2012/02/24 by F. De Martini, Francesco De Martini, Fabio Sciarrino
Computer Science · Physics and Astronomy · #Open quantum system #Photon #Physics #Quantum #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum cloning #Quantum decoherence #Quantum dissipation #Quantum entanglement #Quantum error correction #Quantum information #Quantum mechanics #Quantum network #Quantum optics and atomic interactions #Quantum technology #Superposition principle #quant-ph
paper · pdf · doi:10.1103/revmodphys.84.1765
published as Rev. Mod. Phys. 84, 1765 (2012) · 26 pages, 17 figures
arxiv created 2012/02/24 · openalex publication_date 2012/12/04 · arxiv updated 2013/08/05 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
This work reports on an extended research endeavor focused on the theoretical and experimental realization of a macroscopic quantum superposition (MQS) made up of photons. This intriguing, fundamental quantum condition is at the core of a famous argument conceived by Schr"odinger in 1935. The main experimental challenge to the actual realization of this object resides generally in unavoidable and uncontrolled interactions with the environment, i.e., ``decoherence,'' leading to the cancellation of any evidence of the quantum features associated with the macroscopic system. The present scheme is based on a nonlinear process, ``quantum-injected optical parametric amplification,''which, by a linearized cloning process maps the quantum coherence of a single-particle state, i.e., a microqubit, onto a macroqubit consisting of a large number M of photons in quantum superposition. Since the adopted scheme was found resilient to decoherence, a MQS demonstration was carried out experimentally at room temperature with M\ensuremath≥104. The result led to an extended study of quantum cloning, quantum amplification, and quantum decoherence. The related theory is outlined and several experiments are reviewed, such as the test of the ``no-signaling theorem'' and the dynamical interaction of the photon MQS with a Bose-Einstein condensate. In addition, the consideration of the microqubit-macroqubit entanglement regime is extended to macroqubit-macroqubit conditions. The MQS interference patterns for large M are revealed in the experiment and bipartite microqubit-macroqubit entanglement was also demonstrated for a limited number of generated particles: M\ensuremath\precsim12. Finally, the perspectives opened by this new method for further studies on quantum foundations and quantum measurement are considered.