Probing the quantum coherence of a nanomechanical resonator using a superconducting qubit: I. Echo scheme
Probing the quantum coherence of a nanomechanical resonator using a superconducting qubit: I. Echo scheme
复制标题
DOI：
10.1088/1367-2630/10/9/095004
复制
发表时间：
2008-09-30
影响因子：
3.3
通讯作者：
Blencowe, M. P.
中科院分区：
文献类型：
--
作者：
Armour, A. D.;Blencowe, M. P.
我们提出了一个方案，在该方案中，纳米机械谐振器的量子相干性可以使用超导量子比特探测。我们考虑一个机械谐振器耦合到一个库珀对盒的电容，并假设超导量子比特被调谐到简并点，使其相干时间最大化，机电耦合可以近似为色散哈密顿量。当量子比特以叠加态的方式制备时，这将驱动机械谐振器逐渐进入叠加态，这反过来又导致量子比特的明显退相干。将合适的控制脉冲施加到量子位允许其布居被反转，从而导致谐振器动力学的反转。然而，谐振器与其环境的相互作用意味着动态不完全可逆。我们表明，这种不可逆性在很大程度上是由于退相干的机械谐振器，可以推断出从适当的测量单独的量子位。使用估计所涉及的参数的基础上的具体实现的系统，我们表明，它应该是可能的，以现有的设备技术进行此计划。
We propose a scheme in which the quantum coherence of a nanomechanical resonator can be probed using a superconducting qubit. We consider a mechanical resonator coupled capacitively to a Cooper pair box and assume that the superconducting qubit is tuned to the degeneracy point so that its coherence time is maximized and the electro-mechanical coupling can be approximated by a dispersive Hamiltonian. When the qubit is prepared in a superposition of states, this drives the mechanical resonator progressively into a superposition which in turn leads to apparent decoherence of the qubit. Applying a suitable control pulse to the qubit allows its population to be inverted resulting in a reversal of the resonator dynamics. However, the resonator's interactions with its environment mean that the dynamics is not completely reversible. We show that this irreversibility is largely due to the decoherence of the mechanical resonator and can be inferred from appropriate measurements on the qubit alone. Using estimates for the parameters involved based on a specific realization of the system, we show that it should be possible to carry out this scheme with existing device technology.