Quantum Gate Operations on a Spectrally Addressable Photogenerated Molecular Electron Spin-Qubit Pair
Quantum Gate Operations on a Spectrally Addressable Photogenerated Molecular Electron Spin-Qubit Pair
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DOI：
10.1021/jacs.3c01243
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发表时间：
2023-03-13
影响因子：
15
通讯作者：
Wasielewski, Michael R.
中科院分区：
文献类型：
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作者：
Mao, Haochuan;Pazera, Gediminas J.;Wasielewski, Michael R.
从分子供体到受体的亚纳秒光驱动电子转移可用于产生具有处于明确定义的纯初始单重量子态的两个纠缠电子自旋的自由基对（RP），以用作自旋量子位对（SQP）。实现良好的自旋量子位寻址能力是具有挑战性的，因为许多有机自由基离子除了显著的g-各向异性之外还具有大的超精细耦合（HFC），这导致显著的光谱重叠。此外，使用g因子显著偏离自由电子的g因子的自由基导致难以产生具有足够大带宽的微波脉冲以同时或选择性地操纵两个自旋，这对于实现量子算法所必需的受控非（CNOT）量子门是必要的。在这里，我们通过使用共价连接的供体-受体（1）-受体（2）（D-A1-A2）分子来解决这些问题，其中氢氟碳化合物显着减少，该分子使用完全氘化的过氧杂蒽（PXX）作为D，萘单酰亚胺（NMI）作为A1，C60衍生物作为A2。PXX在PXX-d9-NMI-C60内的选择性光激发导致亚纳秒、两步电子转移以产生长寿命的PXX中心点+-d9-NMI-C60中心点- SQP。PXX中心点+-d9-NMI-C60中心点-在双相液晶4-氰基-4 '-（正戊基）联苯（5CB）中在低温下的排列导致每个电子自旋的良好分辨的窄共振。我们演示了单量子位门和两个量子位CNOT门操作使用选择性和非选择性高斯形微波脉冲和宽带光谱检测的自旋状态后的门操作。
Sub-nanosecond photodriven electron transfer from a molecular donor to an acceptor can be used to generate a radical pair (RP) having two entangled electron spins in a well-defined pure initial singlet quantum state to serve as a spin-qubit pair (SQP). Achieving good spin-qubit addressability is challenging because many organic radical ions have large hyperfine couplings (HFCs) in addition to significant g-anisotropy, which results in significant spectral overlap. Moreover, using radicals with g-factors that deviate significantly from that of the free electron results in difficulty generating microwave pulses with sufficiently large bandwidths to manipulate the two spins either simultaneously or selectively as is necessary to implement the controlled-NOT (CNOT) quantum gate essential for quantum algorithms. Here, we address these issues by using a covalently linked donor-acceptor(1)-acceptor(2) (D-A1-A2) molecule with significantly reduced HFCs that uses fully deuterated peri-xanthenoxanthene (PXX) as D, naphthalenemonoimide (NMI) as A1, and a C60 derivative as A2. Selective photoexcitation of PXX within PXX-d9-NMI-C60 results in sub-nanosecond, two-step electron transfer to generate the long-lived PXX center dot+-d9-NMI-C60 center dot- SQP. Alignment of PXX center dot+-d9-NMI-C60 center dot- in the nematic liquid crystal 4-cyano-4 '-(n-pentyl)biphenyl (5CB) at cryogenic temperatures results in well-resolved, narrow resonances for each electron spin. We demonstrate both single-qubit gate and two-qubit CNOT gate operations using both selective and nonselective Gaussian-shaped microwave pulses and broadband spectral detection of the spin states following the gate operations.