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arXiv 1107.4027quant-ph
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实时量子反馈准备和稳定光子数态

Real-time quantum feedback prepares and stabilizes photon number states

Clément Sayrin, Igor Dotsenko, Xingxing Zhou, Bruno Peaudecerf, Théo Rybarczyk, Sébastien Gleyzes, Pierre Rouchon, Mazyar Mirrahimi, Hadis Amini, Michel Brune, … 展开作者

Clément Sayrin, Igor Dotsenko, Xingxing Zhou, Bruno Peaudecerf, Théo Rybarczyk, Sébastien Gleyzes, Pierre Rouchon, Mazyar Mirrahimi, Hadis Amini, Michel Brune, Jean-Michel Raimond, Serge Haroche

摘要:

反馈回路是大多数经典控制程序的核心。控制器将由传感器测量的信号与目标值进行比较。然后,它调整致动器,以稳定朝向其目标的信号。推广这种方案来稳定微系统的量子态依赖于量子反馈,这必须克服一个基本的困难:传感器的测量对系统具有随机反作用。最佳折衷采用提供具有最小扰动的部分信息的弱测量。控制器应该包括在计算致动器的酉操作中的这种扰动的影响,使增量扰动状态更接近目标。虽然这种情况的某些方面已经在实验上证明了量子或经典微系统变量的控制,但将量子系统永久稳定在目标状态周围的连续反馈回路操作尚未实现。我们已经实现了这样一个实时稳定的量子反馈方案。它在超导腔中按需制备微波场的光子数态(Fock态),随后逆转退相干引起的场量子跃迁的影响。传感器是一束穿过腔体的原子,它重复地对光子数进行弱量子非破坏测量。该控制器是在一个实时计算机中实现的命令注射,测量之间,调整小经典领域的腔。微波场是一个量子振荡器,可用作量子存储器或原子之间交换信息的量子总线。通过证明主动控制可以产生该振荡器的非经典态并对抗它们的退相干,该实验是实现复杂量子信息操作的重要一步。

英文摘要:

Feedback loops are at the heart of most classical control procedures. A controller compares the signal measured by a sensor with the target value. It adjusts then an actuator in order to stabilize the signal towards its target. Generalizing this scheme to stabilize a micro-system's quantum state relies on quantum feedback, which must overcome a fundamental difficulty: the measurements by the sensor have a random back-action on the system. An optimal compromise employs weak measurements providing partial information with minimal perturbation. The controller should include the effect of this perturbation in the computation of the actuator's unitary operation bringing the incrementally perturbed state closer to the target. While some aspects of this scenario have been experimentally demonstrated for the control of quantum or classical micro-system variables, continuous feedback loop operations permanently stabilizing quantum systems around a target state have not yet been realized. We have implemented such a real-time stabilizing quantum feedback scheme. It prepares on demand photon number states (Fock states) of a microwave field in a superconducting cavity and subsequently reverses the effects of decoherence-induced field quantum jumps. The sensor is a beam of atoms crossing the cavity which repeatedly performs weak quantum non-demolition measurements of the photon number. The controller is implemented in a real-time computer commanding the injection, between measurements, of adjusted small classical fields in the cavity. The microwave field is a quantum oscillator usable as a quantum memory or as a quantum bus swapping information between atoms. By demonstrating that active control can generate non-classical states of this oscillator and combat their decoherence, this experiment is a significant step towards the implementation of complex quantum information operations.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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