Neutron spin echo is a "quantum tale of two paths''

• URL: http://arxiv.org/abs/2309.03987v2
• Date: Thu, 14 Mar 2024 13:56:00 GMT
• Title: Neutron spin echo is a "quantum tale of two paths''
• Authors: S. McKay, A. A. M. Irfan, Q. Le Thien, N. Geerits, S. R. Parnell, R. M. Dalgliesh, N. V. Lavrik, I. I. Kravchenko, G. Ortiz, R. Pynn,
• Abstract summary: We show that the usual semi-classical, single-path treatment of Larmor precession of a polarized neutron in an external magnetic field predicts a damping as a function of the spin echo length of the SESANS signal. No such damping is observed experimentally, implying either that the Larmor model is incorrect or that the transverse extent of the wave packet is very large. In contrast, we demonstrate theoretically that a quantum-mechanical interferometric model in which the two mode-entangled spin states of a single neutron are separated in space when they interact with the grating accurately predicts the measured SESANS signal.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We describe an experiment that strongly supports a two-path interferometric model in which the spin-up and spin-down components of each neutron propagate coherently along spatially separated parallel paths in a typical neutron spin echo small angle scattering (SESANS) experiment. Specifically, we show that the usual semi-classical, single-path treatment of Larmor precession of a polarized neutron in an external magnetic field predicts a damping as a function of the spin echo length of the SESANS signal obtained with a periodic phase grating when the transverse width of the neutron wave packet is finite. However, no such damping is observed experimentally, implying either that the Larmor model is incorrect or that the transverse extent of the wave packet is very large. In contrast, we demonstrate theoretically that a quantum-mechanical interferometric model in which the two mode-entangled (i.e. intraparticle entangled) spin states of a single neutron are separated in space when they interact with the grating accurately predicts the measured SESANS signal, which is independent of the wave packet width.

Related papers

• Conventional and unconventional Dicke models: Multistabilities and nonequilibrium dynamics [0.0]
  The stability and dynamics of the system in the thermodynamic limit are examined using a semiclassical approach. We perform small-scale full quantum-mechanical calculations, with results consistent with the semiclassical ones.
  arXiv  Detail & Related papers  (2023-07-11T18:00:12Z)
• Spin-Textured Neutron Beams with Orbital Angular Momentum [0.0]
  We present a rigorous theoretical framework underpinning the technique of spin-echo modulated small-angle neutron scattering (SEMSANS) We show how the technique can be extended in order to generate spin-textured neutron beams with orbital angular momentum (OAM) via birefringent neutron spin-polarization devices known as magnetic Wollaston prisms.
  arXiv  Detail & Related papers  (2022-07-25T18:00:01Z)
• Quantum chaos and thermalization in the two-mode Dicke model [77.34726150561087]
  We discuss the onset of quantum chaos and thermalization in the two-mode Dicke model. The two-mode Dicke model exhibits normal to superradiant quantum phase transition. We show that the temporal fluctuations of the expectation value of the collective spin observable around its average are small and decrease with the effective system size.
  arXiv  Detail & Related papers  (2022-07-08T11:16:29Z)
• Dispersive readout of molecular spin qudits [68.8204255655161]
  We study the physics of a magnetic molecule described by a "giant" spin with multiple $d > 2$ spin states. We derive an expression for the output modes in the dispersive regime of operation. We find that the measurement of the cavity transmission allows to uniquely determine the spin state of the qudits.
  arXiv  Detail & Related papers  (2021-09-29T18:00:09Z)
• Fano interference in quantum resonances from angle-resolved elastic scattering [62.997667081978825]
  We show that probing the angular dependence of the cross section allows us to unveil asymmetric Fano profiles in a single channel shape resonance. We observe a shift in the peak of the resonance profile in the elastic collisions between metastable helium and deuterium molecules.
  arXiv  Detail & Related papers  (2021-05-12T20:41:25Z)
• Geometrical Hall effect and momentum-space Berry curvature from spin-reversed band pairs [0.0]
  nanometric, noncoplanar spin textures with scalar spin chirality (SSC) are coupled to itinerant electrons. The resulting deflection of moving charge carriers is termed geometrical (or topological) Hall effect. We show that SOC mixes electronic bands with equal or opposite spin, while SSC is much more effective for opposite spin band pairs.
  arXiv  Detail & Related papers  (2020-10-19T14:10:03Z)
• Fractional quantum Hall physics and higher-order momentum correlations in a few spinful fermionic contact-interacting ultracold atoms in rotating traps [0.0]
  This paper provides benchmark results for $N$-body spin-unresolved, as well as spin-resolved, momentum correlations measurable in time-of-flight experiments with individual particle detection. The application of a small perturbing stirring potential induces, at the ensuing avoided crossings, formation of symmetry broken states exhibiting ordered polygonal-ring structures. Analysis of the calculated LLL wavefunction enables a two-dimensional generalization of the Girardeau one-dimensional 'fermionization' scheme, originally invoked for mapping of bosonic-type wave functions to those of spinless fermions.
  arXiv  Detail & Related papers  (2020-06-17T02:08:13Z)
• Geometric phase of very slow neutrons [0.0]
  The geometric phase acquired by a neutron passing through a uniform magnetic field elucidates a subtle interplay between its spatial and spin degrees of freedom. In the standard setup using thermal neutrons, the kinetic energy is much larger than the typical Zeeman split. This causes the spin to undergo nearly perfect precession around the axis of the magnetic field and the GP becomes a function only of the corresponding cone angle.
  arXiv  Detail & Related papers  (2020-03-30T18:39:40Z)
• Theory of waveguide-QED with moving emitters [68.8204255655161]
  We study a system composed by a waveguide and a moving quantum emitter in the single excitation subspace. We first characterize single-photon scattering off a single moving quantum emitter, showing both nonreciprocal transmission and recoil-induced reduction of the quantum emitter motional energy.
  arXiv  Detail & Related papers  (2020-03-20T12:14:10Z)
• Zitterbewegung and Klein-tunneling phenomena for transient quantum waves [77.34726150561087]
  We show that the Zitterbewegung effect manifests itself as a series of quantum beats of the particle density in the long-time limit. We also find a time-domain where the particle density of the point source is governed by the propagation of a main wavefront. The relative positions of these wavefronts are used to investigate the time-delay of quantum waves in the Klein-tunneling regime.
  arXiv  Detail & Related papers  (2020-03-09T21:27:02Z)
• Optical Magnetometer: Quantum Resonances at pumping repetition rate of 1/n of the Larmor frequency [58.720142291102135]
  Quantum sub-resonances at a repetition rate of $1/n$ of the Larmor frequency of the magnetic field inside the shield are experimentally observed and theoretically explained. Investigations in single alkali atoms cells as well as mixed alkali atoms of K and Rb are presented.
  arXiv  Detail & Related papers  (2020-02-20T09:14:56Z)

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.