Noise-Aware Mixed-State Quantum Computation via Parameterized Quantum Channels

Non-unitary protocols are already at the base of many hybrid quantum computing applications, especially in the noisy intermediate-scale quantum (NISQ) era where quantum errors typically affect the unitary evolution. However, while the framework for Parameterized Quantum Circuits is widely developed, especially for applications where the parameters are optimized towards a set goal, we find there are still interesting opportunities in defining a unified framework also for non-unitary protocols in the form of Parameterized Quantum Channels as a computing resource. We first discuss the general parameterization strategies for controlling quantum channels and their practical realizations. Then we describe a simple example of application in the context of error mitigation, where the control parameters for the quantum channels are optimized in the presence of noise, in order to maximize channel fidelity with respect to a given target channel.