An interferometer, mimicking an amplitude damping channel for vortex modes, is presented. Experimentally the action of the channel is in good agreement with that predicted theoretically. Since we can characterize the action of the channel on orbital angular momentum states, we propose using it to investigate the dynamics of entanglement.
Quantum optics plays a crucial role in developing quantum computers on different platforms. In photonics, precise control over light's degrees of freedom, including discrete variables (polarization, photon number, orbital angular momentum) and continuous variables (phase, amplitude quadratures, frequency), is fundamental. Our model manipulates photonic systems to encode and process quantum information via the photon's spatial degree of freedom, employing polarization as an auxiliary qubit. We propose a programmable photonic circuit that simulates quantum channels, including phase-damping, amplitude-damping, and bit-flip channels, through adjustable interferometric parameters. Furthermore, the interferometer extends to complex channels, such as the squeezed generalized amplitude damping. This work contributes to advancing quantum simulation techniques and serves as a foundation for exploring quantum computing applications, while highlighting pathways for their practical implementation.
We describe a simple experiment that is ideally suited to analyze the high-dimensional entanglement contained in the orbital angular momenta (OAM) of entangled photon pairs. For this purpose we use a two-photon interferometer with a built-in image rotator and measure the two-photon visibility versus rotation angle. Mode selection with apertures allows one to tune the dimensionality of the entanglement; mode selection with spiral phase plates and fibers allows detection of a single OAM mode. The experiment is analyzed in two different ways: either via the continuous two-photon amplitude function or via a discrete modal (Schmidt) decomposition of this function. The latter approach proves to be very fruitful, as it provides a complete characterization of the OAM entanglement.
The dynamics of maximum entangled coherent state travels through an amplitude damping channel is investigated. For small values of the transmissivity rate the travelling state is very fragile to this noise channel, where it suffers from the phase flip error with high probability. The entanglement decays smoothly for larger values of the transmissivity rate and speedily for smaller values of this rate. As the number of modes increases, the travelling state over this noise channel loses its entanglement hastily. The odd and even states vanish at the same value of the field intensity.