Testing macroscopic local realism using cat-states and Bell inequalities in time

Abstract

We show how one may test macroscopic local realism where, different from conventional Bell tests, all relevant measurements need only distinguish between two macroscopically distinct states of the system being measured. Here, measurements give macroscopically distinguishable outcomes for a system observable and do not resolve microscopic properties (of order $\hslash$). Macroscopic local realism assumes: (1) macroscopic realism (the system prior to measurement is in a state which will lead to just one of the macroscopically distinguishable outcomes) and (2) macroscopic locality (a measurement on a system at one location cannot affect the macroscopic outcome of the measurement on a system at another location, if the measurement events are spacelike separated). To obtain a quantifiable test, we define $M$-scopic local realism where the outcomes are separated by an amount $\sim M$. We first show for $N$ up to $20$ that $N$-scopic Bell violations are predicted for entangled superpositions of $N$ bosons (at each of two sites). Secondly, we show violation of $M$-scopic local realism for entangled superpositions of coherent states of amplitude $\alpha$, for arbitrarily large $M=\alpha$. In both cases, the systems evolve dynamically according to a local nonlinear interaction. The first uses nonlinear beam splitters realised through nonlinear Josephson interactions; the second is based on nonlinear Kerr interactions. To achieve the Bell violations, the traditional choice between two spin measurement settings is replaced by a choice between different times of evolution at each site.

arXiv comment5 pages, 4 figures, presented at PQE2019, DAMOP 2019

References in corpus (61)

• Bell nonlocality
• Direct Observation of Tunneling and Nonlinear Self-Trapping in a single Bosonic Josephson Junction
• Collapse and Revival of the Matter Wave Field of a Bose-Einstein Condensate
• 14-qubit entanglement: creation and coherence
• Quantum Optical Metrology -- The Lowdown on High-N00N States
• Super-resolving phase measurements with a multi-photon entangled state
• Generation and manipulation of Schrödinger cat states in Rydberg atom arrays
• Observation of quantum state collapse and revival due to the single-photon Kerr effect
• De Broglie Wavelength of a Nonlocal Four-Photon
• Quantum Superposition States of Bose-Einstein Condensates
• Leggett-Garg Inequalities
• Experimental violation of a Bell's inequality in time with weak measurement
• Macroscopic quantum self-trapping and Josephson oscillations of exciton-polaritons
• Quantum Nonlocality in Phase Space
• A Schrodinger Cat Living in Two Boxes
• Bell-type inequalities to detect true n-body non-separability
• Violation of the Leggett-Garg inequality with weak measurements of photons
• Weak values and the Leggett-Garg inequality in solid-state qubits
• Unconditional violation of the shot noise limit in photonic quantum metrology
• Macroscopic quantum states: measures, fragility and implementations
• Experimental violation of a spin-1 Bell inequality using maximally-entangled four-photon states
• Experimental Violation of Two-Party Leggett-Garg Inequalities with Semi-weak Measurements
• Condition for macroscopic realism beyond the Leggett-Garg inequalities
• An atomic Hong-Ou-Mandel experiment
• Quantum limited amplification and entanglement in coupled nonlinear resonators
• Ideal negative measurements in quantum walks disprove theories based on classical trajectories
• Quantum state of two trapped Bose-Einstein condensates with a Josephson coupling
• Violation of a temporal Bell inequality for single spins in solid by over 50 standard deviations
• A strict experimental test of macroscopic realism in a superconducting flux qubit
• Experimental violation of Svetlichny's inequality
• The Two Bell's Theorems of John Bell
• Contradiction of Quantum Mechanics with Local Hidden Variables for Continuous Variable Quadrature Phase Amplitude Measurements
• Leggett-Garg inequality with a kicked quantum pump
• Microwave-Induced Amplitude and Phase Tunable Qubit-Resonator Coupling in Circuit Quantum Electrodynamics
• No Fine theorem for macrorealism: Limitations of the Leggett-Garg inequality
• Creation of maximally entangled photon-number states using optical fiber multiports
• Probing macroscopic realism via Ramsey correlations measurements
• Experimental detection of quantum coherent evolution through the violation of Leggett-Garg-type inequalities
• Strong Violations of Bell-type Inequalities for Path-Entangled Number States
• Proposal for demonstrating the Hong-Ou-Mandel effect with matter waves
• Dynamical Realization of Macroscopic Superposition States of Cold Bosons in a Tilted Double Well
• Signatures for generalized macroscopic superpositions
• Quantum non-demolition measurement enables macroscopic Leggett-Garg tests
• Violation of multi-particle Bell inequalities for low and high flux parametric amplification using both vacuum and entangled input states
• Violation of Bells inequality using continuous variable measurements
• Criteria for generalized macroscopic and mesoscopic quantum coherence
• Quantifying the mesoscopic quantum coherence of approximate NOON states and spin-squeezed two-mode Bose-Einstein condensates
• Demonstrating mesoscopic superpositions in double-well Bose-Einstein condensates
• Macroscopic Local Realism Incompatible with Quantum Mechanics: Failure of Local Realism where Measurements give Macroscopic Uncertainties
• Conditional generation of path-entangled optical NOON states
• Macroscopic Hong-Ou-Mandel interference
• Filtering of the absolute value of photon-number difference for two-mode macroscopic quantum superpositions
• Probabilistic quantum phase-space simulation of Bell violations and their dynamical evolution
• Signifying the nonlocality of NOON states using Einstein-Podolsky-Rosen steering inequalities
• Leggett-Garg tests of macro-realism for multi-particle systems including double-well Bose-Einstein condensates
• Leggett-Garg tests of macro-realism for dynamical cat-states evolving in a nonlinear medium
• Violations of Bell Inequalities for Measurements with Macroscopic Uncertainties: What does it Mean to Violate Macroscopic Local Realism?
• Testing the Clauser-Horne-Shimony-Holt inequality using observables with arbitrary spectrum
• Signifying the Schrodinger cat in the context of testing macroscopic realism
• Proposal for a macroscopic test of local realism with phase-space measurements
• Experimental Demonstration of Macroscopic Quantum Coherence in Gaussian States

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