbital dynamics of a spin 1/2 particle in a harmonic potential subject to ultrastrong spin-orbit interaction and external…

Mesoscale and Nanoscale Physics · Physics 2014-01-21 C. Echeverria-Arrondo , E. Ya. Sherman

We propose and analyze a new scheme of realizing both spin filtering and spin pumping by using ac-driven double quantum dots in the Coulomb blockade regime. By calculating the current through the system we demonstrate that the spin…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Ernesto Cota , Ramon Aguado , Gloria Platero

We propose a scheme to control the evolution of a two-level quantum system in the strong coupling regime based on the idea of reverse-engineering. A coherent control field is designed to drive both closed and open two-level quantum systems…

Quantum Physics · Physics 2020-07-15 Du Ran , Bin Zhang , Ye-Hong Chen , Zhi-Cheng Shi , Yan Xia , Reuven Ianconescu , Jacob Scheuer , Avraham Gover

We propose to use the spin-orbit interaction as a means to control electron spins in quantum dots, enabling both single qubit and two qubit operations. Very fast single qubit operations may be achieved by temporarily displacing the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Christian Flindt , Anders S. Sorensen , Karsten Flensberg

Coherent control of two-state systems is traditionally achieved by resonant pulses of specific Rabi frequency and duration, by adiabatic techniques using level crossings or delayed pulses, or by sequences of pulses with precise relative…

Quantum Physics · Physics 2019-01-23 Boyan T. Torosov , Nikolay V. Vitanov
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