Li and Rau Reply:

Li, J.; Rau, C.

doi:10.1103/physrevlett.100.179701

Cited by 64 publications

(124 citation statements)

References 20 publications

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“…Thus, despite of the three times reduction in the effective strength (χ/3) of the transformed Hamiltonian H eff , the time for observing the optimal SS remains almost the same. Consequently, we expect degradation from atomic losses will be similar to the case of OAT [27].…”

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confidence: 94%

Spin Squeezing: Transforming One-Axis Twisting into Two-Axis Twisting

et al. 2011

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Squeezed spin states possess unique quantum correlation or entanglement that are of significant promises for advancing quantum information processing and quantum metrology. In recent back to back publications [C. Gross et al, Nature 464, 1165 and Max F. Riedel et al, Nature 464, 1170Nature 464, (2010], reduced spin fluctuations are observed leading to spin squeezing at −8.2dB and −2.5dB respectively in two-component atomic condensates exhibiting one-axis-twisting interactions (OAT). The noise reduction limit for the OAT interaction scales as ∝ 1/N 2/3 , which for a condensate with N ∼ 10 3 atoms, is about 100 times below standard quantum limit. We present a scheme using repeated Rabi pulses capable of transforming the OAT spin squeezing into the two-axis-twisting type, leading to Heisenberg limited noise reduction ∝ 1/N , or an extra 10-fold improvement for N ∼ 10 3 .PACS numbers: 42.50.-p, 03.75.GgSqueezed spin states (SSS) [2,3] are entangled quantum states of a collection of spins in which the correlations among individual spins reduce quantum uncertainty of a particular spin component below the classical limit for uncorrelated particles [2]. Research in SSS is a topical area due to its significant applications in high-precision measurements [3][4][5][6][7][8][9][10] and in quantum information science [11][12][13][14][15]. Squeezed spin states were first introduced by Kitagawa and Ueda, who considered two ways to produce them. The simplest to implement uses a "one-axis twisting" (OAT) Hamiltonian, but the state it produces does not have ideal squeezing properties. A more complex approach uses a "two-axis twisting" (TAT) Hamiltonian and produces an improved state. Other mechanisms for producing SSS have also been investigated, especially those based on atom-photon interactions [16,17] and quantum non-demolition measurements [18][19][20][21].Atomic Bose-Einstein condensates are promising systems for observing spin squeezing. Assuming fixed spatial modes, condensed atoms are described by a collection of pseudo-spin 1/2 atoms, with spin up (|↑ ) and down (|↓ ) denoting the two internal states or spatial modes [12,[22][23][24][25]. The two recent experiments [4, 5] raise significant hope for reaching the theoretical limit of spin squeezing ∝ 1/N 2/3 with N the total number of atoms for the OAT model [2]. Both experiments utilize two internal hyperfine states of condensed atoms, with the OAT interaction cleverly constructed from binary atomic collisions, possibly accompanied by systematic and fundamental imperfections not confined to the two state/mode approximation. They can be further degraded by atomic decoherence and dissipation [4,5]. This Letter describes a readily implementable idea for improved spin squeezing in the two experiments. Given the reported OAT model parameters [4,5], we propose a coherent control scheme capable of transforming the OAT into the effective TAT spin squeezing, leading to a Heisenberg limited noise reduction ∝ 1/N , or a further 10 fold improvement for a condensate with ∼ 10 3 at...

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confidence: 94%

Spin Squeezing: Transforming One-Axis Twisting into Two-Axis Twisting

et al. 2011

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“…The electrons in the current sheet can also be pre-energized by reflections between the two bubbles, which is a Fermi-like process. Therefore, the current sheet is thermalized, corresponding to a high-beta magnetic reconnection which has a low efficiency at converting magnetic energy into the electron kinetic energy [54]. This is why the electron energization by magnetic reconnection is less significant than the enegization by the magnetic flux pileup and plasma bubble expansion.…”

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confidence: 99%

Particle-in-cell simulations of electron energization in laser-driven magnetic reconnection

Guo

et al. 2016

New J. Phys.

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Electrons can be energized during laser-driven magnetic reconnection, and the energized electrons form three super-Alfvénic electron jets in the outflow region (Lu et al 2014 New J. Phys. 16 083021). In this paper, by performing two-dimensional particle-in-cell simulations, we find that the electrons can also be significantly energized before magnetic reconnection occurs. When two plasma bubbles with toroidal magnetic fields expand and squeeze each other, the electrons in the magnetic ribbons are energized through betatron acceleration due to the enhancement of the magnetic field, and an electron temperature anisotropy T T e e > develops. Meanwhile, some electrons are trapped and bounced repeatedly between the two expanding/approaching bubbles and get energized through a Fermi-like process. The energization before magnetic reconnection is more significant (or important) than that during magnetic reconnection.

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“…The double‐ζ and single‐ζ plus polarization basis sets are chosen for carbon and gold atoms, respectively. The electrode temperature is set to 300 K. Although the energy of the spin‐polarized state is about 20 meV per edge atom lower than that of spin‐unpolarized state, the energy is too small to stabilize the spin‐polarized state which would become unstable at finite temperature or in the presence of ballistic current through the device 15. To show the detectable transport properties in experiments, we just consider the spin‐unpolarized state.…”

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confidence: 99%

Effects of contact oxidization on the transport properties of Au/ZGNR junctions

Zhang

Xiao

et al. 2012

Physica Rapid Research Ltrs

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The transport properties of the junction assembled by zigzag graphene nanoribbons (ZGNRs) and Au electrode (Au/ZGNR) are investigated using first‐principles calculations. It is found that the Au/ZGNR junction behaves as a typical diode with Schottky barrier at the contact. Our results indicate that although the oxidization at the contact slightly influences the Schottky barrier, the I –V characteristic is effectively modulated. Such effect derives from the impact of the oxidization on the coupling between the ZGNRs and Au electrode. Au/ZGNR junction oxidized by C=O groups at the contact and relative I –V curves. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Li and Rau Reply:

Cited by 64 publications

References 20 publications

Spin Squeezing: Transforming One-Axis Twisting into Two-Axis Twisting

Spin Squeezing: Transforming One-Axis Twisting into Two-Axis Twisting

Particle-in-cell simulations of electron energization in laser-driven magnetic reconnection

Effects of contact oxidization on the transport properties of Au/ZGNR junctions

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