It's not possible to connect two QML objects living in different threads

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include <QQmlComponent>
#include <QDebug>
#include <thread>

int main(int argc, char *argv[])
{
  QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
  QGuiApplication app(argc, argv);

  // Create a first engine in the main thread
  QQmlApplicationEngine engine;
  engine.load(QUrl(QLatin1String("qrc:/main.qml")));

  std::thread t{
    [&] {
      QEventLoop loop;

      // A second engine in another thread ; the main engine's root object is put as a context property.
      QQmlEngine engine2;
      engine2.globalObject().setProperty("hello", engine2.newQObject(engine.rootObjects().first()));
      QQmlComponent comp(&engine2, QUrl(QLatin1String("qrc:/dada.qml")));

      auto obj = comp.create();
      obj->setParent(&engine2);
      loop.exec();
    }
  };

  return app.exec();
}

import QtQuick 2.7
import QtQuick.Controls 2.0
import QtQuick.Layouts 1.0

ApplicationWindow {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")

    property real tutu
    Slider {
        onVisualPositionChanged: tutu = visualPosition
    }
}

import QtQuick 2.5
import QtQml 2.2

Item {
    id: self
    property real tata

    // The part that does not work : 
    Binding {
        target: self
        property: "tata"
        value: hello.tutu
    }
}