Adiabatic elimination of a nearly resonant quantum state
Adiabatic elimination of a nearly resonant quantum state
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近共振量子态的绝热消除
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
N. Vitanov
中科院分区：
文献类型：
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作者：
B. T. Torosov;N. Vitanov
具有多态的量子系统通常通过绝热消去远共振态而简化为更简单的系统。这种方法提供了精确的耦合和斯塔克位移在简化系统非常大的失谐值，远远大于相关的耦合。我们介绍了两种基于绝热近似和超绝热近似的非共振态排除技术，它们为简化系统中的耦合和斯塔克位移提供了更精确的表达式，并且比传统的绝热消除方法在更广泛的相互作用参数范围内有效。原因是绝热近似和超绝热近似的条件只要求，对于光滑的脉冲形状，失谐大于脉冲的傅立叶宽度；因此，即使耦合超过失谐，也可以使用这些近似，即当被排除的状态可以被描述为“接近共振”时。绝热近似和超绝热近似的误差可以很容易地抑制在量子计算基准10−4以下，这是传统绝热消除方法难以实现的目标。
Quantum systems with multiple states are often reduced to simpler systems by adiabatic elimination of far-off-resonant states. This method provides accurate coupling and Stark shifts in the reduced system for very large values of the detunings only, far greater than that of the relevant couplings. We introduce two alternative techniques for exclusion of an off-resonant state based on the adiabatic and superadiabatic approximations, which provide far more accurate expressions for the coupling and the Stark shifts in the reduced system, and which are valid in much broader ranges of interaction parameters than the traditional adiabatic elimination method. The reason is that the conditions for the adiabatic and superadiabatic approximations only demand, for smooth pulse shapes, the detuning to be greater than the Fourier width of the pulse; hence, these approximations can be used even when the couplings exceed the detunings, i.e. when the excluded states can be described as ‘nearly resonant’. The error of the adiabatic and superadiabatic approximations can be easily suppressed below the quantum computing benchmark of 10−4, an objective that is hard to achieve with the traditional adiabatic elimination method.