Quantum Fourier Transform on Photonic Qubits Using Cavity QED

Phys. Rev. A 106, 013709 (2022)https://ireap.umd.edu/10.1103/PhysRevA.106.0137092022Journal ArticleAdvanced Materials and NanotechnologyNonlinear and Quantum Photonics

We propose a quantum Fourier transform on photons in which a single atom-coupled cavity system mediates the photon-photon interactions. Our protocol utilizes time-delay feedback of photons and requires no active feedforward control. The time-delay feedback enables a single atom-cavity system to implement a quantum Fourier transform on an arbitrary number of photonic qubits on-the-fly, while rapid tuning of the atomic transition implements arbitrary controlled-phase gates. We analyze the performance of the protocol numerically and show that it can implement quantum Fourier transforms with tens of photons using state-of-the-art cavity quantum electrodynamics.