Measurement Method of Logical Gate in Bulk Spin Quantum Computer

提出一种核磁共振量子计算机两量子位逻辑门测量的方案。该方案通过设置适当的标记量子位可显著缩减测量所需输入态数目,给出量子门和具体输入状态集合的实验脉冲序列。包含较少J偶合演化的脉冲序列设计可有效减少操作时间,削弱环境对量子系统的退相干影响。A scheme of measuring two-qubit logical gate is proposed based on nuclear magnetic resonance,which includes the specific input states and complete pulse sequences.In comparison with the approach not using ancillary qubit,this method remarkably reduces the number of the inputs at the cost of flag qubit resource.The pulse sequence with fewer J-coupling evolution can effectively shorten the experiment time and weaken the quantum system decoherence effect by environment.福建省自然科学基金(2008J0219;2009J05152

Subspace quantum process tomography via nuclear magnetic resonance

基于三核自旋量子系统实现了内嵌两量子位子空间量子过程重构.通过输入完备态集合对执行的量子过程进行了表征.由于量子过程内嵌于子空间,使得重构实验所需输入次数及时间显著减少,同时实验尽量避免使用时间较长的J偶合演化,有效控制了系统的退相干。Experimental investigation of subspace quantum process tomography in three-spin system was implemented via nuclear magnetic resonance.A quantum process was characterized by measuring a complete set of input states and corresponding outputs.The method using ancillary qubit remarkably reduces the number of the initial input states.And the pulse sequences used in this paper have fewer J-coupling evolutions.The experiment time was shortened and quantum decoherence of the system was weakened efficiently.福建省自然科学基金(批准号:2008J0219)资助的课题---