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Related Experiment Video

Updated: May 29, 2026

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators

Published on: May 30, 2014

Real-time quantum feedback prepares and stabilizes photon number states.

Clément Sayrin¹, Igor Dotsenko, Xingxing Zhou

¹Laboratoire Kastler Brossel, ENS, UPMC-Paris 6, CNRS, 24 rue Lhomond, 75005 Paris, France.

|September 3, 2011

Summary

This summary is machine-generated.

This study demonstrates real-time quantum feedback to stabilize microwave fields in a superconducting cavity, preparing photon number states and reversing decoherence. This advances quantum control for complex quantum information operations.

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Area of Science:

Quantum physics
Quantum control
Superconducting circuits

Background:

Classical feedback loops stabilize systems by comparing sensor output to a set-point.
Quantum feedback faces challenges due to measurement back-action on quantum states.
Weak measurements offer a compromise between information gain and system perturbation.

Purpose of the Study:

To implement a real-time stabilizing quantum feedback loop for a microwave field.
To prepare photon number states (Fock states) on demand.
To counteract decoherence effects in a quantum oscillator.

Main Methods:

Utilized a real-time computer-controlled feedback system.
Employed weak quantum non-demolition measurements using an atomic beam sensor.
Implemented an actuator injecting classical fields to adjust the microwave field state.

Main Results:

Successfully prepared photon number states of a microwave field in a superconducting cavity.
Demonstrated the reversal of decoherence-induced quantum jumps.
Showcased active control's ability to generate non-classical states and combat decoherence.

Conclusions:

The experiment represents a significant step towards implementing complex quantum information operations.
Real-time quantum feedback can actively stabilize quantum systems against decoherence.
This work paves the way for advanced quantum memory and quantum bus applications.