Theoretical description and experimental simulation of quantum entanglement near open time-like curves via pseudo-density operators

Abstract

Closed timelike curves are striking predictions of general relativity allowing for time-travel. They are afflicted by notorious causality issues (e.g. grandfather's paradox). Quantum models where a qubit travels back in time solve these problems, at the cost of violating quantum theory's linearity - leading e.g. to universal quantum cloning. Interestingly, linearity is violated even by open timelike curves (OTCs), where the qubit does not interact with its past copy, but is initially entangled with another qubit. Non-linear dynamics is needed to avoid violating entanglement monogamy. Here we propose an alternative approach to OTCs, allowing for monogamy violations. Specifically, we describe the qubit in the OTC via a pseudo-density operator - a unified descriptor of both temporal and spatial correlations. We also simulate the monogamy violation with polarization-entangled photons, providing a pseudo-density operator quantum tomography. Remarkably, our proposal applies to any space-time correlations violating entanglement monogamy, such as those arising in black holes.

References in corpus (22)

• Quantum correlations with no causal order
• Quantum computations without definite causal structure
• Hawking Radiation and Black Hole Thermodynamics
• Experimental Verification of an Indefinite Causal Order
• Information Loss
• Quantum Logic and the Histories Approach to Quantum Theory
• Monogamy of nonlocal quantum correlations
• The Black Hole information problem: past, present, and future
• Closed timelike curves via post-selection: theory and experimental demonstration
• Can closed timelike curves or nonlinear quantum mechanics improve quantum state discrimination or help solve hard problems?
• Statistical Estimation of Quantum Tomography Protocols Quality
• Localized closed timelike curves can perfectly distinguish quantum states
• Can a quantum state over time resemble a quantum state at a single time?
• Quantum Entanglement in Time
• Experimental Simulation of Closed Timelike Curves
• Geometry of quantum correlations in space-time
• Relativistic quantum information and time machines
• Dispersion spreading of biphotons in optical fibres and two-photon interference
• Quantum state cloning using Deutschian closed timelike curves
• Open timelike curves violate Heisenberg's uncertainty principle
• Quantum state cloning in the presence of a closed timelike curve
• Replicating the benefits of closed timelike curves without breaking causality

Cited by in corpus (14)

• Temporal teleportation with pseudo-density operators: how dynamics emerges from temporal entanglement
• Quantum Uncertainty Principles for Measurements with Interventions
• Inferring the arrow of time in quantum spatiotemporal correlations
• Quantum space-time marginal problem: global causal structure from local causal information
• Causal classification of spatiotemporal quantum correlations
• Unification of spatiotemporal quantum formalisms: mapping between process and pseudo-density matrices via multiple-time states
• Different instances of time as different quantum modes: quantum states across space-time for continuous variables
• Quantum Causal Inference with Extremely Light Touch
• Agnostic Phase Estimation
• Certifying Quantum Temporal Correlation via Randomized Measurements: Theory and Experiment
• Equivalence of Grandfather and Information Antinomy Under Intervention
• Quantum dynamics as a pseudo-density matrix
• A paradox regarding monogamy of entanglement
• Entanglement of temporal sections as quantum histories and their quantum correlation bounds