Quantum entanglement, dephasing and decoherence effects in neutron experiments

01.01.2009 - 19.05.2014
Research funding project
Fundamental quantum properties like quantum coherence and entanglement are amoung the most interesting features of quantum mechanics which are studied nowadays. They form the basis for the new, fast developing fields of quantum information and computation. The project aims at a deeper understanding of quantum physics, by investigating especially two peculiar features: entanglement and decoherence. The physical system of interest is the (massive) neutron subjected to interferometric and polarimetric measurements. The study of quantum features in massive systems, in contrast to photonic systems, is appealing but also challenging. Neutrons are proper objects for a study of quantum mechanical behaviour of spin-1/2 systems: they allow for rather easy experimental control and the neutron spin is the simplest two-level system with easy manipulation by magnetic fields. As seen in the past, many quantum phenomena have first been observed with neutrons and afterwards studied in other systems. In combination with interferometric measurements the system has enough intrinsical richness to show interesting quantum features such as entanglement. The coupling of the neutron to an external magnetic field allows for selective manipulations of the spinor quantum states. This can be used, on the one hand, to create entangled states where the entanglement occurs between different degrees of freedom (e.g., spin and path) and, on the other hand, one can introduce dephasing and decoherence by varying magnetic fields. Both aspects of quantum physics manifested in neutron interferometry are of importance and will be investigated in detail during the research project. The results obtained in this research proposal are of fundamental interest. It is clear that neutrons are very suitable particles to test and implement the basic features of quantum mechanics because they can be easily manipulated and controlled during the experimental procedure without disturbances in contrast to atoms or molecules. Besides analysis of fundamental quantum physical questions such as entanglement and decoherence, the project delivers answers on how a particle with spin behaves and interacts with a magnetic field. The obtained results have a wide range of applications, e.g. in atom optics where the behaviour of atoms and their coupling to magnetic fields is of interest and the theoretical results can be directly applied to these systems. Beyond the theoretical work of the proposal it is possible via the intensive contact with experimental physicists to develop experimental strategies to check the results directly in suitably designed experiments. The experimental work is done at the Institute Laue-Langvine (ILL) in Grenoble, France.

People

Project leader

Institute

Grant funds

  • FWF - Österr. Wissenschaftsfonds (National) Austrian Science Fund (FWF)

Research focus

  • Quantum Metrology and Precision Measurements: 20%
  • Quantum Modeling and Simulation: 40%
  • Design and Engineering of Quantum Systems: 40%

Keywords

GermanEnglish
Neutroneninterferometrie, NeutronenpolarimetrieNeutron interferometry, neutron polarimetry
Verschränkung für EinzelteilchenEntanglement for single particles
Dekohärenz und DephasierungDecoherence and dephasing
Zeitabhängige MagnetfelderTime-dependent magnetic fields
PhotonenaustauschprozessePhoton exchange processes

Publications