Distribution of Squeezed States through an Atmospheric Channel

Abstract

Continuous variable quantum states of light are used in quantum information protocols and quantum metrology and known to degrade with loss and added noise. We were able to show the distribution of bright polarization squeezed quantum states of light through an urban free-space channel of 1.6 km length. To measure the squeezed states in this extreme environment, we utilize polarization encoding and a postselection protocol that is taking into account classical side information stemming from the distribution of transmission values. The successful distribution of continuous variable squeezed states is accentuated by a quantum state tomography, allowing for determining the purity of the state.

Quantum estimation of the Schwarzschild spacetime parameters of the Earth

“…However, in practical implementations of quantum metrology schemes, losses and noise can't be ignored [26,[39][40][41][42]. Quantum communication between ground users and space links has become recently an active area of research driven by proposals fro global communication networks [8,9,43,44].…”

Quantum measurements of signals from the Alphasat TDP1 laser communication terminal

“…MPL Erlangen implements free space CV quantum communication (see Fig. 1) based on binary phase-shift keying of coherent states and homodyne detection of the optical field quadratures [46][47][48][49][50]. This operating principle is equal to the one of the TESAT/DLR LCTs [51][52][53].…”

Continuous-variable quantum key distribution in uniform fast-fading channels

“…In this case, the transmissivity η of the link between the two parties is not constant and may take values according to some probability distribution [43]. This description usually emerges from the fact that the parties use a free-space link [44] that is susceptible to the atmospheric turbulence [45][46][47][48][49][50][51]. Previous studies (e.g., see Ref.…”