Quantum searching amidst uncertainty

具有两个混合器和不确定性量化的量子近似贝叶斯优化算法

Quantum Approximate Bayesian Optimization Algorithms with Two Mixers and Uncertainty Quantification

本文提出QABOA的扩展算法，通过交替使用探索与利用两个混合器，并引入基于基态分布峰度的新量子Matérn核进行不确定性量化，显著提升了量子近似优化算法的搜索效率，在多个测试问题中表现最佳。

Composite particles with minimum uncertainty in spacetime

Composite particles---atoms, molecules, or microspheres---are unique tools for testing joint quantum and general relativistic effects, macroscopic limits of quantum mechanics, and searching for new physics. However, all studies of the free propagation of these particles find that they delocalise into separate internal energy components, destroying their spatial coherence. This renders them unsuitable for experimental applications, as well as theoretical studies where they are used as idealised test masses or clocks. Here we solve this problem by introducing a new class of states with minimal u…

Geometric aspects of analog quantum search evolutions

We use geometric concepts originally proposed by Anandan and Aharonov to show that the Farhi-Gutmann time optimal analog quantum search evolution between two orthogonal quantum states is characterized by unit efficiency dynamical trajectories traced on a projective Hilbert space. In particular, we prove that these optimal dynamical trajectories are the shortest geodesic paths joining the initial and the final states of the quantum evolution. In addition, we verify they describe minimum uncertainty evolutions specified by an uncertainty inequality that is tighter than the ordinary time-energy u…

Uncertainty and symmetry bounds for the quantum total detection probability

We investigate a generic discrete quantum system prepared in state $|ψ_\text{in}\rangle$, under repeated detection attempts aimed to find the particle in state $|d\rangle$, for example a quantum walker on a finite graph searching for a node. For the corresponding classical random walk, the total detection probability $P_\text{det}$ is unity. Due to destructive interference, one may find initial states $|ψ_\text{in}\rangle$ with $P_\text{det}<1$. We first obtain an uncertainty relation which yields insight on this deviation from classical behavior, showing the relation between $P_\text{det}$ an…