论文标题
杂交量子经典质量无变化或参数门
Hybrid Quantum-Classical Eigensolver Without Variation or Parametric Gates
论文作者
论文摘要
缺乏量子误差校正（解决量子化学问题和物理问题）的近期量子设备需要混合量子量子古典算法和技术。在这里，我们提出了一个获得电子量子系统特征力谱的过程。这是通过将量子系统的哈密顿量投影到由一组计算基础指定的有限有效的希尔伯特空间上来实现的。从这个投影中，获得了有效的哈密顿量。此外，给出了有效哈密顿量的相应的对角线和异对决项的准备短深度量子电路的过程，并使用量子纠缠和ancilla量子。然后使用数值算法在经典计算机上对对角线进行对角线，以获取特征值。对于Beh $ _2 $和LIH分子的地面和激发态，该方法的用例得到了证明，以及与确切解决方案非常吻合的状态密度。此外，使用h $ _2 $分子的IBM量子设备进行了硬件演示。
The use of near-term quantum devices that lack quantum error correction, for addressing quantum chemistry and physics problems, requires hybrid quantum-classical algorithms and techniques. Here we present a process for obtaining the eigenenergy spectrum of electronic quantum systems. This is achieved by projecting the Hamiltonian of a quantum system onto a limited effective Hilbert space specified by a set of computational bases. From this projection an effective Hamiltonian is obtained. Furthermore, a process for preparing short depth quantum circuits to measure the corresponding diagonal and off-diagonal terms of the effective Hamiltonian is given, whereby quantum entanglement and ancilla qubits are used. The effective Hamiltonian is then diagonalized on a classical computer using numerical algorithms to obtain the eigenvalues. The use case of this approach is demonstrated for ground sate and excited states of BeH$_2$ and LiH molecules, and the density of states, which agrees well with exact solutions. Additionally, hardware demonstration is presented using IBM quantum devices for H$_2$ molecule.
