Violations of the Leggett–Garg inequality for coherent and cat states

Azuma, Hiroo; Ban, Masashi

doi:10.1140/epjd/s10053-021-00180-x

Cited by 2 publications

(4 citation statements)

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“…with Ω = ω − iΓ [5,23,24]. Here, we draw attention to the fact that the time evolution of the initial state |α is given by |α exp(−iΩt) .…”

Section: This Work Was Supported By Mext Quantum Leap Flagship Progra...mentioning

confidence: 99%

“…Because the LGI requires QND measurements, a simple quantum circuit for measuring the observable is preferable. So far, the Pauli operators for a qubit system and the displaced parity operators for a boson system have been used as the observables [4,5]. The LGI for a damped qubit system with Pauli operators as the observables was examined by solving the master equation with the quantum regression theorem [4].…”

Section: Introductionmentioning

confidence: 99%

“…The LGI for a damped qubit system with Pauli operators as the observables was examined by solving the master equation with the quantum regression theorem [4]. Further, the LGI of a boson system weakly coupled to a zero-temperature environment with displacement parity operator observables was shown for a coherent initial state to produce a larger violation than the cat state [5].…”

Section: Introductionmentioning

confidence: 99%

“…We study the LGIs for a boson system weakly coupled to a zero-temperature environment. In this scenario, we can solve the master equation of the boson system exactly in a closed-form expression [5,23,24].…”

Section: Introductionmentioning

confidence: 99%

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Leggett-Garg inequalities with deformed Pegg-Barnett phase observables

Azuma¹,

Munro²,

Nemoto³

2022

Preprint

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We investigate the Leggett-Garg inequalities (LGIs) for a boson system whose observables are given by deforming the Pegg-Barnett phase operator. We consider two observables for the LGIs and show that the quantum Fourier transform is useful to realize the required measurements. Deriving explicit forms of the LGIs with a coherent state |α input, we examine whether or not they are violated when the time difference between observations of the phase operators is varied. We show that the system remains nonclassical in the large amplitude limit without dissipation. By contrast with dissipation, our violation of the LGI diminishes rapidly.

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“…with Ω = ω − iΓ [5,23,24]. Here, we draw attention to the fact that the time evolution of the initial state |α is given by |α exp(−iΩt) .…”

Section: This Work Was Supported By Mext Quantum Leap Flagship Progra...mentioning

confidence: 99%