Large violation of Leggett-Garg inequalities with coherent-state projectors for a harmonic oscillator and chiral scalar field

• URL: http://arxiv.org/abs/2401.10692v2
• Date: Mon, 29 Jan 2024 08:02:31 GMT
• Title: Large violation of Leggett-Garg inequalities with coherent-state projectors for a harmonic oscillator and chiral scalar field
• Authors: Tomoya Hirotani, Akira Matsumura, Yasusada Nambu, Kazuhiro Yamamoto
• Abstract summary: We investigate violations of Leggett-Garg inequalities (LGIs) for a harmonic oscillator and a (1+1)-dimensional chiral scalar field with coherent-state projectors. We find that the vacuum and thermal states violated the LGIs by evaluating the two-time quasi-probability distribution function. We also find a violation of the LGIs for the local mode of a quantum chiral scalar field by constructing a coherent-state projector.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We investigate violations of Leggett-Garg inequalities (LGIs) for a harmonic oscillator and a (1+1)-dimensional chiral scalar field with coherent-state projectors, which is equivalent to a heterodyne-type measurement scheme. For the harmonic oscillator, we found that the vacuum and thermal states violated the LGIs by evaluating the two-time quasi-probability distribution function. In particular, we demonstrate that the value of the two-time quasi-probability reaches -0.123 for a squeezed coherent-state projector, which is equivalent to 98% of the L\"uders bound corresponding to the maximal violation of the LGIs. We also find a violation of the LGIs for the local mode of a quantum chiral scalar field by constructing a coherent-state projector similar to the harmonic oscillator case. In contrast to the harmonic oscillator, the periodicity in the time direction of the quasi-probability disappears, which is related to the existence of quantum entanglement between the local mode and its complementary degrees of freedom.

Related papers

• Violation of the two-time Leggett-Garg inequalities for a harmonic oscillator [0.0]
  We develop a new formula to compute the two-time quasi-probability distribution function. We discuss when the Leggett-Garg inequalities are violated in an intuitive manner.
  arXiv  Detail & Related papers  (2023-10-25T08:52:00Z)
• Finite Pulse-Time Effects in Long-Baseline Quantum Clock Interferometry [45.73541813564926]
  We study the interplay of the quantum center-of-mass $-$ that can become delocalized $-$ together with the internal clock transitions. We show at the example of a Gaussian laser beam that the proposed quantum-clock interferometers are stable against perturbations from varying optical fields.
  arXiv  Detail & Related papers  (2023-09-25T18:00:03Z)
• Unconditional Wigner-negative mechanical entanglement with linear-and-quadratic optomechanical interactions [62.997667081978825]
  We propose two schemes for generating Wigner-negative entangled states unconditionally in mechanical resonators. We show analytically that both schemes stabilize a Wigner-negative entangled state that combines the entanglement of a two-mode squeezed vacuum with a cubic nonlinearity. We then perform extensive numerical simulations to test the robustness of Wigner-negative entanglement attained by approximate CPE states stabilized in the presence of thermal decoherence.
  arXiv  Detail & Related papers  (2023-02-07T19:00:08Z)
• Slow semiclassical dynamics of a two-dimensional Hubbard model in disorder-free potentials [77.34726150561087]
  We show that introduction of harmonic and spin-dependent linear potentials sufficiently validates fTWA for longer times. In particular, we focus on a finite two-dimensional system and show that at intermediate linear potential strength, the addition of a harmonic potential and spin dependence of the tilt, results in subdiffusive dynamics.
  arXiv  Detail & Related papers  (2022-10-03T16:51:25Z)
• Quantum vibrational mode in a cavity confining a massless spinor field [91.3755431537592]
  We analyse the reaction of a massless (1+1)-dimensional spinor field to the harmonic motion of one cavity wall. We demonstrate that the system is able to convert bosons into fermion pairs at the lowest perturbative order.
  arXiv  Detail & Related papers  (2022-09-12T08:21:12Z)
• Coherently Coupled Mechanical Oscillators in the Quantum Regime [0.0]
  We show coherent exchange of single motional quanta between harmonic oscillators. We demonstrate high-fidelity quantum state transfer, entanglement of motional modes, and Hong-Ou-Mandel-type interference.
  arXiv  Detail & Related papers  (2022-05-30T04:04:26Z)
• Leggett-Garg tests for macrorealism in the quantum harmonic oscillator and more general bound systems [0.0]
  We present a simple method to calculate the temporal correlation functions appearing in the LG inequalities for any bound system. We find substantial regions of parameter space in which the LG inequalities at two, three and four times can each be independently violated or satisfied. We also show that two-time LG violations in a gaussian state are readily found if the dichotomic variable at one of the times is taken to be the parity operator.
  arXiv  Detail & Related papers  (2021-09-07T14:27:21Z)
• Localized vibrational modes in waveguide quantum optomechanics with spontaneously broken PT symmetry [117.44028458220427]
  We study theoretically two vibrating quantum emitters trapped near a one-dimensional waveguide and interacting with propagating photons. In the regime of strong optomechanical interaction the light-induced coupling of emitter vibrations can lead to formation of spatially localized vibration modes, exhibiting parity-time symmetry breaking.
  arXiv  Detail & Related papers  (2021-06-29T12:45:44Z)
• Leggett-Garg tests for macrorealism: interference experiments and the simple harmonic oscillator [0.0]
  Leggett-Garg tests for macrorealism were originally designed to explore quantum coherence on the macroscopic scale. We show that LG violations are always accompanied by destructive interference. We also exhibit examples of some surprising relationships between LG inequalities and NSIT conditions that do not exist for dichotomic variables.
  arXiv  Detail & Related papers  (2020-09-08T16:46:36Z)
• Non-Markovianity of Quantum Brownian Motion [0.0]
  We study quantum non-Markovian dynamics of the Caldeira-Leggett model, a prototypical model for quantum Brownian motion. A comparison of our results with the corresponding results for the spin-boson problem show a remarkable similarity in the structure of non-Markovian behavior of the two paradigmatic models.
  arXiv  Detail & Related papers  (2020-07-06T16:35:09Z)
• Equivalence of approaches to relational quantum dynamics in relativistic settings [68.8204255655161]
  We show that the trinity' of relational quantum dynamics holds in relativistic settings per frequency superselection sector. We ascribe the time according to the clock subsystem to a POVM which is covariant with respect to its (quadratic) Hamiltonian.
  arXiv  Detail & Related papers  (2020-07-01T16:12:24Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.