Quantum Feedback for preparing and stabilizing photon number states of a field stored in a cavity

Yves Bérubé-Lauzière

C. Sayrin, I. Dotsenko, Xingxing Zhou +9 more

I. Dotsenko, X. Zhou, Bruno Peaudecerf +6 more

We present a cavity QED experiment on quantum feedback in a microwave superconducting cavity with Rydberg atoms used as quantum sensors and actuators. Our feedback scheme prepares and stabilizes against decoherence photon-number states of light.

I. Dotsenko, Mazyar Mirrahimi, M. Brune +3 more

We propose a quantum feedback scheme for the preparation and protection of photon-number states of light trapped in a high-$Q$ microwave cavity. A quantum nondemolition measurement of the cavity field provides information on the photon-number distribution. The feedback loop is closed by injecting into the cavity a coherent pulse adjusted to increase the probability of the target photon number. The efficiency and reliability of the closed-loop state stabilization is assessed by quantum Monte Carlo simulations. We show that, in realistic experimental conditions, the Fock states are efficiently produced and protected against decoherence.

J. M. Geremia

J. M. Raimond, C. Sayrin, I. Dotsenko +6 more

We implement a permanent quantum feedback procedure. It prepares on-demand and stabilizes photon-number states in a high-quality superconducting microwave cavity. The feedback uses sensitive circular atoms to probe the cavity field in a Quantum Non Demolition way. This information is used by a controller and an actuator to feed small coherent amplitudes into the cavity, leading it deterministically towards the target state with a high fidelity. Quantum jumps of the photon number are detected and their effect is then actively compensated, protecting this fragile quantum resource against decoherence.