Abstract
We present the experimental realization of a theoretical effect discovered by Olivares and Paris (2009 Phys. Rev. A 80 032329), in which a pair of entangled optical beams undergoing independent losses can see nonlocal correlations restored by the use of a nonlocal resource correlating the losses. Twin optical beams created in an entangled, Einstein–Podolsky–Rosen (EPR) state by an optical parametric oscillator above threshold were subjected to 50% loss from beamsplitters in their paths. The resulting severe degradation of the amplitude-quadrature correlations between the two beams was then suppressed when another, independent EPR state impinged upon the other input ports of the beamsplitters, effectively entangling the losses inflicted to the initial EPR state. The additional EPR beam pair was classically coherent with the primary one but had no quantum correlations with it. This result may find applications as a ‘quantum tap’ for entanglement.
Highlights
Quantum decoherence is a major impediment to experimental advances in quantum optics and quantum information. It arises from the unitary coupling of the physical system of interest to an infinite reservoir, upon which an average must be taken in order to yield tractable predictions
A concrete and general example of a reservoir for boson fields is the infinite reservoir of vacuum modes which are coupled to the system by the Hamiltonian [2]
In the theoretical proposal by Olivares and Paris [1], a nondegenerate optical parametric oscillator (OPO) below threshold generates an optical Einstein-Podolsky-Rosen (EPR) entangled state [5], a pair of “twin” beams emitted by spontaneous parametric downconversion and filtered by the doubly resonant OPO cavity [6, 7]
Summary
Quantum decoherence is a major impediment to experimental advances in quantum optics and quantum information It arises from the unitary coupling of the physical system of interest to an infinite reservoir, upon which an average must be taken in order to yield tractable predictions. Equation (3) clearly suggests that taking the sum of photodetected signals after a beam splitter will restore the photon number statistics of input signal a(0), with the vacuum input playing no role in this case This is a well known quantum optical detection technique. The characteristic time tc ∼ g−1 that leads to significant admixing of a with vacuum supermode V becomes extremely small when the size of the reservoir increases This evolution is still unitary, and still reversible, even though it involves a broadband mode distribution. We will claim the option of accessing both input ports, which still corresponds to realistic and feasible, if not universal, experimental situations
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
