Is state tomography an unambiguous test of quantum entanglement?

Abstract

We provide an alternative interpretation of recently published experimental results that were represented as demonstrating entanglement between two macroscopic quantum Josephson oscillators. We model the experimental system using the well-established classical equivalent circuit of a resistively and capacitively shunted junction. Simulation results are used to generate the corresponding density matrix, which is strikingly similar to the previously published matrix that has been declared to be an unambiguous demonstration of quantum entanglement. Since our data are generated by a classical model, we therefore submit that state tomography cannot be used to determine absolutely whether or not quantum entanglement has taken place. Analytical arguments are given for why the classical analysis provides an adequate explanation of the experimental results.

Four pages, two figures

References in corpus (6)

• Rabi Oscillations and Few-Level Approximations in Time-Dependent Density Functional Theory
• Rabi-type oscillations in a classical Josephson junction
• Classical analysis of phase-locking transients and Rabi-type oscillations in microwave-driven Josephson junctions
• A Classical Analysis of Capacitively Coupled Superconducting Qubits
• On the Classical Model for Microwave Induced Escape from a Josephson Washboard Potential
• Classical analogs for Rabi-oscillations, Ramsey-fringes, and spin-echo in Josephson junctions

Cited by in corpus (10)

• A survey of classical and quantum interpretations of experiments on Josephson junctions at very low temperatures
• Josephson junction-based axion detection through resonant activation
• A Review of Design Concerns in Superconducting Quantum Circuits
• Dynamic Quantum Tunneling in Mesoscopic Driven Duffing Oscillators
• Breakdown of the classical description of a local system
• A classical statistical model for distributions of escape events in swept-bias Josephson junctions
• Optical squeezing for an optomechanical system without quantising the mechanical motion
• Switching Current Distributions in Josephson Junctions at Very Low Temperatures
• Analysis of patent activity in the field of quantum information processing
• Strictly nonclassical behavior of a mesoscopic system