10 research outputs found
Squeezed states generation by nonlinear plasmonic waveguides: a novel analysis including loss, phase mismatch and source depletion
Abstract In this article, a full numerical method to study the squeezing procedure through second harmonic generation process is proposed. The method includes complex nonlinear coupling coefficient, phase mismatch, and pump depletion. Attention has been also paid to the effects of accumulated noises in this work. The final form of the numerical formula seems to be much simpler than the analytical solutions previously reported. The function of this numerical method shows that it works accurately for different mechanisms of squeezed state generations and does not suffer from instabilities usually encountered even for non-uniform, coarse steps. The proposed method is used to examine the squeezing procedure in an engineered nonlinear plasmonic waveguide. The results show that using the nonlinear plasmonic waveguide, it is possible to generate the squeezed states for the pump and the second harmonic modes with high efficiency in a propagation length as short as 2 mm which is much shorter than the needed length for the traditional nonlinear lithium niobate- based optical waveguides being of the order of 100 mm. This new method of squeezed states generation may find applications in optical communication with a noise level well below the standard quantum limit, in quantum teleportation, and in super sensitive interferometry
High-Dimensional Single-Photon Quantum Gates: Concepts and Experiments
Transformations on quantum states form a basic building block of every
quantum information system. From photonic polarization to two-level atoms,
complete sets of quantum gates for a variety of qubit systems are well known.
For multi-level quantum systems beyond qubits, the situation is more
challenging. The orbital angular momentum modes of photons comprise one such
high-dimensional system for which generation and measurement techniques are
well-studied. However, arbitrary transformations for such quantum states are
not known. Here we experimentally demonstrate a four-dimensional generalization
of the Pauli X-gate and all of its integer powers on single photons carrying
orbital angular momentum. Together with the well-known Z-gate, this forms the
first complete set of high-dimensional quantum gates implemented
experimentally. The concept of the X-gate is based on independent access to
quantum states with different parities and can thus be easily generalized to
other photonic degrees-of-freedom, as well as to other quantum systems such as
ions and superconducting circuits.Comment: 7 pages, 4 figure