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Spin-orbit coupling is a source of strong spin dephasing in two- and three-dimensional semiconducting systems. We report that spin dephasing in a two-dimensional electron gas can be suppressed by introducing a quantum point contact.…

Mesoscale and Nanoscale Physics · Physics 2012-01-23 Jae-Seung Jeong , Hyun-Woo Lee

Decoherence is a major challenge for quantum technologies. A way to mitigate its negative impact is by employing quantum optimal control. The decoherence dynamics varies significantly based on the characteristics of the surrounding…

Spin amplification is the process that ideally increases the number of excited spins when one of them is excited initially. We show that by applying optimal control techniques to design classical drive pulse shapes, spin amplification can…

Quantum Physics · Physics 2025-11-18 Ivan Iakoupov , Victor M. Bastidas , Yuichiro Matsuzaki , Shiro Saito , William J. Munro

Squeezed spin states have important applications in quantum metrology and sensing. It has been shown by S{\o}rensen and M{\o}lmer [Phys. Rev. A 66, 022314(2002)] that an effective one-axis-twisting interaction can be realized in a cavity…

Quantum Physics · Physics 2019-05-08 Gang Liu , Ya-Ni Wang , Li-Fen Yan , Nian-Quan Jiang , Wei Xiong , Ming-Feng Wang

Quantum optimal control is a technique for controlling the evolution of a quantum system and has been applied to a wide range of problems in quantum physics. We study a binary quantum control optimization problem, where control decisions…

Quantum Physics · Physics 2024-10-15 Xinyu Fei , Lucas T. Brady , Jeffrey Larson , Sven Leyffer , Siqian Shen

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

Spin chains have long been considered as candidates for quantum channels to facilitate quantum communication. We consider the transfer of a single excitation along a spin-1/2 chain governed by Heisenberg-type interactions. We build on the…

Quantum Physics · Physics 2010-09-14 Michael Murphy , Simone Montangero , Vittorio Giovannetti , Tommaso Calarco

Spin squeezing via atom-field interactions is considered within the context of the Tavis-Cummings model. An ensemble of N two-level atoms interacts with a quantized cavity field. For all the atoms initially in their ground states, it is…

Quantum Physics · Physics 2009-11-10 Claudiu Genes , P. R. Berman , A. G. Rojo

We present a theoretical study of the optimal control of a qubit interacting with a structured environment. We consider a model system in which the bath is a bosonic reservoir at zero temperature and the qubit frequency is the only control…

Quantum Physics · Physics 2022-10-04 Quentin Ansel , Jonas Fischer , Dominique Sugny , Bruno Bellomo

We study a bulk fermionic dipolar molecular gas in the quantum degenerate regime confined in a two-dimensional geometry. We consider two rotational states that encode a spin 1/2 degree of freedom. We derive a long-range interacting XXZ…

This paper considers the optimal control for hybrid systems whose trajectories transition between distinct subsystems when state-dependent constraints are satisfied. Though this class of systems is useful while modeling a variety of…

Optimization and Control · Mathematics 2018-03-21 Pengcheng Zhao , Shankar Mohan , Ram Vasudevan

Squeezing of collective atomic spins has been shown to improve the sensitivity of atomic clocks and magnetometers to levels significantly below the standard quantum limit. In most cases the requisite atom-atom entanglement has been…

In this review, we present recent theoretical developments on spin transport phenomena probed by ferromagnetic resonance (FMR) modulation in two-dimensional systems coupled to magnetic materials. We first address FMR linewidth enhancements…

Mesoscale and Nanoscale Physics · Physics 2025-10-28 Yuya Ominato , Masaki Yama , Ai Yamakage , Mamoru Matsuo , Takeo Kato

We show that the two-axis counter twisting interaction squeezes a coherent spin state into three states of interest in quantum information, namely, the twin-Fock state, the equally-weighted superposition state, and the state that achieves…

Quantum Physics · Physics 2015-01-07 Emi Yukawa , Gerard Milburn , Masahito Ueda , Kae Nemoto

Propagation of information encoded in spin degrees of freedom through networks of coupled spins enables important applications in spintronics and quantum information processing. We study control of information propagation in networks of…

Quantum Physics · Physics 2019-10-15 Frank Langbein , Sophie Schirmer , Edmond Jonckheere

A system's configurational state can be manipulated using dynamic variation of control parameters, such as temperature, pressure, or magnetic field; for finite-duration driving, excess work is required above the equilibrium free-energy…

Statistical Mechanics · Physics 2022-09-16 Miranda D. Louwerse , David A. Sivak

We propose a quantum feedback scheme for producing deterministically reproducible spin squeezing. The results of a continuous nondemolition atom number measurement are fed back to control the quantum state of the sample. For large samples…

Quantum Physics · Physics 2009-11-07 L. K. Thomsen , S. Mancini , H. M. Wiseman

Spin squeezed states provide a seminal example of how the structure of quantum mechanical correlations can be controlled to produce metrologically useful entanglement. Such squeezed states have been demonstrated in a wide variety of…

The interaction of classical and quantized electromagnetic fields with an ensemble of atoms in an optical cavity is considered. Four fields drive a double-lambda level scheme in the atoms, consisting of a pair of lambda systems sharing the…

Quantum Physics · Physics 2007-05-23 A. Dantan , M. Pinard , P. R. Berman

Quantum phase transitions have long been studied in their relation to quantum fluctuations. These fluctuations can be quantified as the degree of spin squeezing in spin models, where one of the two non-commutative observables breaks the…

Strongly Correlated Electrons · Physics 2023-08-11 Cheuk Yiu Wong , Hadi Cheraghi , Wing Chi Yu