New article in PRX Quantum

Our article "Enabling Deterministic Passive Quantum State Transfer with Giant Atoms" has just been published in PRX Quantum!

Quantum state transfer between two qubits coupled to a common electromagnetic field is strongly limited by the intrinsic temporal asymmetry of the single-photon pulse emitted by the first qubit, which cannot be perfectly absorbed by a second one. In conventional quantum networks, this problem is solved by actively modulating the qubit-photon coupling in time. In this work, we show that the same goal can be achieved passively by using giant atoms, whose coupling to a waveguide is distributed over multiple spatially separated points. By engineering the positions and strengths of these coupling points, the emitted photon can be shaped into a time-symmetric pulse that can be perfectly absorbed by a second qubit. We derive analytical conditions for perfect state transfer and show that fidelities above 99% can be achieved with ten or more coupling points, while already reaching 87% with just two. Our results, derived with the teams of Francesco Ciccarello, Stefan Rotter, Peter Rabl, and Alejandro Gonzalez-Tudela, demonstrate how time-dependent control can be encoded directly into the design of the quantum system.

Figure: O. Diekmann