An adaptive variational algorithm for exact molecular simulations on a quantum computer
An adaptive variational algorithm for exact molecular simulations on a quantum computer
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DOI：
10.1038/s41467-019-10988-2
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发表时间：
2019-07-08
影响因子：
16.6
通讯作者：
Mayhall, Nicholas J.
中科院分区：
文献类型：
--
作者：
Grimsley, Harper R.;Economou, Sophia E.;Mayhall, Nicholas J.
化学系统的量子模拟是量子计算机近期最有前途的应用之一。变分量子本征解算器是量子硬件上分子模拟的一种领先算法，它有一个严重的局限性，因为它通常依赖于一个预先选择的波函数和近似的波函数和能量。在这里，我们提出了一个任意精确的变分算法，而不是固定一个anonymous前期，它的增长系统一个运营商在一个时间的方式所规定的分子被模拟。这会产生一个具有少量参数的模拟器，从而导致浅深度电路。我们提出了数值模拟，包括一个原型的强相关分子，这表明我们的算法比一个单一的耦合簇的方法，在电路深度和化学精度方面表现得更好。我们的研究结果突出了我们的自适应算法的潜力，与当今和近期的量子硬件精确模拟。
Quantum simulation of chemical systems is one of the most promising near-term applications of quantum computers. The variational quantum eigensolver, a leading algorithm for molecular simulations on quantum hardware, has a serious limitation in that it typically relies on a pre-selected wavefunction ansatz that results in approximate wavefunctions and energies. Here we present an arbitrarily accurate variational algorithm that, instead of fixing an ansatz upfront, grows it systematically one operator at a time in a way dictated by the molecule being simulated. This generates an ansatz with a small number of parameters, leading to shallow-depth circuits. We present numerical simulations, including for a prototypical strongly correlated molecule, which show that our algorithm performs much better than a unitary coupled cluster approach, in terms of both circuit depth and chemical accuracy. Our results highlight the potential of our adaptive algorithm for exact simulations with present-day and near-term quantum hardware.