Decoherence in a double-slit quantum eraser

Abstract

We study and experimentally implement a double-slit quantum eraser in the presence of a controlled decoherence mechanism. A two-photon state, produced in a spontaneous parametric down conversion process, is prepared in a maximally entangled polarization state. A birefringent double-slit is illuminated by one of the down-converted photons, and it acts as a single-photon two-qubits controlled not gate that couples the polarization with the transversal momentum of these photons. The other photon, that acts as a which-path marker, is sent through a Mach-Zehnder-like interferometer. When the interferometer is partially unbalanced, it behaves as a controlled source of decoherence for polarization states of down-converted photons. We show the transition from wave-like to particle-like behavior of the signal photons crossing the double-slit as a function of the decoherence parameter, which depends on the length path difference at the interferometer.Comment: Accepted in Physical Review

Extracting an electron's angle of return from shifted interference patterns in macroscopic high-order-harmonic spectra of diatomic molecules

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“…For example, if one measures the distribution P (x), then the distributions P (n) and P (r) can be calculated directly using definitions (6). The same is true for the momentum variables.…”

“…The early discussions between Bohr and Einstein concerning the validity of the complementarity principle and wave-particle duality centered around the appearance (or not) of double-slit interference when one attempts to mark the passage of the particle through the slits [1]. Later, it was shown that the entanglement between the particles and a quantum "which-path" marker allows one to register the passage of the particle through the double slit and subsequently erase that information, recovering an interference pattern [2][3][4][5][6].…”

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