Elementary test for nonclassicality based on measurements of position and momentum

Fresta, Luca; Borregaard, Johannes; Sørensen, Anders S.

doi:10.1103/physreva.92.062111

Cited by 3 publications

(3 citation statements)

References 24 publications

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“…Experimental measurement of Wigner function negativity requires the development of mechanical state tomography [66]. It may be shown that squeezing a state does not hamper the ability to reconstruct the state Wigner function from measurements of its marginal distributions [67]. As part of this, the quadrature squeezing could also be introduced as simultaneous with the Kerr evolution rather than as a prior step.…”

Section: Discussionmentioning

confidence: 99%

Enhancing the Formation of Wigner Negativity in a Kerr Oscillator via Quadrature Squeezing

Rosiek¹

2022

Preprint

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Motivated by quantum experiments with nanomechanical systems, the evolution of a Kerr oscillator with focus on creation of states with a negative Wigner function is investigated. Using the phase space formalism, results are presented that demonstrate an asymptotic behavior in the large squeezing regime for the negativity of a squeezed vacuum state under unitary evolution. The analysis and model are extended to squeezed vacuum states of open systems, adding the decoherence effects of damping and dephasing. To increase experimental relevance, the regime of strong damping is considered. These effects are investigated, yielding similar asymptotic results for the behavior of these effects in the large squeezing regime. Combining these results, it is shown that a weak nonlinearity as compared to damping may be improved by increasing the squeezing of the initial state. It is also shown that this may be done without exacerbating the effects of dephasing.

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Section: Discussionmentioning

confidence: 99%

Enhancing the Formation of Wigner Negativity in a Kerr Oscillator via Quadrature Squeezing

Rosiek¹

2022

Preprint

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“…We term this the phase space distribution (PSD) criterion. The PSD criterion has already been experimentally verified for the electromagnetic field associated with a single photon [38], and expanded theoretically to some more general cases [39] in quantum optics.In this Rapid Communication, we apply a modified PSD criterion to the magnetization measurement of the atomic ensemble reported in Ref. [40].…”

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Strictly nonclassical behavior of a mesoscopic system

Vendeiro

Chen

et al. 2017

Phys. Rev. A

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We experimentally demonstrate the strictly nonclassical behavior in a many-atom system using a recently derived criterion [E. Kot et al., Phys. Rev. Lett. 108, 233601 (2012)] that explicitly does not make use of quantum mechanics. We thereby show that the magnetic-moment distribution measured by McConnell et al. [Nature (London) 519, 439 (2015)] in a system with a total mass of 2.6 × 10 5 atomic mass units is inconsistent with classical physics. Notably, the strictly nonclassical behavior affects an area in phase space 10 3 times larger than the Planck quantumh. DOI: 10.1103/PhysRevA.95.030105 Ever since the advent of modern quantum theory almost a century ago, one perplexing question has been the boundary between quantum mechanics and classical physics. Considering just two particles, Bell showed [1,2] that reasonable assumptions consistent with classical physics lead to predictions that are inconsistent with the measurement results [3][4][5][6][7]. For macroscopic systems, Schrödinger's gedanken experiment of a simultaneously dead and alive cat highlights the question about the quantum-classical boundary in larger and larger systems [8][9][10][11][12][13][14][15]. Within the conceptual framework of quantum mechanics, one can establish definite and quantitative criteria for entanglement [16][17][18][19][20], and hence potential nonclassicality. However, one may argue that an experiment never confirms a theory as valid, but only fails to violate it. Therefore, mere consistency with results derived from quantum mechanics does not rule out a description within classical physics. It is therefore interesting to identify and experimentally test criteria that are formulated within classical physics, without assuming the validity or concepts of quantum mechanics [21].In quantum optics, criteria that distinguish nonclassical states of light from classical ones [22][23][24][25][26][27][28][29] were developed early, and tested successfully in experiments [30,31], such as antibunching [22,23,30], Klyshko's criterion [24,25], and nonclassical statistical properties [22,[26][27][28][29]31]. Some of these demonstrations [30,31] have become standard methods to verify classes of nonclassical states, such as the singlephoton states [30], and sub-Poissonian states [31].More tests have been performed on atomic and molecular systems. One such approach is to test the wave properties of larger and larger molecules, and one day perhaps even living objects, through double-slit interference experiments [32]. The largest objects to date for which matter-wave interference fringes have been observed are molecules consisting of 430 atoms, with a total mass of 6910 atomic mass units (amu) [12], and interference experiments with even larger molecules appear possible [13][14][15]. Another possible test ground are superconducting qubits, where superpositions of current involving several thousand electrons have been inferred [33].Other methods to detect the breakdown of classical physics have been proposed [34][35][36], and some of them have...

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Quadrature Squeezing Enhances Wigner Negativity in a Mechanical Duffing Oscillator

Rosiek,

Rossi,

Schliesser

et al. 2024

PRX Quantum

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Generating macroscopic nonclassical quantum states is a long-standing challenge in physics. Anharmonic dynamics is an essential ingredient to generate these states, but for large mechanical systems, the effect of the anharmonicity tends to become negligible compared with the effect of decoherence. As a possible solution to this challenge, we propose using a motional squeezed state as a resource to effectively increase the anharmonicity. We analyze the production of negativity in the Wigner distribution of a quantum anharmonic resonator initially in a squeezed state. We find that initial squeezing increases the rate at which negativity is generated. We also analyze the effect of two common sources of decoherence—namely, energy damping and dephasing—and find that the detrimental effects of energy damping are suppressed by strong squeezing. In the limit of large squeezing, which is needed for state-of-the-art systems, we find good approximations for the Wigner function. Our analysis is significant for current experiments attempting to prepare macroscopic mechanical systems in genuine quantum states. We provide an overview of several experimental platforms featuring nonlinear behaviors and low levels of decoherence. In particular, we discuss the feasibility of our proposal with carbon nanotubes and levitated nanoparticles. Published by the American Physical Society 2024

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Elementary test for nonclassicality based on measurements of position and momentum

Cited by 3 publications

References 24 publications

Enhancing the Formation of Wigner Negativity in a Kerr Oscillator via Quadrature Squeezing

Enhancing the Formation of Wigner Negativity in a Kerr Oscillator via Quadrature Squeezing

Strictly nonclassical behavior of a mesoscopic system

Quadrature Squeezing Enhances Wigner Negativity in a Mechanical Duffing Oscillator

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