Robotized polarization characterization platform for free-space quantum communication optics

Abstract

We develop a polarization characterization platform for optical devices in free-space quantum communications. We demonstrate an imaging polarimeter, which analyzes both incident polarization states and the angle of incidence, attached to a six-axis collaborative robot arm, enabling polarization characterization at any position and direction with consistent precision. We present a detailed description of each subsystem, including the calibration and polarization-test procedure, and analyze polarization measurement errors caused by imperfect orientations of the robot arm using a Mueller-matrix model of polarimeters at tilt incidence. We perform a proof-of-principle experiment for an angle-dependent polarization test for a commercial silver-coated mirror for which the polarization states of the reflected light can be accurately calculated. Quantitative agreement between the theory and experiment validates our methodology. We demonstrate the polarization test for a 20.3 cm lens designed for a quantum optical transmitter in Canada’s Quantum Encryption and Science Satellite mission.

Towards a realistic model for cavity-enhanced atomic frequency comb quantum memories

“…We have performed our experiments in a 0.1% thulium-doped Y 3 Al 5 O 12 (Tm:YAG) crystal cavity, the same as used in [31]. The optical transition wavelength of Tm 3+ is well suited for free-space quantum communication, making it attractive for ground-to-satellite communication, for example, for Canada's QEYSSat satellite mission [44][45][46][47]. Furthermore, its wavelength is compatible with quantum memories based on rubidium gas, allowing the possibility of designing hybrid platforms [48,49].…”

Polarization bases compensation towards advantages in satellite-based QKD without active feedback

“…Hence, it is important to circumvent such polarization changes in both free-space and fiber-based QKD. Conventional mitigation techniques involve active polarization tracking devices 16,[29][30][31][32][33] . For instance, Lee et al 29 used a robotized polarization correction based on an active control system.…”

“…Conventional mitigation techniques involve active polarization tracking devices 16,[29][30][31][32][33] . For instance, Lee et al 29 used a robotized polarization correction based on an active control system. Again, Toyoshima et al 16 established a 1 km free space QKD link with an active control system-based polarization tracking jitter error of 0.092°.…”