December 1, 2022

Enhancement of noise tolerance of photonic entanglement

Enhancement of noise tolerance of photonic entanglement Noise tolerance of photonic entanglement can be significantly enhanced (Credit: Harald Ritsch for IQOQI Vienna)

Quantum measurements are prone to noise, which can enter the system in many ways. For quantum communication, increasing the system’s dimensionality – the number of available encoding levels – can increase its resistance to noise.

Researchers studied the noise performance of high-dimensional entanglement, and found the effects are more nuanced than expected. Rather than using a theoretical quantifier for noise, they studied how realistic sources of noise, such as those from loss or background, affect photonic entanglement. They showed that these parameters can be condensed into a single, routinely measured single-to-noise parameter, which is sufficient for predicting the upper bound of how well the system can operate.

Schematic of experiment to generate and measure high-dimensional entanglement in the pixel basis. BBO = type I beta barium borate; IF = interference filter; SLM = spatial light modulator; SMF = single-mode fiber. The distance from the crystal to the f = 100 mm lens is 100 mm; the distance from the lens to the SLM is ≈300 ≈ 300  mm.
Schematic of experiment to generate and measure high-dimensional entanglement in the pixel basis. BBO = type I beta barium borate; IF = interference filter; SLM = spatial light modulator; SMF = single-mode fiber. The distance from the crystal to the f = 100 mm lens is 100 mm; the distance from the lens to the SLM is ≈300 ≈ 300 mm.

The team found that modest increases to the size of an entangled photonic system can improve its noise tolerance by multiple orders of magnitude. If the size of the entangled state is kept constant, just doubling the operational dimensions of the system would allow entanglement to be measured with detectors that are hundreds of times less efficient or noisier. (AIP Publishing)

The work has been published in AVS Quantum Science.

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