A size criterion for macroscopic superposition states

Björk, Gunnar; Mana, PierGianLuca Porta

doi:10.1088/1464-4266/6/11/001

Cited by 67 publications

(138 citation statements)

References 43 publications

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“…It is clear that for large excitations the two coherent states are macroscopically distinct in their quadrature degree of freedom. The mean phase-space separation between the two states is D = 2 √ 2α (as also noted in [40]) and the success rate in discriminating them with the dichotomic homodyne detector is P = 1 − (1 − erf( √ 2α))/2 [41] which is rapidly increasing with the excitation.…”

Section: Coherent State Superpositionsmentioning

confidence: 99%

Heralded generation of a micro-macro entangled state

Andersen

Neergaard-Nielsen

2013

Phys. Rev. A

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Using different optical setups based on squeezed state and photon subtraction we show how optical entanglement between a macroscopic and a microscopic state-the so-called Schrödinger cat state or micro-macro state-can be generated. The entangled state is heralded and is thus produced a priori in contrast to previous proposals. We define the macroscopicity of the macroscopic part of the state as their mean distance in phase space and the success rate in discriminating them with homodyne detection, and subsequently, based on these measures we investigate the macroscopicity of different states. Furthermore, we show that the state can be used to map a microscopic qubit onto a macroscopic one thereby linking a qubit processor with a qumode processor.

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Section: Coherent State Superpositionsmentioning

confidence: 99%

Heralded generation of a micro-macro entangled state

Andersen

Neergaard-Nielsen

2013

Phys. Rev. A

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“…These measures are called measures of quantum macrosopicity. To this end, various proposals have been suggested [10,[13][14][15][16][17][18][19][20]. The basic idea used in all these proposals is that macroscopic superposition entails a large amount of uncertainty when a suitably chosen macroscopic observable is measured.…”

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confidence: 99%

Scaling of macroscopic superpositions close to a quantum phase transition

Abad¹,

Karimipour²

2016

Phys. Rev. B

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It is well known that in a quantum phase transition (QPT), entanglement remains short ranged [Osterloh et al., Nature 416 608-610 (2005)]. We ask if there is a quantum property entailing the whole system which diverges near this point. Using the recently proposed measures of quantum macroscopisity, we show that near a quantum critical point, it is the effective size of macroscopic superposition between the two symmetry breaking states which grows to the scale of system size and its derivative with respect to the coupling shows both singular behavior and scaling properties.

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“…The most notable approaches have been based on the number of particles that are e ectively involved in the quantum superposition of distinguishable states of a sys-*Corresponding Author: Andrew Carlisle: Centre for Theoretical Atomic, Molecular, and optical Physics, School of Mathematics and Physics, Queen's University Belfast, BT7 1NN Belfast (UK), E-mail: appassionale1@gmail.com tem [12][13][14][15] and distinguishability between the constituent states [13,[16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%