Development of wave-packet interference control with an attosecond accuracy and is application to quantum computing

波函数的量子相位操纵通过量子计算和键选择化学等“相干控制”开辟了一项新技术。一种有希望的方法是使用相干光来调制具有光学相位的波函数。例如，用飞秒（fs）光脉冲照射双原子分子，其带宽足以覆盖几个振动本征态，相干叠加这些本征态以产生称为核“波包（WP）”的空间局域波函数，沿着键轴来回传播。在这个WP的generalon中，光场的相位作为其量子相位印在WP上。因此，工程的光学相位的精度优于光学周期允许我们工程的相位的WP具有相同的精度。我们已经开发了“阿秒相位调制器”，通过它，我们可以操纵的相对相位的两个fs激光脉冲的精度为7阿秒。利用这对飞秒激光脉冲实现了对单个Hg-Ar分子中两个核WP的高分辨干涉，干涉条纹对比度接近100%，证明了重粒子的纯粹波动性质。这种高-分辨率WP干涉已被用来编码9个典型的三进制码成一个3三量子寄存器组装在一个单一的分子作为WP的节点模式。原则上，它可用于存储包含在光场中的相位信息。此外，通过使用这种WP干涉控制，我们已经开发了一个高精度的相位shiffer上的qubitorqutrit由相干叠加的两个或三个振动本征态在一个单一的分子操作。目前的研究表明，大规模量子计算的可能性，使用许多振动本征态在一个单一的分子。

Quantum phase manipulation of wave functions opens a novel technology through "coherent control" such as quantum computing and bond selective chemistry. One promising approach is to use coherent light to modulate a wave function with its optical phase. For example, irradiating a diatomic molecule with a femtosecond (fs) optical pulse, with bandwidth broad enough to cover several vibrational eigenstates, coherently superpose those eigenstates to yield a spatially localized wave function called a nuclear "wave packet (WP)" traveling back and forth along the bond axis. In the generalon of this WP, the phase of an optical field is imprinted on the WP as its quantum phase. Hence engineering the optical phase with an accuracy better than the optical cycle allows us to engineer the phase of the WP with the same accuracy.We have developed the "attosecond phase modulator", by which we can manipulate the relative phase of two fs laser pulses with an accuracy of 7 attoseconds. This phased pair of fs laser pulses has been used to realize unprecedented high-resolution interference of two nuclear WP's moving in a single Hg-Ar molecule where its fringe contrast is almost 100 %, demonstrating a pure wave nature of heavy particles.This high-resolution WP interference has been utilized to encode 9 typical trinary codes into a 3 tritquantum reglster assembled within a single molecule as nodal patterns of a WP. In principle it can be used for fhe storage of the phase information contained in an optical field. Moreover, by using this WP interference control, we have developed a high-precision phase shiffer operated on a qubitorqutrit composed of coherent superposition of two or three vibrational eigenstates within a single molecule. The present studies indicate a possibility of large-sale quantum computing using many vibrational eigenstates within a single molecule.