Heralded Bell State of Dissipative Qubits Using Classical Light in a Waveguide
Abstract
Maximally entangled twoqubit states (Bell states) are of central importance in quantum technologies. We show that heralded generation of a maximally entangled state of two intrinsically open qubits can be realized in a onedimensional (1D) system through strong coherent driving and continuous monitoring. In contrast to the natural idea that dissipation leads to decoherence and so destroys quantum effects, continuous measurement and strong interference in our 1D system generate a pure state with perfect quantum correlation between the two open qubits. Though the steady state is a trivial product state that has zero coherence or concurrence, we show that, with carefully tuned parameters, a Bell state can be generated in the system's quantum jump trajectories, heralded by a reflected photon. Surprisingly, this maximally entangled state survives the strong coherent state input—a classical state that overwhelms the system. This simple method to generate maximally entangled states using classical coherent light and photon detection may, since our qubits are in a 1D continuum, find application as a building block of quantum networks.
 Publication:

Physical Review Letters
 Pub Date:
 April 2019
 DOI:
 10.1103/PhysRevLett.122.140502
 arXiv:
 arXiv:1809.00685
 Bibcode:
 2019PhRvL.122n0502Z
 Keywords:

 Quantum Physics;
 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 6+4 pages