Qubit-efficient variational algorithm for nuclear structure
用于核结构的量子比特高效变分算法
Chandan Sarma, Paul Stevenson
AI总结 本文比较了三种量子比特映射策略,使用变分量子本征求解器(VQE)研究壳模型描述下的核基态结构,并评估了量子资源需求,其中SD映射在噪声模拟和量子硬件上对$^{10}$B基态实现了0.21%的误差。
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在这项工作中,我们比较了三种量子比特映射策略,以使用变分量子本征求解器(VQE)方法研究壳模型描述下的核基态结构。尽管不同映射的起点是多体粒子基或斯莱特行列式(SD)基下的哈密顿矩阵,但每种映射的试探波函数结构和资源计数不同。这三种映射在中等$p$壳核$^{10}$B上进行了测试,并比较了每种映射找到基态所需的量子资源。此外,我们将量子比特高效映射扩展到研究另一个中等$p$壳核$^{12}$C的基态。我们在噪声模拟器(IBM的FakeFez后端)和量子硬件($ibm\_fez$)上运行了多达26个量子比特的电路来表示它们的基态。从硬件获得的$^{10}$B基态的最佳后误差缓解结果来自SD到量子比特映射,百分比误差为0.21%。对于相同状态,cSD和pnSD映射的百分比误差分别为3.37%和8.88%。另一方面,对于cSD映射,$^{12}$C的后误差缓解基态能量与精确结果相差6.82%。我们进一步评估了从硬件获得的VQE波函数相对于cSD映射的壳模型波函数的保真度。这种cSD映射在量子比特效率方面,对于将VQE算法扩展到不同质量区域的复杂核是有用的。
In this work, we compare three qubit-mapping strategies to study the structure of the nuclear ground state within the shell model description employing the Variational Quantum Eigensolver (VQE) approach. Although the initial point for different mappings is a Hamiltonian matrix in many-body particle basis or Slater determinant (SD) basis, the structure of the trial wavefunction and resource counts are different for each mapping. These three mappings are tested for a mid $p$-shell nucleus $^{10}$B and compared the quantum resources required to find the ground state for each mapping. Further, we extend the qubit-efficient mapping to study the ground state of one more mid $p$-shell nucleus $^{12}$C. We run circuits up to 26-qubits representing their ground states on a noisy simulator (IBM's FakeFez backend) and quantum hardware ($ibm\_fez$). The best post-error mitigated results from the hardware for $^{10}$B ground state is obtained following SD to qubit mapping with a percent error of 0.21 \%. The percent errors for the same state following cSD and pnSD mapping are 3.37 and 8.88 \%, respectively. On the other hand, following the cSD mapping, the post-error mitigated ground state energy of $^{12}$C is 6.82 \% away from the exact result. We further evaluate the fidelity of the VQE wavefunctions obtained from hardware with respect to the shell model wavefunctions for the cSD mapping. This cSD mapping can be useful for scaling the VQE algorithm for complex nuclei across different mass regions in terms of qubit efficiency.