Universal deterministic quantum operations in microwave quantum links: Part II*

We present a scheme for the implementation of deterministic quantum operations in a quantum network [1]. For that, we consider a setup inspired in state-of-the-art experiments based on superconducting circuits connected via microwave quantum links [2,3]. Here we propose to use quantum state transfer and photon scattering processes based on pulse-shaping protocols (see part I) to implement deterministic quantum gates among distant quantum nodes without resorting to entanglement distribution or measurements. In particular, we show that a quantum gate transfer can be realized by concatenating two state transfers, while a controlled-phase gate exploits the phase-imprinted in the scattered photon. In both cases we find a trade-off between the bandwidth of the itinerant microwave photon and decoherence effects. This allows us to find optimal operation points depending on the parameters of the setup. Considering realistic qubit decay times we find gate infidelities of the order of 10^-2. 

[1] G. F. Penas, R. Puebla, T. Ramos, P. Rabl, J.-J. Garcia-Ripoll, arXiv:2110:02092

[2] P. Magnard et al., Phys. Rev. Lett. 125, 260502 (2020)

[3] H.-S. Chang et al., Phys. Rev. Lett. 124, 240502 (2020)