Manipulating Transverse Modes of Photons for Quantum Cryptography

MARCELO LUDA; MIGUEL LARROTONDA; JUAN PABLO PAZ; CHRISTIAN SCHMIEGELOW

PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS

AMER PHYSICAL SOC

Lugar: New York; Año: 2014 vol. 89 p. 4325 - 4335

1050-2947

Several schemes have been proposed to extend Quantum Key Distribution protocols aiming at improving their security or at providing new physical substrates for qubit implementation. We present a toolbox to jointly create, manipulate and measure qubits stored in polarization and orbital angular momentum degrees of freedom of single photons. The toolbox includes local operations on single qubits, controlled operations between the two qubits and projective measurements over a wide variety of non-local bases en the 4D space of states. We describe how to implement the toolbox to perform an extended version of the BB84 protocol for this four dimensional Hilbert space (ideally transmitting two key bits per photon). We present the experimental implementation of the measurement scheme both in the regimes of intense light beams and with single photons. Thus, we show the feasibility of implementing the protocol providing an interesting example of a new method for quantum information processing using the polarization and the orbital angular momentum of light as qubits.