Optimal linear optical implementation of a single-qubit damping channel

TL;DR

This paper demonstrates an optimal linear optical implementation of a single-qubit decohering channel, including amplitude-damping and bit-flip cases, with high fidelity using entangled photons and process tomography.

Contribution

It presents the first experimental realization of an optimal single-qubit damping channel using linear optics, maximizing success probability and characterizing it with high fidelity.

Findings

Achieved average process fidelities above 0.97 for both channels.

Implemented the channel with a static optical setup.

Validated the implementation with ancilla-assisted process tomography.

Abstract

We experimentally demonstrate a single-qubit decohering quantum channel using linear optics. We implement the channel, whose special cases include both the amplitude-damping channel and the bit-flip channel, using a single, static optical setup. Following a recent theoretical result [M. Piani et al., Phys. Rev. A, 84, 032304 (2011)], we realize the channel in an optimal way, maximizing the probability of success, i.e., the probability for the photonic qubit to remain in its encoding. Using a two-photon entangled resource, we characterize the channel using ancilla-assisted process tomography and find average process fidelities of 0.9808 \pm 0.0002 and 0.9762 \pm 0.0002 for amplitude-damping and the bit-flip case, respectively.